wk 5 7 physiology pharmacology of fluid balance

Question 1

t/f were sodium goes water will follow

Answer 1

true

Question 2

2 routes which water will move in reabsorption

Answer 2

transcellular and paracellular

Question 3

reabsorptio of na+ provides an osmotic force for reabsorption of water, what are the co-transporters in small intestine alone?

Answer 3

Na+/glucose co-transport
na+/amino acid co-transport (both in postprandial period)
Na/H+ exchange - duoenum and jejunum, stimulated by HCO3-

Question 4

aldosterone regulates which mechanisms of transport for water and sodium ? found in distal region of colon

Answer 4

Epithelial na+ channels (ENaC)

Question 5

Parallel Na+/H+ and Cl-/HCO3- exchange occurs in the 2

Answer 5

ileum and colon

- interdigestive period

Question 6

to enter the membrane in mechanisms of postprandial Na+ absorption, the Na+/glucose and Na+/amino co-transport are used, how does it pass through the membrane

Answer 6

na+/K+atpase exchange

Question 7

`t/f Na+/H+ exchange occurs at both the basal and apical membranes

Answer 7

true
NHE 1 - ph housekeeper
NHE3- enters lumen,

Question 8

exchange at the apical membrane in the jejunum is stimulated by the alkaline environment, what causes this

Answer 8

presence of bicarbonate

Question 9

which cellular mechanism of Na+ absorption is important in the fasting stage

Answer 9

Na+/H+ and Cl-/HCO3- exchange in parallel

Question 10

t/f cAMP reduces NaCl absorption

Answer 10

true
cause of diarrhoea
also cGMP and Ca2+ reduce NaCl absorption

Question 11

outline how secretery diarrhoea due to infection of E.Coli

Answer 11

heat stable entertoxin
activates adenylate cyclase
-incr intracellular cAMP
- reduced NaCl absorption

Question 12

t/f ENaC is not a transporter

Answer 12

true

ion channel

Question 13

how is Cl absorbed in small intestine

Answer 13

eletrogenic transport of Na+
(Na+/glucose and Na+/amino)
-this causes lumen to become negative, creating a driving force

Question 14

t/f ENaC provides a negative lumen

Answer 14

true

drives Cl- in large intestine

Question 15

t/f there are K channels in basolateral membrane

Answer 15

true

Question 16

where does Cl- secretion occur

Answer 16

from crypt cells

Question 17

which channel does Cl- travel accross for secretion

Answer 17

CFTR

Question 18

what activates CFTR

Answer 18

bacterial endotoxins
heat stable enterotoxins
hormones/neurotransmitters (VIP,acetylcholine…)
immune cells products - prostaglandins,histamine
laxatives

Question 19

opening of CFTR causes

Answer 19

secretory diarrhoea

Question 20

diarrhoea causes

Answer 20

dehydration (Na+ and H20 loss), metabolic acidosis (HCO3- loss) and hypokalaemia
can be fatal - cholera

Question 21

outline treatment for acute diarrhoea

Answer 21

usually no treatment - due to viral infection and not much can be done

maintenance of fluid and electrolyte balance (rehydration)
anti-ifective agents (if appropriatee) (ciprofloxin)
non-antimicrobial antidiarrhoeal agents

Question 22

diarrhoea can occur due to impaired absorption of NaCl, what 4 things can cause this

Answer 22

congenital defects - absence of Cl-HCO3- exchanger
inflammation
infection (enterotoxins)
excess bile acid in colon

Question 23

other than impaired absorption of NaCl, give 3 other causes of diarrhoea

Answer 23

non-absorbable solute (lactase defiency)
hypermotility
excessive secretion

Question 24

what channel is required for adenylate cyclase to produce cAMP

Answer 24

GTP protein

cholera activates

Question 25

t/f cholera toxin is a reversible modification

Answer 25

true

Question 26

rehydration therapy exploits SGLT1 (sodium glucose transporter 1) is used for absorption, how many molecules are transporter? does water transport

Answer 26

2 Na
1 glucose
yes water

Question 27

effect of opiods on alimentary tract 5

Answer 27

inhibition of enteric neurons (hyperpolarisation)
decreased peristalsis (incr segmentation - constipation)
incr fluid absorption
constriction of sphincters
incr tone of large intestine

Question 28

list 3 opiod agonists used in diarrhoea

Answer 28

codeine
diphenoxylate
loperamide (most common)