B3.2 spec Flashcards
define what a hormone is
a chemical messenger
how are hormones released?
secreted by endocrine glands (organs that makes hormones that are released directly into the blood and travel to tissues and organs all over the body)
how are hormones transported around the body?
through the bloodstream
explain the role of adrenaline in the body
- responsible for ‘fight 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) (6 points)
- hypothalamus detects thyroxine levels are too low
- pituitary gland releases TSH (thyroid stimulating hormone)
- 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? (3)
- 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? (2)
- as only TARGET organs respond
- hormones only bind to specific receptors in target organs
where are receptors for hormones found?
on the membrane/cytoplasm of cells in target organs
where is progesterone made in the body?
in ovaries (produced by corpus luteum)
what is the acronym to remember the interactions of hormones in the menstrual cycle?
FOLP
fsh -> oes + oes STOPS -> fsh
o -> l
LOOK at mia’s digram on b3 folder (11b)
what do LH and FSH do?
FSH - stimulates one egg to mature/ripen
LH - stimulates follicle to release egg
when do progesterone levels fall?
after day 21
state 3 examples of non-hormonal contraception
(and explain how each works)
condom - prevents sperm entering vagina
diaphragm/cervical cap - into vagina + covers cervix, prevents sperm entering uterus
IUD - releases copper + kills sperm in uterus/fallopian tubes
what is the downside of using a diaphragm or cervical cap?
you must use spermicide with it
state 3 examples of hormonal contraception
(and explain how each one works)
combined pill - oestrogen + progesterone
( oestrogen prevents FSH from being released, and therefore no ovulation, progesterone thickens mucus in cervix so sperm no enter uterus + stops LH being released so egg does not enter oviduct
progesterone only pill - thickens mucus in cervix + stops ovulation 60% of the time (less side effects like nausea)
IUS - inserted into uterus
(same effect on body as progesterone-only pill)
how does IVF work? (4)
- LH and FSH given to stimulate eggs to mature
- eggs collected + fertilized
- egg developed into embryo
- embryo implanted into uterus
how are hormones used to treat infertility?
- FSH and LH given to mother for eggs to mature to be collected
causes of infertility in women (2)
women - lack of mature eggs
- ovaries cannot release egg
causes of infertility in men (2)
men - blocked sperm ducts
- not enough sperm cells
