small inestine Flashcards
(103 cards)
1
Q
what is it made up of
A
duodenum
jejunum
ileum
2
Q
how is the surface area increased
A
mucosal folds called villi
3
Q
how is the surface area on villi increased
A
microvilli
4
Q
what does villus core contain
A
- blood vessels
- lacteals
- cells
5
Q
what are the spaces between the villi called
A
crypts of Lieberkuhn
6
Q
where are enterocytes formed
A
at the bottom of the crypts
7
Q
where do enterocytes migrate to
A
tops of the villi
8
Q
what is the blood supply to the small intestine via
A
branches of the superior mesenteric artery
9
Q
what are the terminal branches
A
end arteries
10
Q
are there anastomoses in small intestine
A
no
11
Q
what does the enteric nervous system coordinate
A
- absorption
- secretion
- blood flow
- motility
12
Q
what are the 2 plexus of the enteric nervous system
A
myenteric
submucosal
13
Q
how does the enteric nervous system communicate with the central nervous system
A
via the autonomic afferent and efferent pathways
14
Q
where do interstitial cells of cajal lie within
A
smooth muscle
15
Q
when does migrating motor complex occur
A
during fasting
16
Q
how many phases is the MMC
A
3
17
Q
how long does MMC cycle last
A
90 minutes
18
Q
what is MMC like after a meal
A
irregular lasts for 2-5 hours
19
Q
what cells secrete CCK
A
I cells
20
Q
what does CCK cause
A
gall bladder contraction and sphincter of oddi relaxation
21
Q
what cells secrete gastrin
A
G cells
22
Q
what does gastrin stimulate
A
acid secretion
23
Q
what cells secrete secretin
A
S cells
24
Q
what does secretion stimulate
A
pancreatic bicarbonate secretion
25
what releases glucagon
alpha cells
26
what does glucagon do
opposes insulin in blood glucose control
27
what cells secrete VIP
enteric nerves
28
what cells secrete GIP
K cells
29
what does GIP cause
greater insulin release by islets
30
what cells release glucagon-like peptide-1
L cells
31
what does GLP1 cause
insulin synthesis
inhibits glucagon secretion and gastric emptying
32
what cells release pancreatic polypeptide
PP cells
33
what does pancreatic polypeptide cause
inhibits pancreatic and biliary secretions
34
what cells secrete peptide YY
L cells
35
what does peptide YY do
inhibit pancreatic exocrine secretion
reduces food intake and appetite
36
what does motilin do
increase gastric emptying and small bowel contraction
37
what does ghrelin do
stimulate appetite, increase gastric emptying
38
what does obestatin do
opposes ghrelin
39
what does oxyntomodulin do
inhibit appetite
40
what cells secrete somatostatin
D cells
41
what does somatostatin do
inhibit secretion and action of most hormones
42
what cells secrete insulin
pancreatic beta cells
43
what does insulin do
increases glucose utilisation
44
what do epithelial cells of small bowel form
physical barrier that is selectively permeable to ions
45
what cells produce protease and disaccharides
intestinal cells
46
what organ produces lipase
pancreas
47
does simple diffusion require energy
no
48
when does simple diffusion take place
when there is a concentration gradient
49
where is vitamin B12 absorbed
jejunum
50
what kind of concentration gradient does facilitated diffusion need
that down a concentration gradient
51
example of facilitated diffusion
fructose transport
52
what is sodium/glucose transporter called
SGLT1
53
what is SGLT1 powered by
energy from the flow of Na+ ions
54
how does glucose leave the cell
through GLUT 2
55
where is GLUT2
basolateral membrane
56
what do dietary carbohydrates consist mainly of
starch
57
what is starch
polysaccharide
58
what must starch be converted to for absorption
monosaccharide
59
what is polysaccharide breakdown catalysed by
salivary amylase
60
what are the breakdown products of starch
maltose and maltotriose
sucrose
lactose
61
what is dietary protein digested by
pancreatic proteolytic enzymes
62
what is dietary protein broken down into
amino acids and peptides
63
what does dietary fat consists of
triglycerides mainly
| some cholesterol and fat soluble vitamins
64
how is fat emulsified
by mechanical action in the stomach
65
what does bile do
solubilise fat and promote hydrolysis of triglycerides
66
what is it called when there is a cluster of bile acids, phospholipids and products of fat digestion
mixed micelles
67
what is trapped in the centre of a micelle
hydrophobic monoglycerides, fatty acids and cholesterol
68
what do unabsorbed lipids do to gastric emptying
delay it via peptide YY to allow more time for absorption
69
what are medium chain triglycerides transported via
portal vein
70
what is the absorption of water and electrolytes coupled with
monosaccharides, amino acids and bicarbonate
71
what does commensal bacteria maintain
the integrity of the small bowel
72
what makes up the physical defence
- mucus layer
- continous shedding of surface epithelial cells
- physical movements of luminal contents
- colonisation resistance
73
what cells secrete lysosomes and phospholipase A2
paneth cells at the base of crypts
74
what cells secrete trefoil peptides
goblet cells
75
what is the principal mucosal antibody
IgA
76
how does IgA mediate mucosal immunity
agglutinating and neutralising pathogens in the lumen
77
what is IgA secreted from
immunocytes in the lamina propria
as dimers
78
how are antigens from the bowel transported by
M cells and dendritic cells
79
what do activated B cells produce
IgA
80
what does lamina propria contain mostly
CD4
81
what are most common symptoms of small bowel disease
- diarrhoea
- steatorrhoea
- abdominal pain
- weight loss
- nutritional defences
82
when does steatorrhoea occur
when stool is fat
83
what do stools look like in steatorrhoea
pale, bulky and offensive and float leaving a fatty film on the water
they are difficult to flush away
84
what is weight loss due to
anorexia
occurs because of malabsorption
85
what are nutritional defences of
- iron
- vitamin B12
- folate
86
what does nutritional deficiencies lead to
anaemia
87
what does vitamin K deficiency cause
bruising
88
what does calcium deficiency cause
tetany
89
what does vitamin D deficiency cause
osteomalacia
90
what symptoms can multiple deficiencies cause
- stomatitis
- sore tongue
- aphthous ulceration
91
what deficiency can occur in Crohn's
vitamin B12
92
what disease of small intestine cause malabsorption
- coeliac disease
- dermatitis herpetiformis
- tropical sprue
- Whipple's disease
- radiation enteropathy
- parasite infestation
93
examples of anaerobic bacteria
anaerobes
e.g. bacteroides
94
what's more abundant anaerobic or aerobic
anaerobic
95
what is function of the gut microflora
fermentation of non-digestible dietary residues into short chain fatty acids
96
what does bacteria initiate
vitamin K production
97
is the upper part of the intestine sterile
| TRUE or FALSE
true
98
what bacteria does the terminal ileum contain mainly
e.coli
99
what does a bacterial overgrowth occur with
stricture or diverticulum
100
what are clinical features of overgrowth
- diarrhoea
| - steatorrhoea
101
why does steatorrhoea occur with bacterial overgrowth
conjugated bile salt deficiency
102
why can B12 deficiency occur with bacterial overgrowth
bacteria cna metabolise vitamin B12 and interfere with its binding to intrinsic factor
103
how to treat bacterial overgrowth
antibiotics such as metronidazole, tetracycline or ciprofloxacin
