Skeletal Muscle And Nerve Tissue Histology Flashcards
What are the differences between skeletal, cardiac, and smooth muscle?
Skeletal muscle is striated, strong, quick, voluntary, fatiguable and multinucleated
Cardiac is striated, strong, quick, involuntary and can never fatigue, uninucleated, branched and separated by intercalated discs
Smooth muscle is not striated, weaker, slow and rhythmic, involuntary and uninucleated
What is a sarcomere?
The contractile unit of muscle made up of actin and myosin myofilaments
What is endomysium?
The fascia covering over myofibers
What is a myofibril?
A chain of sarcomeres. It makes up muscle cells
What is a fascicle?
A group of myofibers surrounded by perimysium
A muscle is made up of a group of ____, and is surrounded by ____
Fascicles, epimysium
What is myosin made up of?
2 heavy chains with a globular head (actin binding site with ATPase domain)
2 light chains
Held in place by Titian proteins connected to Z disk
What is nebulin?
A ruler for determining the length of actin filaments
What is the M-line?
Attachment site for myosin
What is the Z-disk?
Separates sarcomeres; attachment site for actin and Titian
What is the H band?
Space on either side of the M line where there is no actin
What is the A band?
Distance from the end of one myosin head to the head of opposite myosin (overlap of actin + myosin and H band)
What is the I band?
Space on either side of the z-disk where there is no myosin
What does troponin do?
Blocks the myosin binding sites on actin filaments
What does calcium binding to troponin cause?
A conformational change that makes the actin binding site accessible to myosin heads
Describe the sliding filament mechanism
Thin filaments slide past thick filaments (myosin heads crawl across actin filaments)
This brings Z-disks closer together
What is the main difference between Type 1 and Type 2 skeletal muscle fiber types?
Type 1 is slow, less powerful contraction with many mitochondria, abundant myoglobin, slow fatiguability and aerobic respiration
Type 2a is fast/intermediate powerful contractions, many mito, myo, intermediate fatiguability and aerobic
Type 2b is fast powerful contractions, few mito, few myo, rapid fatiguability and anaerobic respiration.
What is a sarcolemma?
Membrane around each muscle cell
What is a sarcoplasm?
Cytoplasm of muscle cells
What is the sarcoplasmic reticulum?
Tubular system acting like the smooth ER
What is the terminal cisternae?
A flattened sac of SR on either side of a transverse T Tubule
What is a transverse (T) Tubule?
Membrane system penetrating the muscle cell to convey electrical impulses from sarcolemme into cell
What is a triad?
T-tubule and 2 terminal cisternae
What do End Feet do?
Connect t-tubules with SR to allow Ca release
What is the neuromuscular spindle apparatus?
A reflex response to help prevent over stretching of muscles
What do extrafusal muscle fibers do?
Contract the muscle
What do intrafusal muscle fibers do?
Sense length and rate of change of the extrafusal muscle fibers, which will cause the reflex response
What are Type 1a sensory nerve fibers?
Afferent innervation of intrafusal fibers; these will sense the change in length and will send a signal to the spinal cord
What are a-motor nerve fibers?
Efferent innervation of extrafusal muscle fibers; reflex reaction
What are g-motor nerve fibers?
Efferent innervation of intrafusal muscle fibers; reflex reaction
What is the Nissle substance?
An abundant rER within the cytoplasm of the soma
What is a multipolar neuron?
A neuron with an axon with multiple dendrites and one axon
What is a bipolar neuron?
A neuron with a single dendrite (multiple extension) and one axon
What is a pseudounipolar neuron?
one cell process with a single dendrite branch and axon branch
What does the myelin sheath do?
It allows for faster signal conduction velocity
What is the neuromuscular junction? How many nerves per muscle fiber and how many muscle fibers per nerve?
Skeletal muscle innervated by peripheral alpha-motor neurons from the anterior horn of the spinal cord;
1 nerve per muscle fiber
More than one muscle per nerve
