Quick GI/ Liver flashcards
(115 cards)
1
Q
oral phase of swallowing
A
tongue presses against hard palate
bolus passes into oropharynx
soft palate lifts to close nasopharynx
voluntary
2
Q
pharyngeal phase of swallowing
A
tongue seals off oropharynx
nasopharynx closed
epiglottis prevents aspiration by swinging down
pharynx widens and shortens - longitudinal muscles
3
Q
oesophageal phase of swallowing
A
LES relaxes
4
Q
what do mucous cells produce?
A
mucin
5
Q
where is vitamin B12 absorbed?
A
terminal ileum
6
Q
what do chief cells produce?
A
PEPSINOGEN!
7
Q
what do these cells produce, and what is the result?:
ECL cells
G cells
D cells
A
ECL
- histamine
- stimulates HCl secretion
G
- gastrin
- stimulates HCl and histamine
D
- inhibits HCl secretion
8
Q
mucosal protective mechanisms
A
alkaline mucus on luminal surface
tight junctions between epithelial cells
rapid replacement of damaged cells by stem cells in base of gastric pits
feedback loops regulate HCl secretion
9
Q
causes of peptic ulcers
A
NSAIDS
H Pylori
gastrinoma
chemical irritants e.g alcohol, bile salts
10
Q
which nerve mediates cephalic phase of digestion?
A
vagus
11
Q
what mediates gastric phase of digestion
A
vagus
gastrin
12
Q
volume of empty and full stomach
A
50 ml
1500ml
13
Q
what increases strength of gastric contractions?
A
gastrin
stomach distension
14
Q
what decreases strength of gastric contractions?
A
duodenal distension
low duodenal pH
increase in duodenal fat/ osmolarity
an increase in sympathetic stimulation
decrease in parasympathetic stimulation
15
Q
where are entrogastrones released?
A
duodenum
16
Q
BMI measurement
A
weight / height2
kg/m2
17
Q
BMI ranges
A
under 18.5 = underweight
18.5 - 25 = normal
25 - 30 = overweight
30 - 40 = obese
over 40 = morbidly obese
18
Q
normal BMR
A
24kcal/kg/day
19
Q
increase BMR
A
male
pregnangy
hyperthyroidism
exercise
20
Q
decrease BMR
A
female
malnutrition/ starvation
hypothyroidism
21
Q
how are fat soluble vitamins absorbed?
A
with fat in micelles
ileum
22
Q
where are water soluble vitamins absorbed?
A
B and C
but not B12
23
Q
where and how is B12 absorbed?
A
with intrinsic factor in terminal ileum
24
Q
function of vitamin A
A
cellular growth and differentiation
vision
lymphocyte production
25
sources of vitamin A
liver
dairy
oily fish
26
function of B12
erythrocyte formation
DNA synthesis
27
source of B12
eggs
milk
meat
fish
28
consequence of B12 deficiency
pernicious anaemia
29
function of vitamin C
collagen synthesis
antioxidant
30
source of vitamin D
UV light
fish oils
egg yolk
31
sources of vitamin E
nuts
seeds
32
symptoms of vitamin E deficiency
muscle weakness
retinal degeneration
33
source of vitamin K
bef
liver
leafy green veg
34
protein digestion
small intestines
- protein to polypeptides
SI
- polypeptides to endopeptidases (trypsin, chymotrypsin, elastase) by pancreatic endopeptidases
final digestion
- endopeptidases to amino acids by exopeptidases
- aminopeptidases on luminal membranee of epithelial cells
- also intracellular peptidases
35
how much water passes through GI tract per day?
9L
36
water from
food and drink
saliva
gastric secretions
bile
pancreatic secretions
intestinal secretions
colonic mucous secretions
2L
1.5L
1.5L
0.8L
0.8L
2L
0.2L
37
where does most water absorption occur?
small intestine - 80%
only 1.5L enters large intestine
38
what percentage of fluid is reabsorbed?
98%
39
how is sodium absorbed?
active transport
cotransport with glucose, amino acids
water follows with sodium
40
how is potassium absorbed?
passive diffusion
41
how is Cl- absorbed
exchanged with bicarbonate - active transport
42
liver embryology
foregut
begins forming week 3
hepatocytes derived from endoderm (like all foregut derivatives)
start processing bile at week 12
mesenchymal tissue and Kuppfer cells arise from mesoderm
43
function of foetal liver
haematopoeisis
cells migrate to bone marrow
44
hepatic diverticulum
liver cranially
gallbladder caudally
45
functional unit of liver
lobule
hexagonal
- central vein
- portal triad branches at each corner
46
is the sinusoid fenestrated?
sinusoid is fenestrated
47
what separates sinusoid and hepatocytes
space of Diesse
48
sinusoid lining
specialised endothelial cells
Kupffer cells
49
junctions in bile canaliculi
tight junctions, gap junctions, desmosomes
50
how is bile pumped towards bile duct?
actin filament
51
what does liver store?
vitamins
- fat soluble ones
- 3-5 year supply of non-fat soluble B12
minerals
- iron
- copper
glycogen
- 100g
- 12h supply
52
function of copper
RBC formation
53
copper transport
in plasma bound to ceruloplasmin
54
how much glycogen stored?
100g
12 hours supply
55
which types of protein does liver produce?
plasma proteins
clotting proteins
complement proteins
56
plasma protein examples
albumin, fibrinogen, globulin
57
which clotting factors are not made in liver?
3,4,8
58
function of complement proteins
innate immunity
59
albumin functions
oncotic pressure
transport large hydrophobic molecules
60
xenobiotic
foreign chemicals not normally found or produced in the body and cannot be used to produce energy
61
phase 1 reactions
transformation of substance from one type to another
oxidation/ hydrolysis reaction
adds -SH or -OH
.g cytochrome p450
62
phase 2 reactions
glucuronidation - adds glucuronic acid
conjugation - adds chemical group to substance
excretion (often in bile/urine)
63
UDPGT
glucuronyl transferase
- liver enzyme. It changes bilirubin into a form that can be removed from the body through the bile.
64
aim of phase 1 and 2 reactions
transform substance to be less toxic
more water soluble so it can be excreted
2 different ways of doing this
65
glucose alanine cycle purpose
move proteins from muscles to liver when glycogen is low
66
what can be used to measure liver health?
ALT
alanine aminotransferase
67
glucose alanine cycle
excess alanine transferred to liver and converted to pyruvate (transamination)
pyruvate is used to produce glucose in gluconeogenesis
glucose enters blood and is used by muscles (glycolysis)
- also removes excess ammonia
glutamate to ammonium by oxidative deamination
dissociates to ammonia
converted to urea for urea cycle
68
urea cycle function
remove excess nitrogen
ammonia converted to less toxic urea
69
urea cycle
arginine (from diet or protein breakdown) + arginase --> ornithine + urea
ornithine + CO2 + ammonia --> citrulline
citrulline + ammonia --> arginine
70
only product of urea cycle
urea
71
why must ammonia be excreted?
neurotoxic - crosses bbb
would require lots of water to excrete - dehydration
very water soluble
72
lipid metabolism
lipids + bile salts --> micelles
micelles constantly break and reform
lipids + pancreatic lipase --> glycerol and fatty acids
fatty acids absorbed by enterocytes and link to form triglycerides
triglycerides combine with proteins to form chylomicrons in Golgi
chylomicrons enter lacteal and are transported away from intestine to liver
VLDL transport lipids from liver into blood to adipose tissue
triglycerides diffuse into adipocytes for storage
73
where are LDLs made?
plasma
cholesterol delivery to all body cells
74
where are HDLs made?
liver
removes excess cholesterol from blood and tissues via excretion in bile
75
where are VLDLs made?
hepatocytes
triglyceride delivery from liver to adipocytes
76
fatty acid beta oxidation
catabolism of fatty acids to produce energy
in mitochondria of hepatocytes
each cycle shortens fatty acid chains by 2 carbons, continues until only 2 carbons remain
if odd number of chains, e.g 3C, cannot be oxidised further
leads to production of CO2 and ATP via Krebs
2 carbons removed as acetyl CoA is 2C
dduring every round, 2 carbons are cleaved to form acetyl CoA
77
what is in bile
bile salts
phospholipids
bicarbonate
cholesterol
bile pigments e.g bilirubin
78
how is bile concentrated in gallbladder?
microvillous epithelial cells
rugae
79
bilirubin metabolism
haem converted to biliverdin and Fe2+ by haem oxygenase
biliverdin to unconjugated bilirubin by biliverdin reductase
unconjugated bilirubin transported to liver by albumin
in the liver, unconjugated bilirubin is converted to conjugated bilirubin by glucuronyl transferase (glucuronidation by UDPGT)
conjugated bilirubin enters duodenum in bile
conjugated bilirubin is converted to urobilinogen by colonic bacteria
some urobilinogen is reabsorbed into blood, to liver, to urobilin
urobilin is recycles to bile or excreted by kidneys - yellow urine
most is oxidised to stercobilin by bacteria for excretion - brown faeces
80
what carries out glucuronidation?
UDPGT
81
pancreatic embryology
originates as 2 buds
dorsal bud
- neck, body, tail, part of head
ventral bud
- ucinate process, part of head
dorsal and ventral buds undergo clockwise rotation
pancreas sits in C shape of duodenum
exocrine and endocrine cells - endoderm, foregut derivative
mesenchymal tissue - mesoderm
insulin secretion at week 20
82
pancreatic histology
lobulated connective tissue that stains dark
lighter stained circular cells that lack lumen are islets of langerhans (endocrine)
83
how are beta cells stained?
blue by aldehyde fuchsin
84
where are delta cells and what do they produce?
in pancreas
somatostatin
85
other hormones produced by pancreas
pancreatic polypeptide
vasoactive intestinal polypeptide
substance p
serotonin
86
function of islets
endocrine
87
function of tissues surrounding islets
exocrine
88
terminal secretory units
acini
pyramidal cells arranged in a circle without visibe lumen
89
pancreatic secretion pathway
acini, interlobular ducts, pancreatic ducts, pancreatic sphincter, sphincter of Oddi
90
lining oof pancreatic ducts
simple columnar epithelia
91
exocrine pancreas
acini of pancreas --> digestive enzymes as zymogens
released via pancreatic duct to duodenum
acini are exocrine to duodenum (enzymes)
92
endocrine pancreas
islets of langerhans produce insulin, glucagon, somatostatin
to regulate glucose
islets are endocrine to blood (hormones)
93
is most pancreas endocrine or exocrine?
exocrine
94
what activates zymogens?
enterokinase on brush border
95
pancreatic juice
amylase - starch to maltose
lipase - triglycerides to fatty acids
endopeptidase - peptides to amino acids
nuclease - DNA to nucleosides
bicarbonate ions neutralise stomach acid
96
what stimulates bicarbonate release from pancreas?
stimulated by secretin
bicarbonate secreted into duct lumen via Cl-/ HCO3- exchanger on cells lining ducts
Cl- recycled back into lumen by CFTR channel
97
cells in endocrine pancreas
alpha, beta and delta
delta = somatostatin
- inhibit exocrine secretions of pancreas
- reduce gastric emptying
98
main enzyme required in phase 1 detoxification reactions
cytochrome P450
99
urea cycle
in cytosol and mitochondria
100
which mesenteries does the foregut have?
midgut
hindgut
dorsal and ventral
dorsal
ventral
101
gag reflex
afferent ticking - glossopharyngeal
efferent response - motor vagus
102
what passes through parotid gland?
facial
external carotid
retromandibular vein
103
submandibular secretions
mixed serous and mucus
wharton's duct
serous acini form crescents around mucous acini
facial
104
parotid gland
serous
stensens duct
105
sublingual
mucus
whatrons duct
anterior to submandibular
106
cells in cardia
foveolar - mucus
107
cells in fundus
parietal
chief
ECL
108
cells in body of stomach
G cells
109
duodenal cells
D - somatostatin
I - choleocystokinin
S - secretin
110
action of gastrin and histamine
more H+/K+ ATPase pumps
111
enterogastrones
secretin and CCK
112
effect of secretin
stimulate somatostatin
inhibit gastrin
113
gastric embryology
week 4
trilaminar disc folds medially and horizontally
endoderm fuses to form primitive gut tube
end of week 4
- oropharyngeal membrane ruptures
week 7
- cloatal membrane ruptures
114
midgut and hindgut development
longation
herniation
rotation
retraction
fixation
115
foregut development
week 4 - fusiform dilation in primitive gut tube
week 7 - 90 degree clockwise longitudinal rotation creates lesser sac
week 8 - ventrodorsal rotation - curves up
