consequences of fluid loss from the GI tract

Question 1

what is osmotic diarrhoea

Answer 1

decreased electrolyte/nutrient absorption due increase in osmotic particles in the gut

Question 2

what is deranged motility diarrhoea

Answer 2

increased rate of flow of intestinal contents

Question 3

what is secretory diarrhoea

Answer 3

abnormal increase in GIT secretions - ach, substance P, 5-HT, neurotensin act to increase rate of intestinal secretion via inc. [Ca2+]

Question 4

what causes osmotic diarrhoea

Answer 4

disaccharide deficiency - can be drug induced - malabsorption of galactose

Question 5

what causes secretory diarrhoea

Answer 5

excessive laxative use, digestion/absorption defects, infection

Question 6

how does cholera cause diarrhoea

Answer 6

survives acidity of GIT

enterotoxin stimulates adneylate cyclase - inc cAMP - more Na, Cl, H2O loss

Question 7

how is secretory diarrhoea treated

Answer 7

water, electrolyte, glucose replacement

Question 8

causes of bloody diarrhoea

Answer 8

chronic disease
ulcerative colitis
neoplasm

Question 9

consequences of severe diarrhoea

Answer 9

hypovolaemia

metabolic acidosis due to loss of HCO3

Question 10

what is vomiting

Answer 10

retrograde giant contraction - oral expulsion of gastric contents and bile

Question 11

causes of vomiting

Answer 11

symptom of illness in children
pregnancy
alcohol dependency
metabolic disorders
removal of ingested toxic substances

Question 12

physiological changes associated with vomiting

Answer 12

inc: salivation, HR, sweating
pallor
nausea

Question 13

how is vomiting stimulated

Answer 13

neuronal inputs from the body to the vomiting centre in the medulla oblongata

Question 14

inputs that can initiate vomiting

Answer 14

SI/stomach distension
substances that act on chemoreceptors in brain/intestine
increased ICP
motion sickness
intense pain
gag reflex
sight/smell/emotional circumstances

Question 15

how does vomiting occur

Answer 15

nausea 
deep inspiration, closure of epiglottis
inc abd. pressure
retrograde giant contraction
breath held, chest fixes
dec. oeso pressure - relaxation of UOS & LOS
inc abd pressure
forceful explosion

Question 16

consequences of excessive vomiting

Answer 16

inc salt/water loss
sever dehydration
circulatory problems
metabolic alkalosis due to loss of gastric acid

Question 17

what is lost in vomit

Answer 17

food
mucus (& na, k, cl, hco3)
gastric acif
upper intestinal contents, incl bile
blood

Question 18

consequences of fluid loss from GIT

Answer 18

hypovolaemia
haemoconcentration
dehydration
ionic imbalances
malnutrition, inc mortality

Question 19

consequences of hypovolaemia

Answer 19

dec. venous return
arterial hypotension
inc myocardial O2 demand w/ dec perfusion leads to dysfunction
inc anaerobic metabolism > acidosis

Question 20

what does a combo of acidosis and myocardial dysfunction lead to

Answer 20

multi organ failure :D

Question 21

consequences of dehydration

Answer 21

heat shock, fainting
higher blood viscosity; higher BP; clotting more likely
kidneys get overloaded - toxins accumulate
digestive problems

Question 22

how does the body respond to water loss

Answer 22

CV adaptation
Renal adaptation
behavioural adaptation - stimulates fluid intake when possible

Question 23

consequences of na and h2o loss

Answer 23

decreased plasma volume and venous pressure

Question 24

cv result of decreased venous pressure

Answer 24

dec: venous return, atrial pressure
ventricular EDV
SV
CO
arterial BP

Question 25

Renal consequences of decreased venous pressure

Answer 25

increased activity of renal sympathetic nerves inc constriction of renal arterioles dec GFR dec na, h20 secretion

Question 26

consequence of severe sweating

Answer 26

loss of hypo osmotic salt soln

Question 27

result of loss of hypo-osmotic salt soln

Answer 27

dec plasma vol | inc plasma osmolarity

Question 28

consequences of dec plasma volume

Answer 28

dec GFR inc plama aldosterone increased plasma vasopressin

Question 29

consquence of dec GFR w/ inc plasma aldosterone

Answer 29

dec na secretion

Question 30

result of inc plasma vasopressin

Answer 30

dec h2o secretion

Question 31

systemic response of the body to dec arterial pressure due to dec plasma vol

Answer 31

inc renin secretion by renal juxtaglomerular cells inc plasma renin inc plasma ang2 inc aldosterone secretion by adrenal cortex inc plasma aldosterone inc na reabsorption in collecting ducts dec na excretion

Question 32

response of the body to dec GFR/flow to macula densa

Answer 32

dec NaCl concentration in macula densa | inc renin secretion

Question 33

physiologic response to consequences of hypovolaemia

Answer 33

``` dec venous/atrial/arterial pressure detected by CV baroreceptors inc ADH secretion by post pit. inc. plasma vasopressin inc h2o permeability in collecting ducts inc h2o reabsorption dec h2o excretion ```

Question 34

what stimulates the sensation of thirst

Answer 34

inc ang2 inc plasma osmolarity dry mouth/throat monitoring of h2o intake by GIT

Question 35

effect of dehydration on calcium levels

Answer 35

dec nacl, k, INC [Ca2+] > hypercalcaemia

Question 36

clinical consequences of hypercalcaemia

Answer 36

inc risk of kidney stones, kidney failure, arrhythmia, dementia

Question 37

symptoms of hypercalcaemia

Answer 37

``` nausea/vomiting loss of appetite constipation abdominal pain excessive thirst fatigue, lethargy, paresis, joint pain, confusion ```

Question 38

how does ADH work

Answer 38

inserts aquaporin 2 channels into renal collecting ducts | increases h2o permeability of ducts - results in concentred urine

Question 39

effect of h2o on adh secretion

Answer 39

dec in osmolarity of blood and interstitial fluid | dec in ADH secretion - water channels removed

Question 40

what happens if there are no water channels in the collecting ducts

Answer 40

decreased permeability - increased water loss

Question 41

factors that regulate release of ADH

Answer 41

``` large decrease in blood vol severe dehydration - causing gfr decrease - less h2o in urine hyperventilation - inc fluid loss vomiting/diarrhoea fever, heavy sweating ```

Question 42

how does the thirst centre in the hypothalamus work

Answer 42

stimulates desire to drink - water gain if thirst is quenched

Question 43

how does ANG2 work

Answer 43

stimulates aldosterone secretion - dec volume of h2o lost in urine

Question 44

how does aldosterone work

Answer 44

promotes water/na/cl reabsorption - dec water loss in urinw

Question 45

how does ANP work

Answer 45

stimulates natriuresis - inc excretion of na/cl/h2o - increased water loss in urine

Question 46

how does ADH/vasopressin work

Answer 46

increase collecting duct permeability and hence water reabsorption - decreased loss of water in urine