Nervous System

Question 1

Briefly explain the link between the NS and the endocrine system.

Answer 1

Both the NS and the endocrine system detect changes both inside and outside the body and respond accordingly.

BUT

NS acts through nerve impulses and the response is FAST and SHORT lasting.

Endocrine system acts through hormones and is SLOWER and LONGER lasting.

Becoming more common to think of them as two parts of the NEURO-ENDOCRINE SYSTEM.

Question 2

1. What are the 3 sub systems of the NS?

Answer 2

1. NS sub systems:
   i. Central Nervous System (CNS) - brain & spinal cord
   ii. Peripheral Nervous System (PNS) - everything else
   iii. Enteric Nervous System (3rd part, covered in digestion)

Question 3

How is the NS organised?

Answer 3

1. Somatic (voluntary)
   Controls skeletal muscle
2. Automonic (involuntary)
   Controls smooth muscle, blood vessels, cardiac muscles and glands
   2 subdivisions: Sympathetic & Parasympathetic
3. Enteric (involuntary)
   Controls smooth muscle and glands of digestive tract.

Question 4

What is a nerve?

Answer 4

Enclosed, cable like bundle of axons in the peripheral NS

Each nerve follows a defined path and serves a specific region of the body.

Question 5

What are meninges?

Answer 5

3 layers of connective tissue coverings around the brain and spinal cord.

3 layers are:

1. dura mater
2. arachnoid mater
3. pia mater

Question 6

How many pairs of spinal nerves are there?

Answer 6

31 pairs

Question 7

What do spinal nerves contain?

Answer 7

Sensory neurones going in

Motor neurones coming out

Question 8

What happens to all the sensory neurones in a nerve as they enter the spinal cord?

Answer 8

They enter the BACK of the spinal cord and separate out - sensory root.

Question 9

Where do the motor neurones leave the spinal cord?

Answer 9

Leave through the FRONT of the spinal cord.

Question 10

What is a reflex?

Answer 10

Its a fast, involuntary sequence of actions that occurs in response to a particular stimulus. Some are inborn, some are learned.

Question 11

1. What are plexi in the nervous system?

2. Name 4 plexi.

Answer 11

1. web like connections of nerones

2. cervical plexus, brachial plexus, lumbar plexus, sacral plexus

Question 12

1. What is the hypothalamus?

2. Why is it so important?

Answer 12

1. Anterior and mid line of the brain, just above the pituitary gland
2. so important as it controls the autonomic NS and the pituitary gland. It is essential for the homeostasis of the body and regulates:
   - emotional / behavioural patterns
   - eating and drinking
   - body temperature
   - circadian rhythms and states of consciousness

Question 13

1. Where is the cerebellum located?

2. What does it do?

Answer 13

1. Back of the brain stem

2. Coordinates movement, balance & hand-eye coordination

Question 14

What part of the NS regulates the Autonomic NS?

Answer 14

Mainly the hypothalamus and brain stem.

Question 15

Briefly compare the functions of the Somatic NS (voluntary) and the Automonic NS (involuntary).

Answer 15

Somatic NS:

• Neurones convey pain, temp, touch to brain and spinal cord where we become aware of them.
• A response if organised and sent down somatic motor neurones to skeletal muscles to action as required.

Automonic NS:

• Neurones convey sensations associated with internal conditions e.g. blood CO2, stretching in walls of organs or.
• Usually unaware of them unless you’re sick or have eaten too much.
• Automonic Motor Neurones control cardiac muscle, smooth muscle and glands.

Question 16

Between which levels of the spinal cord do sympathetic motor neurones emerge?

Answer 16

Between D1 and L2

Question 17

From which levels of the brain and spinal cord do the parasympathetic motor neurones emerge?

Answer 17

Cranial nerves 3, 7, 9 & 10 and S2, S3, S4

Question 18

1. What is the most extensive parasympathetic motor nerve?

2. What does it supply?

Answer 18

1. Cranial nerve X (The Vagus Nerve)

2. Supplies everything in the thorax and abdomen, up to the transverse colon

Question 19

Name 4 organs which do have a sympathetic nerve supply but not a parasympathetic nerve supply.

Answer 19

1. Sweat glands
2. Arrector pilli
3. Spleen
4. Most blood vessels
5. Adrenal medulla

Question 20

Briefly describe the effects that PARAsympathetic nerve supply activities have on the body

Answer 20

Stimulates: (SLUDD)

• Salivation
• Lacrimation
• Urination
• Digestion
• Defecation

Decreases:

• heart rate
• airway diameter
• pupil constriction

Question 21

Briefly describe the effects that Sympathetic nerve supply activities have on the body

Answer 21

The Sympathetic NS cuts in under stress - Fight or flight. Effects include:

• pupils dilate
• heart rate and blood pressure increase
• airways dilate
• blood vessels supplying non essential organs contract reducing blood flow
• blood vessels supplying organs involved in exercise dilate (to help fight or flight) e.g. skeletal muscle, cardiac muscle, liver, adipose tissue.
• liver cells break down glycogen to glucose and adipose cells break down triglycerides to fatty acids and glycerol that can be used by cells for ATP production.

Question 22

1. What is alzheimers disease?

2. What causes it?

Answer 22

1. Progressive degenerative disorder of the brain causing memory loss, personality changes and eventually death.
2. Caused by Plaques and Neurofibrillary tangles in the brain:

Plaques - sticky deposits of protein (beta amyloid). When accumulates in brain it stimulates an inflammatory response what kills brain cells.

Neurofibrillary tangles - ineffective protein (tau) stops supporting nerve cells so they collapse, twist then shrink and die.

Hippocampus - in brain also shrinks so patient loses and can’t process new memories.

Question 23

1. What is Peripheral Neuropathy?

2. What are the signs and symptoms?

Answer 23

1. Symptom / complication of other underlying conditions. Peripheral nerve(s) are damaged through lack of blood supply, chemical imbalance, trauma or other factors.
   It’s usually a consequence of injury, infection of systemic disease.
2. • Burning or tingling pain
     - Cramping or twitching
     - hyperesthesia
     - autonomica dysfunction (inc probs with digestion, heart rate or breathing)

Question 24

1. What is Parkinson Disease?

2. What causes it?

Answer 24

1. PD is a movement disorder involving the degeneration of nerve tissue and a reduction in neurotransmitter production in the CNS.
2. Basal ganglia cells in brain (responsible for coordination and controlled movement) die.
   Its not clear why they degenerate but risk factors include:
   - pesticides
   - herbicides
   - fertilisers
   - other industrial chemicals.
   - sometimes genetic link.

Question 25

What are signs and symptoms of someone developing Parkinson’s?

Answer 25

1. non specific achiness, weariness, weakness and fatigue
2. Resting tremor
3. Bradykinesia (difficulty initiating or sustaining movement)
4. Rigidity
5. Uncoordinated movement and poor balance
6. Shuffling
7. Monotone and expressionless speech
8. Shrinking, cramped handwriting
9. Sleep disorders
10. Depression and anxiety
11. Loss of memory and understanding

Question 26

1. Describe signs and symptoms of tension, migraine and cluster headaches.
2. What symptoms might indicate a serious underlying condition?
3. Name 3 possible serious underlying conditions.

Answer 26

1. Tension - may be episodic or chronic. Often bilateral or diffuse. Patients may describe tight band around head or deep, dull ache rather than precise focal point of pain.

Migraine (with and without aura) - both can have throbbing pain on one side with same eye/nostril watering, light and noise sensitivity, nausea and vomiting, tingling or other sensations in extremities. Can last hours or days.

with aura (20%) - as above but also with flashing lights, blurred vision, auditory hallucinations

Cluster - rarer, unilateral, may cuase same side eye/nostril to water. Few moments to several hrs. Come in clusters (eg 1-4/day for 4-8wks). Usually at night, can wake from sleep. Restlessness.

2. • Severe, repeating or sudden onset.
   • Occuring in new pattern 50+yrs.
   • gradual onset but no remission
   • slurred speech, numbness in body
   • difficulty with motor control.
3. Encephalitis, meningitis, stroke, tumor, aneurysm

Question 27

1. What is Multiple Sclerosis?
2. What can trigger MS?
3. What are main signs and symptoms?

Answer 27

1. An autoimmune condition where macrophages (part if immune response), attack the Myelin Sheaths which protect the nerves.
   Once damaged, scar tissue forms (sclerosis) which inhibits nerve functioning.
2. Triggers include: genetic predisposition, lack of sunlight (distance from equator) - possible Vit D link.
3. • weakness
   • spasm
   • altered sensation (numbness)
   • eye pain/loss of function of optic nerve
   • incontinence/difficulty urinating
   • sexual dysfunction
   • difficulty walking
   • loss of short term memory and procedural memory
   • nausea/diarrhea/constipation
   • heat sensitivity
   • fatigue
   • depression

Question 28

1. What is Motor Neurone Disease?

2. What are the main signs and symptoms?

Answer 28

1. Progressive and fatal condition that destroys motor neurons in the central and peripheral NS leading to wasting of voluntary muscles. The cause is unknown.
2. 75% of cases affect spinal nerves (as opposed to cranial).
   - arms: difficulty with fine motor skills eg writing
   - legs: frequent stumbling
   one side can be affected more than the other
   Fatigue, cramping, stiffness and weakness move up the limbs to trunk breathing muscles.

25% of cases affect cranial nerves

• dif with speech, swallowing or motor control of tongue
• extreme and rapid mood swings

Can also be:
- exaggerated reflexes, weakness, atrophy, cramps and twicthing.

Question 29

1. What is Neuralgia

2. What causes it?

Answer 29

1. Intense burning or stabbling pain often like a ‘shooting pain’. Pain usually brief but can be severe.
2. Caused by irritation of or nerve damage, inflammation, infection, compression or physical irritation of nerve.

Question 30

1. What is Epilepsy?

2. What happens in an epileptic seizure?

Answer 30

1. Condition that affects the brain and causes repeated seizures
2. Cells in brain (neurones) communitcate via electric impulses. During a seizure these impulses are disturbed which can cause the brain and body to behave strangely.