CH. 6 Hunger

PSYC 305 Brain and Behavior

Homeostasis

The action of a system to maintain internal stability when faced with a disturbance of its normal condition. These systems allow us to maintain energy in a safe range and are mostly autonomic.

Examples of homeostasis

Hunger, thirst, thermoregulation

Examples of where body gets energy from

Water, oxygen, minerals, vitamins, carbohydrates, fats, proteins

Basal metabolism

Energy used to keep the body functioning and to maintain body temperature

Glucose

A sugar that comes mostly from carbohydrates

Insulin

A hormone in the bloodstream that helps glucose enter a cell

Adenosine triphosphate (ATP)

A molecule produced when glucose is broken down inside a cell; this provides energy

Glycogen molecules

Stored in the liver when too much glucose is present

When blood glucose levels drop, ____ signals for _____ to be converted back into ____ for additional energy

glucagon; glycogen; glucose

Fat

Where most of the bodys long-term energy comes from

Triglyceride molecules

Composed of fatty acids and a glycerol molecule, stored inside adipose cells

Broken down when energy is low, releasing fatty acids for use by cells

Glucostatic theory

We eat to restore blood glucose levels

Lipostatic theory

We eat to maintain fat levels within a stable range

Glucose-sensitive neurons

In the hypothalamus; detect energy levelsHo

What eating behaviors can homeostasis not explain

Having dessert when you are already full; eating for pleasure, habit, or other social influences

Ghrelin

A peptide hormone that is released to signal hunger when the stomach is empty

Vagus nerve

Activates in response to the stretching of the stomach when full and satiated

Cholecystokinin (CK)

Satiety signal released as food enters the small intestine

Leptin

A longer-term satiety signal released in response to accumulation of adipose cells

Neurons in the ____ of the _____ detect ghrelin and activate to signal hunger

arcuate nucleus; lateral hypothalamus

The ____ detects satiety and activates the ______

vagus nerve; solitary nucleus

A separate set of ____ activate the ____ after eating to signal satiety

arcuate neurons; paraventricular nucleus

Arcuate “hunger” neurons

Release neuropeptide Y (NPY) to excite LH neurons

Arcuate “satiety” neurons

Release alpha melanocyte-simulating hormone (a-MSH) to excite the PVN

Orexin

Peptide that stimulates appetite

Factors that can change body weigt

Pregnancy, physical illness, stationary lifestyles, social/cultural influences, disordered eating habits

Three main eating disorders

Anorexia, bulimia, binge eating disorder