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MUSCLE SPASMS (DIRECT CAUSE
patient has been infected with clostridium…
MUSCLE SPASMS
DIRECT CAUSE
- patient has been infected with clostridium tetani
(common name tetanus)
tetanospasmin acts by blocking
the release of inhibitory neurotransmitters
(IPSP's) such as gamma aminobutyric (GABA)
at neuromuscular junction too few
IPSP's result in EPSP's causing the neuron
to hit threshold too often and too quickly
-
this results in muscle spasms
which typically begin superior in body
and move to inferior in body.
Lockjaw is often the first symptom
followed by abdominal muscle and
limb spasms
contaminated needle injected
clostridium tetani (c tetani) deep
enough into skin to allow the
bacteria to take hold and grow
when threshold is reached, the
neuron will activate its action
potential along the axon of the neuron
cell
once the action potential reaches the
axon terminal, it releases another
neurotransmitter which begins
the process of muscle contraction
with fewer IPSP's this action potential
is happening too often
(please refer physiology section highlighted
in purple below for extended
details on these processes when acting
properly)
ANATOMY
-
Structure of a Neuron
- made up of cell body, dendrites, nucleus,
nucleolus, axon and axon terminals
Axon can be myelinated
- covered in myelin sheath
(fatty substance)
Pre-synaptic Neuron
- neuron that brings the message
Post Synaptic Neuron
- neuron that receives message
-
PHYSIOLOGY
-
-
Neurons Send Messages
[At dendrites, chemically gated ion channels
- K+ channels, Cl- channels and Na+ channels
Due to relative amounts of these ions inside and
outside the cell (think Salty Banana, more K+ inside and
more Na+ and Cl- outside), when chemically gated channels open, ions will diffuse from high concentration to low
concentration (K+ flows out, Cl- and Na+ flow in)
-
Neuron is constantly receiving
IPSP's and EPSP's. EPSP's are
bringing the neuron's. At Axon Hillock,
summation occurs. (addition of all
EPSP's and IPSP's)
This is the crucial issue with our patient
Because the IPSP known as GABA is being
blocked, the neurons are reaching threshold
potential too much, (imagine diagram to the
left with only the green sections of the graph without
the red ones)
This leads originally to
lockjaw and then travels
to the rest of the body and results
in widespread activation of motor
neurons and spasming of muscles
throughout the body
Once summation of -55mV is reached
at axon hillock, action potential continues
down axon, Voltage gated sodium channels
on the axon help electrical charge move down the axon
(voltage gated potassium channels quickly follow the opening
of the sodium channels and do the important job of
repolarizing the neuron's membrane.
This continues down the axon hilllock
until axon terminal is reached. At this point
chemically gated calcium channels will open
and do the important job of releasing neurotransmitters
Muscular System
The muscle spasms caused by the affects of the
nervous system begin with the jaw and continue to the
inferior parts of the body, primarily the throat, chest,
abdomen and extremities. It is through these muscular affects
that several other organ systems are affected as well.
Respiratory System
Because there are muscles
that play important roles in the
respiratory system such as the diaphragm
and the intercostal muscles are integral
to breathing in and breathing out. Although rare
death from tetanus would most likely be due to
the affects on the respiratory system.
Lymphatic System
Tetanus in this patient was
originally caused by Clostridium
tetani, which is a bacterium.
It is in fact, the lymphatic system, which
is unable to fight off this particular pathogen
that disseminate the toxin throughout the body.
Cardiovascular System
Since the walls of the heart are
lined with cardiac muscle, this can also
be affected by tetanus and lead to heart
palpitations.
Nervous System
Tetanus is primarily a condition
of the nervous system As discussed in the upstream
causes, one of the toxins from this bacteria blocks the release
of an IPSP known as GABA which leads to widespread activation
of motor neurons and spasming throughout the body.
Left untreated tetanus can lead to death. Most common cause
of death is suffocation due to affects on breathing.
Digestive System
Due to the affects in particular on the
jaw caused by muscular difficulties, the
digestive system is also affected by this illness.
Without receiving proper nutrients, the patient will be
less likely to be able to get what it needs from food
Skeletal System
As with any illness when a patient is
less active, there will be bone loss as physcial
activity plays a role in bone remodelling. Bone remodelling
cells known as osteoclasts will break down bone faster than
bone making cells known as osteoblasts will build new bone.
INDIRECT CAUSE
- patient did not received tetanus vaccine
(or tetanus booster required every 10 years)
