coordination and control part 1
responding to change;
- the nervous system has receptors to detect stimuli.
- the receptors are found in sense organs, the eye, ear, nose, tongue and the skin.
- light simulates the eye and electrical impulses then pass to the brain along neurones (nerve cells).
- other stimuli include sound chemicals, temp change, tough or pain.
- the brain coordinates responses to many stimuli.
- the brain and spinal hord form the centeral nervous system (CNS)
- nerves contain nurones:
- sensory neurones carry impuleses from receptors to the CNS.
- Motor neurones carry impulses from the CNS to the effector organs which may be muscles or glands.
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coordination and control part 2
the main steps are:
- receptor detects a stimulus (e.g a sharp pain).
- a sensory nurone transmits the impulse to the CNS.
- a relay nurone passes the impulse on.
- a motor nurone is stimulated.
- the impulse passes to an effector (muscle or gland)
- action is taken (the response)
- the gaps between the nurones are called synapses.
- THIS IS CALLED THE REFLEX ARC
hormones and the menstral cycle
- FSH is made in the pituitary gland- this makes the egg mature.
- oestrogen is produced by the ovaries and stops any more FSH being made.
- this stimulates LH to be made and stimulates the womb linng. LH releases the egg.
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coordination and control part 3
the artificial control of fertility:
- the contraceptive pill (oral contraceptive) may conatin oestrogen and progesterone. some pills are progesterone only pills and have fewer side effects.
- these pills stop the production of FSH so no eggs are matured.
- if a woman cannot produce mature eggs FSH and LH can be given. ths is known as fertility treatment. the FSH causes the egg to mature and LH releases it.
- the body controls its internal enviroment. internal condition that include: water content, ion content, temprature and blood sugar level.
- water leaves the body as we breath, sweat and pee. we loose ions in our sweat and the urine.
- the level if sugar in our bodies is contolled by the pancreas.
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coordination and control part 4
hormones nad the conrol of plan growth;
- plants are sensitive to gravity, light and moisture.
- plants shoot towards light (phototropism)
- roots grow towards gravity (gravitropism)
- roots also grow towards water.
- auxin is a hormone that controls phototropism and gravitropism.
- un equal auxin can cause un equal growth and bending stems.
- plant hormones can be used by gardeners and farmers on their crop.
- weed killers are used to kill unwanted plants.
- when cuttings are taken from plants, hormones are used to encourage roots to grow before the cutting is planted.
- some hormones are used to encourage fruit to ripen.
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