Peripheral Nervous System

Question 1

what does the peripheral nervous system do

Answer 1

Takes messages from receptors to and from the central nervous system to muscles and glands.

Question 2

what is the peripheral nervous system composed of

Answer 2

1. Nerve fibres that carry information to and from the CNS
2. Groups of nerve cell bodies called ganglia

Question 3

what are the two types of nerves

Answer 3

1. cranial nerves
2. Spinal nerves

Question 4

how many cranial nerves arise from the brain

Answer 4

12 pairs of nerves

Question 5

how many spinal nerves arise from the spinal cord

Answer 5

31 pairs of nerves

Question 6

describe what cranial nerves are

Answer 6

Cranial nerves carry impulses to and from the brain.

Question 7

what are sensory fibres

Answer 7

Fibres that carry impulses into the CNS

Question 8

what are motor fibres

Answer 8

Fibres that carry impulses away from the CNS

Question 9

what are the two different divisions of the peripheral nervous system

Answer 9

1. afferent division
2. efferent division

Question 10

describe what the afferent division is

Answer 10

Has fibres that carry impulses into the CNS by sensory neurons from receptors in the skin and around muscles and joints.

Question 11

describe what the efferent division is

Answer 11

Has fibres that carry impulses away from the CNS.

Question 12

what are the divisions of neurons found in the afferent division

Answer 12

1. somatic sensory neurons
2. visceral sensory neurons

Question 13

what are somatic sensory neurons

Answer 13

Bring impulses from the skin and muscles

Question 14

what are visceral neurons

Answer 14

Bring impulses from the internal organs

Question 15

what are the two main divisions of the efferent division

Answer 15

1. somatic division
2. autonomic division

Question 16

what is the somatic divison

Answer 16

Takes impulses from the CNS to skeletal muscles

Question 17

what is the autonomic divison

Answer 17

carries impulses from the CNS to the heart, involuntary muscles and glands. Controls the body’s internal environment.

Question 18

what are five body functions regulated by the autonomic division

Answer 18

1. heart rate
2. blood pressure
3. body temperature
4. digestion
5. pupil diameter

Question 19

what are the sub-categories of the autonomic division?

Answer 19

1. sympathetic division
2. parasympathetic division

Question 20

what is the sympathetic division

Answer 20

control flight or fight responses

Question 21

what are three changes the sympathetic division will have on the body during a stressful or fearful situation

Answer 21

1. contraction of the heart will increase causing a rise in blood pressure
2. blood vessels contract in organs not involved in a activity
3. secretion of sweat glands increases

Question 22

what is the parasympathetic division

Answer 22

controls normal day-to-day activities.

Question 23

What is the dorsal root?

Answer 23

Contains axons of sensory neurons that have their cell bodies in a small swelling known as the dorsal root ganglion.

Question 24

What is the ventral root?

Answer 24

Contain the axons of motor neurons that have their cell bodies in the grey matter of the spinal cord.

Question 25

Compare both the autonomic and somatic divisions (effectors, general function, efferent pathways, neurotransmitter at effector, control, nerves to target organ, effect on target organ.

Answer 25

Autonomic division -
1. Heart muscle, involuntary muscle, glands
2. Adjustment of the internal environment.
3. Two nerve fibres from the CNS to the effector with synapse in a ganglion.
4. Acetylcholine or noradrenaline
5. Usually involuntary
6. Two sets - sympathetic and parasympathetic
7. Excitation or inhibition.
Somatic division -
1. Skeletal muscles
2. Response to the external environment
3. One nerve fibre from the CNS to the effector. No synapse and no ganglion.
4. Acetylcholine
5. Usually voluntary
6. One set
7. Always excitation

Question 26

Outline the effects of sympathetic stimulation

Answer 26

Heart - Increases heart rate and strength of contraction.
Lungs - Dilates bronchioles.
Stomach - Decreases movement.
Liver - Increases breakdown of glycogen and release of glucose.
Iris of the eye - Dilates pupil.
Sweat glands - Increases sweat secretion.
Salivary glands - Decreases secretion of saliva.
Blood vessels (skin) - constrict vessels.
Blood vessels (skeletal muscles) - Dilates vessels.
Blood vessels (internal organs) - COntricts vessels.
Urinary bladder - Relaxes muscles of the wall.
Adrenal medulla - Stimulates hormone secretion.

Question 27

Outline the effects of parasympathetic stimulation.

Answer 27

Heart - Decreases rate and strength of contraction.
Lungs - contract bronchioles.
Stomach - Increases movement.
Liver - Increases uptake of glucose and synthesis of glycogen.
Iris of the eye - Contricts pupil.
Sweat glands - no effect.
Salivary glands - Increase secretion of saliva.
Blood vessels (skin) - Little effect.
Blood vessels (skeletal muscles) - No effect.
Blood vessels (internal organs) - Little effect.
Urinary bladder - Contricts muscles of the wall.
Adrenal medulla - No effect.