Liver: The Master Filter — Transcript

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1. 0:00LIVER BLOOD SUPPLY
2. 0:05The liver is a 1.3 to 3.0 kilograms weigh,
3. 0:09soft,
4. 0:09pinkish-brown organ
5. 0:11that is responsible for a whole range of functions,
6. 0:14including drug detoxification,
7. 0:17glycogen storage,
8. 0:18protein synthesis,
9. 0:19and the production of bile,
10. 0:20which is necessary for digestion.
11. 0:22Before diving into the liver’s blood supply,
12. 0:24it would be helpful to revisit the anatomy
13. 0:27of the largest internal organ of the human body
14. 0:29very briefly.
15. 0:30The human liver can be grossly divided into 2 lobes,
16. 0:33a Right and a Left,
17. 0:35by the falciform ligament.
18. 0:37There are 2 additional lobes
19. 0:38that can only be seen from behind.
20. 0:40The Quadrate is situated
21. 0:41between the gall bladder and the round ligament,
22. 0:44while the Caudate lobe is found facing caudally
23. 0:47between the inferior vena cava,
24. 0:49the ligamentum venosum,
25. 0:50and the porta hepatis.
26. 0:52It must be kept in mind
27. 0:54that a lot of anatomists classify these two lobes
28. 0:56as the sub-parts of the right lobe of the liver.
29. 0:59The blood supply of the liver involves 2 major vessels:
30. 1:02The Portal vein and the Hepatic artery.
31. 1:05Hepatic tissue receives oxygenated blood
32. 1:07via the Hepatic artery.
33. 1:09Whilst the Portal vein collects the deoxygenated blood
34. 1:12from the gastrointestinal tract,
35. 1:14spleen, and pancreas,
36. 1:16filters it in the liver,
37. 1:18eliminates toxins,
38. 1:19and processes the nutrients it absorbs
39. 1:21from the Gastrointestinal tract.
40. 1:23Let’s look at both systems one by one.
41. 1:26Hepatic Artery:
42. 1:27The hepatic artery contributes about 30%
43. 1:31of the entire hepatic blood supply.
44. 1:32The celiac trunk,
45. 1:34arising at the level of T-12 from the abdominal aorta,
46. 1:37gives rise to 3 arteries:
47. 1:39the Left Gastric artery,
48. 1:41the Splenic artery,
49. 1:42and the Common Hepatic artery
50. 1:44that will supply blood to the liver.
51. 1:45The common hepatic artery travels retroperitoneally
52. 1:49towards the right,
53. 1:50in the Hepatoduodenal ligament of the liver
54. 1:52and divides into the Gastroduodenal artery below,
55. 1:55which supplies the stomach or gastro,
56. 1:58and the duodenum,
57. 1:59and Proper Hepatic arteries which supply the liver.
58. 2:02The Proper Hepatic Artery
59. 2:04branches into the Right and Left Hepatic arteries
60. 2:07that supply the liver’s right and left lobes, respectively.
61. 2:10The Right Hepatic artery gives off an important branch
62. 2:13called the Cystic artery
63. 2:15to supply the gallbladder and the cystic duct.
64. 2:17Hepatic Portal Vein:
65. 2:19The Portal Vein contributes about 70% of the Hepatic blood supply,
66. 2:23but all of the blood is deoxygenated.
67. 2:26Hepatic Portal Vein is located in the abdominal cavity
68. 2:30and is formed by the union
69. 2:31of the Splenic veins and the Superior Mesenteric vein
70. 2:34that channel the deoxygenated blood from the spleen,
71. 2:37gastrointestinal tract,
72. 2:39and its accessory organs to the liver.
73. 2:41The veins that contribute to the Splenic vein include:
74. 2:44- The Pancreatic veins
75. 2:46- The Left Gastroepiploic vein
76. 2:48- The Short Gastric veins
77. 2:51and The Inferior Mesenteric Vein with its branches.
78. 2:55The second component of this merger,
79. 2:57the Superior Mesenteric Vein,
80. 2:58collects blood from:
81. 3:00- The Ileal veins
82. 3:01- The Jejunal veins
83. 3:03- The Ileocolic veins
84. 3:04- The Middle and Right Colic veins
85. 3:07- The Anterior inferior,
86. 3:09anterior superior,
87. 3:10Posterior inferior Pancreaticoduodenal vein
88. 3:15- The Right Gastroepiploic vein.
89. 3:18Few veins drain directly into the Portal Vein,
90. 3:21including the Left and Right Gastric veins,
91. 3:23the posterior Superior Pancreaticoduodenal vein,
92. 3:27and the Cystic vein.
93. 3:29One must keep in mind
94. 3:30that the Portal Venous system
95. 3:32enables the blood from one set of capillary beds
96. 3:34to be drained into another set of capillary beds,
97. 3:37without first returning to the heart.
98. 3:39The Hepatic Portal system
99. 3:41links the capillary bed of the gastrointestinal tract
100. 3:44with its counterpart of the liver.
101. 3:45From the gastrointestinal tract,
102. 3:47the blood that is rich in nutrients
103. 3:49is first brought to the liver for processing.
104. 3:51In the liver,
105. 3:52amino acids and monosaccharides
106. 3:54are either stored
107. 3:55or used to make new proteins and carbohydrates.
108. 3:58The liver filters the toxins
109. 4:00that might have been absorbed with the food,
110. 4:02and also removes vitamins and cofactors
111. 4:05from the blood for storage.
112. 4:06When the body needs the stored substances,
113. 4:09they are released back into the circulation
114. 4:11via the central veins.
115. 4:12The blood flowing through the liver tissue
116. 4:14empties into the central vein of each Hepatic lobule.
117. 4:17The central vein of each lobule
118. 4:20merges into the interlobular vein
119. 4:23which then coalesces together
120. 4:24to form mainly three hepatic veins
121. 4:26and bring the deoxygenated blood
122. 4:28to inferior vena cava
123. 4:30just before it passes up through the diaphragm
124. 4:32and travels back to the Heart.
125. 4:34That’s how the liver is able to maintain its dual blood supply.
126. 4:38From this, the three key takeaways are:
127. 4:40- The hepatic portal vein supplies 70% of the blood to the liver,
128. 4:44while the hepatic arteries supply the remaining 30%.
129. 4:48- Hepatic arteries supply oxygenated blood to the liver
130. 4:51while the portal vein brings deoxygenated blood,
131. 4:54along with the nutrients and substances
132. 4:56from the gastrointestinal tract.
133. 4:58- The hepatic portal system
134. 5:00connects the capillaries of the gastrointestinal tract
135. 5:03with the capillaries in the liver.
136. 5:04From the gastrointestinal tract,
137. 5:07the blood that is rich in nutrients
138. 5:08is brought to the liver for processing
139. 5:10before return to the heart.