2. Hypothalamic hormones

Question 1

What is the anatomical connection between the hypothalamus and the anterior pituitary gland?

Answer 1

Hypothalamo-hypophyseal-portal system

• A system of tiny capillaries that moves hormones quickly from the hypothalamus to the anterior pituitary.

Question 2

What are the 3 parts of the hypothalamus that regulate food intake?

Answer 2

1. Ventral posteromedial nucleus (VPN)
2. Lateral hypothalamic area
3. Arcuate nucelus

Question 3

The ventral posteromedial nucleus is the _____ center. It stimulates the sensation of ______.

Answer 3

1. Satiety center
2. Sensation of fullness.

Question 4

The lateral hypothalamic center is the _____ center. It causes the sensation of ______.

Answer 4

1. Feeding center.
2. Sensation of hunger.

Question 5

What is the function of the arcuate nucleus?

Answer 5

Regulates the feeding center + satiety center

Receives signals from the GI tract

Question 6

Describe the pathway/structure of the hypothalamus in appetite regulation.

Answer 6

Question 7

Describe the mechanism that happens when you are feeling hungry.

Answer 7

Hunger

Hypothalamus action:
1. Mechanoreceptors in the Stomach
-> Detect empty stomach
-> Causes Vagus Nerve to fire slowly
-> To the Solitary Nucleus in the Medulla
-> Sends nerve fires to the Arcuate Nucleus

2. Arcuate nucleus
   -> Activates the feeding center via Orexigenic neurones - stimulates appetite
   -> Inhibits the satiety center via Anorexigenic neurones

Lining of the stomach:
Empty stomach
↓↓ firing of mechanoreceptors + ↓↓ glucose
-> Triggers P/D1 (Gr cells)
-> Secrete Ghrelin into the body
-> Ghrelin travels directly to Arcuate Nucleus to stimulate the feeding center and inhibits the satiety center

Question 8

What is the hunger hormone?

Answer 8

Ghrelin

Question 9

Describe the initial response when you have a meal.

Answer 9

↑ Stretch
↑ Mechanoreceptor firing
Vagus Nerve passes this information to the Arcuate nucleus

Decreases stimulation of feeding center
Increases stimulation of satiety center

Question 10

What is the role of the SI?

Answer 10

Food is broken down into: Glucose, Amino Acids, Fats
-> Detected by Chemoreceptors
-> Send signals through the Enteric Nervous System and GI tract

Stimulates Enteroendocrine cells –> Hormone Secretion

Question 11

What is the long term satiety hormone and why?

Answer 11

Leptin

Stable throughout the day

Question 12

What is the function of leptin?

Answer 12

Reduces Hunger + Increases Satiety

• Acts directly on the hypothalamus
• Produced by adipose cells

Question 13

What are the 4 acute satiety hormones?

Answer 13

1. Cholecystokinin (CCK)
2. Peptide YY
3. GLP-1
4. Insulin

Question 14

CCK -
Produced by:
Action:
Affect on appetite:

Answer 14

CCK -
Produced by: enteroendocrine I-cells

Action:
1. Regulates nutrient-stimulated enzyme secretion
2. ↑↑ gallbladder contraction
3. ↑↑ enzymatic pancreatic secretion output
4. Regulates gastric emptying via delivering food from stomach -> SI

Affect on appetite:
- Reduces appetite
- Induces satiety

Question 15

Peptide YY (PYY) -
Produced by:
Action:
Affect on appetite:

Answer 15

Peptide YY (PYY) -
Produced by: L-cells in the SI, enteroendocrine cells in the pancreas and colon

Action:
1. Inhibits gastric acid secretion
2. Slows gastric + intestinal motility
3. Inhibits exocrine pancreatic secretions
4. Inhibits ghrelin (hunger hormone) secretion

Affect on appetite:
- Reduces appetite
- Induces satiety

Question 16

Glucagon-like peptide 1 (GLP-1)
Produced by:
Action:
Affect on appetite:

Answer 16

GLP-1
Produced by: intestinal L-cells

Action:
1. ↑↑ insulin secretion from pancreatic beta-cells

Affect on appetite:
- Reduces appetite
- Induces satiety

Question 17

Insulin
Produced by:
Action:
Affect on appetite:

Answer 17

Insulin
Produced by: pancreatic beta-cells

Action:
1.↓↓ blood glucose

Affect on appetite:
- Reduces appetite
- Induces satiety