Skeletal and cardiac muscle physiology Flashcards
what are 2 types of striated muscle
skeletal
cardiac
what kind of contraction does skeletal muscle have
voluntary
what kind of contraction does cardiac muscle have
involuntary
dimensions of skeletal muscle
20-100 μm duameter, 12cm length
dimensions of cardiac muscle
brick shaped 10-20 μm diameter, 100 μm length
which is branches and unbranched out of skeletal and cardiac muscle
skeletal = unbranched
cardiac = branches
which one has a motor unit out of skeletal and cardiac muscle
skeletal = The motor unit: multiple fibres can be innervated by a single motor neuron
cardiac = No motor nerve (impulse arrives by conduction)
label this image of striated muscle
where do you find z lines
Z lines repeat along the length of the muscle approximately every 2 µm.
whats found in between 2 adjacent z lines
sarcomere - when we talk about sarcomere length we’re talking about the distance between two adjacent Z lines.
what does sarcomere contain
all of the protein filaments necessary for muscle contraction and these sarcomeric units simply repeat along the length of the muscle fibre.
what 2 structures are within the sarcomere
A band (which is the thick myosin filaments) and the I band (which is the thin actin filament) (which are anchored to the Z-line).
what is the a band
thick myosin filaments
what is the i band
thin actin filament
what are the small holes at every z line called
These are a blind-ended tubes of membrane called T-tubules
which is the thick and thin filaments in this diagram
what is a triad made up of?
1 T-tubule and 2 terminal cisternae
These T-tubules make junctions with the sarcoplasmic reticulum to form triads.
how many cisterns do skeletal cells have compared to cardiac cells
skeletal = triple (triad)
cardiac = double (dyad)
compare the mitochondria elvels in skeletal vs cardiac
more mitochondria in cardiac and bigger
arrangement of sarcoplasmic reticulum
repeating series of networks around myofibrils
where they meet is called terminal cisterna
what are t tubules surrounded by?
two terminal cisternae, called “triad”
what is the function of a t tubule
These t-tubules are necessary in larger cells to bring the action potential down into the centre of the cell and ensure synchronous coordinated contraction.
what cells are t tubules absent in
t-tubules are absent in small cells like atrial cells, neonatal cells and avian heart cells.
the association between Sarcoplasmic Reticulum and t tubule is essential for what
excitation-contraction coupling.