Chapter 4.2 Peripheral Nervous System ✓

Question 1

What is the role of the peripheral nervous system?

Answer 1

PNS takes messages from receptors to the CNS and from the CNS to muscles and glands

Question 2

What does the PNS consist of?

Answer 2

It consists of:
-Nerve fibres that carry information to and from the CNS
-Groups of nerve cell bodies, called ganglia, which lie outside the brain and spinal cord.

Question 3

Define cranial nerve

Answer 3

Cranial nerves are one of the 12 pairs of nerves that arise from the brain

Question 4

What are some examples of cranial nerves?

Answer 4

-Optic nerve
-Auditory nerve

Question 5

What does it mean for a cranial nerve to be a mixed nerve?

Answer 5

It means the nerve can contain both sensory and motor nerve fibres

Question 6

What types of fibres do mixed cranial nerves contain?

Answer 6

They contain sensory fibres (carrying impulses into the brain) and motor fibres (carrying impulses away from the brain).

Question 7

What are sensory fibres?

Answer 7

Sensory fibres are fibres that carry impulses into the CNS

Question 8

What are motor fibres?

Answer 8

Motor fibres are fibres that carry impulses away from the CNS

Question 9

Define spinal nerves

Answer 9

Spinal nerves are one of the 31 pairs of nerves that arise from the spinal cord

Question 10

Why are spinal nerves considered mixed nerves?

Answer 10

Because they contain both motor and sensory fibres

Question 11

Are all cranial nerves mixed nerves?

Answer 11

No, some are just are purely sensory, some are purely motor, and others are mixed.

Question 12

How is each spinal nerve connected to the spinal cord?

Answer 12

By two roots: the ventral root and the dorsal root.

Question 13

What does the ventral root of a spinal nerve contain?

Answer 13

The axons of motor neurons.

Question 14

Where are the cell bodies of motor neurons located?

Answer 14

In the grey matter of the spinal cord.

Question 15

What does the dorsal root of a spinal nerve contain?

Answer 15

The axons of sensory neurons.

Question 16

Where are the cell bodies of sensory neurons located?

Answer 16

In the dorsal root ganglion, a small swelling on the dorsal root.

Question 17

How many pairs of cranial and spinal nerves is the PNS made up of?

Answer 17

12 pairs of cranial nerves and 31 pairs of spinal nerves

Question 18

What are the two divisions of the PNS?

Answer 18

The afferent and efferent division

Question 19

Define the afferent division

Answer 19

The afferent division contains sensory neurons that transmit impulses from sensory receptors (in the skin, muscle and internal organs) to the brain and spinal cord, where in information is processed.

Question 20

What another word for the afferent division?

Answer 20

the sensory division

Question 21

What does the afferent division divide into?

Answer 21

Somatic and visceral sensory neurons

Question 22

Define the role of somatic sensory neurons

Answer 22

They bring impulses from the skin and muscles

Question 23

Define the role of visceral sensory neurons

Answer 23

They bring impulses from the internal organs

Question 24

Define the efferent division

Answer 24

The efferent division contains nerve fibres that carry impulses out of the brain and spinal cord

Question 25

What another word for the efferent division?

Answer 25

motor division

Question 26

What does the efferent division divide into?

Answer 26

Somatic and autonomic division

Question 27

Define the role of the somatic division

Answer 27

It takes impulses from the CNS to the skeletal muscles

Question 28

Define the role of the autonomic division

Answer 28

It takes impulses from the CNS to heart muscle, involuntary muscles and glands

Question 29

What does the autonomic division divide into?

Answer 29

Sympathetic and parasympathetic division

Question 30

What is the main function of the sympathetic division?

Answer 30

It prepares the body for stress, emergencies, or high activity ("fight or flight").

Question 31

What are the main functions of the parasympathetic division?

Answer 31

It promotes relaxation, energy conservation, and homeostasis ("rest and digest").

Question 32

Define autonomic nervous system (ANS)

Answer 32

The ANS controls the body's internal environment and is involved in many of the mechanisms that keep it constant.

Question 33

What regulates the autonomic nervous system?

Answer 33

Groups of nerves cells in the medulla oblongata, hypothalamus and cerebral cortex

Question 34

What are some of the body functions regulated by the ANS (9)?

Answer 34

-Heart rate -Blood pressure -Body temperature -Digestion -Release of energy -Pupil diameter -Air flow to the lungs -Defecation -Urination

Question 35

What is the role of the nerve fibres of the ANS?

Answer 35

They carry impulses to the heart muscle, other muscles of the internal organs and the glands

Question 36

How do impulses travel in the ANS?

Answer 36

Impulses travel along two neurons: -First neuron extends from the CNS to a ganglion -Seconds neuron extends from the ganglion to the target effector (heart, glands, or smooth muscles)

Question 37

How are the two neurons in the ANS structured?

Answer 37

-First neuron is myelinated and releases acetylcholine at the ganglion -Second neuron is unmyelinated and releases either acetylcholine or noradrenaline depending on whether its part of the parasympathetic or sympathetic division

Question 38

What happens to heart rate during a sympathetic response?

Answer 38

Increases to pump more blood to muscles.

Question 39

How does the parasympathetic system affect heart rate?

Answer 39

Decreases heart rate to maintain a resting state.

Question 40

How does the sympathetic nervous system affect the lungs?

Answer 40

Dilates bronchioles to increase airflow.

Question 41

How does the sympathetic nervous system affect the liver?

Answer 41

Increases glycogen breakdown to release glucose.

Question 42

What happens to the pupils during sympathetic activation?

Answer 42

Dilate to improve vision.

Question 43

How does the sympathetic system affect sweat glands?

Answer 43

Increases sweat secretion to cool the body.

Question 44

How does the parasympathetic nervous system affect digestion?

Answer 44

Increases movement in the stomach and intestines.

Question 45

How does the parasympathetic nervous system affect saliva production?

Answer 45

Increases secretion of saliva

Question 46

What happens to the pupils during parasympathetic activation?

Answer 46

Constrict to reduce light intake.

Question 47

How does the sympathetic nervous system affect the heart?

Answer 47

Increases heart rate and strength of contraction.

Question 48

How does the parasympathetic nervous system affect the heart?

Answer 48

Decreases heart rate and strength of contraction

Question 49

How does the parasympathetic nervous system affect the lungs?

Answer 49

Constricts bronchioles to reduce airflow.

Question 50

What is the effect of sympathetic stimulation on digestion?

Answer 50

Decreases movement (reduces digestion).

Question 51

What does the parasympathetic nervous system do to the liver?

Answer 51

Increases glucose uptake and glycogen synthesis (stores energy).

Question 52

How does the parasympathetic system affect sweat production?

Answer 52

No effect (sweat glands are mostly controlled by the sympathetic system).

Question 53

What happens to saliva secretion during sympathetic activation?

Answer 53

Decreases saliva production.

Question 54

How does the sympathetic system affect blood vessels in the skin?

Answer 54

Constricts them to reduce blood flow to the skin.

Question 55

How does the sympathetic system affect blood vessels in skeletal muscles?

Answer 55

Dilates them to increase blood flow to muscles.

Question 56

What does the sympathetic nervous system do to the bladder?

Answer 56

Relaxes bladder muscles (reduces urination).

Question 57

What does the parasympathetic nervous system do to the urinary bladder?

Answer 57

Contracts bladder muscles (increases urination).

Question 58

How does the sympathetic nervous system affect the adrenal medulla?

Answer 58

Stimulates hormone secretion (releases adrenaline and noradrenaline).

Question 59

How does the parasympathetic nervous system affect the adrenal medulla?

Answer 59

No effect (only the sympathetic system controls it).

Question 60

What is the overall difference between the sympathetic and parasympathetic nervous systems?

Answer 60

The sympathetic system prepares the body for fight-or-flight, while the parasympathetic system helps the body rest and digest.