U14 Nervous system Flashcards
Define sensitivity
The ability to detect stimuli in the internal or external environment and to make appropriate response.
What is a nerve impulse?
An electrical signal that passes neurones
CNS
Central nervous system, consisting of the brain and the spinal cord
PNS
peripheral nervous system, consisting of the nerves outside of the brain and spinal cord
What is the role of the nervous system?
Coordination and regulation of body functions
How do humans respond to stimuli? (explain what happens
Stimulus
Receptor (PNS)
Sensory neurone (PNS)
Brain/spinal cord (CNS)
Motor neurone (PNS)
Effector (PNS)
Response
List examples of stimulus
Light, sound, chemical, touch, temperature
List examples of response
Muscle contracts, secrete digestive fluids, secrete hormones
What is a sense organ
Sense organ is a group of receptor cells detecting specific stimulus
Explain what happens during a reflex arc
stimulus
receptor
sensory neurone
relay neurone
motor neurone
effector
response
What are the characteristics of a reflex action?
Automatic
Involuntary
Same response
Fast response
Why are reflex actions important
it protects the individual from physical damage
some are essential for surviving
How are neurones adapted to their functions? Name 2
It has very long cytoplasm - allows transmission of nerve impulse over long distances
Presence of myelin sheath (fats) increase the speed of transmission
What is a synapse
a junction between two neurones
How does electrical impulse pass from one neurone to another? (5)
Nerve impulse arrives at the end of the presynaptic neurone
Neurotransmitter is released into synaptic cleft
Neurotransmitter diffuses across the synpase
Neurotransmitter binds with a receptor on the membrane of the postsynaptic neurone
Binding of neurotransmitter to receptor stimulates impulse in postsynaptic neurone
