P7: Hunger/Thirst

Question 1

What hormone regulates thirst?

Name 2 main functions.

Answer 1

Vasopressin, synthesized in the hypothalamus,

2 functions: it increases the amount of solute-free water reabsorbed back into the circulation from the filtrate in the kidney tubules of the nephrons. Second, AVP constricts arterioles, which increases peripheral vascular resistance and raises arterial blood pressure.

Question 2

Which hormones are involved in hunger?

Answer 2

Ghrelin, Orexin, MCH, Endocannabinoids, Gluco+Lipoprivation,

Question 3

Which hormones are involved in satiety? Which ones are short - and which ones are long-term?

Answer 3

Short-term: Insulin, CCK, PYY

Long-term: Leptin, Serotonin

Question 4

Which brain/body areas are involved in hunger?

Answer 4

Ghrelin: released from doudenum
Gluco+Lipoprivation: detected in Liver, Glucoprivation also detected in medulla
VTA/Motivation areas in the brain

Question 5

Which brain/body areas are involved in satiety?

Answer 5

CCK+PPY: released from stomach in to the blood stream –> detected in the brain
CCK: response to the presence of nutrients: proteins and fat. delays gastric emptying
PYY: proportional to the calories ingested. last part of small intestine, colon/large intestine. Also delays gastric emptying
Insulin: released from pancreas: is detected by Hypothalamus
Leptin: secreted by well-nourished adipose tissue/fat cells: decreases food intake and increases metabolic rate. Fat people might be resistand to the effects of Leptin.
Serotonin: serotonin agonists reduce hunger

Question 6

What functions has insulin(4)?

Answer 6

• Permits organs other than the brain to metabolize glucose(in fasting phase)
• Promotes entry of nutrients into fat cells(in absorption phase) which reduces hunger increasing glucose uptake into peripheral tissue–> release Leptin
• Glucose to Glycogen in Liver

Question 7

Which brain areas are involved in hunger in connection with NPY?

Answer 7

ghrelin from stomach and Gluco/Liporprivation from Liver and Medulla receive at hypothalamus: the arcuate nucleus integrates and releases NPY+AGRP to the Lateral hypothalamus and the paraventricular nucleus(also hypothalamus). The lateral hypothalamus releases MCH and Orexin which create hunger and reduce metabolic rate. The paraventricular nucleus innvervates the brain stem nuclei which control the Autonomic Nervous system –> decreased Insulin secretion, decreased breakdown of fatty acids, body temperature is decreased