Digestive Objectives

Question 1

What are the 4 processes of the digestion system?

Answer 1

Secretion, Digestion, Absorption, Motility

Question 2

Define Secretion

Answer 2

movement of material from cells into the lumen or ECF

Question 3

What is the method of motility in the digestive system?

Answer 3

Peristaltic Contractions

Question 4

Describe the creation of HCL in the stomach lumen.

Answer 4

1. Water comes into the cell and is split into H and OH.
2. H is pumped into the Lumen, using K gradient
3. Oh and CO2 combine to form HCO3 and are pumped into the interstitial fluid using Cl gradient.
4. Cl leaves the cell through leak channels.

Question 5

What is the enzyme that combines OH and CO2 in the the parietal cells?

Answer 5

carbonic anhydrase

Question 6

Describe the events of bicarbonate secretion by the pancreas

Answer 6

1. CO2 enters the cell and combines with H2O to form bicarbonate and H.
2. H is pumped into the interstitial fluid using an NA gradient
3. Cl is brought into the cell using a Na K Cl atpase
4. Cl is leaked into the lumen through the CFTR gland.
5. HCO3 is pumped out of the cell using a CL gradient

Question 7

How does a watery ion solution leak into the lumen of the small intestine?

Answer 7

Cl is leaked out of colonic crypt cells, and the negative charge draws Na into the lumen through gaps. H2O is also drawn through the gaps, but through osmosis.

Question 8

What type of glands are salivary glands?

Answer 8

Exocrine Glands

Question 9

Describe the Digestion of Fat droplets.

Answer 9

1. Through emulsification bile salts separate the large fat droplets into smaller ones.
2. Colipase displaces some bile salts and allows lipase to reach the fatty droplets.
3. Lipase breaks triglycerides into one monoglyceride and two free fatty acids.
4. They are stored in the lumen as micelles.

Question 10

Describe the absorption of fat droplets

Answer 10

1. Fatty acids and Monoglycerides are absorbed into cells through simple diffusion.
2. They recombine into triglycerides in the smooth Er.
3. Join with cholesterol to form chylomicrons.
4. These leave the cell by exocytosis.
5. They are then absorbed and distributed by the lymph system.

Question 11

Describe the Digestion of Carbs.

Answer 11

1. amylase breaks long chains of gluclose into smaller disaccharides and malatose.
2. disaccharides and malatose are broken down into glucose, galactose, and fructose by disaccharidases.

Question 12

Describe the absorption of Carbs

Answer 12

1. Gluclose and galactose is transported into intestinal cells using the SGLT symporter with NA.
2. Fructose enters cells through Glut5 and leaves cells through Glut2. Gluclose and Galactose also use the Glut2 transporter.

Question 13

Describe the Digestion of protein and abosrption.

Answer 13

1. Chains of Amino acids are broken down either in the middle of the chain, or the end of the chain.
2. Proteins are broken down into free amino acids or small chains of amino acids.
3. Free amino acids are carried by NA transporters.
4. Dipeptides and Tripeptides are carried by H dependent carriers.
5. In the cell they are broken down by peptidase into free amino acids.
6. Free amino acids leave the cell through Na transporters.
7. Some smaller peptides can be carried by transcytosis.

Question 14

What enzyme breaks amino chains at the ends?

Answer 14

Exopeptidase

Question 15

What are the two categories of Exopeptidase?

Answer 15

Aminopeptidase and Carboxypeptidase.

Question 16

What enzyme breaks amino chains in the middle of the chain?

Answer 16

Endopeptidase.