Division of nervous system

Question 1

The essential purpose of the nervous system is to:

Answer 1

receive and process information from sense organs

to bring about responses to the information received.

Question 2

The two main parts of the nervous system are the:

Answer 2

1.Central nervous system (CNS)
consists of the brain and spinal cord

2.Peripheral nervous system (PNS)
consists of nerves that connect the CNS with the receptors, muscles and glands
and ganglia (groups of nerve cell bodies outside the brain and spinal cord)

Question 3

The peripheral nerves arise from the brain and the spinal cord:

Answer 3

cranial nerves = 12 pairs of nerves arise from the brain

spinal nerves = 31 pairs of nerves arise from the spinal cord.

Question 4

3 types of nerve

Answer 4

Sensory fibres = fibres that carry impulses into the CNS
Motor fibres = Those that carry impulses away from the CNS
Mixed nerves contain fibres that carry impulses into and away from CNS

Question 5

Are all cranial nerves mixed nerves ?

Answer 5

No. Most cranial nerves are mixed nerves. A few cranial nerves carry only sensory impulses or only motor impulses.

Question 6

Are all spinal nerves mixed nerves ?

Answer 6

All spinal nerves are mixed nerves and each is joined to the spinal cord by two roots.

Question 7

Describe ventral root

Answer 7

The ventral root contains the axons of motor neurons that have their cell bodies in the grey matter of the spinal cord.

Question 8

Describe the dorsal root

Answer 8

The dorsal root contains the axons of sensory neurons that have their cell bodies in a small swelling on the dorsal root known as the dorsal root ganglion

Question 9

Explain the afferent sensory division

Answer 9

Carry impulses into the CNS
1. somatic sensory neurons
sensory nerve cells from receptors in the skin and around the muscles and joints

2. visceral sensory neurons
   sensory nerve cells that take impulses from the internal organs into the CNS

Question 10

Explain the efferent motor division

Answer 10

Carry impulses away from the CNS
1.Somatic division
takes impulses from the CNS to the skeletal muscles

2.Autonomic division
carries impulses from the CNS to heart muscle, involuntary muscle and glands. Further subdivided into:
sympathetic division
parasympathetic division

Question 11

Function of autonomic nervous system

Answer 11

Involved in many of the mechanisms that keep the internal environment constant.

Question 12

How does autonomic nervous system operates?

Answer 12

without conscious control

Question 13

How are the autonomic nervous systems regulated by?

Answer 13

regulated by groups of nerve cells in the medulla oblongata, hypothalamus and cerebral cortex.

Question 14

Which part does nerve fibres of ANS make up ?

Answer 14

Nerve fibres of the ANS make up part of the spinal nerves and part of some of the cranial nerves.

Question 15

Where does the nerve fibres of ANS carry impulses to ?

Answer 15

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

Question 16

How many motor neurons relay impulses from CNS to effector in the autonomic pathway ?

Answer 16

2

Question 17

Where is the motor neurons in the autonomic pathway?

Answer 17

The first neuron’s cell body is in the CNS, but the cell body of second neuron is in a ganglion (group of nerve cell bodies outside the CNS)

Question 18

How many motor neurons relay impulses from CNS to effector in the somatic pathway ?

Answer 18

1

Question 19

Where is the motor neurons in the somatic pathway?

Answer 19

nerve cell body in grey matter of spinal cord

Question 20

Most organs under autonomic control receive two sets of nerve fibres, which are?

Answer 20

Sympathetic fibres - produce responses that prepare the body for strenuous physical activity (fight-or-flight responses). Sympathetic nerve endings release noradrenaline
Parasympathetic fibres - produce responses that maintain the body during relatively quiet conditions. Parasympathetic nerve endings release acetylcholine

Question 21

What is the neurotransmitter that carries the message from neuron to the skeletal muscle in somatic nervous system?

Answer 21

acetylcholine

Question 22

At rest, parasympathetic stimulation keeps heart rate to

Answer 22

~ 70 to- 80 beats per minute.

Question 23

In threatening situation which division is more dominant?

Answer 23

sympathetic becomes dominant.

Question 24

Explain the actions of response in sympathetic stimulation

Answer 24

• The rate and force of contraction of the heart increase, with a consequent increase in blood pressure.
• Blood vessels in organs involved in strenuous activity – such as the skeletal muscles, heart and liver – dilate.
• Blood vessels of organs not involved in activity – such as the kidney, stomach, intestines and skin – constrict.
• Airways in the lungs dilate and the rate and depth of breathing increases.
• Blood glucose level rises, because the liver converts more glycogen into glucose.
• Secretion from sweat glands increases.
• The adrenal medullae release the hormones adrenaline and noradrenaline, which intensify and prolong the above responses.

Question 25

The difference in nervous and hormonal coordinations :

Answer 25

1. Nervous responses are more rapid because nerve impulses travel rapidly along nerve fibres.

Hormonal responses are slower, because hormones are transported in the bloodstream.
3. Nervous messages are an electrochemical change that travels along the membrane of a neuron.

Endocrine messages are chemicals (hormones) that are usually transported by the blood
4. Nerve impulses travel along a nerve fibre to a specific part of the body and often influence just one effector

Hormones travel to all parts of the body, are carried by the blood and often affect a number of different organs.

Question 26

The similarities of hormonal and nervous coordinations :

Answer 26

Some substances function as both hormones and neurotransmitters. Examples: noradrenaline, antidiuretic hormone and dopamine.

Some hormones such as oxytocin and adrenaline are secreted by neurons into the extracellular fluid.

Some hormones and neurotransmitters have the same effect on the same target cells.
Example: noradrenaline and the hormone glucagon both act on liver cells to cause glycogen to be broken down into glucose.