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A&P 2 Lecture: Urinary System Part 1 — Transcript

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0:01this lecture is going to cover the
0:03urinary system this is going to be the
0:05first part of a two-part
0:07lecture as we have done with our other
0:10systems we're going to look at the who
0:12the what the where the when the why the
0:13how of this system we start with the
0:17gross anatomy of the urinary system we
0:19talk about who are the major players we
0:22look at the kidneys the ERS the bladder
0:27and the
0:28urethra the function is going to be to
0:30maintain homeostasis and it does this by
0:32managing the volume and composition of
0:35fluid reservoirs primarily the blood the
0:38kidneys are going to be your go-to
0:40organs for monitoring managing
0:44maintaining uh blood volume blood
0:46composition
0:48Etc we can use this picture to guide us
0:51through and talk about all the different
0:53uh macro structures of the urinary
0:55system and we'll use a female in this
0:57picture as an example so a couple things
1:01we want to point out as we identify some
1:03of these organs is going to be well
1:05number one we see the kidney here right
1:08and we could say well how many do we
1:11have and the answer would be two so we
1:14can number them we have one two and the
1:17first thing somebody's going to say is
1:19well what's going on here why is one
1:22kidney higher than the other and that's
1:24a great observation and the answer is
1:27pretty simple if you start adding some
1:30of our other organs in and we think
1:32about what the largest organ the second
1:35well the second largest organ in our
1:37body is and it occupies this space in
1:39the upper right quadrant we say the
1:41liver so anatomically because the liver
1:45occupies this space when the kidneys
1:47develop the right kidney had to be
1:50pushed down a little bit to accommodate
1:53that other organ now dropping down from
1:56the kidney if we follow this down we
1:58have our left and right ERS again we
2:01have them on both side then we have our
2:04storage tank right here this is our
2:07bladder and the bladder is going to
2:09store amounts of urine uh typically
2:13could be 4 to 800 milliliters again
2:15depending on the size of the male or
2:17female and then from there our urethra
2:21that is going to allow us to eliminate
2:24this waste
2:26product remember we said that our kidney
2:29was a major player in regulating all
2:32things blood so when we talk about the
2:35homeostatic functions of the kidney we
2:38can isolate exactly what we are doing to
2:40blood other than filtering so we are
2:43regulating blood ionic composition so
2:45you say which ions are we regulating the
2:48first being sodium the second being
2:51potassium and the third being
2:54chloride aside from those ions we also
2:57regulate blood pH so if we think about a
3:01acid base relationship we should be
3:03thinking positive and negative the
3:06positive ions would govern uh acidity
3:09and the negative ions will cover bases
3:12or basicity so we look at our two major
3:16portions hydrogen ions and bicarbonate
3:20ions and we think back to our previous
3:23lecture with respiratory when we talked
3:25about carrying oxygen and carbon diox
3:29oide and we talked about how bicarbonate
3:32is moved and carried in Venus blood as
3:36part of our carbon dioxide shift and
3:39then the hydrogen shift as well U
3:42bouncing off that weak acid uh to also
3:45contribute to the acidity of blood we're
3:48going to regulate blood volume we do
3:50this by monitoring our water
3:55concentrations okay and we can uh adjust
3:59a quarter and you see this throughout
4:01your daily life if you wake up in the
4:04morning and you uh use the bathroom as
4:06one of the first things you do and you
4:08notice your urine is pretty well
4:10concentrated meaning it is a dark dark
4:12dark yellow so we can say well what
4:15happened overnight our kidneys were
4:17still functioning they were still
4:19filtering blood still producing urine
4:21but because you weren't eating or
4:23drinking or or hydrating your body went
4:26into a water
4:28conservation period period water
4:30conservation State at which point your
4:32urine will become more concentrated to
4:34keep that interstitium to keep those
4:36tissues well hydrated and on the flip
4:38side as you navigate through the day and
4:39you drink more water more fluids your
4:42body becomes well hydrated and we can
4:44release more water our urine becomes
4:45more dilute and takes on a more clearer
4:48pale yellow appearance so again
4:50regulating water concentrations through
4:52blood volume the next thing we're going
4:55to do is regulating blood pressure this
4:57is going to be important we'll look at a
4:59scenario later on remember pretty much
5:02everything from here on out in this
5:03semester when we talk about respiration
5:05when we talk about uh formation of urine
5:09uh we're dealing with pressur driven
5:11systems cardiovascular pressure driven
5:13systems so it makes sense since the
5:16kidneys are dealing with a massive
5:17amount of blood every day that they are
5:20the go-to player for regulating blood
5:23pressure we can now look at the
5:25homeostatic functions of the kidney
5:28number one is going to be maintenance of
5:30blood blood osmolarity it does this by
5:32monitoring maintaining uh fluid balance
5:35electrolyte balance within the body
5:37within the tissues and within the
5:39intertia the second function is going to
5:41be production of hormones two hormones
5:44are produced here the first one we're
5:46going to talk about is arthin or EPO EPO
5:50is a glycoprotein its function is to act
5:53on bone marrow and by acting on bone
5:55marrow it's going to increase the
5:57production of red blood cells so the
5:58question is why why would this happen
6:00when would this happen well as usual we
6:03respond to a stimuli the stimuli that
6:06will increase EPO production from the
6:08kidneys would be bleeding or if you move
6:11to somewhere that is of high altitude
6:13where uh oxygen is scarcer it's going to
6:16trigger the release of
6:18eepl the second hormone we talk about uh
6:22being produced here is calet triol or
6:24calcitrol uh calcitriol is vitamin D3
6:29it's the active form of vitamin D uh we
6:32can talk about where it's made and how
6:34it acts but let's look at uh the first
6:38action of calcat triol calcat trial's
6:41main action is going to uh communicate
6:43with the cells of the intestines and
6:45what it does it's going to promote the
6:46absorption of calcium and phosphate from
6:49food from there it's going to move to
6:52the bones to mobilize calcium and from
6:56bone to blood the Third thing the
6:59kidneys do is excretion of metabolic
7:02waste and foreign substances this can
7:04include drugs or toxins we talk about
7:07metabolic waste the kidneys are
7:09primarily involved in removing uh
7:11nitrogen containing wastes and it does
7:13this to prevent toxic
7:15buildup you say well where does this
7:17metabolic waste come from well the
7:18metabolic waste occurs during breakdown
7:21of nitrogen containing proteins uh this
7:24metabolism also involves a removal of
7:26nitrogen from amino acids and amino
7:28nitrogen is often removed removed as
7:30ammonia so we go back to protein
7:32degradation we go to digestive system
7:35that's breaking down protein breaking
7:38down the amino acids as ammonia storing
7:41it in the liver and then converting it
7:43to
7:44Ura so from there that Ura is going to
7:48be safely removed from our body as waste
7:51and the kidneys are going to be the
7:52major player in that the last thing
7:56blood's going to be doing I'm sorry the
7:58kidneys are going to be doing doing is
8:00regulation of blood glucose levels now
8:03sugar is a smaller compound it does make
8:06its way through those fenestrated
8:09capillaries inside the kidneys inside
8:12Bowman's capsule of the glomerulus and
8:15it will get ricked up by our blood uh
8:20once it's in the filtrate the problem
8:23occurs when we have clinical conditions
8:25like diabetes where way too much sugar
8:28is in the blood the kidneys can't
8:30possibly reabsorb all that glucose and
8:32as a result it gets excreted in our
8:35urine so when we do Ur analysis and we
8:37see high levels of sugar this could
8:40indicate uh a host of issues number one
8:42being uh
8:44diabetes renal
8:47Anatomy we're going to examine exactly
8:49where the kidneys are located what
8:51cavity and how they are protected so the
8:55kidneys are retrop peronal so retro
8:58meaning beh behind peronal meaning
9:01behind the
9:02peritoneum and we're going to see that
9:04half of the kidneys are going to be
9:05partly protected by the lower ribs this
9:08is an important uh bony structure that
9:11can protect the upper half of these
9:13kidneys if you look on the leftand side
9:15over here we have our different layers
9:18we go from superficial to deep and we'll
9:20relook at this again in its own private
9:23slide but we have Arenal fascia which is
9:27a grouping of uh fibrous connective
9:30collagen fibers a fibrous connective
9:31tissue anchoring these kidneys in place
9:34kind of like Spider-Man came by and shot
9:37a web and stuck these to the back of
9:39your body an adapost capsule so we have
9:41one adapost capsule number two followed
9:44by a renal capsule number three which is
9:46going to be continuous and surrounding
9:49the ERS and we have our right kidney
9:52followed by again since we have two our
9:54left kidney we can take a different cut
9:57and look at a parasagittal PL
9:59and we can really see rib 12 here coming
10:03down protecting a portion of that kidney
10:06this is our right kidney our layers
10:09again we can count them as we go to the
10:12renal fascia right here and then we have
10:15our fat or adose layer and then our
10:18renal capsule when we look at the kidney
10:21we'll look at the renal capsule right
10:25there we look at renal Anatomy so the
10:28entire kidney as a whole remember like
10:31we saw with the lungs we have an
10:33indented area right here called the
10:36renal hilum this is going to be an
10:38entrance for tubular structures like the
10:41urer blood vessels the renal artery the
10:44renal vein nerves and
10:48lymphatics we can go back to those
10:50external layers look at that connective
10:52tissue again uh bundles of collagen
10:55fibers dense fibrous connective tissue
10:58that's going to form that renal fascia
11:01that's going to Anchor those kidneys
11:03down with uh the adrenal glands on top
11:07and anchor them to other structures we
11:08have a fat capsule again that is an
11:10adapost Capsule that's going to help
11:12protect as well as anchor and then
11:14lastly a renal capsule that is going to
11:17surround the entire kidney and it's
11:19going to be continuous with
11:22ERS if we look at internal renal Anatomy
11:26it brings us to the divisions we go from
11:29large to small we start with and like
11:33every other capsular structure we looked
11:35at when we looked at the adrenal gland
11:37in um an endocrine when we did the
11:42spleen uh in the um lymphatic system we
11:47deal with an outer layer and an inner
11:49layer we deal with the renal cortex
11:52being the outer layer right here renal
11:55cortex outer layer and our inner renom
11:58medulla so so the medul layer in the
12:00inner
12:02portion we're going to have renal
12:03pyramids this is going to group together
12:06to form the renom medulla it's going to
12:09be our secreting apparatus and this is
12:11where we're going to find our tubules
12:13right this functional unit the nephron
12:16uh of our kidneys we're going to have
12:20extensions of the renal cortex that goes
12:22in between the renal pyramids they're
12:24called renal columns and they're again
12:26they're going to help right here
12:28function anchor that cortex in
12:31place so we can look at this two ways
12:34we're going to focus more on the picture
12:35on the left uh to look at some of this
12:39internal anatomy and we can start on the
12:43outside right here this dark purple that
12:45you see is going to be our renal capsule
12:48we can now bracket this region right
12:50here this is our cortex we look at the
12:53extensions in between those renal
12:55pyramids where that cortex extends
12:57forming our renal cont columns now every
13:02pyramid that you see here 1 2 3
13:074 right these renal pyramids are going
13:10to have a base here and an apex at the
13:15top the Apex is going to extend into our
13:18series of funnels we'll talk about that
13:20in a second so for our renom medulla we
13:24have our renal pyramids our renal
13:27columns and and arvina pill so again
13:31Pilla projection now that we have our
13:35first set of funnel open this whitened
13:38area right here is going to be our renal
13:41Pilla from there we enter into a series
13:45of funnels from small funnel to large
13:49funnel this is where we're going to
13:51direct the path of urine and where it's
13:54going to drain into the ERS into the
13:56bladder so we start at our first funnel
13:58so before we outline our funnels let's
14:01go ahead and erase all the marks that
14:04we've done so far so we get a nice clear
14:07picture and we start right here this is
14:11our first
14:13set of funnels smallest funnel it is
14:17known as the minor kaix now all these
14:21one two three minor kaces are going to
14:25drain into this larger fun funnel so
14:30let's erase
14:32let's outline that larger funnel that
14:36larger funnel is a major Kix from there
14:40it's going to drain into this larger
14:42region so notice we went from small to
14:45larger to largest this is our funnel
14:48system forming our renal pelvis once in
14:51that renal pelvis we're going to take
14:53that urine and we're going to drain it
14:56right down into the ERS and it's going
14:58to to pool inside the urinary
15:02bladder blood and nerve supply to the
15:05kidneys play an important role number
15:08one we look at blood supply when we look
15:10at the size of the kidneys they make up
15:12less than 05% of our total body but
15:15remember we said that they are massive
15:17players in blood volume recognition and
15:21reg regulation so they receive 20 to 25%
15:25of your resting cardiac output that's a
15:27massive amount of blood
15:30our nerve Supply we talk about the
15:33kidneys nerves primarily carrying
15:35sympathetic outflow and we say well why
15:38does sympathetic system so we deal with
15:41fight or flight and it influences on the
15:45renal regulation uh of arterial pressure
15:48and specifically body fluid composition
15:52so we see that sympathetic nerves are
15:54going to mediate changes in the urinary
15:57sodium and water excretion and it does
15:59this by regulating the renal tubular
16:01water and sodium reabsorption throughout
16:04the nefron so ultimately changes in
16:07renal blood flow and the glomerular
16:09filtration rate are regulated by
16:11constriction of all those arteries and
16:14veins those well specifically the
16:16arteries that renal
16:18vasculature as well as changes in the
16:22activity of that Raa that Ren renin
16:24Angiotensin aldosterone system it does
16:27this by regulating the release of renin
16:30from the jux jux glomular cells these
16:33are all points that we're going to
16:35discuss further on um but from a general
16:39perspective realize that we're dealing
16:41with sympathetic outflow and they're
16:43going to be regulating so on that
16:45arterial end they're regulating blood
16:47flow through the
16:49kidneys blood supply through the kidney
16:51and the nefron so if we're going to talk
16:54about how blood moves from uh to the
16:56kidney through the kidney and then back
16:58out
16:59we're going to start right here market
17:02number one our renal artery so blood's
17:05going to come in it's going to pass
17:06through the hilum and it's going to
17:08reach this portion right here market
17:10number two this is going to be our
17:12segmental artery from there we're going
17:14to go in
17:16between we'll mark it three in between
17:18our renal pyramids and our renal column
17:21and we're going to call this our ENT
17:23lowbar artery from there we're going to
17:26go to the base of the pyramid this arter
17:29is going to be called aru and then we're
17:31going to radiate into the cortex calling
17:36it our cortical radiate from there we're
17:38going to Loop all the way up just to
17:41zoom on in to that nefron we're going to
17:45come in so we pick up right here from
17:46the cortical radiat and we're going to
17:48come in so if we label four here for aru
17:54five cortical radiate six we come into
17:58our aphant arterial from there we go
18:02into the Glarus and the glus is going to
18:05um filter out the plasma the blood
18:09filter the blood and then we go to
18:11number seven to our ephant arteria now
18:14this is where it gets a little bit
18:16tricky because we're going to go in
18:19between the tubules now if we have a jux
18:22medul nefron which have longer Loops
18:25it's going to have something called if
18:26you see right here the Vas arcta if we
18:29have cortical nephrons we're going to go
18:32right to peritubular capillaries okay so
18:35if we look on our list here we go ephant
18:37arterial then to peritubular capillaries
18:40so from those peritubular capillaries
18:42we're going to switch over to Venus flow
18:45and we see that we have our peritubular
18:48veins or
18:50venules and we'll find those right up
18:53here now from our peritubular our
18:57peritubular venu we're going to now
18:59reverse back down we're going to have
19:01our cortical radiate vein so if we come
19:04back and we're going to switch it over
19:05to White and we'll pick up right here
19:08our cortical radiate vein remember we're
19:11flowing this way from our cortical
19:13radiate vein we're going to hit our aru
19:16Vein from our arcu we're going to go in
19:18between the pyramids our inter lobar and
19:21from our inter lobar there is no
19:23segmental we go directly out to our
19:26renal vein
19:30now we could talk about the structures
19:32of that nefron that we just got looking
19:34at the blood flowing through it so we
19:36can start right
19:39here at the renal cor pusle so we'll
19:42check it the renal cor pusle is going to
19:44be comprised of two major structures a
19:47glomular
19:49capsule and a glomerulus so that
19:52glomular capsule is similar to our
19:56Cirrus membranes where it has two layers
19:58a outer parietal layer and an inner
20:01visceral layer and it's going to set up
20:04a capsular space and that space is going
20:08to be important for allowing the
20:11filtrate of of what's been filtered from
20:13the blood to move through and into the
20:15tubules now once we take care of this
20:19structure the Reno corle cor pusle
20:22filtrate is going to flow this way and
20:24we're going to hit a couple different
20:27regions we think about squiggly anytime
20:30we have a tube that squiggles we're
20:32going to call it
20:34convoluted okay and we have two squiggly
20:38tubules we have one here and one here
20:42now we just name these tubules based on
20:46where they are in relation to the pole
20:49of this nefron or the renal cor pusle
20:52and we're going to use words kind of
20:53like we used when we were naming bones
20:55and landmarks on our appendages words
20:57like proximal and distal so we go to
21:00this first squiggly tubule and it's
21:03close to the polar close to the renal
21:05cor puzzle so we're going to call it the
21:07proximal convoluted tubule and then
21:11we're going to move down we're going to
21:13travel down and we're going to hit our
21:15nefron Loop or our Loop of Henley and
21:18they're pretty much named just on the
21:20direction of the filtrate we have the
21:23descending Limb and as we hit that Loop
21:26and we go up we have the ascending limb
21:30and then we hit our next squiggly tubule
21:33that's going to take us to further away
21:36from the nephron and it's called our
21:38distal convoluted tubal now again if we
21:41assume that this is a straight line
21:42where it really in real life it really
21:44isn't and I'm going to erase a lot of
21:48this stuff because I want to go back and
21:51point something out with all my markings
21:52you can't see it
21:54anymore so in real life when we get to
21:58the the actual orientation of this Loop
22:02this distal convoluted tubule actually
22:05turns back around this way and if you
22:09see this V from the formed right here
22:12from the aphr and eph uh arterial this
22:16portion of the distal convolute tub on
22:18the ascending limb is going to move back
22:20between this V so if we think of it like
22:24this we're putting the end of this
22:26system back at the beginning beginning
22:29and that's a little weird to think about
22:30to say well why would we put the end of
22:36this structure and if we go back to the
22:37nefron and what the function of the
22:38nefron is we're essentially making urine
22:41right we're absorbing reabsorbing
22:44secreting we're concentrating diluting
22:47we're making uh urine or waste product
22:51and urine to be released out of the body
22:53so why at the end are we putting this
22:56back to the beginning and this
22:58essentially a checks and balance system
23:01we're checking the end result so we know
23:03what to do at the beginning now we're
23:06going to elaborate on this a little
23:07later but keep that in the back of your
23:09mind now we can examine each separate
23:12structure of its own and talk about
23:16specifically what they're responsible
23:17for doing so we're going to focus in on
23:19the renal core pusle and as we said
23:22before the renal core puzle is going to
23:24be made up of two major parts the first
23:27is the glus now I want you to think back
23:29to AP1 when we looked at our uh
23:33epithelium and we talked about simple
23:34squamous epithelium and if you were in
23:37my lab we talked about a ball in a ball
23:39and we looked for this big ball that was
23:41surrounded by this thin little ball well
23:44that's what we're talking about here
23:45we're talking about those two balls that
23:47is the Reno cor pusle the outer ball is
23:52Bowman's capsule right it is this
23:55visceral layer of poyes which is going
23:57to wrap wrap around the capillaries
24:00basically what it's doing is it's
24:02forming a filtration barrier now the
24:05filtrate is going to be collected in
24:07that space between the visceral and the
24:09parietal layers now if we go inside to
24:12that inner ball this is the gulus it's
24:15going to be a massive capillaries and
24:17again if you go back to the capillary
24:18lecture that we talked about we talked
24:20about these fenestrated capillaries and
24:23the example we used was inside the
24:25kidneys inside the renal core pusle
24:28so the glus is going to be a mass of
24:30fenestrated capillaries it's going to be
24:32fed by that aphron arterial that we just
24:35outlined it's going to serve its
24:37function as to filter the blood and it's
24:40going to drain into the ephant
24:43arteria we can zoom on in and really
24:46take a look of this renal take a look at
24:48this renal core pule and we can see a
24:51couple things if we go up to blood
24:54supply and we look at blood coming in
24:57couple things things to notice look how
25:00thick and wide and fat that aphr
25:04arterial is vers the eant or ephant
25:08arterial how thin it is and this is
25:11going to be important as far as
25:13regulating the diameter of that arterial
25:17and controlling the blood pressure and
25:20the amount of blood coming
25:22in we can go to the outside look there's
25:25our simple squamous epithelium that
25:27parietal leg layer of Bowman's gland of
25:31Bowman's capsule sorry not gland capsule
25:33we have the capsular space right here
25:37and then we can see this yellow these
25:40poyes you can see that little nucleus
25:42that cell with all their foot like
25:44projections that visceral layer that
25:47modified visceral layer that are forming
25:50these slitlike
25:52projections
25:54surrounding that that fenestrated
25:56capillary and again we're going to call
25:58them from those poyes to our pedest
26:01cells if we look at the picture in the
26:04lower right hand corner here's our ball
26:06and a ball we have our outer
26:10ball and our inner ball right so our
26:13simple s is epithelium with our
26:15fenestrated capillary in the center now
26:19one more thing I want to point out in
26:21this picture is this tube like structure
26:26right here this is going to be the
26:28ascending limb of the nefron loop could
26:31also be the distal convoluted tubio okay
26:34and notice that it comes back around and
26:38moves between that vlike structure of
26:41the aphron and ephrine arteria now this
26:43is important so we already alluded to
26:45this we said that we're putting the end
26:48back at the beginning okay so let's look
26:51at its Anatomy we have some modified
26:53simple columnar cells these elongated
26:57cells called the immacula densa and then
27:00we're going to get even
27:02further modification of cells called
27:05mezen cells so again just introducing
27:08the terminology and we're going to look
27:10in a little bit exactly what these
27:12structures and cells do with regards to
27:16Contracting with regards to secreting
27:19things
27:21Etc now we can look at the ROC cor pusle
27:25again and look at the glomular
27:26endothelial cells and and see that they
27:28have those large fenestrations those
27:31pores those pores when you go back to
27:34our capillary lecture were leaky it was
27:36allowing for well size restricted stuff
27:40to move in or block and essentially
27:44filter between there is this basil
27:47lamina that's going to lie between that
27:49endothelium and the poyes and again it's
27:52going to help us filter some more and
27:54we'll look exactly what these layers are
27:56filtering from there we have our poyes
27:59their footlik pedicel projections
28:02between which are going to be our
28:03filtration
28:05slits now we can look at it in depth at
28:08a picture look at these pores so we see
28:11that fenestrated capillary right here we
28:13see all these pores this is of that
28:16endothelial cell line its job is going
28:19to be prevent filtration of blood cells
28:21so red blood cells white blood cells but
28:24it's going to let pretty much all the
28:26components of blood plasma to pass
28:28through but luckily we have this blue
28:32basement membrane here that basement
28:34membrane is going to help prevent
28:36filtration of larger proteins like
28:39albumins uh AR globulins are not going
28:43to make it through are going to be
28:44blocked right here and maintained within
28:48the blood and then we go out even
28:51further and we have our SLP membrane
28:55right here between our pedicels so
28:57here's one pedicel another pedicel again
29:00those foot-like projections off of our
29:03poite that's right here okay now those
29:07pedels are going to further prevent
29:09filtration of mediumsized proteins so
29:12again we're blocking the larger proteins
29:14and even the mediumsized proteins again
29:17trying to keep the pressure within the
29:21blood with all those large
29:26components two kinds of
29:28nephrons we mentioned before when we
29:30looked at our blood supply that we have
29:32two different types of nephrons so we're
29:34going to discuss them and then we're
29:35going to show you a picture to kind of
29:37explain exactly what they look like so
29:40the most numerous of our nephrons are
29:41called cortical nephrons about 80 to 85%
29:44of the nephrons in each kidney are
29:47cortical we can look at the total number
29:49of nephrons and we can say that the
29:51average uh person has anywhere from 1 to
29:541.5 million uh nephrons per kidney
29:58so again the majority of these are going
30:00to be cortical and if we look at the
30:01name cortical it kind of tells us where
30:04we find it so cortical sounds like
30:07cortex so we're going to see that the
30:09majority of this nefron is going to lie
30:11in the cortex the outer portion of the
30:14kidney which means that its Loops of
30:17Henley are going to be really really
30:18short and they're only going to extend
30:20into the outer region of the medulla now
30:23the job of these cortical nephrons is
30:26going to be to create urine that's going
30:27to have an osmolarity similar to that of
30:31blood now we look at next slide and we
30:33say well what can we see in this picture
30:37now we look at the nefron we got a lot
30:40of blood vessels intertwining here and
30:42this is going to be important now we see
30:45our arcu artery right down here we have
30:48our cortical radiate going up and now we
30:51go into the actual nefron and we see
30:54that the majority of the nefron if we
30:56look right here the major majority of
30:58that nefron is going to lie in the
31:00cortex and only a small percentage is
31:03going to lie in the upper margins of the
31:05medulla now pay note to these
31:07capillaries look at them they're
31:09sweeping they're swirling they're
31:11twirling
31:13around the tubule okay remember that the
31:17jobs of these nephrons is to make uh
31:20urine that has a similar osmolarity to
31:22that of blood so what's going on here
31:26okay well we're going to look at the
31:28secretion and reabsorption routes and
31:29we're going to see that these
31:32peritubular capillaries remember we're
31:34not vasera that's only in the juxa
31:37nefron here we're in the cortical nefron
31:40we have these peritubular capillaries
31:42that are going to per meaning around
31:45surround the tubal and lead into our uh
31:49venal capillaries so if we look at flow
31:52of fluid through a cortical nefron we go
31:55to our one Bowman's C capsule or
31:58glomular capsule to the proximal
32:01convoluted tubal we come down the
32:03descending limb back up the ascending
32:07limb and then we hit the distal
32:11convoluted tubal okay now let's look I
32:15want you to pay note again that when we
32:17come up that distal convoluted tubule
32:20that ascending limb is moving between
32:24the aphr and ephr arterial again I keep
32:27trying to drill this in because we're
32:29going to look back at that and I want
32:30you to draw back on this as we uh look
32:34at the function of that structure now we
32:37lead we come into these collecting ducks
32:42and from the collecting Ducks we're
32:44going to enter into the renal pill if
32:46you go back to the renal pyramid that
32:48white portion at the bottom and we're
32:50going to slowly drip urine into the
32:54first of our smallest funnels the minor
32:57kic
32:59the second nefron we find is a juxa
33:01medul nefron now let's look at its name
33:04kind of like we did with the cortical
33:05nefron juxa means next to medul means
33:09medulla so this name tells us where we
33:11find these nephrons the majority of
33:14these nephrons are going to be located
33:16in the medulla of the kidney which means
33:19that they're going to have these really
33:21really long long nefron Loops okay so
33:25the renal cor pusle deep in the is going
33:27to be deep in the cortex with these long
33:29long long nefron Loops we're going to
33:32receive blood from peritubular
33:34capillaries and a vasor recta now in the
33:37next picture we're going to see what
33:38that vasor recta looks like because it
33:40looks completely different from those
33:42peritubular capillaries surrounding
33:44those descending and ascending limb in
33:47the lupah Henley that we saw in our
33:49cortical nephrons our ascending limb is
33:52going to have thick and thin regions and
33:55we're going to enable the kidney to
33:56secrete very concentrated urine so the
33:59function of these juxa medul nephrons is
34:02really to create concentrated urine and
34:05F tune that urine output so let's take a
34:08look at what this structure looks like
34:10and right away we see a small part in
34:13the CeX and the majority of this nefron
34:17is going to be located in the medulla
34:19now pay note to these vasera long
34:25sweeping
34:26capillaries okay okay this is going to
34:29help set up something called a
34:31countercurrent exchange me exchange
34:34mechanism so we'll talk about that a
34:36little later on in this lecture and also
34:38in our next next part part two of this
34:41lecture and what that does to form a
34:44concentrated or dilute urine now again
34:48we look at the flow of fluid through a
34:49jux medul nefron pretty much the same as
34:52our cortical uh we have one Bowman's
34:55capsule two proximal convolu to
34:58three descending limb four ascending
35:01limb five we hit that thick ascending uh
35:05limb of the nefron loop and then six we
35:08go to the distal convoluted tubio so
35:11then the question is why are we changing
35:13let's let's
35:16erase some of these structures here and
35:20see what is going on so I want to point
35:23out before we get into too much detail
35:25because we will look at this a little
35:26bit later uh what's going on here so if
35:29you see closely let's zoom on into this
35:31structure if you see that right here
35:34we're going from thick to thin and we
35:38say well what's happening here why are
35:40we switching over and we can think about
35:42this in a common sense fashion right
35:46let's think of it let's think of it
35:48logically when the tube is thinner what
35:51will be happening well in a thinner tube
35:54you would think that we're allowing
35:55things to move in and out pretty readily
35:58well what's going on with this thicker
36:01tube well if we make a thicker tube
36:04we're trying
36:06to block stuff for moving out well in
36:09this ascending portion we are trying to
36:11block something we're going to
36:14specifically block water so the reason
36:17why we block water here is we're trying
36:19to um maintain the dilution of the urine
36:25and again when we look at UR formation
36:28we'll talk about the uh glycoprotein
36:31that is lining that tube that is
36:33preventing water from moving out and how
36:36important that is for maintaining a
36:38countercurrent exchange
36:40mechanism that brings us to one of the
36:42last anatomical structures we're talking
36:44about and that is the juxa glomular
36:48apparatus so let's look at our words
36:50again juxa glomular next to the glus so
36:56let's think back to what we just said
36:58what structure is coming back up in
37:02between the aphron Ephron arterial to
37:04form a complex called the jua glomerular
37:09apparatus or complex well it was that
37:13ascending Loop that ascending limb that
37:16distal convoluted tual it's going to
37:19contact the aphron arterial at a
37:22structure where we saw those modified
37:24elongated colomar epithelial cells
37:27called the the macula
37:29Dena the walls of that arterial is going
37:31to contain smooth muscle cells these are
37:33called juxtaglomerular cells those jual
37:36glomular cells are going to be able to
37:39regulate blood pressure in the kidney
37:41and it's going to work in conjunction
37:43with the autonomic nervous system so we
37:45say why why do we need to regulate blood
37:48pressure well there will be certain
37:50scenarios where say blood pressure is
37:53low remember these are pressure-driven
37:55systems so if blood pressure is low so
37:58we can draw blood pressure if blood
38:00pressure is low that means that the
38:04amount of filtrate that's going to be
38:07created
38:09so filtrate created is going to be also
38:14lower so in order to
38:17increase the amount of filtrate the
38:19amount of blood that we're filtering in
38:21the filtrate being produced we need to
38:25increase this pressure how we going to
38:28do that well there's a series of ways
38:29that we can but number one we're going
38:32to allow for this apparatus these cells
38:35to contract down those mezal cells are
38:37going to contract down and make the
38:41Lumen of those vessels much smaller
38:45while at the same time artificially
38:46increasing blood pressure and increasing
38:49filtrate
38:51production renal physiology looking and
38:55examining your information now we're
38:57going to start quite simply with this
39:00and just look at some basic routes and
39:02processes and then we're going to get
39:05deep into the actual reabsorption and
39:08secretion routes what's being reabsorbed
39:11what's being secreted where it's being
39:14secreted and reabsorbed and how so we
39:17look at a couple things here and this
39:19picture does a pretty good job to show
39:20us the excretion of a solute so how do
39:23we get that we're going to get glomular
39:26filtration plus secretion minus
39:31reabsorption so look at each of these
39:33processes below we start with number one
39:36glomular filtration blood is moving into
39:40and through that fenestrated capillary
39:42through the glus out the ephran arterial
39:45What's Happening Here inside that Glarus
39:48blood plasma and dissolved substances
39:51anything smaller than most proteins
39:54sugar some electrolytes things like that
39:56are going to get fil filtered into the
39:57glomular
39:59capsule and it's going to move this way
40:02once it moves in that capsule it's going
40:04to start moving through the renot tubule
40:07now what happens we get two processes we
40:11get this right here it's number two in
40:14our process which is tubular
40:17reabsorption and basically What's
40:19Happening Here is all along the renal
40:21tubule and the collecting duct water
40:23ions and other substances are going to
40:26get reabsorbed from that renot tubule
40:29the Lumin of that renot tubule and put
40:31back into the peritubular capillaries
40:34and ultimately back into blood now
40:36that's important we have to take that
40:39water now this part right here at that
40:43first portion at our proximal convoluted
40:47tubal we're going to be taking a large
40:49percentage back of that water that was
40:51filtered out from step one so a lot of
40:55plasma a lot of water was filtered out
40:57and then we're going to reabsorb it back
40:59we're going to follow a couple processes
41:01here uh this is going to be called
41:04obligatory water reabsorption so if you
41:07think about the terminology obligatory
41:10right we're going to write this down
41:11we're going to look at this again a
41:12little later
41:13obligatory water reabsorption so here
41:17obligatory means we have to we are
41:20obligated to reabsorb water and this is
41:24to make sure that we keep blood volume
41:25pretty consistent and there for blood
41:27pressure pretty consistent the third
41:31process we see is right here so notice
41:33step two we are going into the blood
41:36capillary step three we are secreting
41:41from the capillary and putting it back
41:44into the Reno tubal so we say what
41:48what's being pushed out of this blood
41:50vessel and sucked back into the renot
41:53tubal
41:54well excuse me along the renot tubul in
41:57that collecting duct we're going to see
41:59waste products drugs and any excess ions
42:03that get secreted from the peritubal
42:04capillaries going to be put back in
42:07secreted back into the renot tubule
42:10ultimately these substances are going to
42:12make their way into our urine and we're
42:13going to excrete
42:15them glomular
42:17filtration we're going to continue by
42:20looking at all the forces that affect
42:22the amount of filtrate and what's being
42:24filtered through that Glarus right off
42:27the bat look at the first bullet we are
42:30driven by blood pressure remember we've
42:34been talking about this and I've been
42:35hinting to this again and again these
42:37are pressur driven systems if our blood
42:40pressure is too low or if our blood
42:42pressure is too high this can directly
42:45affect glomular filtration rate or
42:49GFR okay so some of the forces that are
42:51working with and against glamar
42:53filtration is we're going to see that
42:55that blood pressure is going to be
42:57opposed by a couple things number one
43:01capsular hydrostatic pressure so the
43:05water pressure from the capsule is going
43:08to exert a pressure back onto the Glarus
43:12and then we have this Blood colloidal
43:14osmotic pressure again remember blood
43:17colloid is those large components of
43:20blood that is exerting an esotic
43:23pressure as well on that
43:25glomerulus remember that that we are
43:27going to allow for water and small
43:29molecules to move out of the Glarus and
43:31we say how much cuz we alluded before
43:34that blood or the kidneys were a major
43:37player in focusing on blood volume on
43:41working through blood issues and blood
43:45composition and we said that it it
43:48filters about 20 to 25% of our resting
43:50cardiac or receives 20 to 25% of our
43:53resting cardiac output at any given time
43:56so if we look in one day look at the
43:59amount of water that's passing out and
44:01into the glomular capsule we're dealing
44:03with 150 to 180 lers this is a massive
44:09amount of filtrate being created in the
44:11day through your kidneys so your kidneys
44:13really are workhorses they are pumping
44:16through massive amounts of blood
44:18creating 150 to 180 liters of water
44:22that's moving through this system in uh
44:25in any given day
44:29we can look at glomular filtration a
44:31little more and look at the amount of
44:33filtrate that's formed by both kidneys
44:36each minute we're going to call this
44:39glomular filtration rate so homeostasis
44:42is going to require the kidneys to
44:43maintain a relatively constant
44:46GFR here's the problem if GFR glomular
44:50filtration rate is too high substances
44:53pass too quickly and not and are not
44:56able to be reach reabsorbed here's the
44:59analogy I go back to an episode of I
45:02Love Lucy uh that I saw when I was a
45:04child Lucy worked in a chocolate factory
45:07her job was pretty simple it was to take
45:10the chocolates coming past her around
45:13the conveyor belt put them and package
45:15them in a box close the box and continue
45:17with her job the problem that happened
45:19in this episode was that conveyor belt
45:21got faster and faster and faster as the
45:24conveyor belt got a little faster Lucy
45:26had a hard time putting those chocolates
45:27back into the box she started only
45:30putting instead of the eight that she
45:33was getting in there originally she went
45:34down to five she took the extras by
45:37putting them in her mouth then the
45:39conveyor Bel got even faster and she was
45:41able to get almost no chocolates into
45:45that box so she started throwing them
45:47over her shoulder shoving them down her
45:49shirt and putting whatever she could in
45:50her mouth so this is a good
45:52representation of what happens when
45:53blood pressure gets too high those
45:56substances passed too quickly and just
45:58like I Love Lucy or just like Lucy was
46:00not able to uh keep up with that high
46:03speed and put the chocolates in the Box
46:05your kidneys cannot keep up with that
46:06high speed and
46:09reabsorb components that they need to
46:13adequately now if it's too slow now
46:16imagine if that conveyor belt was too
46:17slow Lucy would be sitting there tapping
46:20her foot waiting for more chocolate and
46:22she would be filling those boxes
46:26perfectly she may even have enough time
46:28to put a bow and wrap it up nice and
46:30neat so this is the same thing in our
46:32kidneys if things move too slowly we're
46:35going to see that nearly all of the
46:38components of that filtrate gets
46:39reabsorbed and that's bad because that
46:42means that some of our waste products
46:44are not being excreted and as a result
46:47as a result we're keeping that back all
46:49those waste products uh reabsorbing it
46:52back into our blood back into our body
46:54so not a good scenario so this is kind
46:56of like that scenario where um moving
47:00away from Lucy and into kind of uh the
47:03Three Bears where the porridge was not
47:06too hot not too cold but just right
47:09that's where our GFR needs to be it
47:11needs to be right in the middle at a
47:12perfect consistent constant pressure to
47:15maintain a relatively constant
47:21GFR we can put GFR to number and to a
47:25calculation
47:27so kind of like what we saw in the
47:30capillaries where we talked about net
47:32filtration pressure we're going to do
47:34the same thing here so we deal with NFP
47:37so right here net filtration pressure
47:39and we're going to take all our
47:41components of the system so we're going
47:44to deal with blood coming in we're going
47:47to call this glomular Blood hydrostatic
47:50pressure so number one glomular blood
47:53hydrostatic pressure we're going to put
47:55that at 55 mm of Mercury now this is
47:59what's coming in we're going to have to
48:01subtract all of our external forces see
48:04these purple and blue arrows that are
48:08moving down and exerting a force onto
48:12that Glarus so the first is that
48:15capsular hydrostatic pressure and that
48:17capsular hydrostatic pressure is going
48:19to be the pressure of essentially what
48:23the filtrate the filtrate inside this
48:26space so all the filate inside this
48:28space the capsule is going to push down
48:30on that filtrate which is going to put a
48:32pressure onto that glus we're going to
48:34put a number to that it's measured at
48:36about 15 mm of
48:37mercury now we deal with blood colloidal
48:41osmotic pressure again we're talking
48:44about the larger components of this
48:48filtrate is going to exert a pressure
48:51back onto the uh Glarus and that's going
48:55to give us a pressure of about 30 mm of
48:58mercury so now let's Zoom back down and
49:00we'll talk about our math so we take our
49:03blood coming in the pressure of the
49:05blood coming in we subtract it from our
49:08CHP capsular hydrostatic pressure is 15
49:11we subtract that from our blood
49:12colloidal osmotic pressure which is 30
49:15it's going to get us a net filtration
49:18pressure of + 10 millim of mercury so
49:23that's good remember we're moving stuff
49:25from a a high pressure to a low pressure
49:28so that means net filtration is going to
49:32be promoted in an outward flow so we'll
49:34keep that green arrow we'll make it a
49:36little bit bigger so
49:38NFP is outward good now when can this
49:43become a skewed let's look at blood
49:46pressure say we're bleeding internally
49:48or we're bleeding externally and we have
49:50some massive blood loss if this number
49:54here drops down to say
49:58uh let's
49:59pick 45 millimeters of mercury now we're
50:03even Steven and we have zero millimeters
50:07of mercury on the NFP side net
50:10filtration side so what happens we have
50:13none of this no net filtration which
50:16means that urine
50:18output goes down and this can be
50:21measured by the amount of urine that's
50:23being created okay so one quick snar we
50:26will look at other scenarios in a little
50:28bit but I just want to show you what
50:30happens when these numbers go arve well
50:33let's look at one other one let's bring
50:34this way high up let's say our blood
50:37pressure is too high and we go to 75
50:40millimeters of mercury now we subtract
50:4245 now we are plus 30 so we'll draw our
50:4730 right here now look that means that
50:50our net filtration pressure is plus 30
50:53we're going to well let's erase this
50:57right
51:01here and we'll redraw it with our big
51:07monstrous blue
51:10arrow so that means that our net
51:13filtration pressure is really high
51:15here's our I Love Lucy scenario this
51:17stuff is going to be flying by these
51:20cells not allowing all these
51:25microvilli on these cells to do their
51:28function which is
51:31reabsorb let's take a look at some GFR
51:34some glomular filtration rates so for
51:38averages in males the average GFR is
51:42about 125 Ms per minute for again the
51:46average male for females our GFR is
51:49about 105 Ms per minute then we say well
51:53what really controls this because again
51:55we go back to pressure too high pressure
51:57too low what can control the amount of
52:01filtrate coming through those tubules at
52:04any given time we can lower this GFR or
52:07increase this GFR so it's going to be
52:10controlled by three things one renal
52:13Auto regulation so the kidney has the
52:15ability to Auto regulate itself so can
52:19control the blood pressure either
52:22increasing it or decreasing it to
52:24artificially increase or decrease
52:27GFR secondly we have neural regulation
52:30so the central nervous system the
52:33autonomic nervous system plays a role
52:35here in controlling the GFR as well as
52:40hormonal regulation we talk about cutic
52:43colomines we talk about adrenaline
52:45norepinephrine epinephrine and other
52:48hormones that are going to increase
52:50heart rate increase blood pressure and
52:53ultimately increasing or decreasing
52:56glomular filtration
52:58rate continuing with renal Auto
53:01regulation we're going to look at a
53:02couple mechanisms that's going to help
53:05allow the kidneys to self-regulate the
53:08first is a myogenic mechanism now we
53:10look at this word here we always look at
53:13prefixes and suffixes Mayo muscle so
53:17we're dealing with smooth muscle cells
53:19that are located within the aine
53:20arterial now if you go back to a couple
53:23slides where I outline the thickness and
53:26aphron arterial so we had that I'll see
53:30if I could draw it real quick for you we
53:32had the aphron arterial coming in and it
53:34was thick walled right whereas the
53:38ephrine arterial coming out was much
53:41thinner okay so the that thick wall was
53:46lined with smooth muscle so that smooth
53:50muscle is going to be so let's draw an
53:52arrow coming in and then we hit the glus
53:54here and then we come out so that's
53:58those smooth muscle cells in the aotter
54:00are going to contract in response to
54:02elevated blood pressure so exactly how
54:05do they do that so increased blood
54:08pressure increases the tension in the
54:10vascular wall and as a result these this
54:14thickened right here that thickened
54:15smooth muscle that vascular smooth
54:17muscle is going to contract now on the
54:20flip side when when a decreasing in
54:23blood pressure is detected so decreased
54:26blood pressure decreases the tension and
54:29the smooth muscle relaxes so overall to
54:33make this a little simple when blood
54:35pressure uh increases the size of this
54:39Lumen decreases as we
54:42contract on this wall when blood
54:45pressure is lower so when a decrease in
54:48blood pressure is detected the Lumen
54:52gets bigger and the wall relaxes moving
54:57outward now let's go ahead and delete
55:01this drawing because we're going to talk
55:04about the second pathway for Arenal Auto
55:07regulation I don't want that drawing to
55:10convolute anything so we talk about
55:13tubuloglomerular feedback so the
55:16feedback between the tubes and the
55:19Glarus now what's happening we already
55:22said that high glome filtration rate is
55:25going to diminish
55:27reabsorption of some of those solutes
55:29and that could be bad the macula densa
55:32is going to use the composition of the
55:34tubular fluid as an indicator of GFR so
55:37what is it so what it does is actually
55:39sense either a large sodium chloride
55:42concentration or a low sodium chloride
55:44concentration if GFR is high it's
55:48detecting a high sodium chloride
55:51concentration which is going to
55:53indicate a high GFR so too high sodium
55:58concentration detected by the maculate
55:59densa as a result it's telling itself
56:03that it's detecting too high a GFR we're
56:06losing too much into the filtrate it's
56:09going to inhibit the release of nitric
56:11oxide if we remember Nitric oxide's a
56:14major
56:15vasodilator so by doing this by
56:18inhibiting nitric oxide we are
56:20essentially allowing for the aphron
56:22arterial to constrict lowering the
56:25amount of blood and uh blood pressure
56:29entering the Glarus ultimately lowering
56:33GFR bringing it back into a normal
56:38range that brings us to a complete cycle
56:41of renal
56:42autoregulation we can look at this
56:45negative feedback loop to see exactly
56:47what's happening we have a stimulus
56:50number one that is disrupting
56:52homeostasis by increasing our glomerular
56:55filtration ation rate as a result the
56:58macula so now we're
57:00here the macula Dena these are the cells
57:03of the JX glomerular appar apparatus are
57:06detecting those high sodium chloride
57:09concentrations so we see right here
57:10sodium chloride high concent of chloride
57:13and water and that JGA is going to be
57:16the control center it's going
57:18to
57:20affect the diameter of the aphron
57:22arterial by constricting it which is
57:25going to decrease blood flow through the
57:27through the glus which is going to
57:29decrease GFR and we're going to maintain
57:32this process until GFR is back into
57:36normal range when it hits at normal 125
57:39Ms per minute for males 105 Ms per
57:42minute for females it will negate shut
57:46down this feedback
57:48loop neural
57:50regulation so first and foremost the
57:52kidneys are going to be supplied richly
57:54by sympathetic fibers so we discussed
57:57about the autonomic nervous system and
57:59how the sympathetic portion is directly
58:03communicating with the kidneys when we
58:05talk about release we talk about
58:07norepinephrine causing Vasa constriction
58:09within the kidneys and it's especially
58:12going to affect that aphron arterial if
58:15we go back to that smooth muscles the
58:17thickness in that aphron arterial that
58:19we that we covered in our past few
58:20slides uh this is where that neuro
58:22regulation is really going to take hold
58:25we can look at some sit situations such
58:27as uh exercise or hemorrhaging this will
58:29be strong stimulation and what
58:32predominates is going to be constriction
58:34of that aphron arteria overall urine
58:37output's going to be reduced and more
58:39blood is going to be available for other
58:41organs again if you think about fight or
58:43flight uh we're sending diverting blood
58:46nutrients to our muscles uh to other
58:48parts of our bodies away from our rest
58:50and digest organs which would be urinary
58:53digestive Etc uh so that we can St stain
58:56a fight or flight
58:58scenario hormonal regulation we've
59:01introduced before the renin Angiotensin
59:04aldosterone system our next slide is
59:06going to go through that but if we look
59:08at a couple hormones that are uh
59:10regulating or working with glomerular
59:13filtration rate Angiotensin 2 is going
59:16to be one of them it's ultimately going
59:18to cause constricting of the aphron and
59:20ephren arterial so we're constricting
59:22both the blood coming into the Glarus
59:25and blood leaving the Glarus overall
59:28decreasing blood flow overall decreasing
59:31glomular filtration rate
59:34GFR atrial ntic
59:37peptide the job of is going to be to
59:40relax those mesangial cells uh
59:42ultimately increasing capillary surface
59:45areas and increasing glomular filtration
59:48rate let me say where does atrial ntic
59:50peptide comes from well the name kind of
59:52tells us so we're dealing with the Atria
59:55of the heart so amp is going to be
59:57secreted when we detect overstretch of
1:00:01the cardiac
1:00:04Atria our renin Angiotensin aldosterone
1:00:08system so we've talked about this when
1:00:09we did cardiovascular we talked about
1:00:12drugs like Ace blockers or ACE
1:00:15inhibitors and beta blockers to reduce
1:00:19and lower blood pressure so we could run
1:00:21through this scenario and see exactly
1:00:24what's going on we start with a disorder
1:00:29an imbalance so we start right at number
1:00:31one where we have uh dehydration sodium
1:00:34deficiency and or hemorrhaging what
1:00:36results is a decrease in blood volume
1:00:39that decrease in blood volume is going
1:00:40to be detected by the juxtaglomerular
1:00:43cells of the kidney which is going to in
1:00:45turn stimulate a release of renin now
1:00:49concurrently the liver is going to be
1:00:51producing this enzyme called
1:00:54angiotensinogen and angiotensinogen is
1:00:57going to help to increase Angiotensin
1:00:59one which is then going to make its way
1:01:02over to the lungs and the lungs is going
1:01:04to produce an enzyme called Angiotensin
1:01:07converting enzyme and this is going to
1:01:09convert Angiotensin one into its active
1:01:12state of angiotensin too now if we take
1:01:15a step back and go back to uh Ace
1:01:18inhibiting enzymes we talked about
1:01:21people with high blood pressure or
1:01:22chronic hypertension tend to get certain
1:01:25drugs like beta blockers and more
1:01:27importantly Ace inhibiting enzymes ACE
1:01:29inhibitors what this does is it blocks
1:01:31Ace which ultimately stops this pathway
1:01:34right here stopping the conversion of
1:01:36angiotensin one to Angiotensin 2 now
1:01:39we'll come back to this but let's follow
1:01:41this route so let's erase what we did
1:01:44here and assume everything is normal no
1:01:47hypertension we continue to angiotensin
1:01:49two which goes up to our arterials and
1:01:54is going to Vaso constrict so it's going
1:01:57to vasal constrict those arterials which
1:01:59will ultimately lead us to an increase
1:02:02in blood pressure until we get to a
1:02:05normal uh level of hydration so again
1:02:08let's go back to our ACE inhibitors we
1:02:11block Ace which blocks Angiotensin 2
1:02:15which blocks Vasa constriction of
1:02:16arterials which does not increase blood
1:02:19pressure okay so let's go get rid of our
1:02:24clinical connection here
1:02:26and start looking at some other
1:02:28scenarios other players here so
1:02:31Angiotensin 2 will also communicate
1:02:34right here with the adrenal cortex of
1:02:37our adrenal gland which will stimulate
1:02:39an increase in aldosterone and if you
1:02:42remember aldosterone played a key role
1:02:45in sodium and pottassium secretion and
1:02:48reabsorption so we're dealing with the
1:02:51kidneys again so aldosterone is going to
1:02:53work with the kidneys it's going to in
1:02:55increase sodium in water reabsorption
1:02:58and increase secretion of potassium and
1:03:01hydrogen ions and then as a result by
1:03:05doing this we increase blood volume
1:03:08which increases blood pressure until we
1:03:11return back to normal
1:03:13circumstances the adrenal cortex if we
1:03:16look right here okay we're going to
1:03:18detect an increase in potassium in the
1:03:20extracellular fluid which will also kick
1:03:22off our aldosterone release which kicks
1:03:25off our renin renin
1:03:30Angiotensin aldosterone
1:03:33system table
1:03:3526.2 summates all parts of glomular
1:03:40filtration rate and the regulation of so
1:03:42we can look at each and every one of the
1:03:45regulation the stimulus that causes it
1:03:48and the mechanism or the site of action
1:03:51and its effect on GFR so first and
1:03:52foremost I want you to go all the way to
1:03:55the effects on GFR and notice the trend
1:03:58what we're doing is mostly decreasing
1:04:02decreasing decreasing decreasing GFR as
1:04:05a result of uh too high of a blood
1:04:09pressure being detected and one instance
1:04:13we are increasing GFR here due to
1:04:18um another issue with the Atri the Atri
1:04:21over stretching so let's look at these
1:04:22mechanisms myogenic mechanism so what's
1:04:26the stimuli increased stretching of
1:04:27smooth muscle fibers in that aphron
1:04:29arterial due to high or chronic
1:04:32hypertension or high blood pressure as a
1:04:35result the stretch smooth muscle fibers
1:04:37contract narrowing the Lumen of the
1:04:40aphron arterial decreasing GFR that
1:04:43tubuloglomerular feedback so we're
1:04:45detecting too much sodium chloride at
1:04:48the macula Dena uh this is due in fact
1:04:51to high systemic blood pressure think
1:04:52back to the Lucy the I Love Lucy
1:04:55scenario
1:04:56where that conveyor Bel is moving way
1:04:57too quickly uh so too high blood uh too
1:05:01high of blood
1:05:02pressure get too much sodium sodium
1:05:05chloride moving through what happens we
1:05:07decrease the release of Nitric oxides
1:05:09those
1:05:10vasodilators by the jux glomular
1:05:12apparatus causing constriction of the
1:05:14aphron arterial overall net effect
1:05:17decreasing GFR our neural regulation
1:05:21increase uh in activity level of the
1:05:23renal sympathetic nerves release
1:05:26norepinephrine this is going to
1:05:28constrict here constrict the aphron
1:05:30arterials through Al through activation
1:05:32of our Alpha 2 receptors and we're going
1:05:34to increase renin
1:05:36release hormone regulation here's our
1:05:39Angiotensin 2 decreased blood volume has
1:05:41been detected or or blood pressure
1:05:44stimulate production tensin to as a
1:05:46result we're constricting uh aphron and
1:05:49ephant so that's one of our differences
1:05:51aphr and ephren arterials giving us a
1:05:54decrease in G dfr here's our one outlier
1:05:58amp Aton ntic peptide detect stretching
1:06:01of the Atria in the heart is going to
1:06:02stimulate secretion of amp what happens
1:06:05we're going to relax those mesal cells
1:06:07in the Glarus increaseing capillary
1:06:09surface area which ultimately gives us
1:06:13our one increase in GFR thank you for
1:06:17listening I hope you found it helpful

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