GI - physiology Flashcards
(289 cards)
1
Q
what regulates gastric emptying
A
pyloric sphincter
2
Q
what regulates flow from ileum to caecum
A
ileocaecal sphincter
3
Q
what opens the ileocaecal sphincter and what closes it
A
ileal distension opens
proximal colon distension closes it
4
Q
what 2 spinchters are skeletal muscle
A
upper oesophageal
external anal
5
Q
how does vomiting cause reflux of gastric and duodenal contents
A
relaxes pyloric sphincter
6
Q
what causes gastrooesophageal reflux
A
lower oesophageal sphincter not closing properly
7
Q
from what does the exocrine pancreas secrete digestive enzymes
A
acinar cells
8
Q
from what does the exocrine pancreas secrete aqueous salt solution
A
duct cells
9
Q
what is motility
A
mechanical activity mostly involving smooth muscle
10
Q
what is digestion
A
biochemical breakdown of complex foodstuffs into smaller absorbable units
11
Q
what is absoprtion
A
transfer of absorbable products of digestion from digestive tract to blood or lymph
12
Q
how are slow waves in the stomach, small intestine and large intestine spread
A
gap junctions
13
Q
what are the pacemaker cells of the gut called
A
interstitial cells of cajal
14
Q
what causes the upstroke in the AP of ICC
A
Ca influx
15
Q
what determines the basic electrical rhythm of the GI tract
A
slow waves
16
Q
where are tonic contractions in the GIT
A
sphincters
17
Q
what is colonic mass movement
A
powerful sweeping contraction that forces faeces into the rectum - few times a day
18
Q
PS cranial outflow is via what nerve
A
vagus
19
Q
PS sacral outflow is via what nerve
A
pelvic nerves
20
Q
where do parasympathetic nerves synapse
A
post ganglionic neurones are intrinsic to ENS
21
Q
where do sympathetic nerves synapse
A
prevertebral ganglia
22
Q
what is an example of a local reflex reaction
A
peristalsis
23
Q
what is a local reflex reaction
A
sensory neurone synapses with interneuron at the myenteric or submucosal plexus
24
Q
where does the synapse occur in a short reflex
A
prevertebral ganglia
25
what is an example of an inshort reflex
intestino-intestinal inhibitory reflex
| over distension in one area of intestine causes relaxation in rest of intestine
26
what is the gastrocolic reflex
strong peristalsis in colon triggered by meals
27
what is the defection reflex
triggered by rectal distension
28
where does the synapse occur in a long reflex
dorsal motor nucleus of the vagus in the medulla oblongata
29
What is an example of a long reflex
Gastroileal reflex
30
what is the gastroileal reflex
when food enters stomach causing vigorous mechanical activity to occur - causes increased motility in the ileum and the opening of the ileocaecal valve to clear previous food remnants from the small intestine
triggers segmentation of ileum through release of gastrin
31
what is peristalsis
orderly wave of contraction to push food distally
32
what triggers peristalsis
distension of gut wall
33
what happens to the muscle behind the food bolus in peristalsis (propulsive segment)
circular muscle contracts - ACh + substance P
| longitudinal muscle relaxes - VIP and NO
34
what happens to the muscle infront of the food bolus in peristalsis (receiving segment)
circular muscle relaxes (VIP and NO)
| longitudinal muscle contracts (ACh + substance P)
35
when does peristalsis occur
in small intestine between meals
36
what is the name of the strong peristaltic contraction passing from the pyloric sphincter to the ileocaecal valve that clears the small intestine
Migrating motor complex/housekeeping mother reflex
37
what triggers the migrating motor reflex
hormone motilin
38
what suppresses the migrating motor reflex
gastrin
| CCK
39
what is the term for rhythmic contractions of circular muscle layer that mixes and divides luminal contents
segmentation
40
in segmentation how many points of circular muscle contraction are there
2
41
what is the name of the lymphoid tissue on the side of the pharynx
palatine tonsils
42
what reflex causes the jaw to open
masseteric
43
what reflex causes the jaw to close
digastric reflex
44
stimulation from pressure from food bolus gets ----- receptors to send -------- -------- to the swallowing centre in the ------
pharyngeal receptors
afferent impulses
medulla
45
what happens to the larynx when you swallow
elevates
46
what happens to the epiglottis when you swallow
tilts
47
what happens to the vocal cords when you swallow
close across larynx opening
48
what happens to the respiratory centre in brain (medulla oblongata) when you swallow
inhibited
49
what happens to the upper oesophageal sphincter when food enters oesophagus
closes
50
what happens in food becomes lodged during swallowing
local pressure receptors stimulate a second wave of peristalsis more forceful than the first and increase saliva secretion
51
what gland produces the most saliva
submandibular
52
where are the parotid glands
over masseter, below ears
53
what kind of mucus do sublingual glands produce
thick viscous
54
what 2 nerves control the parasympathetic innervation of saliva production
facial and glossopharyngeal
55
```
what is the function of the following saliva components
lysozyme
lactoferrin
IgA
amylase
Bicarbonate
```
antibacterial
lysozyme
lactoferrin
IgA
digest carbohydrates
amylase
neutralise acid
Bicarbonate
56
what pH is the oral cavity
alkaline
57
what is the functional unit of a salivary gland
salivon
58
from what does primary secretion of saliva occur and what is it composed of
acinus cells in a salivon
primary secretion with Na K Cl and HCO3 - similar to plasma
+ mucus and amylase
59
what are the 2 types of acinar cell
serous - alpha amylase
| mucous - thicker
60
how do duct cells modify saliva
remove Na+ and Cl-
add K and HCO3
no movement of water
61
true false
| as saliva flow rate increases HCO3 content decreases
false
| as saliva flow rate increases HCO3 content also increases
62
what is the simple saliva reflex
saliva increased in response to food in mouth - pressure receptors in mouth
63
what is the conditioned (learned) saliva reflex
saliva increased in response to stimulus that suggests food is coming
64
where do afferent impulses travel in the simple reflex
salivary centre in medulla
65
where do afferent impulses travel in the conditioned reflex
activates cerebral cortex which activates salivary centre in medulla
66
what kind of stimulation produces
large volume
enzyme rich
watery saliva
parasympathetic
67
what kind of stimulation produces
small volume
mucus rich
thick
sympathetic
68
what receptors are responsible for PS saliva production
M3
69
what receptors are responsible for S saliva production
B1
70
what is retropulsion
process by which food in the body of the stomach is propelled forward by peristaltic waves - chyme hits the pyloric sphincter and bounces back - churning
71
true/false
| fat in the duodenum can delay stomach emptying
true - time needed for digestion and absorption in small intestine
72
what are enterogastrones
inhibit stomach contraction and delay emptying of stomach
CCK
Secretin
73
true/false
| alkali in the duodenum can delay stomach emptying
false
acid in the duodenum delays stomach emptying - time required for neutralisation of gastric acid by bicarbonate secreted from the pancreas
74
true/false
| hypertonicity in the duodenum delays stomach emptying
true
| products of CHO and protein digestion osmotically active and draw water into the small intestine
75
what does acid in the duodenum stimulate the release of
secretin
76
what does fat in the duodenum stimulate the release of
CCK
77
what is the name of the reflex which delays stomach emptying due to signal from duodenum that it has enough chyme
enterogastric reflex
78
what are the 3 secreting cells within the pyloric gland area of the antrum of the stomach
D cells
G cells
Mucosal cells
79
what do D cells secrete
somatostatin
80
what does somatostatin do
inhibits the release of gastrin - inhibits HCl secretion
81
how is somatostatin release inhibited
cholinergic stimulation
82
what do G cells secrete
gastrin
83
what does gastrin do
stimulates HCl and histamine secretion
84
what do mucosal cells secrete
mucous to protect mucosa from ulcer formation - prevents pepsin/HCl reaching apical surface of cells
85
what are the 3 secreting cells within the oxyntic mucosa of the funds and body of stomach
chief cells
enterochromaffin-like cells
parietal cells
86
what do chief cells secrete
pepsinogen (inactive precursor of pepsin)
87
what do enterochromaffin-like cells secrete
histamine
88
what does histamine do
stimulates HCl secretion from parietal cells
89
what receptors work on Enterochrommaffin cells and what does their stimulation cause
M1 receptors
| M1 stimulation causes increased histamine secretion
90
what do parietal cells secrete
HCl and intrinsic factor
91
what does intrinsic factor do
binds to vitamin B12 which allows its absorption in the terminal ileum
92
CO2 and H2O combine under enzyme --------- which dissolves to form -- and --
- --- is transported out of the cell via antiporter in exchange for --- which is driven out into the ------
- - is secreted into canaliculus via proton pump and combines with -- to form ---
CO2 and H2O combine under enzyme carbonic anhydrase
which dissolves to form H+ and HCO3
HCO3 is transported out of the cell via anti porter in exchange for Cl
Cl is driven out into the canaliculus
H+ is secreted into the canaliculus via proton pump where it combines with Cl to form HCl
93
what receptors are present in parietal cells and what happens when they are stimulated
M3 receptors
| M3 stimulation increases HCl secretion
94
parietal cells express PGE2 which inhibits/stimulates secretion
inhibits
95
where in parietal cells are the ion ATPase pumps when resting
within cytoplasmic tubulovesicles
96
where do PPs move in response to secretogogues
active state in apical membrane of parietal cell
97
what are the 3 phases of gastric secretion
cephalic
gastric
intestinal
98
when is the cephalic phase of gastric secretion
before food enters the stomach
99
during the cephalic phase how does the vagus nerve activate parietal cells
- release ACh to directly activate parietal cells
- release of histamine from ECL cells which locally activates parietal cells
- release of GRP (gastrin releasing peptide) causing release of gastrin into systemic circulation activating parietal cells
100
when is the gastric phase of gastric secretion
when food is in the stomach
101
during gastric phase amino acids cause what
stimulate G cell production of gastrin
102
during gastric phase food buffering pH inhibits what
D cells
103
during gastric phase acid secretion is caused by what
distension of stomach activating mechanoreceptors
104
when is the intestinal phase of gastric secretion and what happens
when good has left stomach
| gastric secretions are switched off - secretin, CCK, somatostatin
105
what is pepsinogen activated by
HCl
106
enteric neurones release ACh which acts on D cells to
decrease somatostatin
107
enteric neurones release ACh which acts on ECL cells to
increase histamine
108
enteric neurones release GRP which acts on
G cells
109
increase in gastrin in the blood increases/decreases parietal cell secretion
increases
110
Full activity of pancreatic lipase requires
- what cofactor
- what pH
- what metal ion
- 2 other things
- colipase cofactor
- alkaline
- Ca2+
- bile salts and fatty acids
111
pancreatic lipase is secreted from -- cells of pancreas in response to --- which also ---------
pancreatic lipase is secreted from acinar cells of pancreas in response to CCK which also stimulates bile flow
112
how is a suitable pH for pancreatic lipase achieved
HCO3 in pancreatic juice
113
where does pancreatic lipase hydrolyse the TAGs
1 and 3 position
114
digestion by pancreatic lipase gives
monoglyceride + 2 FAs
115
what are 2 additional lipases
carboxyl ester hydrolase
| phospholipase A2
116
what stops the cephalic phase
decreased vagal nerve activity due to
- cessation of eating and stomach emptying
- pain
- nausea
- negative emotions
117
at the end of the gastric phase what happens to the pH of the antrum
falls
118
is somatostatin released from D cells at the end of the gastrin phase
yes - this decreases gastrin secretion
119
what is continually secreted by gastric mucosa to reduce histamine and gastrin-mediated HCl secretion
Prostaglandin E2 (PGE2)
120
ranitidine and cimetidine are examples of what drug
| how are they administered?
H2 histamine receptor competitive antagonists
| orally
121
Omeprazole is an example of what kind of drug
| how is it administered
PPI
| oral OD
122
how do proton pump inhibitors work
modification of K+/H+ ATPase on the apical membrane of parietal cells
123
how do PPIs reach the secretory cannaliculi
absorbed from GI tract and delivered via systemic system
124
aspirin and ibuprofen are examples of what drugs
NSAIDs
125
what do NSAIDs block irreversibly
COX1 - increase HCl secretion
126
what does blockage of COX1 cause
decreased prostaglandins
127
what is the role of PGI2 and PGE2 in stomach
reduced acid secretion
increase mucus secretion
increase bicarbonate secretion
increase mucosal flow
128
what is given if using NSAIDs longterm
PGE1 analogue e.g. misoprostol
129
what does misoprostol do
inhibits basal and food stimulated gastric acid secretion
| maintains/increases secretion of mucus and bicarbonate
130
name 2 mucosal strengtheners
```
sucralfate (oral)
Bismuth chelate (oral) (also H.pylori toxic)
```
131
sucralfate increases...
mucosal blood flow
mucus
bicarb
prostaglandin production
132
what are the 2 subgroups of starch
amylose
| amylopectin
133
what is the structure of amylose
straight chain
| alpha-1,4 only
134
what is the structure of amylopectin
branched chain
| alpha-1,4 and alpha-1,6
135
what is more branched amylopectin or glycogen
glycogen
136
sucrose and lactose are
disaccharides
137
sucrose is made up of
glucose and fructose
| alpha-1,2 links
138
lactose is made up of
glucose and galactose
| beta-1,4 links
139
glucose and fructose are
monosaccharides
140
in alpha/beta glucose the hydroxyl group is above/below C1
alpha - below
| beta - above
141
what enzymes cause intraluminal hydrolysis of polysaccharides to oligosaccharides (sucrose and lactose)
salivary a-amylase
| pancreatic a-amylase
142
what enzymes cause brush border hydrolysis of oligosaccharides to monosaccharides
lactase
maltase
sucrose-isomaltase
143
maltose is made up of
2 glucose
144
what is the rate limiting step of hydrolysis of CHOs
transport process
145
where does intracellular digestion occur
enterocytes
146
how do ions move between cells
paracellular - across epithelial tight junctions
147
true / false
| a-amylase can break a-1,4 INTERNAL linkages only and is therefore an endozyme
true
148
what enzyme breaks down lactose to glucose and galactose and what bonds are hydrolysed
lactase
| B-1,4
149
what is the rate limiting step of lactase action
hydrolysis of lactose
150
what enzyme breaks down sucrose to glucose and fructose and what bonds are broken
sucrase
| a-1,2
151
what enzyme breaks down a-1,6 bonds
isomaltase
152
how are glucose and galactose absorbed into enterocytes
secondary active transport
| SGLT1
153
what does facilitated diffusion by GLUT5 absorb
fructose
154
how do all monosaccharides exit the basolateral side of an enterocyte
facilitated diffusion by GLUT2
155
can ring or linear glucose be absorbed
ring
156
how are proteins digested to amino acids
luminal enzymes
| or to peptides by luminal enzymes then AA by brush border enzymes or intracellular hydrolysis
157
trypsin
chymotrypsin
elastase
are examples of what enzymes
endopeptidases - produce oligopeptides (2-6 AA)
158
procarboxypeptidase A and B are examples of what enzymes
exopeptidases - produce single AA
159
how many of the 7 AA absorption mechanisms are Na dependent
5 (secondary active transport)
160
AA transport mechanisms at basal side
- Na independent and mediate ---
- Na dependent and mediate --
3 Na dependent and mediate efflux
| 2 Na independent and mediate influx
161
how are oligopeptides transported across the apical membrane of an enterocyte
H+ dependent mechanisms (secondary active transport)
162
what is primary lactase deficiency
lack of lactase persistence allele (LP)
| - can happen to a varying degree due to polymorphisms
163
what is secondary lactase deficiency
lactose intolerance due to damage to proximal small intestine
164
what is congenital lactase deficiency
infants unable to break down lactose
165
undigested lactose causes
acidification of colon
increased osmotic load --> diarrhoea
food for microflora --> produce SCFAs, H, CO2 and methane
166
what is bile secreted in response to
CCK
167
Co-lipase is produced where
pancreas
168
why is collapse necessary
without it bile salts block access of lipase to lipid
169
where is bile stored and concentrated
gallbladder
170
what are the final products of lipid digestion stored in
mixed micelles - emulsified fat globule containing monoglyceride, FAs, phospholipid, bile salt and cholesterol
171
how do short and medium chain (-12C) FAs enter the villus capillaries
diffusion
172
what happens to LCFAs (12C+) and monoglycerides
resynthesised into triglycerides in the ER and incorporated into chylomicrons
173
what carries cholesterol across the enterocyte apical membrane
NCP1L1
174
how does cholesterol bound to NPC1L1 move around cell
myosin runners
175
what drug binds to NPC1L1 to prevent internalisation of cholesterol
ezetimibe
176
how does absorption of Ca2+ occur
```
passive transport (paracellular movement in whole small intestine)
active transport (transcellular movement through calcium channel in duodenum and upper jejunum)
```
177
what vitamin increases the expression of calcium channels
vitamin D
178
how is iron transported
transcellularly by metal transporter across epithelium of intestine
can also be absorbed through harm
179
what form is iron transported in
Fe2+
180
what vitamin stabilise the ferrous ion (Fe2+)
vitamin C
181
how is the ferrous ion absorbed
cotransporter - H+ ion coupled with its transport
| H+ dependent transport
182
how is iron stored
ferratin
183
how does ferrous ion leave enterocyte
ferroportin
184
what is released from liver when body iron levels get too high which negatively regulates ferroportin
hepcidin
185
how is haem transported
transcellularly by haem transporter
| taken up and degraded by haem oxidase
186
what is NCX1
transporter that couples exit of Ca2+ and entry of sodium in enterocytes
187
what does haptocorrin bind to
vitamin B12
188
where is haptocorrin produced
salivary glands, released in the stomach
189
what do pancreatic proteases digest in small intestine to release Vit B12
haptocorrin-B12 complex
190
what binds to B12 in small intestine to allow it to be absorbed in terminal ileum
intrinsic factor
191
what vitamins are incorporated into mixed micelles and passively transported into enterocytes
fat soluble ADEK
192
what joins the forming chylomicron
apolipoprotein apob48
193
how are water soluble vitamins absorbed
active transport - may be Na dependent
194
where is the sodium potassium chloride co-transporter (1 Na, 2Cl, 1 K enter cell)
basolateral side of enterocyte - build up intracellular conc of Cl so that it can move out apical side
195
how does Cl move out of apical side
CFTR channels
196
what illness causes CFTR channels to be overactive
cholera
197
cAMP, cGMP and Ca2+ ------ CFTR channels
up regulate
198
true/false
| SGLT1 Na/glucose channel is not affected by diarrhoea
true
199
what 2 Na transport systems occur throughout small intestine
Na/glucose
| Na/amino acid
200
luminal HCO3 stimulates what transport of Na - duodenum and jejunum
Na/H+
201
where does parallel Na/H and Cl/HCO3 exchange occur
ileum and colon
202
what Na channel is most important in the inter digestive period
Na/H Cl/HCO3
203
where are epithelial Na channels
distal colon
204
what hormone regulates epithelial Na channels
- opens them
- inserts more from intracellular vesicles into membrane
- increases synthesis of them and Na+/K+ ATPase
aldosterone
205
intracellular cAMP, cGMP and Ca2+ ---- absorption of NaCl through -----
decreases
| Na/H+ Cl/HCO3 exchange
206
what does E.Coli enterotoxin do
activates adenylyl cyclase which increases intracellular cAMP - reduced NaCl absorption - diarrhoea
207
does odansetron help motion sickness
no
208
what nerve regulates motion sickness
CN VIII
| vestibulocochlear - found in ear
209
what is the forceful propulsion of gastric contents out of the mouth
vomiting /emesis
210
where is the vomiting centre in the brain
medulla oblongata
211
during emesis the stomach oesophagus and sphincters are relaxed
true/false
true
212
during emesis the abdominal muscles and diaphragm are relaxed
false/true
false - contract to increase pressure
213
what do vagal efferents cause in the vomiting cycle
oesophagus shortens
stomach relaxes
small intestine retrograde contractions
214
toxic materials in the gut stimulate the release of what from ECL cells
serotonin
215
what receptors does serotonin work by
5HT3
216
the depolarisation of sensory afferent terminals in mucosa by serotonin via 5HT3 receptors causes what
vagal afferent AP discharge to vomiting centre in medulla
217
vagal vomiting-inducing afferent discharges are sent to ...
CTZ (chemoreceptor trigger zone)
| NTS (nucleus tractus solitaries)
218
what cranial nerve supplies stomach and small intestine in vomiting
CNX
219
true/false
| vestibular system signals to the vomiting centre through vestibular nuclei to vomiting centre then to CTZ
false
| vestibular systems signals to the vomiting centre through vestibular nuclei to CTZ and then to vomiting centre
220
what is a mallory weiss tear
tear in mucous membrane where oesophagus meets stomach
221
how does cancer therapy induce vomiting
induces release of 5-HT and substance P from ECL cells in gut
222
why would drugs with high dopamine activity cause nausea and vomiting
e.g. drugs used in parkinsons
dopamine D2 receptors are prevalent in the CTZ
223
how can antidepressants cause sickness
enhance 5HT function (5HT3 receptors in CTZ)
224
true/false
| the CTZ lacks an effective BBB so toxic materials in blood can stimulate it directly
true
225
what drug would be prescribed to suppress chemo radiation induced emesis and post op emesis
5HT3 receptor antagonist
226
how can the function of 5HT3 receptor antagonists be improved
addition of a corticosteroid and a NK1 receptor antagonist
227
what drug would be used to treat motion sickness/prophylaxis
Muscarinic ACh receptor antagonist e.g. hyoscine scopolamine (transdermal or PO) - direct inhibition of GI movement - can be seditive
Histamine H1 receptor antagonist - CNS depression and sedation e.g. cyclizine
228
what do all serotonin antagonists end in
-setron
229
what do dopamine receptor antagonists do
block dopamine D2 and D3 receptors in the CTZ
230
what has more unwanted effects - domperidone or metoclopramide
metoclopramide as it crosses the BBB
| both DRAs
231
what drugs are used for drug induced vomiting and vomiting in GI disorders
dopamine receptor antagonists
232
true/false
| DRA can be used in children
false
| avoid in children
233
what do NK1 receptor antagonists do
antagonism of substance P e.g. aprepitant
| used + 5HT3 receptor in chemo
234
when are cannabinoid receptor antagonists used
cytotoxic chemotherapy which is unresponsive to other anti-emetics
235
what are some side effects of cannabinoid receptor antagonists
drowsiness
dizziness
dry mouth
mood changes
236
CCK is produced from what cells
I cells of duodenum and jejenum
237
secretin is produced from what cells
S cells of duodenum
238
what does secretin in response to acid in the duodenal ileum cause
increased secretion of NaHCO3 from pancreatic duct cells
239
what is produced from M cells of duodenum and jejunum
motilin
240
what is produced from K cells of duodenum and jejunum
GIP
| gastric inhibitory peptide
241
what is produced from L cells
glucagon-like peptide-1 (GLP-1)
242
is gastrin produced from just the stomach
no
| stomach and duodenum
243
what 2 hormones report fat status to brain and increase in levels when more fat is stored
insulin and leptin
244
alpha islet cells produce
glucagon
245
beta islet cells produce
insulin
246
delta islet cells produce
somatosatin
247
what hormone added GLUT4 transporters to membrane to increase permeability for glucose
insulin
248
what are incretins
hormones that act upon beta islet cells of pancreas in feed forward way to stimulate release of insulin
249
give 2 examples of incretins
GIP
| GLP-1
250
when are incretins released
in response to chyme entering the duodenum
251
what cells produce ghrelin
Gr cells of gastric antrum and small intestine and pancreas
252
levels of gherkin ---- before a meal and ---- after
increase before a meal and decrease after
253
what cells in the pancreas secrete digestive enzymes
Acinar cells
254
---- cells in duodenum secrete ----- which is a brush borer enzyme that activates ----- to trypsin
mucosal cells in duodenum secrete enterkinase which is a brush border enzyme that activates trypsinogen to trypsin
255
what activates procarboxypeptidase to carboxypeptidase
trypsin
256
what exchanger sits in the apical membrane of duct cells of pancreas to allow transfer of alkaline solution into the lumen of small intestine
Cl/HCO3 exchanger
257
vagal stimulation of acinar cells mediates what stage of pancreatic secretion
cephalic
258
gastric distension which evokes a vasovagal reflex that results in PS stimulation of acinar and duct cells mediates what stage of pancreatic secretion
gastric
259
CCK ---- the secretion of digestive enzymes from acinar cells in pancreas
increases
260
what is xerostomia
dry mouth syndrome due to inadequate production of saliva
261
what is the name for the intermittent circular muscle contraction in the large intestine
haustra
262
in what direction does haustration cause food to move
oral - allow time for reabsorption
263
contraction of the tenai coli causes what
shortening of the colon
264
give an example of a time laxatives wouldn't be used
bowel obstruction
265
what is the mechanism of orlistat
inhibits pancreatic lipase to decrease triglyceride absorption in small intestine
266
what are some side effects of orlistat
abdominal cramps
diarrhoea
steatorrhoea
267
what are sulfasalazine, olsalazine and balsalazine examples of
aminosalicylates
268
what do aminosalicylates do
```
release 5ASA (5-aminosalicylic acid)
used in UC
```
269
where does the hepatic artery and the hepatic portal vein blood mix in the liver
sinusoids
270
what are the functional units of the liver
hexagonal lobules
271
in a liver lobule
blood flows --- through sinusoids towards central ----
bile flows --- through cannaliculi towards ----
blood flows inwardly through sinusoids towards central vein
| bile flows outwardly through cannaliculi towards bile duct
272
what membrane faces the cannaliculi
apical
273
what is the space of disse
pericellular plasma containing space between capillaries (sinusoid) and basolateral membrane of hepatocyte
274
what 3 cells are present in the space of disse
fenestrated endothelial cells
kuppfer cells - resident macrophages - remove bacteria and dead RBCs
Stellate cells - storage of vitamin A
275
what pathology can stellate cells cause
fibrosis and cirrhosis due to storage of collagen
276
what is the first stage of metabolism in the liver
1 - oxidation, reduction, hydrolysis - making the drug more polar therefore permitting conjugation
277
what is the second stage of metabolism in the liver
conjugation - adds endogenous compound to increase polarity
278
what is the fate of most bile entering the duodenum
reabsorbed in terminal ileum via secondary active transport
279
how do bile salts reach the cannaliculi
secreted from apical membrane of hepatocytes via active transport
280
what enzyme initiates the synthesis of primary bile salts from cholesterol
cholesterol 7-alpha-hydroxylase
281
what does the rate of synthesis of bile depend on
hepatic portal blood concentration of bile salts
| - high conc = low synthesis
282
what can be given for relief of biliary spasm in biliary colic
GTN or atropine
283
how do chylomicrons reach the LVA
thoracic duct
284
what metabolises chylomicrons once in the blood
lipoprotein lipase
285
what carries the free fatty acids and glycerol released by chylomicron degradation
albumin
286
what does a chylomicron remnant consist of
cholesterol and phospholipid
287
lesioning ventromedial hypothalamus
obesity
288
lesioning lateral hypothalamus
leanness
289
what makes up the small intestine in size order
duodenum - shortest
jejunum
ileum - longest
