Physiology of the liver

Question 1

what is the circulation of the liver

5

Answer 1

1-Portal circulation
(hepatic artery and vein )
10% (580ml-1L), a lot of blood that can be released in exercise
This circulation of nutrient-rich blood between the gut and liver is called the portal circulation—>systemic circulation
= capacitance vessel + veins

Question 2

what is the function of the liver (overall)

8

Answer 2

1) Albumin Production: Albumin is a protein that keeps fluids in the bloodstream from leaking into surrounding tissue. It also carries hormones, vitamins, and enzymes through the body.
2) Bile Production: Bile is a fluid that is critical to the digestion and absorption of fats in the small intestine.
3) Filters Blood: All the blood leaving the stomach and intestines passes through the liver, which removes toxins, byproducts, and other harmful substances.
4) Regulates Amino Acids: The production of proteins depend on amino acids. The liver makes sure amino acid levels in the bloodstream remain healthy.
5) Regulates Blood Clotting: Blood clotting coagulants are created using vitamin K, which can only be absorbed with the help of bile, a fluid the liver produces.
6) Resists Infections: As part of the filtering process, the liver also removes bacteria from the bloodstream.
7) Stores Vitamins and Minerals: The liver stores significant amounts of vitamins A, D, E, K, and B12, as well as iron and copper.
8) Processes Glucose: The liver removes excess glucose (sugar) from the bloodstream and stores it as glycogen.

Question 3

Metabolic function of the Liver

Answer 3

• Metabolism and production of fats, proteins, and carbohydrates
• STorgae of vitamins ADEK
• SYNTHESIS of AA
• Metabolism of AA
• Production of hormones (AG raas system etc
• clotting factors
• Bile production
• Urea Cycle to remove ammonia from the body
• Production of proteins ( transporter proteins and albumin , transferrin - transports iron etc )

Question 4

outline a liver lobule 
(outline the classic lobule & its parts) -4
Which way does Bile flow?
Which way does Blood flow?
-2

Answer 4

1-central vein
2-6x portal triads (hepatic artery, bile duct, portal vein )
3-Sinusoids = allows passage of blood
4-Kupfer cells (kill any old cells)

• Bile flows from center to portal triads
• Blood floes from rim to center

Question 5

How do we classify a lobule in physiology

3

Answer 5

1-liver acinus lobule model
( zones 1-3, where 3 is most prone to hypoxia )
zone 1 = closest to hepatic artery ( portal area , portal triad on the edges )
zone 3 = closest to the central vein

Question 6

How does the liver control blood glucose?

Answer 6

Blood glucose after a meal
1-glycogen synthase ( works under the influence of insulin ) to produce glycogen

immediate fasting state :
2-Glycogenolysis (phosphorylase breaks glycogen to glucose)

• Fats–>lipolysis –>Fatty acids + glycerol (Fatty acids –>b oxidation & ketones )
  Glycerol –>gluconeogenesis

-AA–>pyruvate / lactate–>gluconeogenesis

Question 7

outline fat metabolism

Answer 7

a) cholesterol & lipoproteins = formed in liver –>
b) after meal = synthesis of TG

c)Fasting state : Beta oxidation
Fat stores -> Fatty acids go to Ketones + ATP
glycerol is able to turn into glucose

Question 8

Outline protein metabolism

what proteins are produced in the liver ?

Answer 8

1-protein produced in the liver : albumin
c -reactive protein
complementary proteins
2-ammonia–>urea

Question 9

Storage of vitamins

Answer 9

1-Fat soluble vitamins = A,D,EK
B12 also stored here
Vit D is activted here :
1-colicaciferol—>25-colicalciferol–>1,25colicalciferol in the kidney –>calcitriol (active form in kidney)

Question 10

What is the function of Bile

4

Answer 10

1-Get rid of the products of hb break down = bile pigments and bile acids

• Bile acids = micelles around fats= amphoteric
• Bile pigments = CB and urobilinogen = faeces and intestine ( waste products)

Question 11

What is the composition of bile

Answer 11

97% water

Question 12

Bilirubin Metabolism and excretion

5

Answer 12

1-Hb–>Albumin bound bilirubin ( big molecule so don’t get filtered )–>hepatocyte –>CB>bile canaliculi –>urobilinogen = easily into the intestine ( brown colour for your faeces )
- UBG –> can penetrate the intestine walls so it can actually be reabsorbed and enter again into bile ->Enterohepatic Circulation

Question 13

gall stones overview

3

Answer 13

• Cholesterol
• Gall bladder concentrates bile
• Micelles in the gall bladder can increase ( from 97% water to 89%)