14.3: A reflex arc Flashcards
Two major divisions of the nervous system
central nervous system (CNS)
peripheral nervous system (PNS)
Central nervous system
made up of the brain and the spinal cord
Peripheral nervous system
made up of pairs of nerves that originate from either the brain or the spinal cord
The peripheral nervous system is divided into
2
sensory neurones
motor neurones
Sensory neurones
Carry nerve impulses from receptors towards the central nervous system
Motor neurones
Carry nerve impulses away from the central nervous system to effectors
Nerve impulses aka
electrical signals
Motor nervous system can be divided into
2
voluntary nervous system
autonomic nervous system
Voluntary nervous system
carries nerve impulses to body muscles and is under voluntary (conscious) control
Autonomic nervous system
carries nerve impulses to glands, smooth muscle and cardiac muscle and is not under voluntary control, its involuntary (unconscious)
The spinal cord
A column of nervous tissue that runs along the back and lies inside the vertebral column for protection
Reflex arc
the pathway of neurones involved in a reflex
Reflex
Involuntary response to a sensory stimulus
Why are reflex arcs important
3
- don’t require decision making from the brain so it can be used for complex responses
- they protect the body from harm, effective from birth
- fast, important in withdrawal reflexes
