The Liver

Question 1

Where is the liver anatomically?

Answer 1

R upper quadrant, against diaphragm, against hepatic flexure, anterior to aorta

Question 2

How many lobes does the liver have?

Answer 2

2 lobes divided by falciform ligament

Question 3

Why is the liver brown?

Answer 3

Characteristically brown = high levels mitochondria

Question 4

What are the functions of the liver?

Answer 4

Complete UREA CYCLE expressed – coverts ammonia to urea.

STORAGE –> iron, Vit A, B12, D, K, carbs/fat –> glycogen, lipoprotein, triglyceride.

ANABOLISM –> albumin, glycogen, coag factors, adult haematopoiesis for failing bone marrow.

CATABOLISM –> detoxification (cytochrome p450): drugs, hormones, haemoglobin, poisons, can take over removal of aged RBCs after splenectomy.

FILTERING –> macrophages critical

Question 5

What are the exocrine functions of the liver?

Answer 5

BILE: prod/secretion: needed for absorption of fats, leave through common hepatic duct, produces 1L bile per day – common duct to gallbladder – bile duct to duodenum

Question 6

List the endocrine functions of the liver

Answer 6

Produces: Angiotensinogen, Thrombopoetin, Insulin like growth factor 1 (IGF-1)

Question 7

What is the portal triade?

Answer 7

PORTAL TRIADE = portal vein + proper hepatic artery + common hepatic duct

Question 8

What is the livers blood supply?

Answer 8

Portal vein, hepatic vein, hepatic artery

Question 9

What is the role of the portal vein?

Answer 9

Supplies liver nutrient rich blood: food from gut, end up in portal vein, to liver. CARRIES: Water, Water sol vits, Electrolytes, Carbs, pancreatic hormones, Toxins: chemical, bacteria, viruses, Protozoa, nematodes, cestodes, trematodes. Ammonia: toxin, breakdown product of polypeptides, AA, from the gut – to the liver – broken down to urea – to liver – excreted. NOT CARRYING: lipids – taken into cell processed = chylomicrons – requires bile – taken up by lacteals - contain chyle, fat soluble Vit (A, D, E, K)

Question 10

What is a portal system?

Answer 10

Portal system –> 2 capillary beds in series before returning to heart

Question 11

Where are portal systems found in the body?

Answer 11

Hepatic portal system and Hypothalamo-hypophyseal portal system

Question 12

What are hepatocytes?

Answer 12

Liver cells: Constitute 80% of liver cell population. Can regenerate remarkably!

Question 13

Describe kupffer cells

Answer 13

monocyte derived specialist macrophages, form part of lining of sinusoids. Constitute 80% of tissue macrophages present in body. Constantly exposed to gut-derived bacteria, microbial debris, bacterial endotoxins

Question 14

What are stellate cells?

Answer 14

Full of cytoplasmic vacuoles containing vit A. Cirrhosis = hepatic stellate cells lose vit A storage, diff to Myofibroblasts = deposit collagen within perisinusoidal space = liver fibrosis = collagen surrounds central vein, constricting = portal hypertension

Question 15

Outline what a hepatic lobule is

Answer 15

Hepatocytes surrounded by 6 portal triads. Sinosoids –> giving hepatocytes nutients.oxygen, Central vein: taking away deoxygenated blood/toxins

Question 16

What is the space of mall/periportal space?

Answer 16

Space of mall/periportal space –> area surrounding portal triad – where lymphatics arise

Question 17

What is the name given to the functional unit of the liver?

Answer 17

Liver acinus = diamond-shaped; divided into zone I (periportal), zone II (transition zone), and zone III (pericentral)

Question 18

What is a sinusoid?

Answer 18

Sinosoids –> giving hepatocytes nutients.oxygen,

Question 19

What is bile?

Answer 19

Components = cholesterol, bile salts, bilirubin. A bitter greenish-brown alkaline fluid, secreted by the liver, stored in the gall bladder, discharged into the duodenum = digests fats/lipids