L3: Water Absorption and Secretion in the Gastrointestinal Tract

Question 1

Where does most of the non-electrolyte nutrition absorption occur?

Answer 1

Small intestine

Question 2

Both small and large intestines absorb ________ and ________

Answer 2

water, electrolytes

Question 3

The small intestine has villi that extend from ______ of _________

Answer 3

crypts, lieberkuhn

Question 4

What are the main secretory cells called in the colon?

Answer 4

Crypt cells

Question 5

The _________ surface does not contain any _______

Answer 5

colon, villi

Question 6

Small intestine net absorption =

Answer 6

Water, Na+, Cl-, K+

Question 7

Large intestine net absorption =

Answer 7

Water, Na+, Cl-

Question 8

Small intestine net secretion =

Answer 8

HCO3-

Question 9

Large intestine net secretion =

Answer 9

K+, HCO3-

Question 10

Cells in the small intestine

Answer 10

Villous absorptive cell
Goblet cell
Enteric endocrine cell
Stem cell
Paneth cell
Undifferentiated cell

Question 11

Cells of Large intestine

Answer 11

Surface absorptive cell
Goblet cell
Enteric endocrine cell
Stem cell
Undifferentiated cell

Question 12

In Leaky epithelia the _________ pathway is more dominant

Answer 12

paracellular

Question 13

In tight epithelia the __________ pathway is more dominant

Answer 13

transcellular

Question 14

Places that are paracellular dominant

Answer 14

Proximal renal tubule, Small intestine

Question 15

Places that are transcellular dominant

Answer 15

Renal collecting duct, urinary bladder

Question 16

Cl-HCO3 exchanger

Answer 16

Ileum, Proximal colon, Distal colon

Question 17

Locations of apical Na-H antiporters for Cl- absorption

Answer 17

Ileum, Proximal colon

Question 18

What is osmotic diarrhoea?

Answer 18

When sugar is retained in the intestine lumen, increasing osmotic pressure and therefore retaining the water in the lumen.

Question 19

What are the common causes of osmotic diarrhoea?

Answer 19

Lactose intolerance and Coeliac disease

Question 20

What is Coeliac disease?

Answer 20

An autoimmune reaction to gluten resulting in the destruction of epithelial cells

Question 21

Increased __________ in the gut supports __________ growth which increases ____ production leading to _________

Answer 21

carbohydrates, bacterial, CO2, gassiness

Question 22

How does secretory diarrhoea occur?

Answer 22

When cholera toxin permanently activates adenylate cyclase -> elevation of cAMP -> opens CFTR channel -> Cl- secretion and subsequent Na+ and water secretions

Question 23

Location of Na/Glucose and Na/AA transporters

Answer 23

Jejunum(high), ileum(low)

Question 24

Location of Na-H exchanger

Answer 24

Duodenum (mod)

Jejunum (high)

Question 25

Location of parallel Na-H and Cl-HCO3 exchangers

Answer 25

Ileum (mod)
proximal colon (mod)

Question 26

Location of epithelial Na+ channel

Answer 26

Distal colon (high)

Question 27

Location of Passive Cl- absorption

Answer 27

Jejunum (high)
Ileum (low)
Distal colon (high)

Question 28

Location of Cl-HCO3 exchanger

Answer 28

Ileum (mod)
Proximal (high)
Distal colon (mod)

Question 29

Location of passive K+ absorption

Answer 29

Jejunum and ileum (both low)

Question 30

Location of passive K+ secretion

Answer 30

Proximal colon (low)
Distal colon (high)

Question 31

Location of active K+ secretion

Answer 31

Proximal and distal colons (both low)

Question 32

Location of active K+ absorption

Answer 32

Distal colon (low)

Question 33

Location of Cl- secretion

Answer 33

Everywhere (mod)