Unit 8

Question 1

Describe the glucostatic theory of appetite regulation.

Answer 1

Works in a short time manner

• suggests that levels of blood glucose are an important feeding or satiety signal
• low levels of blood glucose stimulate the “feeding center” in the hypothalamus causing hunger
• high levels of blood glucose stimulate the “satiety center” in the HT and reduces appetite

Question 2

Lipostatic theory of appetite regulation

Answer 2

Based on long term regulation of body fat via the hormone leptin

• increased leptin from fat cells causes a decrease in appetite (receptors in HT)
• decreased leptin from a low % body fat cause increase in appetite

Question 3

Distinguish between the endocrine and exocrine secretions of the pancreas.

Answer 3

Endocrine secretions come from clusters of cells called islets and include the hormones insulin and glucagon
Exocrine secretions include digestive enzymes and a watery solution of sodium bicarb (to help neutralize stomach acid)

Question 4

Carbohydrate digestion

Answer 4

Digested by amylase coming from saliva and the pancreas. Broken down into mono and disaccharides

Question 5

How are disaccharides broken down further into monosaccharides

Answer 5

By the enzyme disaccharidase

Question 6

Protein digestion

Answer 6

Proteins are broken down into peptides and amino acids by proteases and peptidases from the small intestine and exocrine cells of the pancreas

Question 7

What begins protein digestion

Answer 7

Pepsin which is secreted from the stomach

Pepsinogen is the inactive form of pepsin which is activated by HCL (low pH)

Question 8

Lipid digestion

Answer 8

Lipids are broken down by bile salts which emulsify large blobs into small blobs. The small blobs are broken down into fatty acids and monoglycerides by lipase.

Question 9

How is glucose and amino acids absorbed

Answer 9

Secondary active transport and leave the cell by facilitated diffusion

Question 10

How do large proteins get absorbed

Answer 10

This mostly happens in infants but are absorbed by endocytosis and leave by exocytosis

Question 11

How do fatty acids and cholesterol enter/exit the cell?

Answer 11

Enter by simple diffusion and the form a chylomicron which leaves the cell by exocytosis

Question 12

Cephalic phase of digestion

Answer 12

Anticipation of food stimulates the parasympathetic neurons which stimulate salivary glands to secrete water, enzymes, and mucous. The enteric nervous system is also stimulated which causes:
Stomach: to increase motility and secretions
Intestines: to increase motility and secretions
Sphincter of Oddi: to relax
Gall bladder: to increase contraction

Question 13

Gastric phase of digestion

Answer 13

Increase parasympathetic activity, gastric stretch, aa and fa in gastric chyme and pH stimulate the hormone gastrin which is secreted by the G cells of the antrum of the stomach.

Question 14

What are the target cells of gastrin secretion in the gastric phase of digestion

Answer 14

• Parietal cells of the stomach which the increase HCl secretion (converting pepsinogen to pepsin)
• Chief cells of the stomach which increase pepsinogen secretion
• Lower esophageal sphincter which increase contraction
• illeum and colon which increase contraction to make room for incoming food

Question 15

Intestinal phase of digestion

Answer 15

Acidic chyme enter the small intestines
-Increased H+ causes the duodenal cells to secrete secretin which causes a decrease in gastric motility and decreased emptying of the stomach. Also causes in increase in pancreatic juice secretion (esp. bicarb)

Increased fatty acids and amino acids cause jejunal cells the release cholecystokinin (CCK) which causes in increase in pancreatic juice secretion (esp. bicarb), decreased gastric motility and emptying of the stomach, and cause contraction of the gall bladder

Increased carbohydrates cause the duodenal cells to secrete glucose-dependent insulinotropic peptide which cause the beta cells of the pancreas to secrete insulin

Question 16

Absorptive state

Answer 16

Mainly anabolic reactions

• use/store nutrients
• glycogenesis, lipogenesis, protein synthesis
• Insulin is the primary hormone

Question 17

Post absorptive state

Answer 17

Mainly catabolic reactions

• mobilize stored nutrients
• glycogenolysis, lipolysis, proteolysis, gluconeogenesis
• Glucagon = primary hormone

Question 18

Insulin

Answer 18

• Comes from the beta cells of the pancreatic islets
• Secreted due to increased glucose, AA, parasympathetic stimulation, GIP, gastrin in the blood
• *inhibited by sympathetic activity

Target tissues are mostly muscle and adipose cause insertion of GLUT 4 proteins in the membranes

Question 19

Glucagon

Answer 19

• Comes from the alpha cells in the pancreatic
• secreted in response to decreased glucose in the blood, increased sympathetic activity, increased amino acids in the blood, increased parasympathetic activity (prevents insulin from lowering blood glucose too much).

Question 20

NE/EPI

Answer 20

Secreted from the adrenal medulla in response to emergency, exercise
*target tissues are the same a glucagon

Question 21

Cortisol

Answer 21

Secreted from the adrenal cortex in response to stress

*target tissues are the same as glucagon plus it causes decreased immune function