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Cell Communication: Cell-to-Cell Contact to the Endocrine System | AP Biology 4.1 — Transcript

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0:00[Music]
0:07our cell phones can communicate through
0:09touch and nfc
0:10protocols that allow us to tap and pay
0:13they can conduct medium range
0:14communication through bluetooth signals
0:17and wi-fi networks
0:18that allow us to use the headphones and
0:20connect the internet
0:21plus they can connect to a cell tower
0:24miles away
0:25to transmit a video call to someone on
0:28the other side of the world
0:30this is all pretty amazing but did you
0:32know that biological cells
0:34have been communicating through very
0:36similar mechanisms for billions of years
0:39there are many different ways that cells
0:41can communicate with one another
0:43some cells communicate with their
0:44neighbors through direct contact
0:47others use short-range signals to
0:49communicate with nearby
0:50cells some cells are even responsible
0:53for creating hormone signals
0:55that travel throughout the entire body
0:57and affect many different cells in
0:59different tissues and organs
1:01this information will definitely be
1:03incorporated into the ap
1:05test so stick with us as we cover the
1:08basics of cell communication
1:12this video covers section 4.1 in the ap
1:15biology curriculum
1:16we'll start with an overview of what
1:18cell communication is
1:20and the different ways it functions then
1:22we'll dive into the different types of
1:24cell communication based on the distance
1:26the signal travels
1:28we'll start with cell communication that
1:29involves direct cell to cell contact
1:32after the first quiz we'll see how local
1:35regulator molecules
1:36can influence cells very close to the
1:38signaling cell
1:40finally we'll take a look at cell
1:42signals like hormones
1:44that can travel throughout an entire
1:45organism to signal many different types
1:47of cells at once
1:49if you only need to review one of these
1:51topics feel free to skip forward to the
1:53times outlined here
1:55otherwise let's get started
1:59let's start by taking a look at how cell
2:01signaling actually works
2:03the process of a signal activating a
2:05certain response in another cell
2:07is called signal transduction though we
2:09will cover
2:10signal transduction pathways in much
2:12more detail over the next few sections
2:14there is a basic structure that most
2:16signal transduction pathways use
2:20most signals start when a protein on the
2:22surface of the cell
2:24receives a signal the signal could be a
2:26chemical
2:27or it could be a physical stimulus like
2:29light touch or sound waves
2:32each receptor protein has evolved to
2:33receive a very specific signal
2:36known as a ligand if it is a chemical
2:40once the receptor protein receives the
2:41signal it catalyzes a reaction on the
2:44inside of the cell
2:46the product of this reaction starts a
2:47cascade of other reactions
2:49a process known as signal transduction
2:52this chain reaction eventually leads to
2:54a cellular response
2:56responses can vary greatly depending on
2:59the cell signal received
3:01for instance an immune cell may initiate
3:04phagocytosis
3:05when receptors on the cell surface
3:07notify the immune cell that it is in
3:09contact with an invasive bacterial cell
3:11or the insulin receptors on a muscle
3:14cell could trigger a cascade of
3:16reactions upon receiving insulin
3:18that cause the cell to send glucose
3:20importers to the cell membrane
3:21and import as much glucose as possible
3:24since there are literally millions of
3:26different specific reactions that cell
3:28communication can elicit
3:30the easiest way to classify cell
3:32communication
3:33is to break it down by the distance the
3:35signal has to travel
3:37some signals can only be sent when two
3:40cells are literally touching
3:42most often this involves surface
3:44proteins on two cells
3:46binding with one another other times
3:49this includes cells passing chemical
3:51messages
3:52through pores like plasmodesmata in
3:54plant cells
3:55that connect two or more cells together
3:59while touch does account for some cell
4:01signaling the large majority of cell
4:03signals are sent via chemical messenger
4:06chemical messages that affect the same
4:08cell they originated in
4:10are known as autocrine signals
4:13local regulator molecules like
4:15neurotransmitters
4:16are known as paracrine signals because
4:18they only affect nearby cells
4:21finally endocrine signaling covers
4:24the most distance of all the chemical
4:26signaling methods
4:28glands that are a part of the endocrine
4:30system send hormones and other signaling
4:32molecules through the bloodstream
4:34to affect target cells across the body
4:38think about this the cells in your body
4:41need to communicate for the same reason
4:43the ants in a colony need to communicate
4:46each ant needs to know when to collect
4:48food
4:49when they need to engage in defense and
4:51when they can rest
4:53as we continue into the many methods of
4:55cell communication
4:57try to remember that the ultimate reason
4:59cells communicate
5:00is to coordinate their actions in
5:02support of the organism
5:03as a whole
5:07cell to cell contact is used by a large
5:10number of cells in order to send and
5:11receive some of the most important
5:13signals that cells within an organism
5:15need to transmit
5:17essentially this form of cell
5:18communication is like a handshake
5:21while there are many many examples of
5:23this we're going to cover a few of the
5:25most important cellular signals that
5:26travel
5:27via cell to cell contact
5:30first consider what happens as normal
5:32cells are growing in your body
5:35as these cells hit other cells around
5:37them proteins on the cell's surface are
5:39activated
5:40and tell the cells to stop growing this
5:43is how
5:44tissues have such an orderly and
5:46standardized arrangement
5:48these signal transduction pathways are
5:50broken in many cancer
5:52cells which is why they continue to cell
5:54division
5:55in a disorderly fashion growing into a
5:57misshapen tumor
5:59and invading other parts of your body
6:03now consider one of the most important
6:05cell communication pathways in your body
6:07the pathway that allows your immune
6:09cells to recognize and kill
6:11invading pathogens like viruses and
6:13bacteria
6:15almost all parts of your immune system
6:17from the white blood cells that catch
6:19and kill
6:19invading bacteria and viruses to the
6:22cells that build and release antibodies
6:24to fight infections
6:26rely on cell to cell contact via signal
6:29transduction pathways
6:30to carry out their work while it is not
6:33necessary to memorize the entire immune
6:35system here
6:36it is important to realize that
6:38different cells can react to
6:39encountering another cell in different
6:41ways for example
6:43helper t cells can learn what the
6:45antigen of an invading virus looks like
6:48when it is trained by a phagocytic
6:50antigen presenting cell
6:52then through another cell to cell
6:53contact helper t
6:55cells can train b cells which go on to
6:58produce the antibodies an organism needs
7:00to fight off an infection
7:04now that we've covered the basics of
7:05cell communication and the specifics of
7:08cell to cell contact
7:09let's see if you can answer some ap
7:11style questions
7:13pause the video now and take the
7:14following quiz you can find answers to
7:17these quiz
7:17questions through the quick test prep
7:19link in this video's description
7:26there are many different examples of
7:27local regulator molecules
7:29that affect only the cells within a
7:31close proximity
7:33sometimes these are referred to as
7:35paracrine signals
7:37the most popular paracrine molecules
7:39used in your body
7:40are neurotransmitters neurotransmitters
7:44are molecules that allow a nerve signal
7:46to pass
7:47between nerve cells this complex process
7:50starts
7:51when the nerve impulse traveling down
7:53the first neuron
7:54reaches a voltage-gated ion channel
7:57this channel allows calcium ions to
7:59flood the sending neuron
8:02the influx of calcium triggers synaptic
8:04vesicles to merge with the cell membrane
8:07causing the release of neurotransmitters
8:09into the synaptic space
8:11these neurotransmitters bind to
8:13ligand-gated channels
8:15causing an influx of sodium ions into
8:17the receiving neuron
8:19this rapid influx of ions depolarizes
8:22the membrane
8:23causing a cascade of ion channels to
8:25open down the length of the neuron
8:26that propagate the signal however this
8:30is not the only good example of local
8:32regulator molecules
8:33in fact a really interesting form of
8:35local regulator
8:36communication comes from the world of
8:39bacterial cells
8:41bacterial cells are more likely to
8:42survive when they form biofilms
8:44with other bacterial cells but biofilms
8:48can only form
8:49when bacterial cells are spaced out just
8:51right
8:52this means that the bacterial cells have
8:54to stop dividing and have to work
8:56together
8:57to excrete substances that create a
8:59stable biofilm that will protect them
9:01so as they grow each bacterium secretes
9:04a small amount of local regulator
9:06molecule
9:10when the bacterial cells reach a certain
9:11density the concentration of local
9:14regulator molecules
9:15causes the bacterial cells to switch
9:17their metabolism slightly
9:19to grow more slowly and secrete biofilm
9:22molecules
9:29these parakeets are communicating that
9:30it's time for a quick nap
9:32if you need a quick break now's a good
9:34time grab a drink
9:36a quick snack and stretch your legs when
9:39we come back
9:40we'll see how organisms use the
9:42endocrine system to send signals across
9:44the entire body
9:47the last category of cell communication
9:49happens over long distances
9:51within an organism these are typically
9:54called endocrine signals
9:55and they are controlled and released by
9:57the endocrine system
9:59the endocrine system is incredibly
10:01complex because it is constantly
10:03coordinating the activities of your body
10:05by releasing a wide variety of hormones
10:08from different organs
10:09these hormones circulate through your
10:11bloodstream and bind to receptor
10:13proteins
10:14on many target cells in different
10:16tissues and organs throughout the body
10:19for example let's take a look at the
10:22complex role that the pancreas plays
10:24in regulating the body's blood glucose
10:27levels
10:28when blood glucose levels are high
10:30glucose importers
10:32move glucose into beta cells within the
10:34pancreas
10:35this activates a signal transduction
10:37pathway
10:38that causes insulin to be excreted from
10:41the beta cells
10:42the insulin travels through the blood
10:45where it binds to insulin receptor
10:47proteins on cells across the body
10:49when insulin binds to liver cells it
10:52transduces a signal that causes liver to
10:54store glucose as glycogen
10:57when insulin binds to receptors on other
10:59tissues throughout your body
11:01the receptors start a series of
11:03reactions that cause vesicles loaded
11:05with glucose importers to bind to the
11:07cell membrane
11:09this causes these cells to import
11:12lots of glucose then
11:16when your glucose levels start to drop
11:18in your bloodstream
11:19your pancreas secretes glucagon
11:23this hormone is specific to receptors on
11:25liver cells
11:26and directs the liver to convert
11:28glycogen back into glucose
11:31this helps regulate your blood glucose
11:33levels until you eat your next meal
11:37keep in mind that all these complex
11:39forms of cell communication between
11:41multiple organ systems and tissues
11:43are required just to maintain your blood
11:45glucose levels in a specific range
11:48your endocrine system is constantly
11:50secreting hormones
11:51for many different purposes that cause a
11:54huge variety of reactions
11:56in different cell types around your body
12:00now that we have covered local
12:02regulators and long distance methods of
12:04cell communication
12:05let's see if you can apply your new
12:07knowledge
12:08pause the video now and answer these
12:11questions
12:12you can find answers to all the
12:13questions in this video through the
12:15quick test prep link
12:16in this video's description as well as
12:19links to all of our other study
12:20resources for this section
12:24thanks for watching please like this
12:26video if you found it helpful and
12:27informative
12:28feel free to leave us any comments you
12:30have about the content or any questions
12:32you still have about cell communication
12:34methods
12:35you can also subscribe to the biology
12:37dictionary youtube channel
12:39to get quick access to all of our ap
12:41biology videos and resources
12:43good luck

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