GI5 Hepatic function

Question 1

What is the largest organ in the body?

2) describe its development
3) describe its blood supply + what they transport

Answer 1

liver
2) Develops as an outgrowth from GI tract –accessory organ
3) Has “double” blood supply
Hepatic artery – oxygenated blood
Portal vein – nutrient rich blood

Question 2

1) Descirbe anatomical structure of liver:

2) What are Kupffer cells:

Answer 2

Series of plates of hepatocytes that radiate from a central vein
Hepatocytes in contact with bloodstream on one side and bile canaliculi on the other
Between hepatocytes are vascular spaces (sinusoids)
2) phagocytic macrophages

Question 3

What is present in the portal triad:

Answer 3

hepatic aa
hepatic portal vv (widest)
bile duct (thinnest)

Question 4

What are the functions of the liver?

Answer 4

Detoxification of blood

Protein synthesis

Carbohydrate metabolism

Lipid metabolism

Secretion of bile

Question 5

How does the liver detoxify the blood?

Answer 5

1.Excretion into the bile
2.Phagocytosis by Kupffer cells.
3.Chemical alteration of the molecules.
e.g. Ammonia is produced by deamination of amino acids in the liver.
Liver converts it into urea.
Excreted in urine.

Question 6

How is ammonia produced in the liver from reactants in the blood?

Answer 6

glutamate undergoes oxidative deamination forming alpha-ketoglutarate and ammonia

Question 7

What happens to ammonia in the liver

Answer 7

ammonias is reacted CO2 to form carbamoyl phosphate. Carbamoyl phosphate reacts ith ornithine to produce citrulline. Citrulline reacts with aspartate to form argininosuccinate. Ammonia also enters cycle here as aspartate can be formed in mitochondria by reacting it with with oxaloacetate to form aspartate which then enters cytosol. where it reacts with Citrulline to form Argininosuccinate then joins the urea cycle to form urea.

Question 8

Strarting from argininosuccinate how is urea produced from the urea cycle?

Answer 8

1) argniosuccinate breaks into fumarate and arginine
2) arginine reacts with water to form UREA and ornithine
3) ornithine then reacts with carbamoyl phosphate to form citrulline
4) citrulline reacts with aspartate to form argininosuccinate
5) argininosuccinate breaks down into fumarate and arginine.
6) Arginine is hydrolysised (reacts with water ) to form ornithine and urea!

Question 9

What is the formula of ammonia?

Answer 9

NH4 +

Question 10

What proteins does the liver synthesise?

Answer 10

Albumin
Globulin
Fibrinogen
Transferrin
Plasma Lipoproteins (A,B,C,E,a)

Question 11

What is the function of :

1) albumin
2) Fibrinogen

Answer 11

1) Constitutes 70% of the total plasma protein
Colloid osmotic pressure
Carrier protein
2) blood clotting

Question 12

What is the function of :

1) transferrin
2) globulin

Answer 12

1) iron transport
2) Transport cholesterol and hormones
Produce blood clotting factors I, II, III, V, VII, IX, XI

Question 13

Liver regulates blood glucose concentration by:

Answer 13

Glycogenesis - Too much glucose
Synthesis of glycogen from glucose
glycogen is stored in the liver
Glycogenolysis - Glucose pools reduce
Glycogen is hydrolyzed (digested)
releasing glucose into the bloodstream
Gluconeogenesis -  If Glucose intake is low
synthesis of glucose from protein or from lipid (via glycerol)

Question 14

Where does gluconeogenesis occur?

Answer 14

liver and a bit in renal cortex, in the cytosol

Question 15

What is a chylomicron ?

2) What is it made up of?
3) What is its function?
4) How is substances making up chylomicron release?

Answer 15

One of several classes of lipoproteins
2) 95 % triglycerides
5 % cholesterol
Apoprotein B-48
3) Transport of fat from intestines to muscle and other energy utilizing tissues via lymph then blood stream
4) As it is circulating in the blood stream, they're recognised by lipoprotein lipases on the lining of blood vessels and other energy utilising tissues. =
•	Chylomicron remanents
•	High density lipoprotein- Cholesterol
•	FFA

Question 16

What does lipases and cholesterolesterases break lipids down into? (what are lipids component parts)

Answer 16

monoglyceride, phosphophlipid, esterified free fatty acid (FFA) and cholesterol.

Question 17

What regulates bile?

Answer 17

CCK (how much is released from the gall bladder)

secretin (amount that gets produced)

Question 18

Describe how lipids are used by the body from the intestine lumen?

Answer 18

1) in intestinal cell via a mechanism cholesterol and monoglycerides, phospholipids and FFA enter
2)combine with Apoprotein B-48
and form a chylomicron and an esterified free fatty acid.
3)

Question 19

What happens to the products of chylomicron after being broken down by lipoprotein lipases:

1) Chylomicron remanents
2) High density lipoprotein- Cholesterol (HDL-C)
3) free fatty acids (FFA)
4) Glycerol

Answer 19

1&2)are taken to liver via hepatic portal vein and taken up by hepatocytes
3) stored in adipose cells as fat or used for energy in cells.

Question 20

What happens to cholesterol in hepatocytes?

Answer 20

be released as low density lipoprotein cholesterol back into the blood stream

Question 21

What happens to the chylomicron remnants in hepatocytes?

Answer 21

The chylomicron remnants will be broken down into cholesterol, free fatty acids and lipoproteins.
used to make bile salts. stored in gall bladder and released when we eat more fat.

Question 22

How much bile is secreted per day by hepatocytes?

2) what colour is it?
3) what is bilirubin a derivative of?
4) How is conjugated bilirubin formed?
5) where is conjugated bilirubin stored?

Answer 22

250-1500ml of bile/day,

2) yellow
3) derivative of the heme groups (without iron) from haemoglobin.
4) Free bilirubin combines with glucuronic acid and forms conjugated bilirubin.
5) gall bladder

Question 23

What happens to conjugated bilirubin when it enters the intestine?
2) What happens to bile acids when they enter the ileum?

Answer 23

1) converted by bacteria in the intestine to urobilogen.
- Urobilogen is absorbed by intestine and enters the hepatic vein
- Recycled, or filtered by kidneys and excreted in urine if we have too much
2) 95% are reabsorbed

Question 24

1) What is bilirubin bound to in the liver?
2) What is it bound to in the gall bladder?
3) What is another word for bilirubin conjugated to glucoronic acid?

Answer 24

1) for glutathione, bilirubin is generally bound to glutathione in the liver – until it forms bile (it likes to be bound to protein), so is stored this way
2) In the liver, bilirubin is conjugated with glucuronic acid by the enzyme glucuronyltransferase, making it soluble in water:
3)glucornoid???
could be wrong blaheaiguh

Question 25

1) What are bile acids a derivative of?

2) How is bile formed?

Answer 25

Bile acids are derivatives of cholesterol.
Major pathways of cholesterol breakdown in the body.
2) Bile is initially formed by transfer of bile acids and salts into small spaces between hepatocytes (bile canaliculi)- flow into the bile duct.

Question 26

In duodenum acid increases as protein digestion products and fat produced. Has 2 effects:

Answer 26

1. is detected by chemoreceptors activating S cells (endocrine cell) producing plasma secretin
2. Chemoreceptors will detect the protein and digestion products of fat. This activates entraendocrine cells so they will produce plasma CCK.

Question 27

What are the2 effects of plasma CCK?

Answer 27

1) Gall bladder contraction

2) Spincter of Oddi ( the sphincter of the joining pancreatic duct and common bile duct) relaxes

Question 28

What does plasma secretin do?

Answer 28

signals to hepatocytes to produce more bile.

Question 29

Patients with liver disorder will have decreased ability to ____a____

Answer 29

a= metabolise

Question 30

What drugs are not prescribed (contraindicated) if a patient has hepatic impairment?

Answer 30

• Miconozole- contraindicated if hepatic impairment
• Ertythromycin, tetracycline and metronidazole- avoided
• NSAID- increase risk of GI bleeding- avoided
• Paracetamol avoided.