Module 5.4 Flashcards
Hormonal communication
what is the endocrine system
communication using hormones as signalling molecules
what does the endocrine system use to transport signals
the blood
what do endocrine glands do
manufacture and release hormones directly into the blood in capillaries running through the gland
how are hormones detected
target cells and target tissues
for peptide hormones the target cell must posses a specific receptor on their plasma membrane that is complimentary in shaped to that of the hormone
what are non-steroid hormones known as and why
first messengers
bind to cell surface membrane and initiate an effect inside the cell (usually cause the release of another signalling molecule (the second messenger))
how do peptide hormones work
G protein is activated when hormone binds to the receptor
G protein activates effector molecule (usually adenyl cyclase)
adenyl cyclase converts ATP to cAMP
cAMP is the second messenger which may initiate an enzyme cascade or act directly on a protein to alter the activity of the cell
what are the two parts of the adrenal glands
adrenal medulla (inner)
adrenal cortex (outer)
what are the three layers of the adrenal cortex
zona glomerulosa (outer)
zona fasciculata (middle)
zona reticularis (inner)
what hormones does the adrenal cortex produce
steroid hormones
cortisol
aldosterone
precursor androgens
what hormones does the adrenal medulla produce
adrenaline
noradrenaline
action of steroid hormones
passes through plasma membrane of target cell
binds with specific receptor in cytoplasm
receptor-steroid complex enters the nucleus and binds to specific receptor on chromosomal material
binding stimulates production of mRNA which code for the production of proteins
what does aldosterone do
help control concentrations of sodium and potassium in the blood
as a result they contribute to maintaining blood pressure
what does cortisol do
helps to control the metabolism of carbohydrates, fats and proteins in the liver
what do precursor androgens do
taken up by the ovaries or tests and converted to sex hormones
role of adrenaline
prepare the body for activity
relax smooth muscles in bronchioles
increase HR and stroke volume
vasoconstriction to raise bp
conversion of glycogen to glucose
inhibits the gut
dilates pupils
what are the two functions of the pancreas
exocrine - secretion of pancreatic juices containing enzymes into the gut
endocrine - islets of Langerhans secrete hormones into the blood
where are the endocrine cells in the pancreas
islets of Langerhans
what do islets of Langerhans contain
alpha cells
beta cells
what do alpha cells secrete
glucagon
what do beta cells secrete
insulin
what channels do beta cells have and which are normally open
potassium and calcium ion channels
potassium is normally open
calcium is normally closed
why are potassium ion channels normally open
potassium ions diffuse out of the cell to make the inside of the cell more negative
what happens to beta cells when glucose concentrations outside the cell are too high
glucose molecules move into the cell
glucose is used to produce atp
what happens when there is extra atp in beta cells
potassium channels close
what happens when potassium channels close
potassium can no longer diffuse out of the cell making the cell less negative inside
change in potential difference opens calcium ion channels
what happens when calcium ion channels are open
calcium ions enter the cell and cause insulin secretion by making vesicles containing insulin move to the cell surface membrane and fuse with it to release insulin by exocytosis
what happens when blood glucose is too high
high blood glucose concentration detected by beta cells
insulin is secreted
target cells are liver cells, muscle cells and other body cells e.g. in the brain
target cells have membrane bound receptors
binding of insulin to receptors activates enzyme cascade
what does insulin do
more transporter proteins specific to glucose are placed into the cell surface membrane
more glucose enters the cell
glucose is converted to glycogen for storage
more glucose is converted to fats
more glucose is used in respiration
what is the conversion of glucose to glycogen called
glycogenesis
what happens when blood glucose drops too low
detected by alpha cells
glucagon is secreted into the blood
targets hepatocytes in the liver
glucagon bind to membrane bound receptor
activates G protein
ATP to cAMP
enzyme cascade
what does glucagon do
glycogen is converted to glucose
more fatty acids are used in respiration
amino acids and fats are converted unto additional glucose
what is the conversion of glycogen to glucose called
glycogenolysis
what is the conversion of amino acids and fats to glucose called
gluconeogenesis
what is diabetes mellitus
when the body is no longer able to produce insulin
type 1 diabetes
usually starts in childhood
autoimmune response where the immune system attacks the beta cells
insulin dependent
type 2 diabetes
non-insulin dependent
produce insulin but not enough
cells are less responsive to insulin
can be brought on by obesity, high sugar diet, lack of exercise, ethnicity
treatment for type 1 diabetes
insulin injections
islet cell transplant
pancreas transplant
stem cell treatment
type 2 diabetes treatments
change in lifestyle
loose weight
exercise
diet monitoring
medication
source of insulin for treating diabetes
genetically modified bacteria
