NSC Hunger and Thirst

Hunger and Thirst

Negative feedback in which a set point is deviated from and compensatory action begins to come back to set point.

Homeostasis

Increase in blood osmolatiry, high extracellular solute concentration (neurons in OVLT respond to rise in salt)

Osmotic thirst

Decreased blood pressure, Decrease in extracellular volume (barrorecepters detect drop on blood pressure, arteries constrict to raise BP, Vasopressin released.)

Hypovolemic Thirst

released by kidneys to trigger formation of angiotensin II (which acts in subfornical organ)

Renin

Why do diets not work?

BMR falls to prevent weight loss at the start of a diet

energy required to fuel brain, can increase with exercise but 40% controlled by hereditary

BMR

produced by fat cells and secreted into the bloodstream

Leptin

what does it mean to be leptin resistent

obesity

what happens to leptin levels as you lose weight

it falls

Principle fuel energy

Glucose

Short term, liver

Glycogen

process by which glucose is converted into glycogen, uses insulin created in pancreas

Glycogenesis

Long term, fatty tissue

Lipids

appetite stimulant released by gut. Rises when fasting and drops after eating.

Ghrelin

Hunger control center

Hypothalamus

refusal to eat, stabilizes weight at lower level, destroys hunger causing LHA

Lateral hypothalamic lesions

Leads to obesity, destroys hunger ending PVN

VMH lesions

stimulates appetite and lowers metabolism —> weight gain

NPY/ AgRP hormone

inhibits appetite and raises metabolism → weight loss

POMC/ CART hormone

Eat less, exercise, Mounjaro or ozempic

Obesity treatments

Glucagon like antagonists which can be used to treat obesity

Mounjaro and ozempic

Leads to hypothalamic scarring, microglial activation and fewer POMC neurons. Inhibits neurogenesis.

Overeating

Chronic thirst

Vasopressin deficiency

Inflames hypothalamus

Overnutrition

never being full

Prader- Willi syndrome

highest mortality rate, leads to larger insula and orbitofrontal cortex

Anorexia

Binge eating and then puking

Bulimia