Lecture 14 - Nervous tissue in MSK Flashcards
How does calcium allow for the contraction of muscle cells?
Ca2+ binds to troponin, and this causes a conformational change were tropomyosin is displaced and the actin binding sites for the myosin heads are exposed, allowing myosin to bind to form a cross bridge
How is the intracellular contraction transmitted to the tendon of the muscle to move bones?
The sarcomeres are attached to ECM by desmin and dystrophin. Dystrophin attaches to the actin filaments, and then leaves the cell through a complex where laminin is present and then attaches to the ECM
Where are slow (type l) fibers found typically?
Slow type l fibers are found mainly in postural muscles in the back
They contain a high content of oxidative enzymes
Where are type lla (Fast, oxidative-glycolytic fibers) fibers found?
In the major muscles of the legs
They contain a similar amount of oxidative and glycolytic enzymes
Where are Type llb (Fast, glycolytic fibers)
Found in the extraocular muscles (Fast, glycolytic fibres)
What makes up a triad in muscles?
A t-tubule and its two adjacent sarcoplasmic reticulum (terminal cisternae)
What are the receptors on the T-tubules which detect an action potential?
Dihydropyridine receptor, and when activated interact with the ryanodine receptor
What are the receptors on the sarcoplasmic reticulum which when activated release calcium?
Ryanodine receptor
What is done to increase the surface area available at the neuromuscular junction?
The motor end plate is folded
How does the synaptic knob sit in the sarcolemma?
The synaptic knob sits in a depression of the sarcolemma
In histology, what are aggregates of rER called?
They are called Nissl bodies. These are within neurons which have extensive endoplasmic reticulum which are required for protein synthesis.
Descirbe a neuron histologically
Neurons are large multi polar cells
Where are the nuclei of motor neurons located, and where are the nuclei of sensory neurons located?
Motor neuron nuclei are in the ventral horn of the spinal cord.
The nuclei of sensory neurons are located in dorsal root ganglions.
What are the connective tissue constiuents of peripheral nerves?
Each axon is surrounded by the endoneurium
Each nerve fascicle is surrounded by the perineurium
The epineurium is the outermost layer of connective tissue that surrounds the entire peripheral nerve
What do motor units form when they come into contact with the sarcolemma?
They form the motor end plate, which is where they are numerous terminal boutons (synapses)
