Co-ordination and Control: Hormones Flashcards
What is a hormone?
a chemical produced by a gland which travels in the blood to have an effect on a target organ
What are the three hormones used in menstrual cycle?
- FSH
- LH
- Oestrogen
Where is FSH produced?
pituitary gland
role of FSH
- causes eggs to mature
- stimulates ovaries to produce oestrogen
Where is LH produced?
pituitary gland
role of LH
- stimulates egg release
Where is oestrogen produced?
ovaries
role of oestrogen
- inhibit FSH
- builds lining of uterus wall
- stimulates production of LH
how does menstrual cycle work?
- pit gland produced FSH
- matures eggs
- oestrogen: uterus lining/ inhibits FSH
- one egg matured
- high conc of oestrogen stimulates gland for LH
- ovulation
- empty follicle dies until fertilsation
What is the menstrual cycle?
preparation of female body for the egg to be fertilised
how long is the cycle?
28 days
stage 1
(days 1-5)
breaking down of uterus wall
stage 2
lining builds up again - thick spongy layer
stage 3
(day 14)
egg released from ovary
stage 4
lining is maintained
no implantation - cycle starts again
what is phototropism?
shoots grow towards light against the force of gravity
what is geotropism?
roots grow towards moisture in the direction of gravity
what is auxin?
a plant hormone that controls growth in tips of shoots and roots of plant
(controls phototropism and geotropism)
where is auxin produced?
in the tips of shoots of plant
How does auxin cause a shoot to grow towards the light?
- auxin accumulates on the side of shoot in the shade
- cells elongate on shaded side
- shoot bends towards light
How does auxin cause a shoot growing sideways to grow upwards?
- auxin on lower side of shoot
- elongates cells on lower side
- shoot grows upwards
How does auxin cause a root to grow in the direction of gravity?
- more auxin on lower side of shoot
- more auxin inhibits growth
- so cells on top of elongate faster
- root bends downwards
How does auxin cause a root to grow towards moisture?
- more auxin on side with moisture
- inhibits growth on that side
- other side is elongated
- root bends in direction of moisture
Uses of plant hormones
- weedkillers
- rooting powders
