Nervous System

Question 1

What 2 things is the nervous system made of and their fucntion?

Answer 1

1- nerve cells - transmit nerve impulses
2- neuroglia - connective tissue which supports the neurones

Question 2

Describe a nerve cell from top to bottom:

Answer 2

1- dendrites
2 - cell body / nucleus
3 - axon (transmits nerve impulses away from cell body)
4 - myelin sheath (white fatty substance covers the axon. speeds up nerve conduction).
5 - node of ranvier - that gaps in the myelin sheath along the nerve. speed up the passage of impulses.
6 - neurilemma - fine delicate membrane which surrounds the myelin sheath. (only is peripheral nerves)
7 - end feet / axon terminals - pass on the impulse to the dendrites of the next nerve cell
8- synapse - where one neurone meets another.

Question 3

Name the 5 different types of nerves and nervous tissue and their function:

Answer 3

1- motor / efferent nerves (carry messages from brain or spinal to muscles or glans which act on the info).

2- sensory / afferent nerves (carry impulses from all parts of the body to the brain)

3- mixed (both motor and sensory. only place they are found is the brain and the spinal cord).

4- white matter (on the inside of brain and outside of spinal cord.)

5- grey matter (on the outside of the brain and inside of the spinal cord)

Question 4

Describe what happens to a cell during a nerve impulse:

Answer 4

• Resting cells have lower concentration of sodium ions inside the cell. Concentration of potassium ions is higher outside.
• When stimuli are detected, axon membrane becomes temporarily permeable which means sodium ions rush in making the inside of the cell positively charged.
• After impulse has passed, cell returns to it’s resting state.

Question 5

What are the three parts of the brain?

Answer 5

1 - the cerebrum
2- the cerebellum
3- the brain stem

Question 6

What is the structure and function (3) of the cerebrum?

Answer 6

Structure: largest part of brain divided into 2. outer layer of grey matter. inside is white matter.

Function:
1- controlling voluntary movement
2- interpreting and perceiving conscious sensations eg pain, heat, cold
3- controlling mental activity eg memory, intelligence, reasoning

Question 7

What is the structure and function (3) of the cerebellum?

Answer 7

Structure: small brain. grey matter outisde, white matter inside.

Function:
1- coordinating muscular activity, making sure movements are smooth and precise
2- subconsciously controlling and maintaining muscle tone and posture
3- maintaining balance and equilibrium of body

Question 8

What is the structure and the function of the hypothalamus?

Answer 8

Structure: located deep within the cerebrum at the top of the brainstem. pituitary gland attached to it’s base.

Function:
1- regulation of body temperature, water balance and metabolism
2- Centre for drives and emotions such as thirst, appetite, sex, pain and pleasure.
3- Regulates pituitary gland and therefore main link between nervous and endocrine systems.
4- Secretes oxytocin and antidiuretic hormone for storage in the posterior pituitary.

Question 9

Name the three parts of the Brain Stem

Answer 9

1- Midbrain
2- Pons Varolii
3- Medulla oblongata

Question 10

What is the structure and function of the midbrain?

Answer 10

Structure: lies between the cerebrum and the cerebellum. 2cm long. consists of nerve cells and fibres.

Function: relay station of the brain. transmit messages to and from the spinal cord, the cerebrum and the cerebellum.

Question 11

What is the structure and function of the pons varolii?

Answer 11

Structure: situated in front of the cerebellum, below the midbrain and above the Medulla Oblongata. consists of nerve fibres which bridge the gap between the two hemispheres of the cerebellum.

Function: transmits messages to and from the spinal cord and cerebrum.

Question 12

What is the structure and function (4) of the Medulla Oblongata?

Answer 12

Structure: lowest part of the brain stem. It has white matter on the surface and grey matter on the inside.

Function: VITAL CENTRES
1- CARDIAC controls rate and force of heart contraciton
2- RESPIRATORY controls rate and depth of breathing
3- VASOMOTOR controls constriction and dilation of blood vessels
4- REFLEX responds to irritants thus controls vomiting, coughing, sneezing and swallowing.

Question 13

What is the structure and function of the spinal cord?

Answer 13

Structure: extends from medulla oblongata through spinal vertebrae ending at first lumbar vertebrae. 31 pairs of spinal nerves and part of 1 cranial nerve.

Function: carries motor and sensory nerve fibres along it’s length. sends messages to and from the body and brain.

Question 14

What are meninges?

Answer 14

membranes that protect the whole of the central nervous system.

Question 15

What are the 3 thee laters of meninges and their structure?

Answer 15

1- dura mater / outer membrane
(double layer of tough fibrous membrane)

2- arachnoid mater
(delicate membrane positioned immediately under the dura mater. Connects to sub-arachnoid space and filled with cerebrospinal fluid).

3- pia mater
(thin, vascular membrane which closely covers the brain and spinal cord. supplies blood to the brain and spinal cord).

Question 16

What is the structure and function (3) of cerebrospinal fluid?

Answer 16

Structure: clear, colourless fluid.
contains protein, glucose, salts and other substances.
secreted into ventricles in brain and circulates round. then reabsorbed into the venous sinuses of the body through arachnoid mater.

Function:
1- protects the brain and spinal cord. shock absorber.
2- keeps the pressure around the brain and spinal cord constant.
3- transports nutrients and removes waste and toxic substances.

Question 17

How many pairs of cranial nerves and spinal nerves does the peripheral nervous system have?

Answer 17

Cranial - 12 pairs
Spinal - 31 pairs

Question 18

What are cranial nerves?

Answer 18

They originate in the brain and relay information from head and neck regions.
sight, hearing, taste and smell.

Question 19

Name the three divisions of the 5th trigeminal nerve and their functions:

Answer 19

1- Opthalmic
(sensory nerves supplying the lacrimal glands, conjunctiva of eye, eye lids, forehead, anterior part of scalp and muscous membrane of nose)

2- Maxillary
(sensory nerves supplying lower eye lids, upper gums, upper teeth and cheeks)

3- Mandibular
(sensory and mort nerves. supplying teeth and gums of lower jaw, ear and tongue. Motor supplying muscles of mastication)

Question 20

What is the function of the 7th Facial nerve?

Answer 20

Motor nerve, supplies the muscles of facial expressions.
Sensory nerve, supplies taste from anterior part of tongue.

Question 21

What are the 2 parts of the 11th accessory nerve and their functions?

Answer 21

1- cranial
(branches joining the vegus nerve to supply larynx and pharynx)

2- spinal
(branches supplying the trapezius and sternocleido mastoid)

Question 22

Describe the breakdown of the different spinal nerves:

Answer 22

Cervical - 8 pairs
Thoracic - 12 pairs
Lumbar - 5 pairs
Sacral - 5 pairs
Coccygeal - 1 pair

Question 23

Are spinal nerves sensory, motor or both?

Answer 23

both

Question 24

Name the 6 plexus from top to bottom and the areas they supply:

Answer 24

1- Cervical Plexus - first four cervical nerves
(supplies muscles of the neck, shoulder and skin. also includes the phrenic nerve which sends impulses to the diaphragm telling it to contract)

2- Brachial plexus - lower four cervical and first thoracic nerve
(supplies muscles from base of the neck to the fingertips and skin).

3- Thoracic (intercostal) nerves
(Thoracic nerves supply chest muscles and main part of abdominal wall)

4- Lumbar plexus - first three lumbar nerves and part of fourth
(supplies skin and muscles of lower abdomen, thighs and groin)

5- Sacral plexus - lower two lumbar, first four sacral nerves
(supplies muscles and skin of pelvic area. includes sciatic nerve which supplies the hamstrings. then divides above knee into tibial and common peroneal nerves to supply lower leg)

6- Cocygeal Plexus
(supplies muscles and skin of pelvic area such as external sphincter of the anus, tissues of the perineum and external genitalia.

Question 25

What is the peripheral nervous system divided into?

Answer 25

Somatic and Autonomic

Question 26

What is the function of the somatic nervous system?

Answer 26

Conducts impulses from CNS to skeletal muscle fibres.
Voluntary branch of PNS.
Allows conscious control over the contraction of skeletal muscle fibres.

Question 27

Where do autonomic nerves arise from?

Answer 27

medulla oblongata

Question 28

What is the function of the autonomic nervous system?

Answer 28

Conducts impulses from CNS to cardiac and smooth muscle fibres.
Involuntary branch of PNS.
Controlled by hypothalamus.

Question 29

Whats controls the autonomic nervous system?

Answer 29

hypothalamus

Question 30

What are the 2 division of the autonomic nervous system?

Answer 30

Sympathetic and Parasympathetic

Question 31

What is the structure and function of the Sympathetic nervous system:

Answer 31

Structure: nerves that arise from spinal cord and the thoracic and lumbar region. form bundles and then extend to organ they supply.

Function: prepares body for stressful situations such as excitement or physical activity (fight or flight).

Question 32

What do neurones release in the sympathetic nervous system?

Answer 32

acetylcholine and noradrenaline

Question 33

When neurones release acetylcholine and noradrenaline in the sympathetic nervous system, what are the effects on the body (6)?

Answer 33

1- accelerates action of heart
2- vasodilation of coronary arteries, increasing blood supply to heart
3- vasodilation of vessels supplying skeletal muscles.
4- causes sustained contraction of spleen, increasing volume of blood circulating.
5- vasoconstriction of vessels that supply the digestive and urinary system, increasing blood available for active muscles and brain.
6- dilation of bronchioles increasing volume of air that can be inspired and expired.

Question 34

What is the structure and function of the parasympathetic nervous system?

Answer 34

Structure: consists of nerves that arise from the brain and sacral region of the spinal cord. form ganglia near to the organ or tissue they supply.

Function: predominant system in non-stressful situations. Keep body functions running when the body is at rest.

Question 35

When neurones release acetylcholine, what are the effect on the body (4)?

Answer 35

1- slows action of heart
2- vasoconstriction of coronary arteries, decreasing supply of blood to heart muscle
3- vasodilation of vessels supplying the digestive and urinary systems. Increases digestion, nutrient absorption, micturition and defacation.
4- constriction of bronchi, decreasing the volume of air inspired and expired.

Question 36

What is neuritis?

Answer 36

inflammation of a nerve caused by infection, injury, poison

Question 37

What is Bell’s Palsy?

Answer 37

injury to facial nerve which becomes inflamed. facial paralysis.

Question 38

What is Neuralgia?

Answer 38

bouts of burning or stabbing pain along the course of one or more nerves.

Question 39

What is Parkinson’s disease?

Answer 39

Progressive disease casued by damage to basal ganglia of the brain and resulting in loss of dopamine. tremor and rigidity in muscles, also difficulty and slowness with voluntary movement.

Question 40

What is multiple sclerosis? (MS)

Answer 40

loss of the protective myelin sheath from fibres in the CNS. muscular weakness, loss of muscular coordination, problems with skin sensations, speech and vision.

Question 41

What is cerebral palsy?

Answer 41

Damage to the brain caused during child birth. Affects motor system control.

Question 42

What is motor neurone disease?

Answer 42

motor neurones in body gradually deteriorate. weakness and wasting of muscles.

Question 43

What is myalgic encephalmoelitis (ME)?

Answer 43

AKA post viral fatigue or chronic fatigue syndrome. exhaustion, general aches and pains, head aches, dizziness, inflammation of the brain and spinal cord.

Question 44

What is epilepsy?

Answer 44

Disorder of the CNS. loss of consciousness and convulsions.

Question 45

What is stroke?

Answer 45

Sudden loss of consciousness resulting when the rupture of a blood vessel leads to a lack of oxygen in the brain.

Question 46

What is alzheimers disease?

Answer 46

Common form of dimentia in older people.

Question 47

What is dementia?

Answer 47

Result of brain injury, resulting in long term decline in cognitive function due to damage or disease in body beyond what might be expected from normal agin.

Question 48

What is meningitis?

Answer 48

Infectious disease characterised by inflammation of the meninges usually caused by bacterial infection. Headache, stiff neck, fever and nausea.

Question 49

What is spina bifida?

Answer 49

Developmental birth defect involving the neural tube. vertebra is malformed and backbone does not form properly.