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What is the role of muscle tissue? and what are the different types of muscle tissue?
Its job is to transform chemical energy(ATP) to directed chemical energy so it can then exert force.
the three different kinds are cardiac,smooth and skeletal muscle.
**Muscle is nearly over half of the body's mass.
Describe Skeletal muscle
they require nervous stimulation. they have elongated cells called muscle fibers that are striated.
they contract quickly and are powerful but they get tired easily.
Describe cardiac muscle tissue
Its striated and can contract without nervous system stimulation.
Not too big in this chapter.
what are the 4 special characteristics of muscle cells
exitability, contractility, extensibitity, elasticity.
What are the main muscle functions
- Movement of bones or fluids.
- maintaining posture
- stabilizing joints
- heat generation
it also protects the organs and controll the eyes and causes goosebumps.
What are the connective tissue seaths that help reinforce the whole muscle?
epimysium-Dense irregular CT that covers entire muscle.
perimysium- Fibrous CT that covers surrounding muscle fibers(fascicles)
endomysium- Areolar CT that covers Each muscle fiber.
What is a direct or indrect attachment?
Direct- epimysium is fused to the periosteum of the bone or perichondrium of the cartilage
indirect- connective tissue wrappings extend beyond muscle like a rope like tendon or sheetlike aponeurosis.
how long is a muscle fiber?
10 to 100 um in diameter and up to 30cm long
**multiple periphreal nuclei.
what is the sarcolemma? sarcoplasm?
lemma is the plama membrane
and plasm is the water like cytoplasm. they contain glycosomes and myoglobin for glygogen storage and oxygen storage.
what are myofibrils?
and what are the contratile units of the myofibrils.
myofibrils are densely packed rod like elements. and are 80% of the cell volume.
the contratile unit is called a sarcomere. and they contain myofilaments.
what is the H-Zone?
what is the M-line?
what is the Z-line
What is the Thick filament?
what is the Thin filament?
what is the sarcomere?
The H-Zone is- lighter reigon in the midsection of the dark A band where the filaments dont overlap.
the M-line is the line of protein that bisects thr H zone.
the Z disc- circle sheet of proteins on the middle of the light I band that anchors thin filaments and connects the myofibrils to one another.
the thick filament runs along the entire lengnth of an A band.
the thin filament-runs the lengnth of the i band and partway into the A band.
and the sarcomere is the contratile unit of the muscle and is the reigon between 2 disks.
what is a sarcomere?
smallest contractile unit of the muscle fiber. the space btween both z lines and contains A band with 1/2 I band at each end.
composed of thick and thin myofilament contractile proteins myosin and actin.
what is the structure of the thick filament?
made of myosin and 2 heavy and 4 light polypeptide chains.
- The TAILS have 2 HEAVY polypeptide chains
- the HEADS have 2 Smaller light polypeptide that act as cross bridges during contraction. they are the binding sites for ATP and actin.
what is the structure of the the thin filament?
Twisted double strand of fiberous protein F actin which also contains Globular actin subunits.
the g actin is the active sites for mysoin head attachments during contraction. Tropomyosin and troponin are regular proteins bound to actin.
what is the structure of myofibril?
its an elastic filament composed of the protein titin. it holds the thick filaments in place and helps recoil after stretch and resists to excessive stretching.
Nebulin,myomesin, C proteins bind the filaments or sarcomeres together and maintains alightment.
What is the Sarcoplasmic reticulum?
Is a network of smooth endoplasmic reticulum surrounding each myofibril.
they have pairs of terminal cisternae form perpendicular cross channels
it stores and realeses intracellular calcium.
What are the T tubules.
they are the continuations of sarcolemma. and they increase muscle fiber's surface area.