Muscle Flashcards
(42 cards)
What is unique about skeletal muscle nuclei?
they are located directly under the plasma membrane
Where are the nuclei located in cardiac muscle?
centrally
two unique traits about cardiac muscle that are not in any others?
branching at ends and intercalated discs
What is the organization of muscle starting with largest to smallest?
muscle->fassicles (bundles of muscle fibres=cells)->muscle fibre=cell->myofibril->myofilament (actin and myosin)
epimysium surrounds what? perimysium? endomysiu,?
surrounds entire muscle
surrounds fassicles
surrounds individiual muscle cells=fibres
sarcoplasmic reticulum surrounds what?
myofibrils (in skeletal muscle)
What are transverse tubules?
also called T-system, invaginations of membrane, there are two present on each sarcomere and are located at the A/I junction. They carry action potentials.
M line contains what? A band? I band? H zone? what marks the border of one complete sarcomere?
M line: center line, has proteins that connect myosin together
I band: just actin
A band: myosin and actin (does not change in length during contraction)
H zone: just myosin
Z lines mark one unit of sarcomere.
What are the two proteins on actin that are involved in contraction?
tropomyosin (surrounds actin) and troponin (3 globular proteins)
what is the structure of actin?
pearl like proteins in two strands twisting around each other forming an alpha helix.
In contraction which band stays constant?
A BAND
Bands besides the A Band do what during contraction? during relaxation?
shorten, lengthen
What cause Ca to be released into the lumen of sarcoplasmic reticulum and into sarcoplasm?
T tubules carrying action potentials
Once Ca is released into cytoplasm what does it do?
binds to troponin which causes tropomyosin (naturally blocking the binding site of mysoin to actin) to un block the binding site. Myosin head can then bind actin and move it forward.
EOMs are unique in that they have fine or course control?
fine. around 3 cells per neuron allowing for fine fast specific movements. most fine control than anywhere else.
is skeletal muscle able to undergo mitosis? what can it do instead?
NO, POST MITOTIC
can undergo hypertrophy (increase in size and number)
Which junctions are present between smooth muscle cells? what do these junctions allow for? what is the cell size range? can smooth muscle undergo mitosis?
gap junctions allows for synhronous stimulation (all stimulated at once).
20-500um
YES.
Where is smooth muscle located?
GI tract vessels (surrounds BVs) respiratory tract hollow organs i.e. bladder/stomach iris sphinctor ciliary body (ciliary muscle) arrector pili in skin
How are the fassicles arranged in smooth muscle?
in parallel sheets.
is contraction the same in smooth muscle as in skeletal?
NO. different processes but uses same proteins actin and myosin.
What are the two layers in smooth muscle?
longitudinal and circular
What is an example of smooth muscle in disease?
Asthma. occurs due to constriction of bronchi occurs due to overactivity of smooth muscle cells.
Cardiac muscle behaves how during contraction? can it undergo mitosis?
does it have an SER and T system?
little or large/many mitochondria?
as one unit.
NO
YES
large/many due to HUGE energy requirements.
What types of junctions are present at the intercalated discs in cardiac muscles? what junctions anchor the cardiac cells together?
gap junctions (for ion flow) and desmosomes (to give structural integrity) adhering junctions.
