endocrine system Flashcards
(32 cards)
hormones
chemical messengers that act on target cells to modify their activity/ cause a reaction
how do hormones work?
- they travel in the bloodstream to different parts of the body
- interact with cell surface receptors
what type of hormones r water-soluble?
amino acid, polypeptide
what type of hormones r lipid-soluble?
steroid (cholesterol), thyroid (tyrosine)
what r water and lipid soluble hormones deprived from?
- water-soluble: amino acids
- lipid-soluble: fatty acids
transport in body of water-soluble hormones
stored in secretory vesicles until needed
transport of lipid-soluble hormones
leave cell by simple diffusion, travel via carrier protein in bloodstream
signal transduction of water-soluble hormones
bind to receptors on target cell surface, stimulates production of second messengers (G proteins, cAMP)
-> affects enzymatic activity within the cell
signal tranduction of lipid-soluble hormones
- passes through cell membrane
- bind to receptors inside target cell
- hormone-receptor complex activates/suppresses transcirption of genes
examples for both water and lipid soluble hormones
water-soluble: adrenaline, insulin, glucagon
lipid-soluble: oestrogen, testosterone, thyroxine
compare the speed and effects of water and lipid soluble hormones
lipid-soluble work slower but with longer lasting effects
speed of hormones
travel from endocrine organs to the target tissue through blood, takes time
specificity of hormones
cells display receptors specific for certain hormones; lock&key mechanism
endocrine system
system of ductless glands that produce hormones involved in regulation of various body functions
3 features of hormones
effective in low concentrations, produced in small quantities, slow and longer lasting compared to nervous responses
what do hormones do?
- stabilise the body’s internal environment through homeostasis
- coordinate longer term processes (growth and sexual development)
what does the thyroid produce and what does it do
thyroxine: regulates metabolic rate, excess causes hyperactivity, deficiency causes overweight n sluggishness
what do the adrenal glands produce and what does it do
adrenaline: causes fight or flight response
* increased heart and breathing rate
* blood diverted to the muscles
* increased respiration -> increase amount of glucose in blood
what do ovaries produce and what do they do (2)
oestrogen: controls development of female secondary sexual characteristics, regulates menstrual cycle
progesterone: thickens uterine wall, prevents contractions until labour
what does the testes produce and what does it do
testosterone: promotes the development of male secondary sexual characteristics
what does the pancreas produce
insulin, glucagon
insulin
- controls the conversion of blood glucose to insoluble glycogen (liver)
- increases metabolic rate by stimulating cellular glucose uptake
- increases protein synthesis in some cells
- deficiency causes unregulated blood sugar levels -> sugar diabetes
glucagon
controls the conversion of insoluble glycogen to glucose in liver
what is the pituitary gland and what hormones does it produce
neurosecretory gland, produces growth, antidiuretic (ADH), and thyroid stimulating hormone (TSH)
