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 kidney2 OF THEM
effects of adrenaline?
increases heart + breathing ratedilates pupilsdiverts blood from digestion to limbsincrease respiration rate
explain thyroxine in terms of its negative feedback loop (ie. when levels are too low)
hypothalamus detects thyroxine levels are too lowpituitary gland releases TSHwhich stimulates thyroid gland to release thyroxinehypothalamus detects energy levels are ‘normal’TSH stops being released from pituitary glandso 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 change2) receptor detects change3) corrective mechanism initiated4) back to original level5) corrective mechanisms switched off
reason for a negative feedback loop?
to maintain homeostasis in the bodyie. 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 heightbody + pubic hair growthenlargement of penis and testes
where is testosterone and oestrogen produced?
T - testesO - ovaries
difference between nerve impulses and hormones (in terms of where they travel)
nerve impulses - only to specific parts of bodyhormones - all around the body
why do all hormones not affect all organs?
as only TARGET organs respond- hormones only bind to specific receptors
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?
FOLPfsh -> oes + oes STOPS -> fsho -> lLOOK at mia’s digram on b3 folder (11b)
what do LH and FSH do?
FSH - stimulates one egg to mature/ripenLH - 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 vaginadiaphragm/cervical cap - into vagina + covers cervix, prevents sperm entering uterusIUD - 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 ovulation, progesterone thickens mucus in cervix = sperm no enter uterus)progesterone only pill - thickens mucus in cervix (less side effects like nausea)IUS - inserted into uterus(same effect on body as progesterone-only pill)
how does IVF work?
LH and FSH given to stimulate eggs to matureeggs collected + fertilizedegg developed into embryoembryo implanted into uterus
