topic 7: animal coordination and homeostasis Flashcards
what is a hormone
a chemical messenger secreted by a gland, they travel through the bloodstream to targeted organs, though they are slower acting that electrical impulses they are longer lasting.
what are the two hormones responsible for controlling blood glucose
insulin-decreases blood glucose by encouraging the liver to turn glucose into glycogen stores
glucagon- signals the liver to break down glycogen back into glucose for respiration
how do contraceptive pills stop women getting pregnant
contains progesterone that inhibits the production of LH and FSH making an egg unable to grow in the uterus
what hormone causes the lining of the uterus to thicken
oestrogen
what is a disadvantage of treating infertility with hormone treatment
increase’s complications and there is a likelihood of more that one birth
what is metabolic rate
the rate at which energy stored in your food is transferred by all the reactions that take place in your body to keep you alive
what is adrenalin do and what are its effects (target organs include heart, muscles and liver)
.binds to receptors in the heart, making it contract more frequently and increase overall heart rate
.increases blood flow to muscles allowing cells to receive more oxygen and glucose for respiration
.adrenaline binds to liver and causes it to break glycogen stores into glucose for respiration
how does thyroxine control metabolic rate (when levels are low)
.low levels of thyroxine stimulate the hypothalamus to release TRH
.TRH stimulates the pituitary gland to release TSH
.TSH stimulates the thyroid gland to release thyroxine, causing thyroxine levels to rise again
how does thyroxine control metabolic rate (when levels are too high)
.higher than normal levels of thyroxine inhibit the production of TRH
.low levels of TRH inhibit production of TSH which cause thyroxine levels to drop
.thyroxine levels get lower as a result of negative feedback
what are the 4 physical stages of the menstrual cycle
stage 1: menstruation starts the lining of the uterus breaks down and is released
stage 2: the uterus lining is repaired from day 4-14 and thickens in preparation for a fertilised egg
stage 3: egg develops and is released by ovaries
stage 4: if no egg is fertilised the spongy lining begins to breakdown by day 28 and the cycle repeats.
what are the hormonal stages of the menstrual cycle
FSH: released by the pituitary causes a follicle to mature in the ovaries and stimulates oestrogen
Oestrogen: released by the ovaries, thickens the uterus lining and stimulates LH surge at high levels
LH: released by the pituitary gland LH stimulates ovulation where the follicle ruptures and an egg is released
the remains turns into a corpus luteum which secrets progesterone
Progesterone: released by corpus luteum after ovulation, maintains the lining and inhibits FSH and LH.
When progesterone levels drop oestrogen gets low and so the uterus lining of the uterus falls.
low progesterone stimulates FSH and the cycle repeats
what are the 5 types of hormonal contraceptives
IUD
combined pill
progesterone only pill
contraception patch
contraceptive implant
how does the combined pill work
oestrogen: stimulates thick mucus preventing sperm from reaching the egg
progesterone: inhibits the production of FSH meaning no egg is released
how does the contraceptive implant work
slowly releases progesterone for up to 3 years
how does the IUD work
implanted into the uterus
releases progesterone
describe the process of IVF
.women are given FSH and LH to stimulate egg maturation
.eggs are collected and fertilised outside the body
.eggs are placed in a incubator to grow into embryo
.some are reinserted back into the mother uterus to grow
pros and cons of IVF
pros: allows for infertile couples
cons: doesn’t always work
stressful and upsetting
often leads to multiple births which could lead to still births
why is thermoregulation so important
to maintain an optimum temperature for enzyme activity, with an optimum of (37), if temp drops the enzyme activity will slow down, if they get too high they might denature
what does the body do when temperature is too hot
.erector muscles relax so hairs lie flat
.sweat forms on the top of the skin, when it evaporates thermal energy is removed from the body
.blood vessels close to the surface of skin dilate to allow more blood to flow near the surface to transfer energy out into the surroundings
what does the body do when temperatures are too low
.erector muscles stand up to trap an insulating layer of air
.little sweat is produced to reduce heat energy transfer
.blood vessels near the skin surface restrict to reduce energy transferred to the surroundings
.shivering allow muscle to contract increasing rate of respiration and more energy
what role does the hypothalamus have in thermoregulation
contains receptors that are sensitive to the blood temperature in the brain
receives impulses from receptors in the skin that give information on external temperatures, located in the epidermis and the dermis
what is the epidermis
outer layer of the skin
what is the dermis
deeper layer of the skin below the epidermis
