Flashcards in Homeostasis Deck (53)
what is homeostasis?
physiological control systems that maintain a constant internal environment
describe positive feedback
a response that amplifies a change eg) voltage gated channels Na +
describe negative feedback
receptors detect change away from normal/optimum and affectors return to normal/ optimum eg) blood temp.
what cells secrete insulin?
beta cells in the islets of Langerhan
what is the role of insulin?
to decerase bllod sugar conc.
describe 3 ways insulin decreses blood sugar conc.
binds to liver and muscle causing increased permeability to glucose……more glucose is absorbed by facilitated diffusion………… glycogenesis…..increased rate of respiration
what cells secrete glucagon?
alpha cells in the islets of langerhan.
how does glucagon restore normal blood sugar level?
gluconeogenesis - non carbs are converted to glucose……glycogenolysis…..decrease rate of respiration.
what is glycogenesis?
the conversion of glucose to glycogen
what is glycogenolysis?
the hydrolysis of glycogen into glucose
what is gluconeogenesis?
the conversion of non carbs eg)lipids/ amino acids into glucose
which hormone decreases blood sugar levels?
which hormone increases blood sugar levels?
when is glucagon secreted?
when the blood sugar is low
when is adrenaline secreted?
when is insulin secreted?
when the bloood sugar is HIGH
where does glucagon attach to receptors?
where does adrenaline attach to receptors?
where does insulin attach to receptors?
liver and muscle
what are the mechanisms of glucagon?
decreases rate of respiration, glycogenolysis, gluconeogenesis
what does adrenaline activate?
glycogenolysis, secretion of glucagon
what does adrenaline inhibit?
glycogenesis, and insulin secretion
what are the mechanisms of insulin?
icrease rate of respiration, glycogenesis, increasing cell permeability to glucose
how does insulin increase cell permeability?
glucose carrier molecules are in vesicles in L + M cells, insulon binds with specific receptors on the cell membrane, causing the fusion of the vesicles with the cell membrane, carrier proteins join the cell membrane (fluid mosaic), so glucose is absorbed by fac dif.
an illness where blood glucose levels are not fully controlled
dangerously high blood glucose concentration
dangerously low blood glucose concentration
What causes Type I diabetes
immune system destroys B cells on the Islets of Langerhan so cannot make insulin
What age does Type I diabetes affect?
Children and adolescents