Unit 2 Chapter 1: Introduction To The Nervous System

Question 1

What is a nervous system?

Answer 1

It is a major control system responsible for rapid regulation of the functions of the various body systems. It receives millions of signals of information from the different sensory organs and then integrates them at different levels of its centers to determine the response to be made by the body.

Question 2

Central nervous system (CNS)

Answer 2

1. Brain
2. Spinal cord

Question 3

Peripheral nervous system (PNS)

Answer 3

1. Peripheral ganglia
2. Peripheral nerves

Question 4

The nervous system is divided anatomically into?

Answer 4

Central nervous system and peripheral nervous system.

Question 5

The nervous system is divided physiologically into?

Answer 5

Somatic (SNS) and autonomic (ANS) nervous systems.

Question 6

Somatic nervous system

Answer 6

Deals with voluntary and conscious aspects.
Eg. Skeletal movements and somatic sensation.

Question 7

Autonomic nervous system

Answer 7

Deals with involuntary mechanisms.
Eg. Regulation of heart, blood vessels, or digestive functions.

Question 8

Functional histology of the nervous system is divided into?

Answer 8

Neurons and synapses.

Question 9

Neurons

Answer 9

Unit of structure of the nervous system.

Question 10

What is the neuron formed of?

Answer 10

1. Cell body
2. Dendrites
3. Axon

Question 11

What is a nerve formed of?

Answer 11

A large number of nerve fibers.

Question 12

Cell body

Answer 12

Surrounded by a cell membrane and contains the nucleus with many cytoplasmic organelles.

Question 13

Dendrites

Answer 13

Receives the ongoing impulses to the cell body.

Question 14

Axon (nerve fiber)

Answer 14

Carries the impulses from the cell body.

Question 15

Axons may be:

Answer 15

1. Myelinated nerve fiber covered by myelin sheath.
2. Non myelinated nerve fiber with absent myelin sheath.

Question 16

What are synapses?

Answer 16

Sites where the axon of one neuron terminates on the dendrites, axons, or soma of another neuron.

Question 17

Synaptic cleft

Answer 17

Space where chemical transmitters are released at synaptic sites.
Eg. No direct communication.

Question 18

Synapses function

Answer 18

Transmission of impulses (signals or electric activity) from one nerve cell to another.

Question 19

Functionally, peripheral nerves are two types:

Answer 19

1. Afferent or sensory fibers
2. Efferent or motor fibers

Question 20

Afferent or sensory fibers

Answer 20

1. Carry nerve impulses from the peripheral receptors to the central nervous system.
2. Bring information about the external world. Eg. Light, sound, temperature, or pressure
3. Bring information about the internal state of the body. Eg. Muscle tension or visceral distention.
4. Enter the spinal cord through the the posterior horn.

Question 21

Efferent or motor fibers

Answer 21

• Carries nerve impulses from the central nervous system to muscles, glands, and other organs.
• Leaves the spinal cord through the anterior horn.

Question 22

Reflex arc

Answer 22

The functional unit of the nervous system.

Question 23

What are the components of the reflex arc?

Answer 23

1. Afferent neuron
2. Efferent neuron
3. A sensory organ
4. One or more synapses in the brain or spinal cord.
5. An effector organ

Question 24

What are the types of reflexes?

Answer 24

Monosynaptic and polysynaptic reflexes.

Question 25

Monosynaptic reflex

Answer 25

The simples reflex arc has a single synapse between afferent and efferent neurons.

Question 26

Polysynaptic reflex arc

Answer 26

One or more interneurons interposed between Afferent and efferent neurons.