Muscles Flashcards
What are the types of muscle
- Smooth muscle: causes peristalsis
- Skeletal muscle: helps us move and breathe
- cardiac: contracts our heart
What are characteristics of muscle
- contractile: causes movement of the body and changes in size/shape of internal organs.
- conductive
- skeletal muscle is a major source of body heat (by product of cellular respiration)
What are characteristics of skeletal muscle
- somatic (voluntary)
- striated
- multinucleated
what are characteristics of cardiac muscle
- heart
- autonomic
- striated
- single nucleus; centrally placed
- intercalated discs
what are characteristics of smooth vessel
- walls of viscera, blood vessels, skin
- autonomic
- not striated
diff between smooth muscle and dense irregular CT:
You see a lot of nuclei (fusiform or corkscrew) and not a lot of extracellular space. Collagen in ECM stains more darkly with eosin in dense irregular CT
What is organization of a skeletal muscle
muscle –> muscle fascicle –> muscle fiber –> myofibrils –>myofilaments
reticular fibers is what type of collagen
type 3
describe endomyseum
- reticular fibers
2. surr ind muscle fibers
describe perimysyium
- thicker CT
- surr muscle fascicles
- blood vessel and nerves withim
what are myofibrils
contain contractile element of the cell
-extend the entire length of the muscle fiber
myofilaments are arranged in:
sarcomores which is a contractile unit; sarcomere shortens with contraction
Sarcomeres:
Thin filaments only present in the I band.
A band is in the center.
M line is where other proteins are that anchor the thick filaments together.
A band never changes in ___but the amount they overlap changes
length
____bands shorten during contraction
I
What are the thin filaments
- actin
- tropomyosin
- troponin
what is the thick filaments
- myosin
- 2 heavy chains (rod and heavy)
- 4 light chains (regulatory)
ONly possible with the prescense of calcium
- Myosin heads bound to thin filament
- ATP binds to mysoin head causeing conformation change which releases actin
- ATP gets hydrolyzed to ADP and phophate; which causes head to get cocked back
- Powerstroke: head reaches up and binds actin which releases inorganic phosphate and ADP; myosin head comes forward again and pulls actin chain
- Back to step 1
I band =
light band
A band =
dark band
H band is the light band witin the
A band.
During contraction only I band and H band
decrease in size; A band is constant
What is SR
Specialized smooth ER involved in sequesteration of calcium
What is T tubule
bring depolarization from sarcolemma along SR within skeletal muscle fiber; leads to release of calcium from SR allowing contraction; lined up at interface of I band and A band.
What is sarcolemma
plasma membrane of muscle fiber which travel all the way down to center of cell
where is mitochondria located
in periphery and between myofibrils
What forms myotubes
myoblasts which are made from progenitor cells.
Each motor end plate of formed from;
presynaptic membrane
describe features of muscle spindles
Proprioceptive elements to the muscles. They consist of spindle fibers within double capsule. Muscle spindle fibers involved with gamma motor neurons
