The nervous system allows you to react to what is going around you.
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What are stimulus detected by?
Sense organs
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Name the 5 different sense organs in humans.
Ears, eyes, tongue, nose, skin.
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What do all sense organs contain?
Different receptors
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What are receptors and what do they do?
Receptors are group of cells sensitive to stimulus. They convert the stimulus energy into electrical impulses.
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List the different receptors.
Sound, light, taste, balance and skin.
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What is the ear sensitive to?
Sound and change in position.
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What are nerves?
A group of neurones.
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What are the three main neurones?
Sensory, relay and motor.
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What does a sensory neurone do?
It transfers signal from the receptor to the central nervous system.
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What does a relay neurone do?
It transfers signal from sensory neurones to relay neurones.
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What does a motor neurone do?
It transfers signal from the central nervous system to effector.
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What are the two type of effectors?
Gland and Muscle
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What do the two effectors do as a response to stimuli?
The gland secretes hormones and muscle contracts.
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What is a synapse?
A gap between two neurones.
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What does a synapse do?
A chemical called neurotransmitter is transferred through the synapse which diffuses across the gap. These chemicals then set off a new electrical impulse on the next neurone.
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What is the genuine series of a reflex arc?
Stimuli - sense organ - receptor - sensory neurone - relay neurone - motor neurone - effector - response
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In a reflex arc which places do the neurones go through?
Through the spinal cord or an unconscious part of the brain.
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What do glands do?
Secrete hormones.
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What substance are hormones and how do they travel through your body?
Hormones are chemicals released directly into the blood.
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Define hormones.
Chemical messengers that travel through the blood to activate target cells.
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How fast do hormones travel through your body?
Hormones travel at the speed of blood.
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In the blood where are hormones carried?
Blood plasma.
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What are hormones needed for?
Control things in the organs and cells that need constant adjustment.
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Name three different glands.
Three from pituitary gland, thyroid gland, pancreas, ovaries, testis, adrenalin.
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What does the pancreas gland secrete and what is it used for?
Insulin to control the blood glucose level and digestive enzymes.
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How are hormones different to nerves?
Hormones give slower action, act for a longer time and act in a general way whereas nerves act on a precise area.
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