23 year old patient is demonstrating severe face and muscle spasms. Patient has fresh tattoo obtained from a "sketchy" tattoo parlor. Blood results show he is infected with Clostridium Tetani, a bacterium that is transmitted by dirty needles. Patient was never vaccinated against this bacterium.
Upstream Causes
Direct Cause - The direct cause is due to the tattoo parlors dirty needles used when given the tattoo, which was contaminated with Clostridium Tetani.
Indirect Cause - Possible indirect cause is lack of choosing a sterile tattoo parlor and not being vaccinated against the bacterium.
Background Information
Systems Involved in this case map
Nervous system
Lymphatic system
Muscular system
Immune systen
The Nervous system receives, integrates, and responds to information.
Sensory Input - Nervous system uses sensory receptors to monitor changes occurring both inside and outside the body. Gathered information is called sensory input.
Integration - processes and interpets sensory input and make decisions
Motor output - the nervous system activates effector organs, the muscles and glands, to cause a response.
CNS PNS SNS ANS
CNS - includes brain and spinal cord, integrative and control centers.
PNS - Cranial nerves and spinal nerves, communication lines between the CNS and the rest of the body.
SNS - Somatic (voluntary) motor nerve fibers, Conducts impulses from CNS to skeletal muscles
ANS - visceral (involuntary) motor nerve fibers, Conducts impulses from the CNS to effectors (muscles and glands)
Events at the Neuromuscular Junction
- Action potential arrives at axon terminal of motor neuron.
- Voltage gated Ca2+ channels open. Ca2+ enters the axon terminal, moving down its electrochemical gradient.
- Ca2+ entry causes ACh (a neurotransmitter) to be released by exocytosis.
- ACh diffuses across the synaptic cleft and binds ACh receptors on the sarcolemma
- ACh binding opens chemically gated ion channels that allow simultaneous passage of Na+into the muscle fiber and K+ out of the muscle fiber. More Na+ ions enter than K+ ions exit , which produces a local change In the membrane potential called the end plate potential.
- ACh effects are terminated by its breakdown in the synaptic cleft by acetylcholinesterase and diffusion away from the junction
Skeletal muscle contraction
Events at Neuromuscular Junction
A motor neuron fires an action potential down its axon
the motor neurons axon terminal releases ACh into the synaptic cleft.
ACh binds receptors on the junctional folds of the sarcolemma.
ACh binding causes a local deporlization called an end plate potential
muscle fiber excitation
The local depolarization triggers an AP in the Adjacent sarcolemma
Excitation contraction coupling
AP in sarcolemma travels down T tubules
Sarcoplasmic reticulum releases Ca2+
Ca2+ binds to troponin which shifts tropomyosin to uncover the myosin binding sites on actin. myosin heads bind actin
Cross bridge cycle
Contraction occurs via cross bridge cycling
Muscle Twitch
The response of a muscle to a single simulation. The muscle fibers contract quickly and then relax.
Latent period - first milliseconds following stimulation when excitation contraction coupling is occurring.
period of Contraction - cross bridge is active
period of relaxation - pumping of Ca2+ back into SR
Temporal or wave, summation
two identical stimuli are delivered to a muscle in rapid succession, the second twitch will be stronger
contributes to contractile force, creates smooth muscle, and continuous muscle contractions by rapidly stimulating specific number of muscle cells
Incomplete tetanus
the degree of wave summation becoming greater and greater , progressing to sustain a quivering contraction
complete tetanus
Evidence of muscle relaxation disappears and contractions fuse into smooth, sustained contraction plateau
Clostridum Tetani
is an obligate anaerobic bacteria whose spores produce two distinct toxins, tetanolysin, which causes local tissue destruction, and tetanospasmin, which causes clinical tetanus.
Tetanus neurotoxin binds to the presynaptic membrane of the neuromuscular junction, is internalized and transported to the spinal cord.
The spastic paralysis induced by the toxin is due to the blockade of neurotransmitter release from spinal inhibitory interneurons.
Widespread intoxication through the systemic circulation results in continuous involuntary muscle contraction of clinical generalized tetanus, whereas local internalization and transport of toxin can result in a localized state of muscle hyperexcitability.
Graded Muscle Contractions
An in increase in the frequency of stimulation causes TEMPORAL SUMMATION.
The higher the frequency, the greater the strength of contraction of a given motor unit.
An increase in the strength of stimulation causes RECRUITMENT
The stronger the stimulation, the more motor units are activated, and the stronger the contraction.
Motor or efferent neuron
carry impulses away from the CNS to the effector organs ( muscles or glands) of the body.
Motor neurons are Multipolar.
Sensory or afferent neurons
transmits impulses from sensory receptors in the skin or internal organs toward or into the central nervous system.
Theses neurons are unipolar
cell bodies are located outside in sensory ganglia outside the CNS
Downstream effects
Effect 1
Effect 2
Effect 3
Effect 4
tetanus toxin is transferred to inhibitory presynaptic terminals surrounding motor neurons. The toxin then destroys a vesicular synaptic membrane protein
This will result in inactivation of inhibitory neurotransmission that normally suppresses motor neuron and muscle activity
Because inhibitory neurotransmission is inactivated. suppression of motor neuron and muscle activity will not occur
This will cause the patients muscles to experience enhanced excitability and activation of the affected motor neurons.
Patient is now experiencing a widespread of the toxin. Leading to enhanced excitability and activation of the affected motor neurons
Patient possibly received the bacterium via needle onto is arm, the toxin is considered to be in a localized state which has resulted in muscle hyperexcitabillity.
Because the toxin is starting to cause muscle spasms in the arm this will result to a widespread intoxication through the circulatory system.
Patient will then begin to experience continuous involuntary muscle contractions such as muscle spasms of the face leading to inability to speak.