Nervous And Hormonal Communication

Question 1

What is a stimulus

Answer 1

Any change in the internal/external environ

Question 2

What are receptors

Answer 2

Detect stimuli, can be cells/proteins on cell surface membrane

Question 3

What are effectors

Answer 3

Cells that bring about a response to a stimulus eg muscles and glands

Question 4

Role of sensory neurones

Answer 4

Transmit electric impulses from receptors to CNS (brain and spinal cord)

Question 5

Role of motor neurones

Answer 5

Transmit electrical impulses from CNS to effectors

Question 6

Role of relay neurones

Answer 6

Transmits electrical impulses between sensory and motor neurones

Question 7

How does eye respond to low light

Answer 7

Photoreceptors in retina detect low light, CNS processes info, radial muscles in iris contract as are stimulated by motor neurones and circular muscles relax to make pupils dilate

Question 8

How does eye respond to bright light

Answer 8

Photoreceptors in retina detect bright light, CNS processes info, circular muscles in iris contract and radial muscles relax as stimulated by motor neurones to constrict the pupils (CCC)

Question 9

What is a gland

Answer 9

Group of cells that are specialised to secrete a useful substance eg a hormone

Question 10

Outline reflex arc

Answer 10

-receptors detect a stimulus and generate a nerve impulse
-sensory neurones conduct a nerve impulse to CNS along sensory neurone which enter spinal cord through dorsal route
-message transmitted to relay neurone via neurotransmitters diffusing across synapse, then to motor neurone that leaves the spinal cord through the ventral route
-motor neurone carries impulse to effector which produces a response

Question 11

Differences between hormonal and nervous communication

Answer 11

-nervous uses electrical impulses, hormonal uses hormones
-nervous is faster response, hormonal is slower
-nervous is localised response as neurone carries electrical impulse to specific cell, hormonal is widespread response
-nervous is short-lived response, hormonal is long-lived

Question 12

Similarities between neurones

Answer 12

-all have axon(carry electrical impulse away from cell body), cell body containing nucleus and organelles and dendrites(carry electric impulse towards cell body from prev neuron)

Question 13

Structure of motor neuron

Answer 13

-short dendrites
-long axon
-cell body at one end of axon

Question 14

Structure of sensory neurone

Answer 14

-long dendrites
-cell body in middle of neurone
-short axon

Question 15

Structure of relay neurone

Answer 15

-short dendrites and axon, no myelin sheath

Question 16

What are Schwann cells and their role

Answer 16

Make up myelin sheath around nerve cells, protects and insulates

Question 17

What is synaptic knob

Answer 17

End of the axon of the presynaptic neuron