Lecture 18

Question 1

Parts of small intestine

Answer 1

duodenum
jejunum
ileum

Question 2

Brunner’s glands

Answer 2

found in submucosa secreting alkaline mucus protecting intestinal wall and neutralising chyme

Question 3

What is secreted by mucosa and sub mucosa? (SI)

Answer 3

ions and water

Question 4

Carbohydrate digestion

Answer 4

Converted to disaccharides by pancreatic amylase, then converted to monosaccharides (glucose, fructose) by glycosidase.

Question 5

Protein digestion

Answer 5

Catabolised by pancreatic trypsin and chymotrypsin.
Digestions completed by peptidases
Peptidases cleave peptides

Question 6

Fat digestion

Answer 6

Fat digestion takes longer, continues into jejunum where absorption will take place, bile salts are important for fat digestion to create emulsions dispersing fat in small entities rather than large globules.

Question 7

Gluctose/ galactose digestion

Answer 7

Absorbed into epithelial cell by co-transport with Na+ via sodium glucose transporters.
Leave epithelial cell sand enter blood via facilitated diffusion via glucose transporters (GLUTs)

Question 8

Peptides

Answer 8

broken down into amino acids in epithelial cell

Question 9

Fat absorbtion

Answer 9

Micelles diffuse passively into epithelial cells, but bile salts remain in lumen of gut and can be reused
Triglycerides accumulate in ER vesicles and form chylomicrons which leave the cell by fusing with plasma membrane. Leave intestine in lymph because they are too large to enter circulation immediately, eventually delivered into venous circulation. Not all fat reabsorbed.

Question 10

Lymphatic system

Answer 10

Absorbs fats, electrolytes fluid and proteins. Remove haemorrhaged RBCs
Lymphatic vessels in small intestine known as lacteals.
Lymphatic pathway BYPASSES LIVER and nutrients/drugs delivered into systemic circulation close to heart.