anatomy muscle tissue
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What are the 6 functions of the skeletal muscles?
- 1. movement
- 2. maintain posture and body position
- 3. support soft tissue
- 4. guard entrances and exits
- 5. maintain body temp
- 6. store nutrient reserve
what are the 3 layers of connective tissue in muscles?
- 1. epimysium
- 2. perimysium
- 3. endomysium
what is the epimysium?
dense layer of collagen fibers that surrounds the entire msucles. It separes the muscles from nearby tissues and organs. COnnected to deep fascia
What is the perimysium?
divides the skeletal muscle into a serious of compartments with each compartment containing a serious of compartments. and each compartment contains a bundle of muscles fibers called fasicle. Contains blood vessels and nerves.
What is the endomysium?
within a fasicle, the delicate connective tissue that surrounds the individual skeletal muscle cells called muscle fibers. Is flexible elastic that contains capillary network that supply blood, myosatellite cells--stems cells that are part of repair for damanged muscle tissue and nerve fibers that control the muscle.
what are myoblasts?
during development,these groups of embryonic cells fuse forming individual multinucleate skeletal muscle fibers
plasma membrane or a muslce fiber. surrounds the sarcoplasm.
what is the sarcoplasm?
cytoplasm of the muscle fiber.
what are Transverse tubules or T tubes?
narrow tubes that continuous with the sarcolemma and extend deep into the sarcoplasm. They are filled with extracellular fluid and form passageways through the muscle fiber. Electrical impulses (conducted by the sarcolemma) travel through them and trigger muscle fiber contractions--action potential
100's-1000's of cylindrical structures inside each muscle fiber. They are actively shorten and are responsible for skeletal muscle contraction.
myofilaments? how many are there?
bundles of protein filaments in myofibrils. 2 of them. thin filaments and thick filaments.
1st type of myofilaments?
thin filaments--composed primarily of actin
composed primarily of myosin. they also contain titin.
what are the smallest functional units of the muscle fiber? what do they do?
sacromeres. They interact between the thick and think filaments of sacromeres are responsible for muscle contraction.
what does a sarcomere contain?:
- 1. thick and thin filaments
- 2. proteins that stabilize the positions of the thick and thin filaments
- 3. proteins that regulate the interactions btwn thick and thin filaments
what are the dark bands of the sarcomere called?
what are the light bands of the sarcomere called?
where are the thick filaments found in a sarcomere?
at the center in the A band.
Three subdivisions of the A bands?
- -M line
- -H band
- -Zone of Overlap
-M line- (The A band)
-connect central portion of each thick filament to neighboring thick filaments.. These dark straining proteins help stabilize the positions of the thick filaments.
-H band- (A band)
in resting sarcomere, is a lighter region on either side of the M line. Contains ONLY thick filaments.
Zone of Overlap (A band)
is a dark region where thin filaments are located btw the thick filaments. Here three thick filaments surround each thin filament, and six thin filaments surround each filament.
I bands? what type of filaments?
Contain ONLY thin filaments. Extends from A band of one sacromere to the next.
make the boundary btwn adjacent sacromeres. Consists of proteins called actinins, which interconnect thin filaments of adjacent sacromeres. At both ends of the sarcomere, thin filaments extend from the Z lines toward the M line and into the zone of overlap.
strands of elastic protein that extend from the tops of the thick filaments to attachment sites at the Z lines. Helps keep the thick and thin filaments in proper alignment and aids in restoring resting sarcomere length after contraction
4 proteins in a single thin filament
- 1. F-actin
- 2. Nebulin
- 3. Tropomyosin
- 4. Troponin
What is Filamentous actin (F actin)
(in thin filaments) a twisted strand composed of two rows of individual globular molcules of G-actin.
Long protein strand (in thin filaments) that extends along the F-actin stands in the cleft btwn the rows of G-actin molecules. Holds the F-actin strands together.
In each G-actin molecule that can bind to myosin in thick filaments.
strands that cover the active sites on G-atin and prevent actin-myosin interactions. It is a double stranded protein that covers seven active sites and is bound to one molecule of troponin midway along its length.
consists of 3 globular subunits. One subunit binds to tropomyosin, locking them together as a troponin–tropomyosin complex, and a second subunit binds to one G-actin, holding the troponin–tropomyosin complex in position. The third subunit has a receptor that binds two calcium ions. In a resting muscle, intracellular Ca2 concentrations are very low, and that binding site is empty
Contain myosin molecules, each made up of a pair of myosin subunits twisted around one anohter.
(thick filaments&myosin) THe long tail is bound to __________. The free head, which does what? and has what?
other myosin molecules in the thick filaments.
Free head which protects outward toward the nearest thin filament, has two globular protein subunits.
what is a cross bridge?
the interaction btwn the myosin heads and thin filaments during a contraction.
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