the hormonal system and glands Flashcards
what is the hormonal system made up of?
endocrine glands and hormones
what are hormones
chemical messengers, mostly proteins or peptides e.g insulin, some are steroids e,f progesterone
what are the ways of intiating hormone secretion?
when an endocrine gland is stimulated.
by a change in a concentration of a specific substrate (sometimes another hormone)
or by electrical impulses.
how do hormones get transported
DIFFUSE DIRECTLY into blood and taken around in circulatory system. they travel all around the body but each hormone will only bind to specific receptors for that hormone, found on the membrane of some cells (target cells)
descrbie the stages of hormonal communciation when blood glucose conc is lower than set point
stimulus- low blood glucose conc
receptors- receptors found on pancreatic cells detect low BGC
hormone- pancreas releases the hormone glucagon into the blood
effectors- target cells in the liver detect glucagon and convert glycogen into glucose (glycogenolysis)
response- glucose is released into the blood, so glucose conc increases
what are endocrine glands?
ductless glands- secrete hormones directly into bloodstream
what are exocrine glands?
groups of cells specialised to secrete chemicals through ducts into cavities or onto the surface of the body e.g sweat glands secrete sweat onto surface of skin. usually secrete enzymes e.g digestive glands secrete hydrolytic enzymes into the gut.
what is a first messenger
a hormone because it carries the chemical message the first part of the way, from the endocrine gland to the receptor on the target cells.
what happens when a hormone binds to it’s receptor
it activates an enzyme in the cell membrane, which catalyses the production of a molecule inside the cells called a signalling molecule- this molecule signals to other parts of the cell to change how the cell works.
what is the hormonal system also called?
the endocrine system
what do second messengers do
singalling! carry chemical messages the second part of the way, from the receptor to other parts of the cell. the activate a cascade of reactions inside the cell
when is adrenalin secreted?
when there’s low concentration of glucose in your blood, when you’re stressed and when you’re excersing
what effect does it have?
prepares the body for action by making more glucose available for muscles to respire, by activating glycogenolysis (conversion of glycogen to glucose)
which messenger is adrenaline
first
describe the action of adrenaline
(endocrine directly into blood)
- adrenaline binds to specific receptors in liver and muscle cells
- creating a adrenaline-receptor complex this causes a G protein to bin with the enzyme adenyl cyclase to become activated (the G protein changes shape to the active site of Acyclase is exposed)
- this enzyme catalyses the conversion of ATP into cyclic Amp (CAMP) which is the second messenger molecule.
- Camp binds to and activates kinase enzymes (exposes the active site) which phosphorylates
- thereby activating glycogen phosphorlylase to convert glycogen into glucose via glycogenolysis
