Digestion Och Absorption Av Proteiner Och Kolhydrater

Question 1

What is the function of endopeptidases?

Answer 1

Attack internal bonds and liberate large peptide fragments.

Question 2

What is the function of exopeptidases?

Answer 2

Exopeptidases cleave off each amino acid at the time

Question 3

How does the stomach brake down proteins?

Answer 3

It excretes gastric juice which contains HCL with pH less than 2. The acid serves to kill microorganisms and denature proteins.

Pepsin breaks down proteins into large fragments. Active at pH 2-3, inactive ph>5

Pepsin is the only protease that can break down collagen.

It is terminated by neutralization by bicarbonate in duodenum.

Question 4

What enzymes are active in the intestine during breakdown of proteins?

Answer 4

Pancreatic juice is rich in pancreatic proenzymes which become activated when reaching the small intestine.

The two primary proteases are trypsin and chymotrypsine.

The are packaged in secretory vesicles and transported as proenzymes.

The secretory veicle also contains pancreatic secretory trypsin inhibitor (SPINK1) as a safeguard if trypsinogen is activated in beforehand. Premature activation of trypsinogen results in auto-digestion of pancreatic tissues.

Question 5

Trypsinogen is activated to trypsin by what kinase?

Answer 5

Enterokinase, secreted by cells in duodenum.

Question 6

Physical and chemical characteristics of trypsine?

Answer 6

pH optimum 7,6 - 8.

Classified as a serine protease.

Question 7

Gluten enteropathy, explain!

Answer 7

• Celiac disease
• Intolerance of protein fraction, gluten!
• Enzyme deficiency, incomplete digestion of gluten!
• Toxic peptides produced during digestion of gluten
• Toxic peptides cause activation of inflammatory responses

Question 8

What do disackarides depend on to be broken down? And what about polysackarides?

Answer 8

Disackarides depend on intestinal surface enzymes to be degraded.
Polysackarides depend on pancreatic alpha amylase and on intestial enzymes.

Question 9

Disackaride deficiency (lactose intolerance)

Answer 9

Lactase is deficient –> unable to absorb lactose –> becomes available for bacteria in lower small intestine –> produces gas, draws water in intestine causing diarrhea