Mod 4. L25 Flashcards
(18 cards)
what is a hormone?
chemical messenger that regulates almost all physiological functions
allows the body to behave as a single unit
both in plants and animals
Endocrine system principles
regulates almost all physiological functions
allows body to behave and function as a single unit
Modes of action of a hormone
autocrine: a cell targets itself
paracrine: a cell targets a nearby cell
endocrine: a cell targets a distant cell through the bloodstream
hormone receptors
hormones need to be bound for them to take action
found on cell membrane or within cell
Receptors for protein and amine hormones
protein hormones ex: Insulin, glucagon
amine hormones ex: epinephrine, adrenaline
expressed on cell membrane, hormones binding = second-messenger cascades
Receptors for steriod hormones
found within cell
Steriod hormones = lopophilic = can pass through cell membrane!
binding of steriod hormones = changes in gene expression and other processes
endocrine system
physiological systsem for hormone synthesis and action within the body
exocrine system
hormones released outside the body to affect other individuales (pheromones)
ex of pheromones:
- Vanderbergh effect = Pheromone in male pee promote sexual maturation of female mice
- must or elephants male discharge (temporin) during mating season
hormones for regulation of glucose levels in the blood
insulin / glucagon
Insulin
made by beta cells of pancreas
stimulated by glucose levels in blood
acts on liver, fat and muscles
increases aerobic metabolism of glucose
increases energy storage (form of glycogen, fat and protein)
overall decrease in glucose concentration in blood
regulated by negative feedback loop
insulin negative feedback loop
b cells of pancreas ->+ insulin -> liver -> + glycolysis, +glycogenesis, +lipogenesis -> - plasma glucose ->(negative feedback) - b cells of pancreas
Glucagon
alpha cells in pancreas
stimulated by low glucose levels in blood
acts on liver
promote conversion of glycogen -> glucose + synthesis of glucose from other building blocks
increase in glucose concentration in bloodstream
(opposite to insulin role)
Hormones involved in food intake regulation
Ghrelin and Leptin
Ghrelin
synthesized by stomach and small intestine
sensation of hunger + promotes food intake
highest before meals, decrease after meals
promotes weight gain (+food intake and + fat synthesis promotion)
Leptin
produced by fat (adipose) cells
Signals brain to stop eating (satiety)
(Opposing role to ghrelin)
link hormone to organ
organs:
Adipose tissue, Pancreas (2x), stomach
hormones:
Ghrelin, Insulin, Leptin, Glucagon
Leptin = Adipose tissue
Insulin and glucagon = pancreas
Ghrelin = stomach
what is “pre-torpor period”
when animals eat a lot of fat before torpor (hibernation)
Grhelin +
Leptin -
Insulin +
Glucagon -
What is Periodic state of arousal
animals that go under torpor and do not store fat before
periodic state of activity, feeding during “arousal” period
