B1- Nervous System Flashcards
What does the nervous system do
Enables humans to react to their surroundings
What are receptors
Cells that detect stimuli (changes in the environment)
Examples of receptors and the stimuli they detect
Receptors in eye are sensitive to light
Receptors in ears are sensitive to sound
Receptors on tongue and nose are sensitive to chemicals that let us taste and smell
Receptors in skin are sensitive to touch, pressure pain and temp change
What do light receptors contain
Nucleus
Cytoplasm
Cell membrane
Role of sensory neurones
Carries signals from receptors to spinal cord and brain
Role of motor neurone
Carries signals from CNS to effectors
Role of relay neurones
Carry message from CNS to another
Role of synapses
Gap where two neurones meet
What happens in a reflex action
Impulse passes along a sensory neurones to the CNS
Impulse reaches synapse between sensory neurones and relay
Chemical released at synapse causing impulse to be sent along neurone
Chemical releases between relay and motor neurone. Triggers impulse to pass down to motor neurone
Impulse reaches effector (muscle or gland) which contracts leading to response
