The document summarizes electrical studies of reflexes and disorders of neuromuscular transmission. It defines a reflex as an involuntary response to a stimulus mediated by neural pathways called reflex arcs. Reflexes are classified based on development, response, complexity of circuit, and processing site. The patellar reflex is described as a monosynaptic somatic reflex. Neuromuscular transmission and the neuromuscular junction are defined. Disorders of neuromuscular transmission can be autoimmune, genetic, or due to neurotoxins. Specific disorders discussed include myasthenia gravis, botulism, and Lambert Eaton myasthenic syndrome.

1. Department Of Biomedical Engineering
GCET Ganderbal, kashmir
Electrical Study Of Reflexes
And
Disorders of Neuromuscular Transmission
By
Naseer Ahmad (190112)

2. Contents
 Reflex Or Reflex Action
Classification Of Reflexes
Reflex Arc
Patellar Reflex
NMT ,NMJ and NMT Process
NMT Disorders

3. Reflex Or Reflex Action
• An automatic and rapid response to stimuli.
• An involuntary response as it does not require
the intervention of consciousness.
• A simple reflex involves only a part
of CNS (one segment of spinal cord
or one small nucleus in the brain)
• An Integral component of famed
survival instinct.
• A reflex is made possible by neural pathways called reflex arcs.

4. Classification of Reflexes
BY
DEVELOPMENT
INNATE
REFLEXES
ACQUIRED
REFLEXES
BY RESPONSE
VISCERAL(AUTONOMIC)
REFLEXES
SOMATIC REFLEXES
BY
COMPLEXITY
OF CIRCUIT
MONOSYNAPTIC
POLYSYNAPTIC
BY
PROCESSING
SITE
SPINAL
REFLEXES
CRANIAL
REFLEXES

5. Reflex Arc
• A neural pathway that controls a reflex.
• A special type of neural circuit that begins with a sensory neuron at
receptor and ends with a motor neuron at an effector.
• Reflex arc can be:
1. Autonomic
2. Somatic
3. Monosynaptic
4. Polysynaptic

6. Parts Of Reflex Arc
1. Receptor ( sense organ)
2. Sensory neuron(sensory nerve)
3. Spinal cord-modulator
4. Motor neuron(motor nerve)
5. Effector organ
• Simplest reflex arc needs only
sensory and motor neurons.
• Many reflex arcs also have a
connection neuron in spinal
cord, called relay interneuron.

7. Clinical Experiment
(Patellar reflex or Knee Jerk reflex)
• It is a Myotatic or muscle stretch
or deep tendon monosynaptic
reflex mediated by spinal nerves
from L2, L3 and L4 in spinal cord.
• No interneuron in its pathway
( Sensory neuron synapses directly
on a motor neuron in spinal cord).

9. Neuromuscular transmission(NMT) and Neuromuscular
Junction(NMJ)
• Neuromuscular transmission(NMT) is a
process that permits the CNS to control
movement of muscles in body.
• Neuromuscular junction(NMJ) is a chemical
synapse formed by contact between a motor
neuron and a muscle fibre.
• NMJ is a part of motor unit responsible for chemical transmission of the
electrical impulse from a nerve to the muscle to produce appropriate
muscle movement.

10. Cont…
NMT process
MOTORNERVE FIBER
AXON TERMINAL
SYNAPTIC CLEFT
POSTSYNAPTIC MEMBRANE
MUSCLE FIBRE
PRESYNAPTIC
NEURON
SYNAPTIC
CLEFT
POSTSYNAPTIC
NEURON

11. Cont…
NMT DISORDERS CAN BE :
 Autoimmune Disorders
Myasthenia gravis
Transient neonatal myasthenia
Lambert Eaton
Acquired neuromyotonia
 Genetic Disorders
Acetylcholine receptor deficiency
Acetylcholine receptor kinetic abnormalities
Arthrogryposis

12. Cont…
• Neurotoxic Disorders
Botulism
Drugs/ insecticides
Envenomation following bites from snakes, spiders, scorpions.
• Disorders of neuromuscular transmission may involve
Postsynaptic receptors (e.g. in MG)
Presynaptic release of acetylcholine (e.g. in botulism)
Breakdown of acetylcholine within the synapse (e.g. due to drugs or
neurotoxic chemicals)

13. Botulism
• It is a neurotoxic NMT disorder .
• Caused by toxins( botulinum toxins) produced by clostridium botulinum
bacteria under low oxygen conditions.
• Botulinum toxins block nerve functions and can lead to respiratory or
muscular paralysis.
• Body attacks VGC (voltage gated channels) required for release of
acetylcholine .
• Spreads easily and can be fatal.
• Human botulism may be foodborne botulism, infant botulism, wound
botulism, and inhalation botulism or other types of intoxication.
• All types of botulism can be harmful and are considered as medical
emergencies

14. Cont…
• Symptoms
Difficulty swallowing, muscle weakness, double vision, drooping
eyelids, blurry vision, slurred speech, difficulty breathing, difficulty
moving the eyes, paralysis.
• Treatment
A drug called an ANTITOXIN, which prevents the toxin from causing any
more harm. Antitoxin does not heal the damage the toxin has already
done.

15. LAMBERT EATON MYASTHENIC SYNDROME
• Lambert-Eaton syndrome is a condition in which the immune system attacks the
neuromuscular junctions.
• It is an autoimmune disorder of NMJ in which antibodies are made against
presynaptic voltage gate calcium ions.
• Often associated with a type of cancer called small cell lung cancer. This
syndrome may result from body's efforts to fight the underlying cancer.
• Symptoms include proximal muscle weakness, fatigue and autonomic
dysfunction.
• Diagnosed by Electromyography test and x-ray or CT scan of lungs to distinguish it
from disorder with similar symptoms called myasthenia gravis .
• Treatment may be surgery, chemotherapy or plasmapheresis along with other
immunosuppressant medicines.

16. Myathenia Gravis
• It is an auto-immune NTM disorder.
• It is the most common primary disorder of neuromuscular
transmission.
• Occurs when communication between nerve cells and muscles
becomes impaired.
• The main symptom of MG is weakness in the voluntary skeletal
muscles
• There's no cure for myasthenia gravis, but treatment can help relieve
signs.

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