Diseases of motor neurons ect.

Question 1

Muscular dystrophy

• why
• symptoms

-what happens after a muscle contraction

Answer 1

Inherited disorder, where you get repeats in chromosome encoding for myotonin protein
Causes muscle weakness and wasting

Myotonia - delayed relaxation after a strong contraction

Question 2

Myasthenia gravis

Answer 2

Autoimmune disease where you get muscle weakness (without wasting) due to loss of ACH receptors
-can enject with edrophonium - blocker of ach esterase

Question 3

Ataxia
Myopathy
Neuropathy

Answer 3

Ataxia- incoordination of movement

Myopathy - disorder of muscles

Question 4

Causes of cell death with a stroke

Answer 4

• increase glutamate after a stroke
• activates many different receptors in the brain AMPA, NMDA, mGlu1/5 recptors
• with NMDA - get increased calcium into the cell (this will activate calcium sensitive enzymes to become activated and go down apoptopic pathways) - delayed nerve cell death
• with AMPA - get increase sodium, cloride and water and get rapid nerve cell death (cell lysis and necrosis)

Treatment - tissue plasminogen activator

Question 5

what is parkinsons disease, cause, symptoms, treatment

Answer 5

Resting tremour, bradykinesia (slowness of movement), no emotional expression ‘

Dopamine neurons damaged in substantria nigra
-genetic subseptibility

Treatment

• L dopa - can reduce tremour
• dopamine agonists
• thalamotoy - for tremour
• Pallidotomy

Late complicaitons - cognitive abnormalities, emotional disturbances, postural hypotension

Question 6

Amyotrophic lateral sclerosis

What is it?
Why?

Answer 6

Progressive wasting, weakness, and atrophy of muscles leading to paralysis

• difficulty with speech and swallowing, impairment of respiration
• muscle stretch reflex exaggerated and muscle tone increased (spasticity)
• fasculations, fibrilations

Why?
-can be due to progressive degeneration of motorneurons in spinal cord, brain stem and upper motor neurons
-autoimmune hypothesis - presence of antibodies against ca2+ channels in some patients
-oxidative stress hypothesis -
free radical damage
-excitotoxic hypothesis - increase glutamate due to a number of different reasons

No effective method yet

Question 7

Function of astrocytes,

Answer 7

Astrocytes

• release and take up neurotransmitters (gliotransmission)
• immune activation

Microglia
-mediate immune response, help modualte neurotransmission

Endothelial cells and pericytes
-perictyes encase endothelial cells in brain and maintain BBB

Question 8

Pyramidal weakness (hameiparesis) 
-upper and lower limb - flexors vs extensors which are stronger 

-characteristic posture and gait

Answer 8

Upper limb - flexors muscles may be weak but stronger than extensors

Lower limb - extensor muscle weak, stronger than flexors

Posture - upper limb held flexed, lower limb extended (may scarpe foot on floor)

Question 9

What happens initially after a complete transection of the spinal cord? at T8 (spinal shock)
-reflexes, blood vessels, touch and feel, sweating

1-3 days

Answer 9

• have a temporary period of areflexia (no reflexes) due to loss of excitatory inputs from descending tracts
• Parapelgia (flacid paralysis)
• Total anaesthesia below T8
• Areflexia - below t8 (no tendon reflexes, or plantar response)
• Blood vessles - maintained by sympathetic nervous system (PSNs - in lateral horn of spinal cord)
• continuous activation of these nerves will release noradrenaline which keeps vessles in state of contract to increase restitance and maintain BO
• PSNS - neurons from medulla
• When get damage to spinal cord than PSNS will not work - blood vessesl will relax and change in hear rate
• lower drop if there are more nerves involved
• Sweating absent (due to PSNS loss)
• bladder and bowels atonic

Question 10

Recovery of complete spinal cord lesion - additional symptoms

tone

Answer 10

• Muscle tone comes back, but no voluntary movements of leg
• Hyperactive stretch reflexes
• reflex of emptying bladder and rectum
• BP returns but is quite unstable (bareceptor reflex)
• flexor withdrawal reflexes on noxious stimulation recover
• extensor plantar reflex
• parenthesis - burnign in abdomen

Question 11

Mechanism of recovery for acute spinal cord lesion (3) 3 s

Answer 11

1. sprouting of axon terminals and formation of new synapses
   - some we degenerate
2. reprogramming of remaining axon connections - synaptic plasticity
3. denerveation - supersensitivity - some axons will increase receptor expression