Chapter 12 - Ingestive behaviours Flashcards
the process by which the body’s substances and characteristics are maintained at their optimal level
homeostasis
a variable that is controlled by a regulatory mechanism
ex: temperature in a heating system
system variable
the optimal value of the system variable in a regulatory mechanism
set point
a polysaccharide often referred to as animals starch; stored in the liver and muscle; constitutes the short-term store of nutrients
- complex, insoluble carbohydrate
glycogen
a pancreatic hormone that facilitates entry of glucose and amino acids into the cell, conversion of glucose into glycogen, and transport of fates into adipose tissue
- a peptide hormone produced by the pancreas
- Promotes use of glucose as 1o energy source.
- Promotes conversion of fuels to storable forms; glucose to glycogen and fat, amino acids to proteins.
- Promotes storage of glycogen in liver and muscle, fat in adipose tissue, and protein in muscles.
insulin
a pancreatic hormone that promotes the conversion of liver glycogen into glucose
- opposite effects of insulin
- stimulates conversion of glycogen to glucose
glucagon
a substance derived from the breakdown of triglycerides, along with fatty acids; can be converted by liver into glucose
glycerol
the form of fat storage in adipose cells; consists of a molecule of glycerol joined with three fatty acids
triglyceride
a substance derived from the breakdown of triglycerides, along with glycerol; can be metabolized by most cells of the body expect the brain
fatty acid
the phase of metabolism during which nutrients are not available from the digestive system; glucose, amino acids, and fatty acids are derived from glycogen, protein, and adipose tissue during this phase
- decrease in insulin
- increase in glucagon
fasting phase
the phase of metabolism during which nutrients are absorbed from the digestive system; glucose and amino acids constitute the principle source of energy for cells during this phase, and excess nutrients are stored in adipose tissue in the form of triglycerides
- nutrients absorbed from the bloodstream to meet body needs (energy source)
- increase in insulin, decrease in glucagon
absorptive phase
preparoty stage, begins with sensory (head) cues) ie: sight, smell, thought of food. ends with beginning of absorption in bloodstream.
- increase in insulin
- decrease in glucagon
cephalic phase
a peptide hormone release by the stomach that increases eating; also produced by neurons in the brain
- stimulate thoughts about food
- released by digestive system
- levels go up before a meal, down after
ghrelin
the first portion of the small intestine, attached directly to the stomach
- contains receptors that control secretion of ghrelin
duedenum
internal state of an animal seeking food
hunger
animals are drawn to eat not by energy deficits but, by the anticipated pleasure of eating
positive incentive theory
anticipated pleasure of a behaviour
positive incentive value
a dramatic fall in the level of glucose avaliable to cells; can be caused by a fall in the blood level of glucose or by drugs that inhibit glucose metabolism.
glucoprivation
a dramatic fall in the level of fatty acids available to cells; usually caused by drugs that inhibit fatty acid metabolism
lipoprivation