5.4-the best one (hormones) Flashcards
what detects when blood glucose levels are too low?
alpha cells in the islets of Langerhans
what is secreted when blood glucose levels are too low?
glucagon
where are glucagon receptors located?
on hepatocytes
what’s the mechanism of glucagon action?
binds to target receptors
stimulates g protein inside membrane
activates adenyl cyclase which converts atp to cAMP
cAMP activates series of enzyme controlled reactions inside cell
what are the effects of glucagon in hepatocytes?
- glycogenolysis
- more fatty acids used in respiration
- amino acids and fats converted to additional glucose by gluconeogenesis
what is glycogenolysis?
converting glycogen to glucose
what is gluconeogenesis?
non carbohydrate sources like amino acids and fats converted into additional glucose
which enzyme does glycogenolysis?
phosphorylase A
what is diabetes mellitus?
a condition caused by the body no longer being able to control blood glucose levels.
what is type 1 also known as?
juvenile onset diabetes
what is type 1?
when the body stops producing insulin/enough insulin
causes of type 1?
autoimmune disease-body attacking its own beta cells
viral attack
what is type 2?
when the body stops responding to insulin or doesn’t make enough of it
what are the type 2 risk factors?
obesity lack of regular exercise diet high in sugars, especially refined afro-carribbean or Asian origin family history
how might stem cell therapy be used to treat type 1?
by using stem cells to grow new islets of Langerhans
what is hyperglycaemia?
constant high blood sugar
what is hypoglycaemia?
constant low blood sugar
what does the pancreas do when blood glucose levels are too high?
releases insulin from beta cells
inhibits glucagon
what does the pancreas do when blood glucose levels are too low?
releases glucagon from alpha cells
insulin inhibited
what is glucagon?
a hormone released by alpha cells in response to low blood sugar levels. it increases the production of glucose from glycogen.
what is insulin?
a hormone released by beta cells in response to high blood sugar levels. it causes the uptake of glucose and its conversion to glycogen.
what is glycogenesis?
the conversion of glucose into glycogen for storage.
what is the endocrine system?
a communication system using hormones as signalling molecules
what are the 2 types of hormone ?
protein/peptide
steroid
what are 3 examples of a peptide hormone?
adrenaline
insulin
glucagon
2 examples of steroid hormone?
oestrogen
testosterone
do the endocrine glands have ducts?
nah
what do endocrine glands consist of?
groups of cells that manufacture + release hormone directly into blood of associated capillaries
what does adenyl cyclase do?
converts ATP to cAMP
when is a G protein activated ?
when the hormone binds to the receptor
what does the G protein activate?
an effector molecule, usually an enzyme, eg adenyl cyclase, that converts an inactive molecule into the active 2nd messenger
what is the adrenal cortex?
outer layer of adrenal gland
where are adrenal glands found?
above kidneys
what is the adrenal medulla?
inner layer of adrenal gland
what are the layers of the adrenal cortex outer to inner?
zona glomerulosa
zona fasciculata
zona reticularis
what does the zona glomerulosa release?
mineralocorticoids eg aldosterone
what does the zona fasciculata release?
glucocorticoids eg cortisol
what does the zona reticularis release?
precursor molecules used to make sex hormones
what does the adrenal cortex use to produce steroid hormones?
cholesterol
what does aldosterone do?
acts on distal tubules and collecting ducts in kidney-increases absorption of Na+ and decreases K+ absorption, increases water retention increasing blood pressure
what do mineralocorticoids do?
control Na+ and K+ concs in blood-contribute to maintaining blood pressure
what do glucocorticoids do?
help control metabolism of carbs, fats and proteins in liver
in what situation is cortisol released?
response to stress or low blood glucose conc
what is glucagon?
hormone that causes increase in blood glucose conc
where is the pancreas located?
below stomach
what do exocrine glands do?
secrete substances into a duct
what is a group of exocrine cells in the pancreas clled?
acinus, plural acini
what are acini grouped together into?
small lobules separated by connective tissue
where do the cells of the acini secrete the enzymes they synthesise?
into the tubule at the centre of the group
what do the tubules of the acini join to form?
intralobular ducts that eventually combine to make pancreatic duct
what odes the pancreatic duct do?
carries fluid containing enzymes into 1st part of small intestine (duodenum)
what enzymes does the fluid from the pancreatic duct contain?
pancreatic amylase
trypsinogen
lipase
what is trypsinogen?
inactive protease-converted to active form trypsin when enters duodenum
what does the pancreatic fluid contain other than enzymes + why?
Na2CO3-makes it alkaline to neutralise contents of digestive system that just left acidic stomach
what do alpha cells secrete?
glucagon
what do beta cells secrete?
insulin
how is type 1 usually treated?
insulin injections
what are alternatives to insulin injections to treat type 1 diabetes?
insulin pump therapy
islet cell transplantation
pancreas transplant
what happens during insulin pump therapy?
small device constantly pumps insulin at a controlled rate into blood through needle permanently inserted under skin
how is type 2 treated?
change in lifestyle
