reflex actions Flashcards
are reflex actions voluntary?
no
why are reflex arcs important
to minimise damage to the body
what happens when a pin is touched (reflex action)
- The pin (the stimulus) is detected by a receptor in the skin
- A sensory neurone sends electrical impulses to the spinal cord (the coordinator)
- Impulse is passed to a relay neurone in the spinal cord
- Relay neurone synapses with a motor neurone
- Motor neurone carries an impulse to a muscle in the leg (the effector)
- Muscle contracts and pulls the foot away from sharp object (the response) when stimulated by the motor neurone
three types of neurons in a reflex action
sensory, relay, motor
what do sensory neurones do
carry impulses from sense organs to the CNS (brain or spinal cord)
what do relay neurons do
connect sensory and motor neurones
what do motor neurons do
carry impulses from the CNS to effectors (muscles or glands)
description of sensory neurons
long and have a cell body branching off the middle of the axon
description of relay neurons
short and have a small cell body at one end with many dendrites branching off it
description of motor neurons
long and have a large cell body at one end with long dendrites branching off it
what is a synapse
gap between two neurons
can electrical impulses pass over synapses?
no
where are synapses found in a reflex acc?
between the sensory and relay neurons
what is the name of the chemical that diffuses across the synapse
neurotransmitters
what is the ordor or action when a stimulus is detected in a reflex action
stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector
