Physiology Flashcards
(168 cards)
1
Q
3 main functions of saliva
+2 others
A
lubrication protection digestion (increases prior to emesis to neutralise facilitates infants suckling)
2
Q
In saliva: \_\_\_ buffer bacterial acids \_\_\_\_ prevents enamel demineralisation \_\_\_ coats teeth decreasing bacterial adherence \_\_\_ attacks bac cell wall \_\_\_ chelates Fe so bac can't grow \_\_\_ for immunity
A
HCO3 and PO4 and mucus buffer high Ca2+ for enamel protein coats teeth lysozyme attacks wall lactoferrin chelates Fe IgA immunity
3
Q
Enzymes in saliva and food they digest
A
α-amylase breaks α-1,4 bonds in carbs
lingual lipase for fats
4
Q
In saliva NA+, Ca2+,Cl-,I-,PO4 2- are in higher/lower concn than in plasma
A
lower concn in slaiva
5
Q
In saliva K+ and HCO3 - are in higher/lower concn than in plasma
A
higher concn in saliva
6
Q
As rate of saliva secretion increases: \_\_\_ increases (provides optimum pH for \_\_\_) and \_\_\_ decreases
A
HCO3- increases ; α-amylase (neutral/alkali)
K+ decreases
7
Q
4 organs that move with respiration
A
spleen
stomach
liver
gallbladder
8
Q
Organs suspended in mesentery move ___ to line of mesentery fixation
A
perpendicular
in 1 plane
9
Q
Primary secretion of saliva is from ____
it is __tonic and has a ___ composition to plasma
A
acinar cells
isotonic + similar in composition to plasma
10
Q
In primary saliva secretion: Basolateral ____ drives K+ __ cell and Na+ __ cell =>
1) basolateral ____ to drive 2Cl-, 1Na+ and 1K+ __ cell
2) Cl- faciliated diffusion __ into ___ by ___
A
NaKATPase - K in and Na out
1) triple transporter - into cell
2) efflux into lumen by Ca2+ activated Cl- channels
11
Q
In primary saliva secretion:
K+ into duct by ___
Na+ into duct through __causes __ to follow through +
A
apical Ca2+ activated K+ channels
Na+ through paracellular pores
H2O follows through paracellular pores + apical aquaporin 5
12
Q
2ndry modification of saliva secretion is by ,+_
Overall effect =
by removing __, adding __ and duct cells being impermeable to __
A
striated, intercalated and excretory ducts
diluting effect (more ions are removed than are added)
Na+ Cl- removed
K+ and HCO3- added
impermeable to H2O
13
Q
Channels involved in 2ndry modification of saliva
A
driven by NaKATPase K+ channel ENaC Na+H+exchanger HCO3-/Cl- antiporter regulated by CFTR
14
Q
Causes Na+ influx into apical cells in 2ndry modification of saliva:
A
ENaC (epithelial Na channel)
Na+H+ exchanger
15
Q
Unconditioned reflex of saliva secretion =
A
chemo+mechano mouth receptors send afferents to NTS -> salivary nuclei in medulla -> parasymp. CNVII (submandibular and sublingual) CNIX (parotids)
16
Q
Conditioned reflex of saliva secretion =
A
Thought/smell of food -> cerebral cortex -> salivary nuclei in medulla -> parasymp. CNVII (submandibular and sublingual) CNIX (parotids)
17
Q
Parasympathetic supply to salivary glands causes:
1) increased synthesis and secretion of ___+__ = __
2) __ of myoepithelium mediated by __ receptors
3) __ blood flow mediated by __
A
α-amylase+ fluid = large volume, watery, enzyme rich secretion
contraction by M3/M1
increased by VIP
18
Q
Sympathetic supply (in stress) to salivary glands causes: 1) increased secretion of _,_+_ = _ 2)\_\_ of myoepithelium 3) \_\_ blood flow mediated by
A
α-amylase, K+ and HCO3- = small volume, mucous-rich secretion
contraction
decreased
α and β1 adrenoceptors
19
Q
Sympathetic supply to salivary glands is via __
A
thoracic via superior cervical ganglia
adrealine
20
Q
Symp/Para usually dominates supply to salivary glands?
A
Parasympathetics
21
Q
__ and ___ cause xerostomia by blocking M1/3 receptors involved in parasympathetic release of saliva
A
M antagonists (eg. atropine) and antidepressants
22
Q
CN__ causes stomach to relax and expand
A
CNX
23
Q
Muscle thickness ___ as go from fundus to antrum
A
increases
24
Q
retropulsion =
A
peristalsis of stomach against closed pyloric sphincter churns food
25
Increased volume and consistency of chyme in the stomach cause the stomach to ____ causing: (4)
distend =>
| Increased SM motility of stomach, activity of intrinsic nerve plexi, gastrin release and CNX activity
26
enterogastrones eg. ___ (2) are ____ that delay the release of chyme into the duodenum
CCK and secretin
| hormones
27
enterogastric reflex ___ stomach emptying into duodenum via __+__
delays
| intrinsic nerve plexi and autonomic NS
28
Factors in the duodenum that delay gastric emptying (4)
distension
fat
acidity
hypertonicity
29
Dumping syndrome is when:
osmotically active products of carb and protein breakdown attract water into duodenum from plasma and cause a decrease in plasma vol. and circulatory disturbance
30
Pyloric gland area in the stomach has _+_+_ cells
mucus secreting
D (somatostatin)
G (gastrin) cells
31
Oxyntic mucosa is found in _+_ of stomach
| Contains _+_+_+_
```
fundus and body
mucus secreting
Chief (pepsinogen)
ECL (histamine)
parietal (HCl, intrinsic factor)
```
32
B12 is absorbed in the ___
terminal ileum
33
H+ is driven into parietal cell canaliculus by ____ on ___ in exchange for __
H+K+ATPase on apical membrane
| K+
34
Inhibitors of HCl secretion in the stomach = _+_
PGE2
| D cells -> somatostatin => decreased gastrin between meals
35
Stimulators of HCl secretion
Parasympathetic postganglionic nerves -> M1 on ECL and M3 on parietal
Gastrin-> parietal+ECL
36
Catalyses CO2+H20 -> H2CO3 in parietal cells
H2CO3 goes on to produce H+
and HCO3 which is basolaterally pumped out in exchange for Cl
carbonic anhydrase
37
3 stages of gastric secretion
cephalic
gastric
intestinal
38
What happens in cephalic stage of gastric secretion?
occurs before food reaches stomach
CNX -> increases ACh, histamine, gastrin, decreases somatostatin =>
INCREASES PARIETAL SECRETION
39
What happens in gastric stage of gastric secretion?
mechanoreceptors (distension) -> increase ACh secretion (for M3) and gastrin
protein digestion products increase gastrin =>
INCREASED PARIETAL SECRETION
40
What happens in intestinal phase of gastric secretion?
small intestine factors decrease acid production and low pH in stomach = somatostatin release =>
DECREASED PARIETAL SECRETION
41
Factors that protect gastric mucosa from HCl and pepsin
mucus gel layer with hydrophobic monolayer on top
PGE2 and PGI2 decrease acid secretion
mucus and HCO3- secretion
mucosal blood flow moves H+ to blood
42
H. pylori is found in ___ in stomach and causes ____ which weakens the mucus barrier
mucus gel layer
| persistent inflammation
43
assimilation =
digestion+absorption
44
absorption in the GI tract =
molecules crossapical and basolateral membrane of enterocytes into interstitium
45
glucose α-1,2-fructose =
sucrose
46
glucose β-1,4- galactose =
lactose
47
oligosaccharide eg.s =
sucrose and lactose
48
brush border enzymes for oligosaccharide>monosaccharide digestion =
lactase, maltase, sucrase-isomaltase
49
intraluminal digestion of polysaccharides to oligosaccharides is by:
hydrolyisis by α-amylase
50
α-amylase is a ___enzyme meaning it only breaks ___ bonds and NOT _/_/_ bonds
endoenzyme breaks internal α-1,4 bonds
| NOT α-1,6/terminal/next to branch point bonds
51
lactase is/isnt the rate limiting step in lactose assimilation
IS
52
Breaks α-1,4 bonds in oligosaccharides of
maltase
53
only enzyme to break α-1,6 bonds in oligosaccharides
isomaltase
54
absorption of the breakdown products of carb.s occurs in the ___+___
duodenum and jejunum
55
glucose and galactose are absorbed across the apical membrane in the gut by ___ by ___ with ___
2ndry active transport by SGLT1 with 2Na+
56
fructose is absorbed across the apical membrane in the gut by ___
GLUT5
57
monosaccharides are absorbed across the basolateral membrane in the gut by __ by ___
facilitated diffusion by GLUT2
58
pepsin is a __peptidase
optimum pH =
Preference for _+_ AAs
Not essential enzyme
endopeptidase
1.8-3.5
aromatic+larger neutral AAs
59
Protein digestion _/_ can be transported across apical and basolateral membrane of enterocytes
peptides
| AAs
60
Locations where peptides can be broken down to AAs (3)
apical brush border enzymes
intracellular hydrolysis
luminal enzymes
61
5 pancreatic enzymes that breakdown protein in ___
| endo + exopeptidases
duodenum
endo = trypsin, chemotrypsin, elastase
exo = carboxypeptidase A+B (cleave at COOH end)
62
pancreatic enzymes convert protein in duodenum to __% oligopeptides and __% AAs
70% oligopeptides
| 30% AAs
63
Brush border peptidases have affinity for __peptides of length
exo+/endo?
longer 3-8AAs
| endo and exopeptidases (carboxy+aminopeptidases - cleave at NH3 end)
64
cytoplasmic peptidases hydrolyse ____
di/tri peptides
65
AA absorption at brush border is by:
1) 5 different ____
It is a form of ___ using E from __ on basolateral membrane
2) 2 ___ mechanisms
1) 5 Na+ co-transporters
2ndry active transport
Na+K+ATPase
2) 2 Na+ independent
66
Hartnup disease caused by:
dysfunction of 5 Na+ co-transporter mechanism for AA absorption at brush border for neutral AAs
67
Cystinuria caused by:
dysfunction of 2 Na+ independant mechanisms of AA absorption at brush border membrane for cationic AAs
68
5 mechanisms of AA transport at the basolateral membrane =
```
3 = efflux Na+ independent
2 = influx of Na+ dependent (AAs needed for cells nutrition)
```
69
Gastric phase of lipid digestion
mix with gastric lipase and slowly broken down
| free FAs stimulate CCK and pancreatic lipase release
70
Secretion of bile is stimulated by __
CCK
71
__ secreted from ___ is needed to allow lipase access to FAs covered in bile salts
colipase
| pancreas
72
digestion of lipids in the duodenum products =
2 FAs
| 2-monoglyceride
73
Absorption of FAs and monoglycerides occurs by __ in the gut
passive diffusion
74
Short and medium (less than 12C) FAs diffuse into __ when absorbed in gut
long and monos are made into _ and transported in __ to __
```
short+medium = villus capillaries
long+monos= tris > chylomicrons > lacteal
```
75
Cholesterol is absorbed from gut by ___into ___ by ___
| carried by ___ to ___ where it is released and __ returned to ___
endocytosis into clatherin coated pits by NPC1L1
myosin > endocytic recylcing compartment
NPC1L1 to membrane
76
Drug that blocks NPC1L1 involved in cholesterol absorption
ezetimibe
77
Vomiting is controlled by ___ in ___ of brain
```
vomiting centre (VC)
medulla oblongata
```
78
Frequently precede vomiting
increased salivation
sweating
nausea
Increased HR
79
Vomiting:
First ___ is suspended
_____ ileum to stomach
stop ___ and close __ to prevent aspiration
__relaxes, _+_ contract to compress relaxed stomach
intestinal slow wave activity
retrograde contractions
breathing ; glottis
LOS relaxes ; diaphragm + abdominal muscles contract
80
Nausea causes relaxation of _+_ => __ in their muscles =>afferents > contraction of __+__ = contents of jej.,duo and pylorus go to _+_
stomach and LOS
tension
upper small intestine and pyloric sphincter
body and fundus
81
Things that stimulate vomiting (5)
toxins in gut/blood
mechanical
motion sickness
psychological/pain
82
In the stimulation of vomiting:
| __+__ go to the CTZ in the area postrema of the brainstem
absorbed toxins in the blood (there is no BBB in CTZ)
| vestibular system>vestibular nuclei (eg. motion sickness)
83
In stimulation of vomiting:
| stimuli from CNS eg. psychological go to ___ and __ then to ___
cerebral cortex+limbic system
| medulla
84
Toxins in the gut lumen/systemically stimulate ___cells to release __ to activate __ receptor and send a depolarising sensory afferent to the mucosa where become ___ to the ___
```
enterochrommafin
5-HT
5-HT3
vagal afferents
brainstem (CTZ and NTS)
```
85
In stimulation of vomiting:
| __+__ cause signals to be sent to brainstem (CTZ and NTS)
mechanical stimuli/pathology in GI tract or other viseral organs
toxins in gut lumen or systemically
86
VC coordinates vomiting , its output is via _+_
vagus nerve
| spinal motor neurones
87
VC = a group of _____ in ___ driven by ___ which receives input from ___
interconnecteed neurones
medulla
central pattern generator
NTS
88
Vagal output from VC causes... (3)
longitudinal muscle in oeso to contract and shorten
proximal stomach relaxes
small intestine = retrograde contraction
89
somatic motor neurones from VC cause ... (2)
anterior abdominal and diaphragm contract
90
autonomic/ somatic efferents from VC cause ... (4)
Heart rate and force increase
increase salivary secretions
pale and clammy skin
anal and bladder sphincters contract
91
Consequences of vomiting =
dehydration
hypokalaemia (due to HKATPase)
loss of H+ and Cl- => hypochoraemic metabolic alkalosis
Mallory-Weiss tear
Rarely - loss of duodenal HCO3- =metabolic acidosis
92
Chemo and radiotherapy cause vomiting due to __
5-HT and substance P from enterochrommafin cells
93
___ for parkinsons stimulates vomiting by agonising __
levodopa
| D2 receptors in CTZ
94
Plicae circulares in small intestine synonym =
folds/valves of Kerckring
95
```
2 eg.s of incretins and where they are secreted from
function =
```
GIP - K cells in duod and jej
GLP-1 - L cells in small int
stimulate β cells in panc to produce insulin
96
```
Secretin is secreted from ___
function =
```
S cells in duodenum
stimulates release of pancreatic, bile release and CCK
chief cells -> pepsinogen
97
```
Motilin is secreted from ___
function =
```
M cells in duodenum and jejunum
| stimulates muscle contractions to clear food to colon
98
```
CCK is secreted from ___
function =
```
I cells in duo + jejunum
decreases gastric emptying, HCl
Increases pancreatic and bile release
99
```
Gastrin is released from ___
function =
```
G cells of antrum (mainly) and duodenum
HCl release
antrum contractions
decreased rate of gastric emptying, pancreatic + gallbladder secretions
100
Ghrelin is released from ___
Gr cells in antrum, small intestine and elsewhere eg. pancreas
101
All peptide hormones secreted from the small intestine act on ___ receptors
G-protein coupled
102
succus entericus from the small intestine contains:
```
mucus (goblet cells)
aqueous salts (crypts of Lieberkuhn, no enzymes
```
103
Succus entericus:
Cl- out via ___ and _+_ follow
excessively activated in __
control mechanisms =
```
CFTR
H2O and Na+
diarrhoea - cholera
distension/irritation, gastrin, CCK and para (increases)
sympathetic (decreases)
```
104
___ in ___ ileum stimulates gastroileal reflex
gastrin
| empty ileum
105
due to segmentation food takes ___ to move through small intestine
3-5 hrs
106
strength of segmentation in small intestine increases with ___ and decreases with __ stimulation
```
increase = para
decrease = symp
```
107
In fasting state peristalsis =
1)
2)
1) few localised contractions
| 2) MMC - every 90-120mins - clears debris
108
MMC controlling factors =
decreased by: feeding, vagal, gastrin, CCK
| increased by motilin (macrolides mimic)
109
Enzymes in zymogen granules in pancreatic acinar cells =
pancreatic amylase and lipase
110
Pancreatic acinar cells secrete:
pancreatic amylase and lipase
trypsinogen
chymotrypsinogen and procarboxypeptidase A+B
111
chymotrypsinogen + Procarboxypeptidase A+B are activated by ___
trypsinogen is activated by ___
chymo + procarb - trypsin
| trypsinogen - duodenal enterokinase from mucosal cells
112
Duct cells in pancreas secrete ___ rich fluid (_+_ follow through pores)
___ pumps out Cl- used to drive ____
HCO3-
Na+ and H2O
CFTR drives Cl-/HCO3- antiporter
113
cephalic phase of pancreas exocrine control
vagal nerve stimulates acinar cells (20% of secretion)
114
gastric phase of pancreas exocrine control
distension>vasovagal reflex> para stim.s acinar and duct cells (5-10%)
115
intestinal phase of pancreas exocrine control
acid> secretin> duct cells> increased aqueous NaHCO3-
fat+protein > CCK>acinar>more enzymes
(70-75%)
116
Length and diameter of colon =
1.5m
| 6cm
117
ileocaecal valve is controlled by:
vagal, symp and enteric neurones
118
Functions of the large intestine
absorb: H2O, Na+, Cl-, short chain FAs (bac fermentation of undigested carb
secrete: K+, HCO3- and mucus
storage
excretion
119
Mass movements in the colon (2)
1) asc and transverse - caused by gastrocolic response - gastrin+extrinsic nerves in response to food: 1-3x daily
2) distal colon - may trigger defaecation reflex
120
rectosphincteric reflex =
distension of rectum > active contraction of rectal SM > internal anal sphincter relaxes
121
Functions of colonic flora
```
immunity
motility promotors
mucosal integrity
obstruction
synthesis vitamin K2 and FAs
activate some drugs
```
122
Hirschprung's disease =
congenital megacolon
| colon lacks part of enteric NS and causes obstruction/severe constipation
123
composition of faeces =
100ml H2O
| 50ml cellulose, bilirubin and bacteria
124
Diarrhoea = loss of fluid and solutes from GI tract in excess of ___
500ml per day
125
Absorption of H2O in gut is ___ and driven by ___
passive
| transport of solutes
126
Gut secretes ___l per day of fluids
small intestine absorbs __l
colon absorbs ___
9.3l
8.3l
90% of the litre left
127
Main cause of postprandial Na+ absorption =
| location =
Na+/glucose and Na+/AA cotransporters
| in small intestine (mostly jejunum)
128
Na+/glucose and Na+/AA cotransporters are a form of ___ as function with Na+K+ATPase on the basolateral membrane.
They are ___ and so make the lumen ___ and drive __ into interstitium
not regulated by
```
2ndry AT
electrogenic
-ve
Cl-
NOT regulated by cAMP or Ca2+
```
129
Na+/H+ exchange (without a parallel Cl-/HCO3- exchanger) occurs in the ___ and is stimulated by ___
duodenum and jejunum
| HCO3- in the lumen
130
Parallel Na/H+ and Cl-/HCO3- exchange occurs in the ___ and is most involved in H2O absorption in ____
ileum and proximal colon
| interdigestive period
131
Parallel Na/H+ and Cl-/HCO3- exchange is regulated by:
| is electroneutral/genic
increased cAMP, cGMP, Ca2+ decrease NaCl absorption
132
E. coli enterotoxin activates ___ to produce ___ which inhibits Parallel Na/H+ and Cl-/HCO3- exchange and so decreases NaCl absorption and causes ___
adenylate cyclase
intracellular cAMP
diarrhoea
133
Na transporter in distal colon =
| is stimulated by ____ which (3)
```
ENaC
aldosterone (NOT cAMP or cGMP)
opens ENaC
increases no. of ENaC on membrane from intracellular pool
increases ENaC + NaKATPase synth
```
134
Na transporters involved in water balance in the GI tract =
Na+/glucose Na+/AA co-transporters
Na+/H+ exchanger (w/wo parallel Cl-/HCO3- exchanger)
ENaC
135
Passive Cl- absorption in the gut is driven by ___ due to
___ small intestine
___ colon
-ve potential
Na+/glucose+AA transporter = small intestine
ENaC = colon
136
In the gut Cl- secretion is greater/less than absorption
| It is secreted from __ cells
less than
| crypt cells
137
Basolateral transporters involved in Cl- secretion
NaKATPase (causes low Na intracellularly) drives
NKCC1 to pump inwards (increases Cl- intra concn)
IK1+BK (recycle/efflux K+ )
138
Apical transporter for Cl- secretion in gut
| Is indirectly activate by ___
CFTR
enterotoxins eg. choler, E. coli, C. diff
hormones and neurotransmitters eg. VIP, bradykinin 5-HT
immune cell products eg. PG and histamine
laxatives
139
Secondary messengers that activators of CFTR stimulate to activate CFTR
cAMP (cholera toxin, VIP and histamine)
cGMP (E. coli toxin and guanylin)
Ca2+ (ACh, bradykinin, 5-HT)
140
Main electrolyte driver of H2O absorption in the gut =
Na+
141
Diarrhoea causes (3) due to loss of fluid and electrolytes
dehydration (na+ and H2O)
metabolic acidosis (HCO3-)
hypokalaemia (K+)
142
Mechanisms behind causes of diarrhoea (4)
hypermotility
non/poor absorption of solutes in intestinal lumen
impaired absorption of NaCl
Excess secretion
143
Treatment of diarrhoea =
fluids and elctrolytes
may need anti-infective agents
may need anti-motility eg. opiates or loperamide
144
Diarrhoea caused by impaired absorption of NaCl eg.s
congenital chloridorrhea = no exchanger
inflammation
infection (E. coli, campylobacter toxins)
excess bile acid in colon
145
Vitamin D is activated by __
liver
146
hepatocytes are arranged between sinusoids in plates _ cells thick
2
147
Basolateral membrane of hepatocytes faces the ___
| which lies between it and the endothelial cells of sinusoid
pericellular space (of Disse)
148
apical membrane of hepatocyte is __+ forms
groove
| forms canaliculi
149
stellate/__ cells store __ and are found in the ___
Ito
vitamin A
space of Disse
150
Intrahepatic biliary system = canaliculi> terminal bile ductules >___ ducts > ___ ducts>___ducts>__ ducts>R+L hepatic ducts
perilobular
interlobular
septal
lobar
151
_-__l of bile is produced each day
0.6-1.2l
152
__+__ are stimulated by chyme in duodenum to cause gallbladder SM to contract
___ opens the sphincter of Oddi
CCK and CNX
| CCK
153
75% of bile comes from secretions from __
| 25% from __
```
75% = hepatocytes
25% = bile duct cells
```
154
bile duct cell secretion is similar to __secretion and properties =
pancreatic
alkaline
aqueous Na+ K+ Cl- HCO3- rich
155
Between meals bile duct cell secretion is similar to __ in ionic composition
during meals flow rate ____ due to secretin and __ transporter activity ___ so HCO3- content ___
```
plasma
increases
HCO3-/Cl-
increases
increases HCO3- content during meals
```
156
Bile secretions that are produced in hepatocyes =
primary bile acids - mainly cholic and chenodeoxycholic acids, H2O and electrolytes, lipids, phosholipids, cholesterol, IgA and bilirubin
157
bilirubin is from ___ of RBCs
porphyrin
158
primary bile acids + __ = bile salts
| many are conjugated to __/__
Na+ or K+
| glycine/taurine
159
__% of bile salts are recycled. The reabsorption occurs in the __
95%
| terminal ileum
160
Ileum bile salt transporter = __
on liver transporter for influx = ___
on liver transporter for efflux to gallbladder/duod =__
ASBT (Na+ coupled)
NTCP (Na+ coupled)
MRCP2+ABCG2 pumps
161
Secretin stimulates a ____ bile secretion
aqueous alkaline
162
Relief of biliary colic =
atropine/GTN
163
Analgesics for biliary colic = __
morphine (but constricts sphincter of Oddi)
buprenorphine
pethidine
164
more/less polar drugs are excreted by the kidney
more polar
165
Liver metabolises __ to active form
| and __ to increased activity form ___
ACEIs
| codeine-> morphine
166
Phase 1 in liver metabolism of drugs =
make drug more polar + make handle for conjugation = functionalisation
167
In phase 1 drug metabolism oxidation is mediated by ___ and is for ___ drugs
CYP family of monooxygenases
| lipid soluble
168
Phase 2 of drug metabolism in the liver = ___ with __
| it increases the ___ and so usually leads to __ products
conjugation with glucaronyl/sulphate/methyl/acetyl
increases polarity
inactive products
