11. Gut Fluid Balancce

Question 1

Diarrhoea occurs when:

1. High secretion from enterocytes
2. Malabsorption from enterocytes
3. Both

Answer 1

Malabsorption causes watery stool

Question 2

Enterocyte/small intestine epithelial cells can:
1 (7) h2o and electrolytes; transport from (blood/gut lumen) to (blood/gut lumen)
2 (6) h2o and electrolytes; transport from (blood/gut lumen) to (blood/gut lumen)
3. The work (faster/slower) in the presence of nutrients

Answer 2

1. Secrete; transport from blood to gut lumen
2. Absorb; transport from gut lumen to blood
3. Faster

Question 3

How many litres of fluid in and out per day

Answer 3

9L/day in and out

Question 4

Movement of substances through small intestine

1. A moves (up/down) X gradient
2. B moves (up/down) Y grad
3. C moves (up/down) Z grad
4. To move solutes against conc grad requires (6), supplied by Na+ and H+ (9) -made by (5)
5. Name 2 routes past cell layer

Answer 4

1. Solute; down; conc grad
2. Water; down; osmotic grad
3. Electrolytes; down; electrochemical grad
4. Energy req
   Supplied by Na+/H+ gradients , made by pumps
5. Paracellular (past tight junctions e.g. water diffuse through)
6. Transcellular (via channels/transporters e.g. aquaporin 10 & 3)

Question 5

Villus structure:
1 Layer 1 name (1 cell type); process occurring here
2 Layer 2 name (3 cell types); rocess occurring here
3 Which process usually exceeds other

Answer 5

1 Villus; mature absorptive cells; absorption
Note: at top, cells shed
2 crypt; (from bottom) stem cells, proliferating cells, differentiating cells; secretion
3. Net absorption usually exceeds net secretion

Question 6

Absorption & secretion affect excretion consistency.

Draw diagram that shows factors that affect absorption and secretion in intestine

Answer 6

MAIN:
Nutrient intake>gastric motility>intestinal motility> absorption & secretion
ABSORPTION FACTORS:
No. and state of enterocytes
Blood & lymph flow (clear nutrient rich fluid)
SECRETION FACTORS:
Hormonal, paracrine, neural factors affect secretion AND gastric motility & intestinal motility
Luminal factors, irritants, bac toxins, bile (bile causes hypersecretion if in wrong place/not reabsorbed)

Question 7

Describe absorption in intestine by enterocytes (jejunum)

Answer 7

NOT DONE
Check screencast

1. Na+ coupled transporter; couple with glucose (SGLT-1) or aa etc; GLUT 2 transports glucose into blood
2. Na+/K+ ATPase ; maintain low Na+ inside cell
   …………………….

Question 8

Describe intestinal secretion

Answer 8

.

Question 9

4 physiological types of diarrhoea; mechanisms; causes

Answer 9

.

Question 10

What cholera does to intestine

Answer 10

1 Makes cholera toxin
2 Alpha-subunit of toxin enters cell
3 subunit hydrolyses NAD+>ADP-ribose
4. ADP-ribose attaches to GTP so GTP cannot be converted back to GDPand adenylate cyclase is continuously converting ATP>cAMP
5. Constant cAMP production means ion channels constantly open and Cl-/HCO3- constantly flow out; water follows
HYPERSECRETION

Question 11

How to combat effects of diarrhoea (name effects & treatment)

Treatment includes
What does

Answer 11

Oral rehydration therapy:

Solution= electrolytes and nutrients (e.g. Na, Cl, K, glucose) dissolved in water

Replenish lost nutrients/fluid and get all mechanisms of enterocytes working again

Question 12

Bugs that cause  travellers diarrhoea
1. Name a bacteria 
2. Name a virus
3. Name a parasite
Include food or water borne

Answer 12

1. • Vibrio cholerae (f&w)
   • ^ flagella, gram-ive, comma shaped*
   • Clostridium dificile (f&w)
   • Shigella sp (f)
   • Salmonella sp (f)
   • E. Coli (f)

2.
Norwalk (f&w)
Hep A (f)
Rotavirus (w)

3. 
Entamoeba histolytica (f&w)
Giardia intestinalis
Cryptosporidium sp (w) -CRYPT of intestine cells