Nervous System

Question 1

What is Coordination?

Answer 1

Coordination is interlinking of various activities like digestion respiration excretion etcetera going on in the body as per the needs internally or externally.

Question 2

How is chemical coordination brought about?

Answer 2

Chemical coordination is brought about the chemical messengers called hormones produced by endocrine glands.

Question 3

What are the functions of the nervous system?

Answer 3

1.It keeps us informed about the outside world.
2. It enables us to think remember and reason out
3. It controls in harmonizes all voluntary muscular activities.
4. It regulates involuntary activities such as beating of heart breathing etc.

Question 4

Name the structural and functional unit of the nervous system

Answer 4

Neuron

Question 5

What are the main parts of the neuron

Answer 5

1. Cyton / cell body / perikaryon
2. Dendron and dendrites
3. Axon
4. Axon Terminals

Question 6

Why have nerve cells lost the ability to divide?

Answer 6

Centrosome is absent in the cell body hence the nerve cells have lost ability to divide.

Question 7

What are association neurons

Answer 7

Association neurons are located in the brain and spinal cord which interconnect the sensory and motor neurons of the body and conduct nerve impulses to the cyton.

Question 8

What is an Axon

Answer 8

It is a long process from the cell body in most neurons it is surrounded by a white insulating sheet called mylin sheet and shows a gap through the length called node of ranvier.
Axon terminals are place near the dendrite of another neuron but are not connected.

Question 9

Define synapse

Answer 9

The point of contact between the terminal endings of the neuron with the dendrites of another neuron separated by a fine gap is called synapse.

Question 10

What is the direction of impulse in sensory neurons.

Answer 10

Sensory neurons carry impulse from a receptor sense organs to the CNS to he brain or spinal cord.

Question 11

What is the direction of impulse in motor neurons.

Answer 11

They carry impulse from the CNS to the effector organ.

Question 12

Define a nerve

Answer 12

Formed of a bundle of axons enclosed in a tubular medullary sheath.

Question 13

What are the three types of nerves and what type of the fibres do they contain?

Answer 13

1. Sensory nerve: contains only sensory nerve fibres. 2. Motor nerve: contains only motor nerve fibres.
2. Mixed nerve: carries both sensory and motor nerve fibres

Question 14

What are the parts of the brain

Answer 14

1. Cerebellum
2. Medulla oblongata
3. Cerebrum

Question 15

Write a short note on cerebrum

Answer 15

– It is the largest portion of the brain.
– It is divided into two cerebral cerebral hemispheres. – Outer surface is highly converted with ridges and grooves called gyri and sulci.
– Each hemisphere is internally hollow though the middle and the walls have two regions - outer cortex containing cyton of the neuron grayish in color called gray matter, and Inner medulla containing axon= white matter.

Question 16

What is function of the cerebrum

Answer 16

It is seat of intelligence centre of consciousness will power and controls all voluntary actions.

Question 17

Why the outer surface of brain highly convolulted?

Answer 17

To increase surface area to accommodate more neurons.

Question 18

Location of the cerebellum

Answer 18

It is a smaller area of brain located at the base and under the cerebrum.

Question 19

State function of the cerebellum

Answer 19

It coordinates the muscular activity and balance of the body.

Question 20

Give reason why alcoholic person when drunk walk clumsily

Answer 20

Alcohol affects cerebellum which coordinates the muscular activities and maintains the balance of the body. As the balance of the body is lost the person walks clumsily.

Question 21

Location of medulla oblongata

Answer 21

It is the lowest portion of the brain located at the base of the skull.
It is continued behind the spinal cord.

Question 22

What is the function of the medulla oblongata

Answer 22

It controls all involuntary activities such as breathing, heartbeat etc.

Question 23

Why does injury to the medulla oblongata results in death.

Answer 23

Medula oblongata controls involuntary actions hence when medulla oblongata is injured the movements like breathing and beating of heart stops and the person dies.

Question 24

What is the location of the spinal cord

Answer 24

Extends from the medulla oblongata to the end of the second lumbar vertebrae and lies within the neural canal of the vertebrae.

Question 25

How is the arrangement of the neurons in the spinal cord

Answer 25

Outer portion is white matter made up of axon and inner portion is grey matter made up of cyton.

Question 26

Functions of the spinal cord

Answer 26

1. Conducts reflexes below the neck.
2. Conduct sensory impulses from the skin and the muscles to the brain.
3. Conducts motor responses from the brain to the muscles of the trunk and the limbs.

Question 27

What is the function of the peripheral nervous system

Answer 27

It consists of nerves which connect the central nervous system to all parts of the body.

Question 28

What is the difference between the cranial and spinal nerves of the somatic nervous system.

Answer 28

The cranial nerves emerge from the brain
they are 12 pairs of cranial nerves
hey can be sensory nerves motor nerves or mixed nerves

Spinal nerves emerge from the spinal cord there are 31 pairs of spinal nerves and every spinal nerve is a mixed nerve.

Question 29

What is the difference between the sympathetic and the parasympathetic nervous system parts of the autonomic nervous system

Answer 29

Sympathetic is stimulated by hormone adrenaline and prepare the body for emergency actions.

Parasympathetic nervous system is brought back to normal conditions by hormone nor-adrenaline and re-establises normal conditions.

Question 30

What is stimulus

Answer 30

Any change in the environment that can cause a response or reaction in the body.

Question 31

Response

Answer 31

Response is changed an organism resulting due to stimulus.

Question 32

What is an impulse

Answer 32

It is a wave of electrical disturbance that runs through the nerves.

Question 33

What are receptors

Answer 33

Highly specialised sensory cells on neurons that are sensitive to a specific stimulus.

Question 34

What are effectors

Answer 34

Muscle or gland that responds to motor nerve impulse.

Question 35

What is a reflex arc

Answer 35

It is a shortest route that can be taken by an impulse from a receptor to an effector.

Question 36

What is reflex action

Answer 36

It is a sudden, spontaneous and involuntary action in the body brought about by a stimulus.

Question 37

What are the two types of reflexes

Answer 37

Natural or simple reflex which is inborn and conditioned reflex which is acquired.

Question 38

Natural reflex short note

Answer 38

–No previous experience is required
–directly related to the stimulus
–similar in all humans

Question 39

Conditioned reflex short note

Answer 39

– Develops due to experience or learning
– unrelated to stimulus
– differs in different individuals.