Chapter 11 Flashcards
what is the endocrine system?
a collection of glands that secrete hormones into the blood stream
how does the endocrine system work?
a gland secretes a hormone to the blood stream
the blood carries the hormone to an organ
the organ carries out the desired action
differences between hormones and nerves (3)
nerves are very fast, hormones are slower
nerves act for a short time, hormones last longer
nerves act on a very precise area, hormones act in a more general way
what does insulin do?
controls blood glucose levels
what does adrenaline do?
prepares body for fight to flight
examples of hormones (2)
insulin
adrenaline
what is the main gland in the endocrine system?
the pituitary gland in the brain
4 examples of hormones produces by pituitary gland
growth hormones in children
ADH
FSH
TSH
what is FSH?
follicle stimulating hormone
stimulates ovaries to make oestrogen
what is TSH?
stimulates thyroid to make thyroxine which controls metabolism
function of hormones produced by thyroid
controls metabolism
function of hormones produced by pancreas
controls glucose levels
function of hormones produced by adrenal gland
prepares body for fight or flight
function of hormones produced by ovaries
menstrual cycle
function of hormones produced by testes
sperm production
where is insulin produced
pancreas
what does insulin do?
it allows or restricts the movement of glucose into cells
what are gibberellins?
they initiate seed growth
what are plant shoots sensitive to?
light and gravity
what are tropisms?
the response of plants to light and gravity
what is the response of plants to light called?
phototropism
what is the response of lights to gravity called?
gravitropism
what is auxin?
a hormone that makes plants grow
what happens when a shoot responds to light?
auxin moves to the unlit side
makes this side grow more
unequal growth
shoot brands towards light
what effect does auxin have on root hair cells?
inhibit growth
what effect does auxin have on shoot cells?
accelerated growth
what happens if there is no auxin in a plant?
no growth
what causes root cells to act towards gravity?
more auxin on lower side
more growth on upper side
shoot bends towards side with least auxin, facing down
when shoot grows down, auxin is evenly spread
what causes shoot cells to grow up?
auxin gathers on lower side grows more on side with auxin bends upwards auxin is redistributed normally shoot continues growing up
what are cuttings dipped in to stimulate growth?
auxin
how is auxin used as a weed killer?
it makes the plant grow rapidly and uncontrollably
how does weed killer not affect crops?
narrow leafed crops donโt absorb as much auxin as broad leaved weeds so they donโt die
why are weed killers important?
kills competition so crops thrive
what are giberellins used for (3)
used in brewing industry to speed up germination of barley
promotes flowering throughout the year
increase size of fruit
what chemical is used to control the ripening of fruit?
ethene
one common cause of infertility
lack of ovulation
when and why does lack of ovulation occur?
women donโt produce enough FSH to mature eggs in ovaries
how can lack of ovulation be treated naturally?
artificial FSH stimulates maturation of eggs
artificial LH can the be used to encourage ovulation
what does IVF stand for?
in vitro fertilisation
when is IVF used? (4)
no obvious cause of infertility
if donor egg is used
if oviducts are blocked
man produces very few sperm