what does the central nervous system consist of?
- brain
- spinal cord
what is stimulus?
change in environment requiring a response
what do receptors do?
sensitive to stimulus and convert stimulus energy into electrical impulses
what are the five sense organs?
eyes ears nose tongue skin
what receptors do eyes contain?
light
what receptors do ears contain?
- sound
- balance (sensitive to changes in position
what receptors does the nose contain?
smell receptors sensitive to chemical stimuli
what receptors does the tongue contain?
taste receptors sensitive to sweet, sour, salt, bitter and other chemical stimuli
what receptors does the skin contain?
receptors sensitive to temperature, touch, pain and pressure
what are neurons and what do they do?
nerve cells - transmit electrical impulses around the body
name three types of neurons
sensory
relay
motor
what are dendrites/ dendrons?
branched nerve endings that connect with other neurons
what are axons made from?
cytoplasm stretched out into long fibre surrounded by membrane
sometimes have myeli sheath as electrical insulator
where does sensory neuron carry impulses from and to?
receptor to CNS
- 1 long dendrite picks up impulses
- 1 short axon carries it to CNS
where does relay neuron carry impulses from and to?
sensory neuron to motor neuron
- many short dendrites picks up impulses from sensory neurons
- many short axons carries it to motor neurons
where does motor neuron carry impulses from and to?
motor neuron to effector (muscles/glands)
- many short dendrites picks up impulses from relay neurons
- 1 long axon carries impulses to muscles or glands
what is reflex arc?
involuntary rapid response to stimuli
explain process of reflex arc
- stimulus detected
- impulse along sensory neuron to spinal cord
- impulse along relay neuron via synapse
- impulse along motor neuron via synapse
what is synpase?
gap between neurons
how do neurons transmit information across a synapse?
transmitter chemical diffuses across gap and binds to receptor molecules
how do drugs like ectasy affect transmission across synapse?
blocks sites in synapse where serotonin is removed
- high concentration of serotonin causes mood changes
