5.1 - Nervous control Flashcards
What two subsystems does the nervous system consist of?
- The central nervous system: brain and spinal cord.
- The peripheral nervous system: pairs of nerves originating from either the brain or spinal cord.
What can the PNS be divided into?
Sensory neurones: carry nerve impulses from receptors towards the CNS.
Motor neurones: carry nerve impulses away from the CNS towards effectors.
How can the motor neurone system be divided up?
- Voluntary nervous system: carries nerve impulses to bodily muscles. Voluntary.
- Autonomic nervous system: carries nerve impulses to glands, smooth muscle, cardiac muscle. Involuntary.
What is the spinal cord?
A column of nervous tissue running along the back that lies inside the vertebral column for protection.
What emerges at intervals along the spinal cord?
Pairs of nerves.
What is a reflex?
An involuntary response to a sensory stimulus.
What is a reflex arc?
The pathway of neurones involved in a reflex.
How many neurones does the reflex arc involve? State them.
3.
What is the first stage of a reflex arc?
The stimulus.
What is the second stage of a reflex arc?
Receptor.
Once the stimuli is received it creates a nerve impulse.
What is the third stage of a reflex arc?
Sensory neurone.
Passes the nerve impulse to the spinal cord.
What is the fourth stage of a reflex arc?
Intermediate neurone.
Links the sensory neurone to the motor neurone in the spinal cord.
What is the fifth stage of a reflex arc?
Motor neurone.
Carries the nerve impulse from the spinal cord to an effector.
What is the sixth stage of a reflex arc?
Effector.
The muscle contracts.
What is the last stage of a reflex arc?
Response.
Why are reflex arcs important?
- They make survival more likely. protect body from harmful stimuli.
- Involuntary, eating the brain to carry out more complex responses. Stops the brain from being overloaded by the same response many times. Some are sent to the brain though, so can be overridden if necessary.
- Effective from birth.
- Fast because few synapses.
