Nervous System

Question 1

State three uses of nervous system

Answer 1

1. Enables us to remember and think
2. Informs us about our surroundings
3. Regulates involuntary activities

Question 2

What are the three main parts of neuron?

Answer 2

1. Cell body (peri karyon or cyton)
2. Dendrites
3. Axon

Question 3

State two characteristics of Cell body

Answer 3

1. It has well-defined nucleus
2. Lost centrosome

Question 4

State two characteristics of Axon

Answer 4

1. It has gaps throughout length called nodes of ranvier
2. It is covered by insulating sheath called Myelin or medullary sheath. This sheath is covered by an even thinner sheath known as Neurolemma

Question 5

Define Stimulus

Answer 5

A sudden change in external and internal environment that evokes a response in an organism.

Question 6

Define receptors

Answer 6

These are parts of NS that gather environmental signals or perceive the stimuli and pass them to CNS for interpretation.

Question 7

Define effectors

Answer 7

Muscles or glands which on receiving the impulse from the brain or spinal cord, contract or secrete substances

Question 8

Conduction of nerve impulse is a wave of _____ followed by ______

Answer 8

1. Depolarization
2. Repolarization

Question 9

Define synapse

Answer 9

It is the point of contact between the axon of a neuron and the dendrite of another neuron

Question 10

What are the three types of neurons?

Answer 10

1. Sensory neurons - receptor to CNS
2. Motor neuron - CNS to effector
3. Association (connecting) neurons - interconnect Motor and sensory

Question 11

Define nerves

Answer 11

Nerve is a bundle of nerve fibers (axons) of secrete neurons, enclosed in a tubular sheath

Question 12

State the three kinds of nerves:

Answer 12

1. Sensory nerves - optic nerve
2. Motor nerve - nerve from brain to eye
3. Mixed nerve - spinal nerve

Question 13

Define ganglia

Answer 13

Ganglia are the aggregates of the futons or cell boxes of nerve cells from which the nerve fibers may arise or enter into.

Question 14

What are the two major divisions of Nervous system?

Answer 14

1. Central Nervous system - brain and spinal cord (contained within vertebral column)
2. Peripheral nervous system - includes nerves that emerge from and enter into Brian and spinal cord.

Question 15

Name the two subdivisions of PNS

Answer 15

1. Somatic nervous system - conveys info to skeletal (voluntary) muscles
2. Autonomic nervous system - involuntary actions (heart muscles, glands)

Question 16

What is the brain protected by?

Answer 16

Brain box or cranium

Question 17

Name the meninges of the brain

Answer 17

1. Outermost - Dura Mater
2. Middle - Arachanoid
3. Innermost- Pia Mater

Question 18

What is meningitis

Answer 18

Meningitis is the inflammation of the meninges

Question 19

State the function of cerebrospinal fluid

Answer 19

Protects the brain and spinal cord from mechanical shocks

Question 20

Name the 3 parts of the brain and state functions of each.

Answer 20

1. Cerebrum : consciousness, voluntary actions
2. Cerebellum : balance of body, coordination of muscular activity.
3. Medulla oblongata : controls activities of internal organs , peristaltic movements, breathing, beating of heart

Question 21

What is outer (cortex) of Brian called

Answer 21

Gray matter

Question 22

What is inner layer of brain called?

Answer 22

White matter

Question 23

What connects the two cerebral hemispheres in the cerebrum?

Answer 23

Corpus Callosum (hard body)

Question 24

What are the fold and grooves in cerebrum called?

Answer 24

1. Folds - gyri
2. Grooves - sulci

Question 25

What cerebellum also called?

Answer 25

Little brain

Question 26

What are the three primary regions of brain?

Answer 26

1. Forebrain - a) cerebrum b) diencephalon 2. Midbrain 3. Hindbrain - a) cerebellum b) pons c) medulla oblongata

Question 27

What layer lies inside and outside of the spinal cord? State two functions of spinal cord:

Answer 27

1. Inside - gray matter 2. Outside - white matter Two functions - a) reflexes below the neck b) conducts sensory and motor responses

Question 28

Name the two divisions of the Peripheral Nervous System

Answer 28

1. Somatic A) cranial nerves - 12 pairs B) spinal nerves - 31 pairs 2. Autonomic A) sympathetic B) parasympathetic

Question 29

Which hormone stimulates the SNS?

Answer 29

Adrenaline secreted by Adrenal Glands

Question 30

What is the function of sympathetic system and parasympathetic system?

Answer 30

Sympathetic - prepares body for violent action against abnormal conditions Parasympathetic - concerned with re-establishing normal conditions after violent act is over

Question 31

Define Reflex Action

Answer 31

It is an automatic/quick/immediate involuntary action in the body brought about by a stimulus.

Question 32

What are the two types of reflexes and give two examples of each.

Answer 32

1. Inborn or natural reflexes No prior experience is required E.g. blinking, coughing, salivation, peristalsis 2. Conditioned or acquired reflexes Involuntary spontaneous automatic response brought about due to previously learned experience. E.g. salivation at seeing familiar food

Question 33

What is a reflex arc?

Answer 33

A reflex arc is the shortest route that can be taken by an impulse from a receptor to an effector.

Question 34

State the reflex arc in humans:

Answer 34

Stimulate —> receptor —> sensory neuron —> brain or spinal cord —> motor neuron —> effector —> response