5.4 Flashcards
definition of endocrine system
a communication system using hormones as signalling molecules
what do endocrine glands do
release hormones directly into the blood
structure of the endocrine glands
- ductless
- consists of cells that manufacture and release the hormones directly into the blood in capillaries running through the gland
what are target cells
the cells receiving the endocrine signal (hormones only have an effect in one type of tissue).
what must target cells have in order to deal with non-steroid hormones
for non-steroid hormones, target cells must possess a specific receptor on their plasma membrane that is complementary to the shape of the signalling molecule
endocrine organs
- pituitary gland
- thyroid gland
- thymus
- adrenal glands
- pancreas
- ovaries
- testes
adrenal cortex definition
the outer layer of the adrenal gland
adrenal medulla definition
the inner layer of the adrenal gland
what hormones are released by the adrenal glands + what does it do
- adrenaline
- mineralcorticoids
- glucocorticoids
- cortisol
adrenaline
stimulates the body to prepare for fight or flight: increases heart rate, mental awareness dilates pupils inhibits action of gut causing body hair to stand erect
mineralcorticoids
help to control conc of Na + K in blood, maintain blood pressure
glucocorticoids
helps to control the metabolism of carbohydrates, fat and proteins in the liver
cortisol
released in response to stress/low blood glucose conc, used to make sex hormones
what do α cells do
secrete glucagon
what do β cells do
secrete insulin
where are the α and β cells found
in a pancreas lobule in the islets of Langerhans
what happens if there is a rise in blood glucose concentration
- detected by β cells
- β cells secrete insulin into blood
- insulin detected by receptors on liver+muscle cells
- liver+muscle cells remove glucose from blood, convert glucose to glycogen
- glucose conc falls
what happens if there is a fallin blood glucose concentration
- detected by α cells
- α cells secrete glucagon into blood
- glucagon detected by receptors on liver cells
- liver cells convert glycogen to glucose and release glucose into blood
- glucose conc rises
mechanism of insulin secretion
.draw diagram
type 1 diabetes vs type 2 diabetes
type 1:
- younger people
- bodies immune system attacks+destroys β cells
- can’t make sufficient insulin
type 2:
- older people
- can’t produce enough insulin
- blood glucose conc permanently raised
causes of type 1 diabetes
-result of an autoimmune response where bodies immune system attacks+destroys β cells, cannot synthesis sufficient insulin and cannot store excess glucose as glycogen
causes of type 2 diabetes
-specific receptors on the surface of the liver and muscle cells become less responsive and cells lose their ability to respond to insulin in the blood
