Microanatomy of the liver

Question 1

what is the liver?

Answer 1

large lobulated exocrine and blood-processing gland, with vessels and ducts entering and leaving at the porta

Question 2

what is the liver enclosed by

Answer 2

thin collagen tissue capsule, mostly covered by mesothelium

Question 3

what provides support to the liver?

Answer 3

collagen tissue of the branching vascular system provides gross support

Question 4

what are parenchymal supported by?

Answer 4

fine reticular fibres

Question 5

portal vein?

Answer 5

bringing food-rich bloodfrom the gut

Question 6

hepatic artery?

Answer 6

bringing arterial blood

Question 7

hepatic veins?

Answer 7

taking away processed blood into the vena cava

Question 8

lymphatics?

Answer 8

taking away some lymph

Question 9

hepatic ducts?

Answer 9

removing bile to the gallbladder and gut

Question 10

blood supply of liver

Answer 10

dual, 25% from hepatic artery, 75% portal vein

Question 11

nerve supply?

Answer 11

sympathetic and parasympathetic supply of perivascular structure, but very little at sinusoidal level

Question 12

first impression of liver microanatomy

Answer 12

uniform mass of large glandular cells throughout the liver substance

Question 13

how are cells in the liver arranged?

Answer 13

perforated plates, one cell wide
between the plates are sinusoidal blood channels 9-12um wide, lined by endothelial cells
scattered in the glandular mass are blood vessel, alone and accompanied by other vessels
the distribution defines or marks out the classic hepatic lobules

Question 14

central vein/terminal hepatic venule

Answer 14

very thin wall
lies in the centre of a lobule
with sinusoids converging towards and opening into it

Question 15

sublobular/ intercalated vein

Answer 15

thicker wall
lies alone at the periphery of the lobule

Question 16

branch of portal vein

Answer 16

at the periphery ofd the lobule but accompanied by one or more small hepatic arteries/arterioles, one or more bileducts/ductules lined by cuboidal epithelium, and lymphatics

Question 17

what forms the portal triad

Answer 17

portal vein, artery, and bile duct
the area in which they lie in is the portal area
(lymphatics are ignored for this naming)

Question 18

hepatic lobular blood flow is…

Answer 18

from the branches of the portal vein and hepatic artery; from the periphery towards the centre
in the sinusoids, between the cell plates
blood collected in central veins goes to sublobular veins, then to collecting veins, and then hepatic veins leaving the liver

Question 19

intralobular bile flow…

Answer 19

is from the lobules centre towards the peripheral bile duct and runs within any one cell plat, between the liver cells in bile canaliculi

Question 20

what is the liver acinus

Answer 20

functional unit comprising parts of three lobules or so

Question 21

what are sinusoids

Answer 21

low pressure vescular channels that receive blood from terminal branches of the hepatic artery and portal vein at the periphery of lobules and deliver it into central veins

Question 22

what are liver sinusoids lined by

Answer 22

fenestrated endothelial cells, loosely attached and hold phagocytic kupffer cells, they rest on microvilli of underlying hepatic cells, without a basal lamina intervening

Question 23

what are kupffer cells

Answer 23

larger, stellate with a pale oval nucleus

Question 24

what does plasma pass through?

Answer 24

seive plate, formed by the lning cells, out into the perisinusoidal space of disse to interact with the hepatocytes, some of this fluid may pass to the periphery of the lobule to be collected as lymph

Question 25

what does the space of disse contain

Answer 25

extracellular matrix materials, but not a visible base lamina

Question 26

what are stellate cells

Answer 26

scarce fat storing cells that lie outside the endothelial cells store vitamin a they responds to a variety of insults by making collagen and causing cirrhosis

Question 27

what does the sinusoidal wall provide for

Answer 27

blood cleansing - eg of gut toxins haemopoiesis - blood cell component formation bringing plasma into intimate contact with the hepatic cells for metabolic functions ( storage, transformations, syntheses, regulation of plasma concentrations, detoxification, the production of bile, assisting defence by producing acute-phase proteins)

Question 28

what are hepatocytes

Answer 28

main functional cells of the liver, 80% of the mass of the liver is hepatocytes

Question 29

how are hepatocyes arranged

Answer 29

plates that anastomose with one another cells are polygonal in shape and their sides are in contact with other sinusoids (sinusoidal face) or neighbouring hepatocytes (lateral faces)

Question 30

what forms bile canaliculi

Answer 30

lateral faces of hepatocytes microvilli are present abundantly on sinusoidal faces, but project sparsely into bile canaliculi

Question 31

what do hepatocyte nuclei look like

Answer 31

distinctly round, with one or two prominent nucleoli, a majority of cells have a single nucleus, but binucleate cells are common

Question 32

features of hepatocytes

Answer 32

ribosomes on outer membrane extensive granular ER smooth er for dteroid hormone and cholesterol metabolism, lipids taken in processed and secreted many mitochondria golgi body lying near the canaliculus lysosomes to help form bile lipofuscin, ageing pigment

Question 33

what can cause cirrhosis

Answer 33

too much alcohol paracetamol overdose

Question 34

what is bilrubin

Answer 34

gives bile its green colour breakdown product from old RBCs

Question 35

function of pancreas

Answer 35

secretes insulin to regulate blood sugar levels

Question 36

what is the function of the liver

Answer 36

toxins go into the liver and with help from nutrients they go through a number of processes to break them down, make toxins that are fat-soluble water-soluble, eliminated via the gall bladder, goes to kidneys or becomes bile and then becomes urine

Question 37

how do stellate cells cause cirrhosis

Answer 37

produce collagen that seal the fenestrate cells, causes pressure in the sinusoids to increase, this causes collagen to go back into the portal triangle, hepatocytes then start to die off

Question 38

what does bile do

Answer 38

assists in the breakdown of fat emulsification of fat secondary bile salts are formed from breaking down bacteria primary bile salts are formed in the liver

Question 39

what is glucose metabolism

Answer 39

downregulates high blood sugar using insulin upregulates low blood sugar using glucagon

Question 40

bilirubin metabolism

Answer 40

haemolysis causes breakdown of haemoglobin to bilirubin

Question 41

what happens when hepatocytes die

Answer 41

enzymes are released into the bloodstream

Question 42

what is albumin responsible for

Answer 42

bloods ability to clot

Question 43

what does blockage of bile ducts cause

Answer 43

leads to cholestasis which leads to jaundice

Question 44

what cause blockage of bile ducts

Answer 44

gallstones, tumours of the head of the pancreas, ampullary lesions

Question 45

what is jaundice

Answer 45

symptom when the skin and eyes become yellow, associated with the accumulation of bilirubin in the skin

Question 46

what do LFTs do

Answer 46

bilirubin assesses anion transport