Coordination systems and neurones
| English | Chinese | Pinyin |
|---|---|---|
| endocrine system | 内分泌系统 | nèi fēn mì xì tǒng |
| nervous system | 神经系统 | shén jīng xì tǒng |
| neurone | 神经元 | shén jīng yuán |
| axon | 轴突 | zhóu tū |
| sensory neurone | 感觉神经元 | gǎn jué shén jīng yuán |
| motor neurone | 运动神经元 | yùn dòng shén jīng yuán |
| effector | 效应器 | xiào yìng qì |
| reflex arc | 反射弧 | fǎn shè hú |
Control and coordination
- The body has two coordination systems.
- The endocrine system 内分泌系统 sends chemical hormones in the blood.
- The nervous system 神经系统 sends fast electrical signals along nerve cells.
A neurone that carries impulses from a receptor to the CNS is a:
Sensory neurones carry signals into the CNS.
Nervous vs endocrine
| Feature | Nervous | Endocrine |
|---|---|---|
| signal | electrical impulse | chemical hormone |
| transport | along nerve cells | in the blood |
| speed | very fast | slower |
| lasts | short | longer |
Compared with the endocrine system, the nervous system is:
Nervous signals are fast electrical impulses with short-lived effects; hormones are slower and longer-lasting.
The nervous system gives a faster but shorter-lasting response than the hormonal (endocrine) system.
Electrical impulses are quick and brief; hormones travel in the blood — slower, but their effects last longer.
Neurones 神经元
- A neurone is a nerve cell, with a long fibre (the axon 轴突) the impulse travels along. Three kinds:
- sensory neurone 感觉神经元 — carries impulses from a receptor towards the brain/spinal cord.
- motor neurone 运动神经元 — carries impulses out to an effector 效应器 (e.g. a muscle).
- intermediate (relay) neurones — connect sensory to motor neurones.
A motor neurone: dendrites, a cell body, and a long myelinated axon carrying the impulse to a muscle
Real neurones stained brown under the microscope, showing their cell bodies and processes
Explore a motor neurone
Tap each part. The impulse travels from the cell body down the long axon to the terminals, jumping between the myelin gaps.
A motor neurone:
Motor neurones carry impulses from the CNS out to effectors; sensory neurones carry them in.
Match each neurone or part to its job.
Sensory in, motor out, relay between; the myelin sheath makes the impulse travel faster.
The reflex arc 反射弧
- A sensory receptor detects a stimulus and starts an impulse.
- The reflex arc: stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector → response.
A reflex arc: stimulus → receptor → sensory → relay → motor → effector
Put the reflex arc in order.
Stimulus → receptor → sensory → relay → motor → effector → response.
A sensory receptor:
A receptor detects the stimulus (e.g. chemicals in a taste bud) and triggers an action potential.
You've got it
- nervous = fast electrical impulses, short-lived; endocrine = slower hormones, longer-lasting
- sensory neurone → towards CNS; motor → out to effector; relay connects them
- a receptor detects a stimulus and starts the impulse
- reflex arc: stimulus → receptor → sensory → relay → motor → effector → response