Please enable JavaScript.
Coggle requires JavaScript to display documents.
23 y/o M pt accompanied to ED by brother, nonverbal, +severe muscle spasms…
23 y/o M pt accompanied to ED by brother, nonverbal, +severe muscle spasms, fresh tattoo to shoulder x1d, - vaccination schedule, brother reports tattoo shop was "sketchy"
BACKGROUND HX
-
-
-
-
-
Preventing muscles from receiving signal to release and relax causing tight continued contraction or spasm
-
SYSTEMS INVOLVED
-
Lymphatic System: Body prepares immune response, but patient was not vaccinated therefore no antibodies are available to fight
Nervous System: toxin travels through the body via the nervous system with the goal of reaching the spinal cord and brain.
Muscular system: toxin blocks neurotransmitters and blocks messages to the brain, resulting in unwanted muscle contractions and spasms
Respiratory System: As muscles have unwanted contractions the muscles become unable to perform as intended
CHAIN OF EVENTS AT NMJ
A nerve signal arrives at synaptic knob and stimulates voltage-gated calcium channels to open. Calcium ions enter the synaptic knob.
Calcium stimulates exocytosis of the synaptic vesicles, which release ACh into the synaptic cleft.
-
Ligand-gated ion channels are opened (channels that ACh binds to) and Na+ diffuses quickly into cell. Sarcolemma reverses polarity and creates end-plate potential (EPP)
Areas of sarcolemma next to the motor end plates have voltage-gated ion channels that open in response to EPP. These ion movements create an action potential. Muscle is now excited.
A wave of action potentials spreads from the end plate in all directions. When this wave of excitation reaches the T tubules, it continues down them into sarcoplasm.
Action potentials open voltage-gated ion channels in the T tubules. These are physically linked to calcium channels in the terminal cisternae of the sarcoplasmic reticulum. Channels in the SR open and calcium diffuses out.
-
The troponin-tropomyosin complex changes shape and sinks deeper into the groove of the thin filaments. This exposes the active site of the actin filaments and makes them available for binding to myosin heads.
The myosin head must have an ATP molecule bound to it to initiate the contraction base. Myosin ATPase, an enzyme in the head, hydrolyzes this ATP into ADP and phosphate. The energy released by this process activates the head, which "cocks" into an extended high-energy position.
The cocked myosin binds to an exposed active site on the thin filament, forming a cross-bridge between myosin and actin
Myosin releases ADP and phosphate and flexes into a bent, low-energy position, tugging the thin filament along with it. (Power stroke)
The binding of ATP to myosin destabilizes the myosin-actin bond, breaking the cross-bridge. The myosin molecule is now prepared to repeat the whole process.
EXOCYTOSIS
-
-
Fusion of the vesicle membrane with the cell membrane releases the vesicle contents outside the cell
-
MUSCLE CONTRACTIONS
-
-
Summation: A second muscle contraction occurs before relaxation from first contraction is complete. 2nd contraction is larger than first contraction because it "sums" off the first one.
Incomplete tetany: Summations occur rapidly, but muscle still relaxes slightly between contractions. Muscle is stimulated again and again before it fully relaxes.
-
NEUROTRANSMITTERS
ACh: Acetylcholine is a very widely distributed excitatory neurotransmitter that triggers muscle contraction and excretion of certain hormones
Dopamine: neurotransmitter involved in controlling movement and posture. It also modulates mood and plays a central role in positive reinforcement and dependency.
GABA: (gamma-aminobutyric acid) is an inhibitory neurotransmitter that is very widely distributed in the neurons of the cortex. GABA contributes to motor control, vision, and many other cortical functions.
-
Norepinephrine: neurotransmitter that is important for attentiveness, emotions, sleeping, dreaming, and learning. Norepinephrine is also released as a hormone into the blood, where it causes blood vessels to contract and heart rate to increase.
Serotonin: contributes to various functions, such as regulating body temperature, sleep, mood, appetite, and pain.
-