B3.2 spec Flashcards
define what a hormone is
a chemical messenger
how are hormones released?
secreted by endocrine glands
how are hormones transported around the body?
through the bloodstream
explain the role of adrenaline in the body
- responsible for ‘flight or flight’ response for survival
- A HORMONE
where is adrenaline released from?
and where is it situated
the adrenal gland
- above each kidney
2 OF THEM
effects of adrenaline?
- increases heart + breathing rate
- dilates pupils
- diverts blood from digestion to limbs
- increase respiration rate
explain thyroxine in terms of its negative feedback loop (ie. when levels are too low)
- hypothalamus detects thyroxine levels are too low
- pituitary gland releases TSH
- which stimulates thyroid gland to release thyroxine
- hypothalamus detects energy levels are ‘normal’
- TSH stops being released from pituitary gland
- so thyroid gland stops releasing thyroxine
what is the role of thyroxine in the body?
- controls metabolic rate (how quickly chemical store converted to energy for body to use)
in general, describe the 5 stages in a negative feedback loop
1) conditions change
2) receptor detects change
3) corrective mechanism initiated
4) back to original level
5) corrective mechanisms switched off
reason for a negative feedback loop?
- to maintain homeostasis in the body
ie. keep internal conditions constant
what is the role of testosterone in males?
in terms of human reproduction
stimulating sperm production
what secondary characteristics are caused by an increase in testosterone levels?
- increase in height
- body + pubic hair growth
- enlargement of penis and testes
where is testosterone and oestrogen produced?
T - testes
O - ovaries
difference between nerve impulses and hormones (in terms of where they travel)
nerve impulses - only to specific parts of body
hormones - all around the body
why do all hormones not affect all organs?
- as only TARGET organs respond
- hormones only bind to specific receptors
