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B1 Chapter 2- Coordination And Control (Reflex Action (Receptor detects…
B1 Chapter 2- Coordination And Control
Responding To Change
Nervous system
Receptors- detect stimuli
Found in sense organs
Eye-Light
Ear -Sound
Nose-Chemicals
Tongue-Chemicals
Skin-Touch
Electrical impulses pass to brain along neurons
Brain and spinal cord-Central nervous system (CNS)
Brain-Coordinates responses to stimuli
Nerves contain neurons
Sensory neurons carry impulses from receptors to CNS
Motor neurons carry impulse from CNS to effector organs , Muscles-contract , glands-secrete chemicals
Reflex Action
Receptor detects stimuli
Sensory neuron transmits impulse to CNS
Relay neurons passes impulse on
Motor neuron stimulated
Impulse passes to effector
Action is taken
Junction between neurons -synapse
Chemicals transmit impulse across gap
Receptor to effector-reflex arc
Hormones And The Menstrual Cycle
Follicle stimulating hormone(FSH)
Made by pituitary gland
Causes egg to mature, oestrogen produced
Oestrogen
Produced by ovaries
Inhibits production of FSH
Stimulates production of LH and womb lining to develop to receive fertilised egg
Luteinising hormone (LH)
Made by pituitary gland
Stimulates mature egg to be released from ovary
The Artificial Control Of Fertility
Contraceptive pill
May contain oestrogen and progesterone
Some progesterone-only pills - have fewer side effects
Prevents production of FSH -no eggs mature
Help reduce family size- caused poverty
Allows planned pregnancies
Side effects and ethical issues
Fertility treatment
Not produce mature eggs- FSH and LH can be given
FSH-causes eggs to mature
LH-Stimulates ovulation
Help infertile couples having IVF
Expensive and some think unethical
Extra embryos produced stored or destroyed