Intestinal Physiology

Question 1

What is the function of the gut?

Answer 1

Take relatively large solids and digest them into smaller molecules that can be absorbed as nutrients, while still serving as a barrier to toxins, bacteria, parasites, etc.

Question 2

What do epithelial cells do?

Answer 2

Secrete water and electrolytes
Absorb water and electrolytes

Question 3

What are the 3 segments of the small intestine?

Answer 3

Duodenum
Jejunum
Ileum

Question 4

What is the first stage of the transcellular process?

Answer 4

Membrane transport protein

Question 5

What is the second stage of the transcellular process?

Answer 5

Na+K+ATPase transporter

Question 6

What happens in intestinal secretion?

Answer 6

Chloride ions enter the crypt epithelial cell by cotransport with sodium and potassium; sodium is pumped back out viasodium pumps, and potassium is exported via a number of channels.

Activation ofadenylyl cyclaseby a number of so-called secretagogues leads to generation of cyclic AMP.

Elevated intracellular concentrations of cAMP in crypt cells activate the CFTR, resulting in secretion of chloride ions into the lumen.

Accumulation of negatively-charged chloride anions in the crypt creates an electric potential that attracts sodium, pulling it into the lumen, apparently across tight junctions - the net result is secretion of NaCl.

Secretion of NaCl into the crypt creates an osmotic gradient across the tight junction and water is drawn into the lumen

Question 7

How is cholera transmitted?

Answer 7

Cholera is transmitted by either contaminated food or water

Question 8

What are the main sources of cholera?

Answer 8

In developed world: seafood is typically the cause
In developing world: it is often water

Question 9

How do toxins induce diarrhoea?

Answer 9

• Cholera toxin released from bacteria in infected intestine
• Binds to Intestinal cells
• Stimulates adenylate cyclase to produce cAMP
• Dramatic efflux of ions and water
• Watery Diarrhoea

Question 10

What is the function of enterocytes?

Answer 10

Enterocytes absorb glucose and galactose through an Na-dependent secondary active transport process, while fructose is absorbed by facilitated transport.

Question 11

How are fats digested?

Answer 11

Fats and water are separated

So bile (an emulsifier) arrives, it has an affinity for both fat and water and can therefore bring the fat into the water

After emulsification, the fat is mixed in the water solution so fat digesting enzymes have access to it.

Question 12

What are the 3 pairs of salivary glands?

Answer 12

Parotid
Sublingual
Submandibular

Question 13

What are the functions of saliva?

Answer 13

Lubricates, cleans oral cavity
Dissolves chemicals
Suppresses bacterial growth
Digest starch by amylase

Question 14

What is the endocrine function of the pancreas?

Answer 14

Secretes insulin and glucagon from islets of langherhans

Question 15

What is the exocrine function of the liver?

Answer 15

Secretion of pancreatic juice

Question 16

What is the function of the liver metabolically?

Answer 16

Store absorbed nutrients, vitamins
Release nutrients as needed

Question 17

What is the haematological function of the liver?

Answer 17

Plasma protein production
Remove old RBCs

Question 18

What is the function of the bile?

Answer 18

Required for fat digestion and absorption

Question 19

What is coeliac disease?

Answer 19

Damaged villi

Question 20

Where does digestion occur?

Answer 20

Occurs in the GI lumen by secreted enzymes and on the surface of enterocytes by membrane-bound enzymes

Question 21

What does absorption occur by?

Answer 21

Occurs by simple diffusion, facilitated diffusion, active transport, endocytosis and paracellular transport.