4.5 Coordination and response in humans
Respond to stimuli
● Voluntary response
○ Normal form of response
○ Think before action
● Involuntary response
○ Withdrawal reflex
○ Rapid, unconscious response to stimuli
○ Same stimuli result in same response, e.g.: shining light into pupils makes
them constrict, cough when something goes into trachea (instead of going
into oesophagus)
M R S G R E N C/H
| ↱ done by effectors, e.g.: muscles (external), glands (internal)
↳Sensitivity: detect and respond to detectable changes in environment
↳ done by receptors ↳ stimuli
Nervous system***
● Central nervous system
○ Brain
○ Spinal cord (脊髓)
■ Lies in canal running through vertebrae of backbone (spine)
● Peripheral nervous system
○ Cranial nerves (顱神經)
○ Spinal nerves (脊神經)
1
, Process of stimulus and response (the reflex arc - involuntary
response)***
BODY
Fire/heat receptor
NERVOUS
sensory neurone SYSTEM
CENTRAL
relay NERVOUS
SYSTEM
motor neurone
Withdraw hand effector
●
Receptors (感覺器官)***
● Mechanoreceptor - (physical) pain, touch, (physical) pressure, hearing
● Chemoreceptor - smell, taste
● Photoreceptor - light
● Thermoreceptor - hot and cold
Neurons (神經元)
● Attached to each other
● Bundle of neurons make up a nerve, transmitting electrical impulses in single
direction
● ***Dendron (樹突): transmits nerve impulses towards cell body
● ***Axon (軸突): transmits nerve impulses away from cell body, where nucleus is
found
● Dendron and axon are surrounded by myelin sheaths (髓磷脂鞘), speeding up
transmission (also acts as protectant [保護劑])
2
Respond to stimuli
● Voluntary response
○ Normal form of response
○ Think before action
● Involuntary response
○ Withdrawal reflex
○ Rapid, unconscious response to stimuli
○ Same stimuli result in same response, e.g.: shining light into pupils makes
them constrict, cough when something goes into trachea (instead of going
into oesophagus)
M R S G R E N C/H
| ↱ done by effectors, e.g.: muscles (external), glands (internal)
↳Sensitivity: detect and respond to detectable changes in environment
↳ done by receptors ↳ stimuli
Nervous system***
● Central nervous system
○ Brain
○ Spinal cord (脊髓)
■ Lies in canal running through vertebrae of backbone (spine)
● Peripheral nervous system
○ Cranial nerves (顱神經)
○ Spinal nerves (脊神經)
1
, Process of stimulus and response (the reflex arc - involuntary
response)***
BODY
Fire/heat receptor
NERVOUS
sensory neurone SYSTEM
CENTRAL
relay NERVOUS
SYSTEM
motor neurone
Withdraw hand effector
●
Receptors (感覺器官)***
● Mechanoreceptor - (physical) pain, touch, (physical) pressure, hearing
● Chemoreceptor - smell, taste
● Photoreceptor - light
● Thermoreceptor - hot and cold
Neurons (神經元)
● Attached to each other
● Bundle of neurons make up a nerve, transmitting electrical impulses in single
direction
● ***Dendron (樹突): transmits nerve impulses towards cell body
● ***Axon (軸突): transmits nerve impulses away from cell body, where nucleus is
found
● Dendron and axon are surrounded by myelin sheaths (髓磷脂鞘), speeding up
transmission (also acts as protectant [保護劑])
2
