3. nervous control

Question 1

nervous control

Answer 1

there are two major systems involved with communication between the nervous + endocrine systems

provides the quickest mean of communication

divided into central nervous system (brain + spinal cord) and the peripheral nervous system which links the CNS with the body’s receptors + effectors

IMAGES ON NOTES

Question 2

reflex action

Answer 2

A reflex action is a rapid, involuntary, automatic response to a sensory stimulus. ​

Stimulation of sensory receptors results in generation of impulses in sensory neurones.​

Impulses travel to the CNS > sensory neurones > intermediate neurones > motor neurones > effectors ​

Within the spinal cord, the impulse will also be passed to other neurones which carry it to the brain.

Question 3

reflex arc (the pathway taken by an electrical impulse during a reflex action)

Answer 3

A stimulus is detected by a receptor cell, which synapses with a sensory neurone. ​

The sensory neurone carries the impulse from site of the stimulus to an intermediate neurone (also called interneurone or relay neurone) in the central nervous system. ​

The intermediate neurone synapses with a motor neurone, which carries the nerve impulse out to an effector, such as a muscle, which responds by contracting.

Question 4

importance of reflex arcs/actions

Answer 4

Involuntary - do not require decision making leaving the brain free to carry out more complex responses​

Protection from unexpected harmful stimuli​

Fast – neurone pathway is short with very few synapses and no decision making is required. Important in withdrawal reflexes​

Inate – don’t need to be learned​

Control many physiological and homeostatic functions – e.g. pupil reflex, blinking, coughing

Question 5

functional classification of neurones
1. sensory neurones

Answer 5

Conduct impulses towards the CNS from sensory receptors.

Impulses travel from receptors to cell bodies occurring in clusters called ganglia next to the spinal cord. Axons then carry the impulse to the CNS.

Question 6

functional classification of neurones
2. motor neurones

Answer 6

Conduct impulses away from the CNS to effectors (muscles and glands).

Cell bodies are located in the CNS. Impulses travel along axons to effectors.

Question 7

functional classification of neurones
3. intermediate/relay neurones

Answer 7

Receive impulses from sensory or other relay neurones. They relay impulses to motor neurones or other relay neurones. Situated mainly in CNS.