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A 23 YEAR OLD WITH MUSCLE SPASMS (STEPS IN NEUROMUSCULAR JUNCTION…
A 23 YEAR OLD WITH MUSCLE SPASMS
SYSTEMS INVOLVED
Integumentary
Circulatory
Muscular
Nervous
STEPS IN NEUROMUSCULAR JUNCTION
Electrical impulse arrives at axon terminal
Voltage-gated Calcium channels open and calcium enters
Snare proteins get activated, attach to synaptic vesicles' membranes and cause exocytosis of these vesicles
Synaptic vesicles fuse with presynaptic membrane and cause release of Acetylcholine into synaptic cleft
Ach receptors open at sarcolemma
(Voltage gated Sodium channels)
Sodium enters muscle fibers and positive charge causes an action potential inside cell
Then muscle contracts
NEUROTRANSMITTERS IN MUSCLE CONTRACTION
Acetocholine
STEPS IN EXOCYTOSIS
Action potential arrives at axon terminal
Membrane potential of axon changes
Voltage gated calcium channels open
Calcium flows in from outside the neuron
Calcium concentration increases inside axon terminal
Fusion of synaptic vesicles and presynaptic membrane occur
Neurotransmitters will then exit the axon terminal by diffusion and attach to receptors at postsynaptic membrane
TWITCH, SUMMATION AND TETANY
Summation is the addition of post-synaptic potentials to reach a threshold and cause an action potential
A twitch is a single muscle fiber contraction that occur when its stimulus threshold is reached
A tetany is involuntary contraction of muscles caused by increasing of the action potential frequency of muscle cells or the nerve that innervate them
CLOSTRIDIUM TETANI AT NMJ
It is a soil bacteria that causes tetanus by releasing a toxin
The toxin prevents the release of neurotransmitters from presynaptic cell
Therefore, inhibitory neurons of postsynaptic cell would not be able to get the message to stop muscle contractions
That will cause the muscle to contract continually until spasms occur
CAUSES
The patient is experiencing spasms because of excessive muscle contraction. Whereas in flaccid paralysis, the muscle can not contract anymore
DIRECT CAUSE: communication between Ach and inhibitory neurons BLOCKED
INDIRECT CAUSE: dirty needles used in tattoos that had the bacterium
EFFECTS
Tetanus spores will germinate and produce bacteria that release poison. Those bacteria will increase in number by dividing.
It is a deadly condition if untreated because the constant contraction of muscle will cause the patient to become stiff and eventually die from lost of oxygen in blood.