Hormonal Communication Flashcards
what is endocrine communication
specialised glands secrete hormones into blood
circulatory system carries blood to target organ/tissue
lipid soluble steroid hormones diffuse into cell and bind to receptor in cytoplasm
peptide hormones bind to receptors on cell surface membrane
what hormone does the medulla secrete
adrenaline
what hormones does the cortex secrete
mineralocorticoids (aldosterone)
glucocorticoids (cortisol and corticosterone)
why is it important that blood glucose concentration remains stable
maintains constant blood water potential preventing shrivel
maintain constant concentration of respiratory substrate
define negative feedback
self regulatory mechanisms return internal conditions to optimum when there is a fluctuation
define glycogenesis
liver converts glucose into glycogen for storage
glycogenolysis
liver hydrolyses glycogen into glucose
gluconeogenesis
liver converts amino acids and glycerol to glucose
outline the role of glucagon when blood glucose decreases
alpha cells detect decrease and secrete glucagon
glucagon binds to surface receptors and activates enzymes for glycogenolysis and gluconeogenesis
glucose diffuses from liver to blood
alpha cells detect glucose conc has returned to normal and stop producing glucagon
outline the role of insulin when blood glucose increases
beta cells detect increase and secrete insulin
insulin binds to surface receptors and activates enzymes for glycogenesis stimulates adipose tissue to synthesise fat
use the secondary messenger model to explain how glucagon works
hormone receptor complex forms
conformational change to activate G protein
activates adenyl cyclase which converts ATP to cAMP
cAMP activates protein kinase A pathway
results in glycogenolysis
how does insulin lead to a decrease in blood glucose conc
increases cell permeability to glucose causes glucose conc gradient
triggers inhibition of enzymes for glycogenolysis
how is insulin secretion controlled
beta cells have K+ and Ca+ channels to maintain PD of -70
as glucose conc increases glucose enters b cell by facilitated diffusion
respiration of glucose produces ATP
ATP gated K+ channels close so K+ dont diffuse out of cell
PD becomes more positive causing depolarisation
Ca+ channels open causing exocytosis of insulin
explain the causes of type 1 diabetes and treatments
body cannot produce insulin due to autoimmune response attacking beta cells
inject insulin from animals or gentically modified bacteria
explain causes of type 2 diabetes and treatments
glycoprotein receptors damaged and become less responsive to insulin caused by poor diet/weight
control diet and exercise frequently
what are the functions of adrenaline
increase blood flow to muscles
increase heart rate
stimualte glycogenolysis
what are the functions of noradrenaline
increase heart rate
increase blood pressure
widen pupils
what are the functions of androgens
regulation of sexual characteristics
cell growth
what are the functions of corticosterone
regulation of metabolism
what hormone does cortex of adrenal gland produce and what are its functions
aldosterone
water reabsorption
what hormone does the medulla of adrenal gland produce
adrenaline
how could blocking calcium channels inhibit insulin secretion
calcium ions do not enter cells so no exocytosis
