what is a hormone
chemical messenger released by glands into the blood
difference between nerves and hormones
nerves = fast, short-lived; hormones = slower, long-lasting
example of a hormone controlling growth
growth hormone from pituitary gland
key phrase for hormone action
target organ responds specifically
which hormone controls metabolic rate
thyroxine
where is thyroxine produced
thyroid gland
effect of too little thyroxine
metabolism slows → weight gain, tiredness
effect of too much thyroxine
metabolism speeds up → weight loss, hyperactivity
four key hormones in the menstrual cycle
FSH, LH, oestrogen, progesterone
role of FSH
matures egg, stimulates oestrogen production
role of oestrogen
repairs and thickens uterus lining
role of LH
triggers ovulation
role of progesterone
maintains uterus lining for pregnancy
hormone that lowers blood glucose
insulin
where is insulin produced
pancreas
hormone that raises blood glucose
glucagon
effect of insulin
glucose → glycogen in liver, cells absorb glucose
cause of type 2 diabetes
body becomes resistant to insulin
risk factors for type 2 diabetes
obesity, poor diet, lack of exercise
treatment for type 2 diabetes
diet control, exercise, sometimes medication
part of brain controlling temperature
hypothalamus
response to overheating
sweat, vasodilation
response to cold
shivering, vasoconstriction
what maintains constant body temperature
negative feedback
