Chapter 9: Homeostasis Hunger and thirst

Gherlin

hunger hormone released by stomach endocrine cells- appetite stimulant rise during fasting; drop after eating some obese people have elevated gherkin levels

Two sets of neurons in hypothalamus have opposing effects

NPY/AgRP POMC/CART

But the brain can recover , if overeating stops

Newborn hypothalamic cells become NPY/AgRP and POMC neurons these new neurons are responsive to fasting and leptin

Osmotic thirst

Occurs when extracellular fluid becomes too salty

LH lesión destroy?

Or exigen if LHA

angiotensin cascade

*Angiotensinogen (in blood)* Enzyme: Renin (from kidneys) *Angiotensin I* Enzyme: Converting enzyme *Angiotensin II* Enzyme: Aminopeptidase *Angiotensin III*

What does VMH destroy ?

A or exigencia PVN

What receptors does hypovolemic thirst use and define it

Baroreceptors in blood vessels and heart detect the initial drop. Brain activates thirst and salt craving arteries constrict to raise BP

Obesity and reduced metabolism

Basal metabolic rate (BMR) energy required to fuel the brain/body and maintain temperature 75% of energy expenditure in average sedentary student of women on a diet, the 1/3 who failed to lose weight had low BMRs heredity accounts for 40% of a person's BMR. But, spontaneous activity can increase it

Larger ínsula

Brain area active when you experience disgust

Larger órbita frontal cortex

Brain area that tells you your shouldn't do that'

Glycogenesis

Converting glucose to glycogen , using pancreases hormone insulin

What's happened if the leptin production are defects

Defects in leptin production or sensitivity give a falsely low report of body fat, causing animals to overeat obese people are leptin-resistant Overnutrition inflames the hypothalamus - obesity , diabetes , and heart disease

Treatment of obesity

Eat less : 500 to 1000 calories modify behavir exercise Don't eat at night treat as an addiction -they have fewer dopamine D2, receptors and associated lower prefrontal lobe metabolism peptides that induce eating target dopamine neurons anti-addiction drugs are somewhat effect in weight loss

Leptin

Fat cells produce leptin and secrete it into the bloodstream

Lipids

For long term storage are fat tissue

Glucose

Fuel for energy

What are the energy utilization for hunger ?

Glucose glycogen glycogenesis lipids

High calorie diets cause

Hypothalamic scarring and microglial activation , and 15% reduction of proopiomelanocortin (POMC) neurons, which are normally activated by leptin to block eating and increase energy expenditure

osmosensory neurons

In anterior hypothalamus (OVLT) Respond to rise in blood osmotic pressure (causes pituitary to release antidiuretic hormone) Their cell membranes shrink, opening mechanical-gated Na+ channels respond to increased osmotic pressure by causing the pituitary to release antidiuretic hormone

Glycogen

Is glucose stored for short term in the liver

Hypovolemic thirst

Is triggered by a loss of lucid volume: the concentration has not changed- salt and ions are also

ventromedial hypothalamus

Lesions cause obesity Lesiones animals exhibit overeat until they become obese increased weight stabilizes - this weight is maintained even after food manipulations

Overeating causes brain damages

Overeating—> hypothalamic inflammation —> inhibits neurogenesis , reset your set point

*Brain Control of Drinking

SFO- subbfornical organ

Leptin inhibits AgRP

Stimulates POMC neurons

What does hypovolemic cause to release ?

Vasopressin (antidiuretic)- induces blood vessel contraction and so reduces blood glow to the bladder diabetes insípidus- vasopressin is not produced - kidneys send more urine to the bladder, resulting in chronic thirst

gastric bypass surgery

Weight loss average 25% and is long-lasting (compared to 5%-10% with dieting and relapse within a year reduces gherkin and increase PYY and GLP-1, reducing hunger reduces mortality and has many health benefits

lateral hypothalamus (LH)

a brain region that produces hunger when activated lesioned animals stop eating , but resume and stabilize their weight at a new , lower level

Bulimia

an eating disorder characterized by episodes of overeating, usually of high-calorie foods, followed by vomiting, laxative use, fasting, or excessive exercise

anorexia nervosa

an eating disorder in which an irrational fear of weight gain leads people to starve themselves

What are the effects of Angiotensin II??

increases blood pressure by stimulating kidneys to reabsorb more water and by releasing aldosterone 1. Blood vessels constrict 2. Circumventricular organs trigger drinking 3. Vasopressin is released 4.aldosterone is released

Homeostatic

self-regulating System use our behavior to keep things balanced negative feedback systems are the main homeostatic mechanisms if a desired set is deviated from, compensatory action begins.

POMC/CART

when these neurons are stimulated they decrease appetite raise metabolism —> weight loss

NPY/AgRP

when these neurons are stimulated they increase appetite lower metabolism —> weight gain