liver and associated organs Flashcards
1
Q
how many lobes does the liver have and what’s the difference?
A
4 - there is no known difference
2
Q
what is the main functions of the liver?
A
- metabolism - control of synthesis and utilisation of carbohydrates, lipids and proteins
- secretory and excretory functions - particularly with respect to the synthesis of secretion of bile and detoxification
- vascular function - formation of lymph and the hepatic phagocytic system
3
Q
what are hepatocytes?
A
main functional cell of the liver
4
Q
what is glycogenesis?
A
when excess glucose is taken up by the liver and stored as glycogen
5
Q
what is glycogenolysis?
A
when blood glucose levels decline there is depolymerisation of glycogen to glucose
6
Q
what is gluconeogenesis?
A
when hepatic glycogen reserves are depleted, glucose is synthesised from amino acids and non-hexose carbohydrates
7
Q
what is the difference between brown and white adipose?
A
brown - lean
white - not so good
8
Q
how does lipid metabolism occur?
A
- involved in oxidation of fatty acids to supply energy for other body functions
- converts products of carbohydrate metabolism to fatty acids and lipids that can be stored in adipose tissue
- synthesise large quantities of cholesterol and phospholipids, some packaged with lipoproteins and available to rest of body
9
Q
how does protein metabolism occur?
A
- synthesises all the non-essential amino acids that don’t need to be supplied in the diet
- deamination of amino acids ( followed by the conversion of the non-nitrogenous parts to glucose or lipids)
- amine group is first converted to ammonia then to urea (excreted)
10
Q
what is transamination?
A
amine groups can be transferred to make new non-essential amino acids
11
Q
what protein does the liver not synthesise?
A
immunoglobulins
12
Q
what does albumin determine?
A
plasma oncotic pressure
13
Q
where is majority of the blood received from the liver by?
A
venous via hepatic portal vein
14
Q
what happens to larger water soluble molecules that can’t be filtered by the kidney?
A
the potentially harmful substances are taken up by the liver, metabolised and excreted in bile
15
Q
what are the two main functions of bile?
A
- bile acids are important for dig digestion and absorption of fats and fat soluble vitamins
- many waste products including bilirubin are secreted into bile and eliminated in faeces
16
Q
what are bile salts conjugated with?
A
glycine or taurine
17
Q
what does amphipathic mean?
A
contains both hydrophobic and hydrophilic faces
18
Q
what’s the role of bile in digestion?
A
- emulsification of lipid aggregates - bile salts have detergent action on dietary fat causing it to break down or be emulsified into droplets that lipases can act on
- solubilisation and transport of lipids in aqueous environment - bile salts are lipid carrie’s and solubilise lipids by forming micelles that remain suspended in water
19
Q
how is bilirubin excreted?
A
- RBCS are phagocytosed and harm is converted to bilirubin
- free bilirubin (stripped of albumin) is absorbed by hepatocytes and conjugated with glucuronic acid or sulfonate
- conjugated bilirubin is secreted into bile and metabolised by bacteria in intestine, for elimination in faeces
20
Q
what vitamin is required for gastrointestinal absorption from bile salts?
A
vitamin K (needed for production of clotting)
21
Q
where are digestive secretion from the liver and pancreas delivered through?
A
small intestine (duodenum and sphincter of oddi)
22
Q
how are cells that synthesise and secrete digestive enzymes arranged?
A
in grape-like clusters called acini
23
Q
where do secretions from acini flow?
A
out the pancreas through tree-like series of ducts
24
Q
what are two main secretions from the pancreas?
A
- digestive enzymes (eg. protease, lipase, amylase)
- can reduce into forms that can be absorbed
- bicarbonate
from epithelial cells in pancreatic ducts
critical for neutralising the acid coming into the small intestine from stomach
25
what is the most important stimulus for secretion?
3 hormones:
Cholecystokinin
Secretin
Gastrin
26
what is the role of cholecystokinin and where is it from?
from enteric endocrine cells in duodenum. binds to receptors on acicnar cells stimulating enzyme secretion
27
what is the role of secretin and where is it from?
from endocrine cells in the epithelium of the proximal small intestines. stimulates duct cells to secrete water and bicarbonate
28
what is the role of gastrin and where is it from?
secreted by the stomach and stimulates pancreatic acinar cells to secrete enzymes
29
where are sympathetic fibres from (liver innervation)
splanchnic nerves
30
where are parasympathetic fibres from (liver innervation)
vagus nerve
31
what effect does parasympathetic fibres have on the liver?
stimulates both exocrine and endocrine secretion
32
what effect does sympathetic fibres have on the liver?
predominantly inhibitory effect
33
what are the 4 main cell types in the islets of langerhams?
alpha - secrete glucagon
beta - secrete insulin
delta - secrete somatostatin
gamma - secrete pancreatic polypeptide
34
what is the gallbladders function?
storage, concentration, acidification and delivery of bile to small intestine
35
what is the anatomy of the gall bladder?
- Fundus: rounded portion
- Body: largest part
- Neck: tapers and becomes continuous with the cystic duct, leading to biliary tree
36
what is the mucosal fold in the neck of the gall bladder called?
hartmanns pouch
37
what is the common bile duct ?
joins the pancreatic ducts which empties into duodenum (controlled by sphincter of oddi)
38
what are the 3 layers of the wall of the gallbladder?
mucosa
muscularis external
adventitia
39
what delivers parasympathetic innervation to the gall bladder?
vagus nerve
40
what carries sympathetic and sensory fibres to gall bladder?
celiac plexus (solar plexus)
41
what does parasympathetic stimulation induce?
contraction and secretion of the gallbladder bile
42
what is the main stimulator of bile secretion?
cholecystokinin
43
what are cholesterol stones?
usually yellow-green making up 80% of gallstones
44
what are pigment stones?
smaller and darker and made of bilirubin
45
what does innate immunity involves or the liver?
- production of acute phase proteins
- nonspecific phagocytosis
- nonspecific cell killing
- disposal of waste molecules
46
what does adaptive immunity involvement of the liver include?
- deletion of activated T cells
- induction of tolerance to ingested and self antigens
- extrathymic proliferation of T cells
- disposal of waste molecules
47
what ligament separates the lobes?
falciform
48
where are sensory nerve endings in the liver?
glissons capsule
49
what does connective tissue from the glissons capsule extend as?
highly branched septae
50
what does each lobule have in the centre?
a central vein
51
what cells are hepatocytes?
epithelial cells
52
how many basal surfaces does hepatocytes have and where are they?
2 basal surface (with microvilli) on opposite end of the cell and each surface faces the blood
53
what is the surface that bile is secreted from?
apical surface
54
what does the lateral surface connect?
neighbouring hepatocytes
55
what is a sinusoid?
vascular space where blood is supplied and drains into central vein (deoxygenated and oxygenated)
56
what is the liver a prime site for ?
metastatic spread of cancer
57
where does the hepatic veins take processed blood?
vena cava
58
what is the portal triad?
hepatic artery, hepatic veins bile duct
59
how do bile ducts run through hepatocytes?
doesn’t touch the blood supply (runs opposite ways)
60
in sinusoids what does the endothelial layer contain?
large intercellular gaps allowing the passage of larger molecules, a further leak is allowed by gene stations that penetrate endothelial cells
61
what membrane is absent or discontinuous in sinusoids?
basement membrane
62
where does blood enter sinusoids from?
portal vein and hepatic artery
64
what is the space that plasma is filtered between endothelium and hepatocytes?
space of disse, fluid from this can drain into lymph nodes
65
what are kupffer cell?
- macrophage lineage found in the sinusoid
- express adhesion molecules that allow them to anchor to where they need to be on endothelial cells
66
what do kupffer cells contain?
red cell fragments and ferritin
67
what may kupffer cells be involved in?
final breakdown of damaged or aged red blood cells
68
what are ito(stellate) cells?
- found in space of disse
- primary storage site for hepatic fat and vitamin A
69
where are ito cells transported from the liver to?
the retina to form rhodopsin
70
what might ito cells become if continuously exposed to injury?
myofibroblasts and produce collagen, leading to fibrosis
71
what are dendritic cell?
plays important roles in liver immunity, autoimmunity and regulation of hepatic allograft acceptance
- important in maintaining homeostasis
72
what is the canaculli?
bile structure
73
how are hepatocytes arranged in?
plates with their basal surface facing the sinusoid
74
what are the apical faces held together to form?
canaliculi (first channel in biliary system)
75
how does hepatocytes reach the bile duct?
hepatocytes -> bile canaliculi -> canal of hering -> interlobar bile duct -> bile duct
76
where are the portal triads placed?
at each of the six corners of the hexagonal shape of the liver lobule
77
what is the liver acinus?
oblong/oval shaped and defined as the smallest function unit of liver
78
what is the short axis?
distance between portal triads at the border between neighbouring lobules
79
what is the long axis?
defined by line drawn between central veins closest to the short axis
80
what are the 3 zones of the liver acinus?
zone 1 - is closest to the short axis
zone 2 - between 1 and 3
zone 3 - furthest from short axis and closest to central vein
81
what is interpretation of zone 1 (periportal vein)
- first to receive oxygen, nutrients and toxins from blood
- first to show morphologic changes after bile duct occlusion
- last cells to die if circulation is impaired
- first cells to regenerate
82
what is zone 3 (perivenous or pericentral) interpretation
- most sensitive to hypoxia
- first to show ischaemic necrosis
- first to show fat accumulation - - last to respond to toxic substances
83
what is interpretation of zone 2 (intermediate zone)
provides overlap of two zones
responses are intermediate
84
what processes occur in zone 1 ?
oxidative metabolism
gluneogenesis
ureagenesis
bile fomation
85
what processes occur in zone 3?
glycogen synthesis
glycolysis
xenobiotic metabolism
86
upon activation of KC what does it release?
cytokines, prostanoides, nitric oxide and reactive oxygen species
87
88
what happens to the KC shape when activated?
becomes ruffled
89
what are the polarised phenotypes of KCs during immune response
M1 (pro-inflammatory)
M2 (alternative) - resolution and wound healing
90
what does dysregulation of inflammatory responses in KCs cause?
chronic inflammation of the liver
91
where are large KCs predominantly located?
periportal region of the liver acinus
92
what scavenger receptor does KC express?
Receptor CD163 which has been invoked in clearance and endocytosis of haemoglobin haptoglobin complexes
93
how much of bile acids secreted to the duodenum in are absorbed back into blood within the ileum?
95%
94
how often are bile salt molecules reused?
about 20 times, often two or three times during a single digestive phase
95
what are albumins in the liver?
synthesised by hepatocytes
maintains intravascular oncotic pressure
carries hormones, ions and medications
96
