nervous system

Question 1

The central nervous system (CNS)

Answer 1

structural and functional centre of the entire nervous system. It consists of brain and spinal cord.

Integrates incoming sensory information
Evaluates the information
Initiates out going respond

Question 2

The Peripheral Nervous System (PNS)

Answer 2

consists of the nerve tissue that lies in the periphery (outer regions) of the nervous system. These are cranial nerves and spinal nerves.

functional approach is divided Somatic and Autonomic.

Somatic system’s effector organ is voluntary (skeletal muscle)

Autonomic system’s effector organ is involuntary (smooth muscle and glands)

Question 3

Two main type of cells made up the nervous system.

Answer 3

Neurons

Glia

Question 4

neurons

Answer 4

excitable cells that conduct (transmits) the impulses that make possible all nervous system function (wiring of NS).

responsible for carrying information (or impulses) from one nerve to another. This nerve impulse also known as Action Potential (AP).

human brain 100 billion neurons

All neurons have a cell body

at least two processes - axon (only one branch) and dendrites (one, two or more branch).

Thread like extension often called nerve fibres.

Question 5

Cell body (soma)

Answer 5

largest part. It has a nucleus, cytoplasm and various organelles such as mitochondria, ER and Golgi.

Question 6

Dendrites

Answer 6

branched extensively like tiny trees

tiny branches receive information.

Question 7

Axon

Answer 7

singe process of a neurone.

It emerges from cell body called axon hillock.

It can be long as 1m

has one or more side branches at the end.

The tip of axon have swellings called synaptic knobs or Synaptic button.

Each synaptic knob contains many small sacs (vesicles).

contains a chemical molecules called a neurotransmitter.

Question 8

Glia

Answer 8

serves various roles in supporting the function of neurons.

Question 9

Astrocytes

Answer 9

star shape glia

largest and most numerous glia in the CNS.

Astrocytes feed the neurons by picking up glucose from the blood.

They recycle chemical transmitters.

Influence the neuronal growth.

webs of astrocytes “feet” attached to brain’s blood capillaries, forms the blood brain barrier (BBB).

Question 10

Encephalitis

Answer 10

inflammation of the brain

Most commonly caused by a viral infections.

The virus replicates outside the CNS and gains entry to the brain either via blood stream (BBB is not functioning).

Sometimes the virus also travel along the olfactory pathways.

Question 11

Microglia

Answer 11

very small cells in the CNS.

stationary.

inflamed or degenerating brain tissue, they get enlarge and move about to get rid of cellular debris.

the immune cells of the brain tissue.

Question 12

Ependymal cells

Answer 12

resemble epithelial cells.

line fluid filled cavities in the brain and spinal cord.

They are responsible for producing the fluid (cerebrospinal fluid).

They have cilia on their surface that help keep the fluid circulation.

Question 13

Oligodendrocytes

Answer 13

smaller than astrocytes and have fewer processes.

Oligodendrocytes means “cell with few branches”.

Oligodendrocytes help hold nerve fibres together. produce the fatty myelin sheath around axons in the CNS.

Myelin sheath speed up nerve conduction

Question 14

Multiple Sclerosis

Answer 14

chronic autoimmune disease of the CNS (the person’s own immune cells are responsible)

Immune cells target and destroy the myelin that wraps the nerves.

Loss of myelin reduces nerve conduction speed and
signals.

Signals are disturbed/abnormal.

The effects vary depending on which areas of the CNS are affected.

Question 15

Sensory symptoms of Multiple Sclerosis

Answer 15

pain, tingling, numbness, visual and vestibular (balance) disturbances.

Question 16

Motor effects - Multiple Sclerosis

Answer 16

difficulty moving, difficulty controlling movement, loss of accuracy of movement, weakening of muscles, tiredness.

Question 17

Schwann cells

Answer 17

only found in the PNS. they have equivalent role with oligodendrocytes.

They also produce the myelin sheath.

Schwann cells also help debris removal and serve as guides for sprouts of regenerating axons after injury.

Question 18

Meninges composed of three layers.

Answer 18

Dura Mater
Arachnoid Matter
Pia Mater

Question 19

The Dura mater

Answer 19

strong fibrous tissue and serves as the outer layer of the meninges.

Question 20

The Arachnoid matter

Answer 20

delicate, spider web like layer between.

Question 21

The Pia Mater

Answer 21

delicate inner most layer of meninges. it is transparent and adhere to the brain tissue containing blood vessels.

Question 22

Meningitis

Answer 22

(inflammation of meninges) is most often caused by bacteria or viruses.

Viral meningitis is self limiting with typically complete recovery.

Bacterial meningitis can have more serious effects.

Other pathogens such as fungi or parasite are also causes.

Bacterial meningitis is life threatening and less common than viral from.

Question 23

Epidural Haematoma

Answer 23

Fracture of the skull can cause an accumulation of the blood outside the dura in the epidural space.

Question 24

Cerebrospinal Fluid (CFS)

Answer 24

The CFS provides protection to brain and spinal cord.

present around the organs and within them.

When production of CFS exceeds resorption, hydrocephalus (also known as water in brain) results.

Question 25

Hydrocephalus

Answer 25

excessive accumulation of Cerebrospinal fluid (CFS) in
the ventricles.

When fluid builds inside the brain, causes pressure which compress the nervous tissue and dilate ventricles.

Due to :
Increased CFS production or
CFS obstruction (blockage in the ventricles) or
Decreased CFS absorption

The compression of the nervous tissue usually results in irreversible brain damage.

Question 26

Peripheral Nervous System

Answer 26

A- Cranial Nerves

B- Spinal Nerves

C- Ganglia

Question 27

Brain

Answer 27

The brain is one of the largest organ in the adults.

Contains of 100 billions neurons and glia.

It weight about 1.4kg (3 pounds).

Consists of two halves ( the left and right cerebral hemispheres).

Question 28

Divisions of the brain

Answer 28

A- Cerebrum

B- Diencephalon

C - Brain Stem

D- Cerebellum

Question 29

Cerebrum

Answer 29

largest and upper most part of the brain. It looks wrinkly, hills are called gyri (gyrus), where as groves called sulci (sulcus).

These increase surface area of the brain. if we open up all cerebrum

If the groves are deeper called fissures.

Question 30

cerebral hemisphere lobes

Answer 30

Frontal lobe, parietal lobe, temporal lobe and occipital lobe. there is also hidden lobe called insula

Question 31

Function of the Cerebrum

Answer 31

Consciousness, thinking, memory, sensation, emotion and willed movements

Question 32

Diencephalon

Answer 32

The small but important part of the brain, between brain stem and the cerebrum.

Question 33

Diencephalon 3 major structures

Answer 33

the thalamus, the hypothalamus and epithalamus.

Question 34

Thalamus

Answer 34

A dun-belled section of the grey matter. Functions as

1- Relays sensory information

2- Associates sensations with emotions

3- Regulates level of consciousness

Question 35

Hypothalamus

Answer 35

located under the thalamus. It is small but one of the most important brain structures.

Question 36

what does hypothalamus control

Answer 36

virtually all internal organs and regulates the autonomic nervous system.

It controls the heart beat, constriction and dilation of the blood vessels, releasing hormones, maintaining body temperature, regulation of the water balance, sleep cycle, control of appetite and many emotion

Question 37

Epithalamus

Answer 37

Tiny mass protruding from the back of the diencephalon called pineal
gland.

It secretes melatonin (time keeping) hormone.

helps the body’s clock “on time” with daily, monthly and seasonal cycles of sunlight and moonlights.

Question 38

Brain Stem

Answer 38

brain stem has three parts:
midbrain, pons and medulla oblongata.

All three parts function as two way conduction paths. Sensory impulses
up from spinal cord to the brain regions, motor impulses down from the
brain to the spinal cord.

many important reflex centres located in the brain stem.

The cardiac, respiratory and vasomotor (collectively called the vital
centres) are located in the medulla. Impulses from these centres control
heart beat, respiration and blood vessel diameter.

Question 39

Parkinson’s disease (PD)

Answer 39

Most common disease of midbrain

PD is characterised by muscular rigidity, loss of facial expression, tremor,
a slow shuffling gait and general lack of movement. Usually occurs after
age 55.

PD is caused by the loss of neurons in the substantial nigra (in the midbrain).

These neurons contain dopamine neurotransmitter which
regulate motor activity. However, cause of this neuronal death in PD is
unknown.

Question 40

Cerebellum

Answer 40

second largest part of the brain.

Similar to the brain it has also wrinkly surface. The grey matter is outer layer. White matter tracts form most of interior.

These tracts branch in a treelike pattern called the “arbor vitae” meaning “living tree”. The cerebellum plays an essential role in coordinated movements, maintain equilibrium (balance) and sustain normal posture.