reflex arcs Flashcards
the nerve pathway shown in the diagram may be regarded as a simple reflex arc. Use the diagram to explain why (1)
only 3 neurones
suggest 2 advantages of simple reflexes (2)
don’t have to be learned
can escape from predators
protect against damage to body tissues
central nervous system
consists of brain and spinal cord
peripheral nervous system
made up of pairs of nerves which originate from the brain or spinal cord
made up of sensory and motor neurones-
sensory neurones- carry impulses from receptor to central nervous system
motor nueorones- carry impulse away from central nervous system and to effector
voluntary nervous system
voluntary/conscious actions
impulses transmitted to body muscles
autonomic nervous system
involuntary/subconscious actions
impulses transmitted to body glands, smooth muscle and cardiac muscle.
what is a reflex?
involuntary response to a sensory stimulus
what is a reflex arc?
the sequence of nerve cells involved in reflex- is reflex arc
sequence
stimulus- detectable change in environment e.g. hot plate.
receptor- cells which detect change e.g. temperature sensitive cells on the back of your hand
sensory neurone carries impulse from receptor to spinal cord/coordination centre
coordinator- links motor and sensory neurones in the spinal cord
motor neurones- tranmits impulse from coordination to effector
effector- muscle in upper arm, which contracts
response- hand moves away from hot object.
benefits of reflex arc
increased speed of transmissions
this is due to few synapses
protects body tissues from damage
doesn’t have to be learnt.