Chapter 5 : The peripheral nervous system

Question 1

What is the peripheral nervous system?

Answer 1

The peripheral nervous system is the entire network of neurons that are located outside the brain and spinal cord.

Question 2

State the two main functions of the peripheral nervous system.

Answer 2

• To carry information to the CNS from the body’s muscles, organs and glands about the internal environment and sensory organs about the external environment.
• To carry information from the CNS to the body’s muscles, organs and glands.

Question 3

True or False.

The CNS does not have direct contact with the outside world.

Answer 3

True.

It’s only contact is through the PNS.

Question 4

Name the two subdivisions of the PNS.

Answer 4

The somatic nervous system and the autonomic nervous system.

Question 5

What is the somatic nervous system?

Answer 5

The somatic nervous system is a subdivision of the PNS, it carries sensory information to the CNS, and motor information from the CNS.

Question 6

What neural pathway is sensory information carried along?

Answer 6

Sensory neural pathway, also called afferent or ascending neural pathway.

Question 7

What neural pathway is motor information carried along?

Answer 7

Motor neural pathway, also called efferent or descending neural pathway.

Question 8

What are sensory neurons?

Answer 8

Sensory neurons, also called afferent neurons are specialized nerve cells that receive and carry sensory messages.

Question 9

True or False.

Different types of sensory neurons respond to different types of sensory information.

Answer 9

True.

Question 10

What are motor neurons?

Answer 10

Motor neurons, also called efferent neurons, are specialized nerve cells that carry messages to skeletal muscles, causing them to contract or relax.

Question 11

What are interneurons and where are they found?

Answer 11

Interneurons, also called connecting neurons, have the important function of making the connection between the sensory and motor neurons, which rarely ever connect directly. They are found only in the CNS.

Question 12

Name the most abundant type of neuron in the brain.

Answer 12

Interneurons.

Question 13

Whenever you reach to pick up a glass of water, both sensory and motor neuron functions of the PNS are involved. Explain this process.

Answer 13

When you want to pick up a glass of water, your brain sends messages via motor neurons to skeletal muscles in the finger, arms and hands to move in specific ways. Then, sensory receptor cells in your skin and muscles send sensory messages via sensory neurons to the brain to figure out how much pressure is needed to hold the glass.

Question 14

What is the autonomic nervous system?

Answer 14

The autonomic nervous system is a subdivision of the PNS that connects the CNS to the body’s internal organs and glands and sends feedback to the brain about their activities.

Question 15

Why is the autonomic nervous system called “autonomous” ?

Answer 15

Because many of the organs, glands and processes under its control are self-regulating and not usually under voluntary control.

Question 16

Name the muscles that are involved in the activity of internal organs and glands.

Answer 16

Visceral muscles.

Question 17

What is a key difference between skeletal muscles and visceral muscles?

Answer 17

Skeletal muscles depend on the voluntary control of the brain, whereas visceral muscles are not dependent.

Question 18

Compare the somatic nervous system with the autonomic nervous system.

Answer 18

The somatic nervous system is responsible for initiating voluntary skeletal muscle movement, whereas the autonomic nervous system is responsible for regulating the activity of visceral muscles, organs and glands.

Question 19

True or False.

The ANS is completely self-regulating.

Answer 19

False.

Question 20

Why is the ANS important for maintaining our survival?

Answer 20

Because the ANS regulates our breathing, heart rate and other vital bodily functions.

Question 21

Name the two divisions of the ANS.

Answer 21

The sympathetic and parasympathetic nervous system.

Question 22

What is the sympathetic nervous system?

Answer 22

The sympathetic nervous system activates internal muscles, organs and glands to prepare the body for vigorous activity and to deal with a stressful or threatening situation. It enhance survival by providing an immediate response to any kind of emergency.

Question 23

Name and describe some of the effects of the sympathetic nervous system.

Answer 23

Heart rate and blood pressure increases, breathing rate increases so that more oxygen can be taken in. Pupils dilate, so that more light can enter into the eyes to enhance vision. Sugar and fat are released from storage to provide instant energy for the skeletal muscles. Sweat glands increase the production of sweat to cool the body down. The digestive system is also slowed down.

Question 24

What is the parasympathetic nervous system?

Answer 24

The parasympathetic nervous system keeps the systems of the body functioning efficiently. It generally has the effect of counterbalancing the activities of the sympathetic nervous system and restores the body to a state of calm, once the need for sympathetic nervous system activation has passed.

Question 25

Name and describe some of the effects of the parasympathetic nervous system.

Answer 25

Regulates heart, breathing and digestion rate, sweat glands decrease the production of sweat, the release of sugars and fat are minimized.

Question 26

Which autonomic nervous system usually dominates over the other?

Answer 26

The parasympathetic nervous system.

Question 27

What is the key difference between the sympathetic and parasympathetic nervous system?

Answer 27

The sympathetic nervous system increases the activity of the internal muscles, organs and glands in times of emergencies. Whereas the parasympathetic nervous system decreases the activity of internal muscles, organs and glands.