Lecture 35: Lower GI Histology II

Question 1

Where does carbohydrate digestion begin?

Answer 1

The mouth

Question 2

What is the role of amylase?

Answer 2

Hydrolyzes starch to form sugars; present in saliva and also secreted by pancreas

Question 3

Where are disaccharides broken down into monosaccharides?

Answer 3

Brush border of small intestine; then monosaccharides are taken up by enterocytes

Question 4

Where does protein digestion begin?

Answer 4

The stomach, where proteins are hydrolyzed into peptides (requires pepsin)

Question 5

What steps of protein digestion occur in small intestine?

Answer 5

Polypeptides broken down into peptides by several enzymes; at brush border, oligopeptides broken down into amino acids and transported into enterocytes via carrier-mediated process

Question 6

Where does lipid digestion begin?

Answer 6

Small intestine, where fats enter as triglyceride droplets

Question 7

Pancreatic lipase

Answer 7

Emulsifies large triglyceride droplets and releases fatty acids, glycerol

Question 8

Micelles

Answer 8

Transport fatty acids, glycerol, phospholipids, vitamins A and K, etc. across enterocyte apical plasma membrane via passive diffusion (requires FABPs)

Question 9

Chylomicrons

Answer 9

Formed from proteins and triglycerides; fuse to plasma membrane, taken up by lacteals where they will dump into lymphatic network and eventually enter blood

Question 10

Cholecystokinin

Answer 10

Secretion site: upper intestinal mucosa of duodenum in response to gastric contents
Acts on pyloric sphincter to slow emptying of stomach, stimulates release of bile from gallbladder and secretion of pancreatic enzymes

Question 11

Gastrin

Answer 11

Secretion site: pyloric-antral portion of stomach
Stimulates HCl production by parietal cells, gastric motility, promotes growth of gastric mucosa, stimulates release of insulin by beta pancreatic cells

Question 12

Secretin

Answer 12

Secretion site: epithelial cells of duodenum in response to acid contents of stomach
Enhances release of insulin by beta pancreatic cells, stimulates release of bicarbonate from pancreas

Question 13

Identify epithelium and musculature present in anal canal

Answer 13

Epithelium: stratified squamous
Musculature: skeletal muscle (external anal sphincter)

Question 14

Which of the following best describes the olfactory mucosa?

A. Stratified columnar epithelium with goblet cells and distinct basement membrane

B. Simple ciliated columnar epithelium with goblet cells and distinct basement membrane

C. Stratified, non-keratinized epithelium lacking goblet cells with thick basement membrane

D. Pseudostratified columnar epithelium lacking goblet cells with no distinct basement membrane

Answer 14

D. Pseudostratified columnar epithelium lacking goblet cells with no distinct basement membrane

Question 15

Which of the following is NOT a necessary part of the respiratory membrane?

A. Pneumocyte I
B. Basal lamina of pneumocyte I
C. Dust cells
D. Basal lamina of endothelial cells
E. Endothelial cell

Answer 15

C. Dust cells

Question 16

Which of the following is characteristic of an arteriole?

A. Thick tunica adventitia and large lumen
B. Thick tunica media in relation to size of lumen
C. Thin tunica media with relatively large lumen
D. Large blood-filled lumen
E. Large amounts of elastic fibers in tunica media

Answer 16

B. Thick tunica media in relation to size of lumen

Question 17

Where in the body of a normal, healthy individual would you expect most erythrophagocytosis to be occurring?

A. Marginal zone of spleen
B. Medulla of thymus
C. Hematopoietic cord in bone marrow
D. Cord of Billroth in spleen
E. Paratrabecular sinus in lymph node

Answer 17

D. Cord of Billroth in spleen

Question 18

Which of the following sequences best describe the flow of RBCs through the spleen?

A. Trabecular arteries, central arteries, splenic arteries, penicillus, venous sinuses

B. Splenic artery, central arteries, trabecular arteries, venous sinuses, penicillus

C. Trabecular arteries, splenic arteries, central arteries, penicillus, venous sinuses

D. Splenic artery, trabecular arteries, central arteries, penicillus, venous sinuses

Answer 18

D. Splenic artery, trabecular arteries, central arteries, penicillus, venous sinuses

Question 19

The simple cuboidal epithelium of this portion of the kidney tubule is composed of cells in the form of truncated pyramids which are characterized by basal striations that mark the location of mitochondria

A. Proximal convoluted tubule
B. Descending thin segment of loop of Henle
C. Ascending thick segment of loop of Henle
D. Distal convoluted tubule
E. Collecting ducts

Answer 19

A. Proximal convoluted tubule

Question 20

Renin is secreted by which of the following

A. Liver
B. Macula densa
C. Atrial cells of the heart
D. Mesangial cells
E. Juxtaglomerular cells

Answer 20

E. Juxtaglomerular cells