Muscle, skin, tissue, etc Flashcards
(34 cards)
What are the principle descriptors of skeletal muscle?
- Voluntary
- On bones
- Multinucleate
- Striated
What is the hierarchy of muscle components/cells
Actin + Myosin -> sarcomere -> myofibril -> myofiber (now considered the muscle CELL–contains organelles and cytoplasm) -> fascicle -> whole muscle
The sarcoplasmic reticulum stores what?
Calcium
The sarcoplasmic reticulum acts like a net that surrounds bundles of what?
myofibrils
How does the calcium stored in the sarcoplasmic reticulum reach into the innermost part of the myofibril bundle?
T tubules! Go crosswise across muscle cell, allowing AP to travel to the interior of the cell.
What level of muscle complexity is the initial unit of contraction?
Sarcomere
What kind of filament(s) make(s) up the I band?
Actin only
What kind of filament(s) make(s) up the A band?
Actin and myosin
What kind of filament(s) make(s) up the H zone?
myosin only
What part of the sarcomere “disappears” during contraction?
H zone disappears and I band shrinks greatly
What step(s) in actin-myosin binding require ATP?
- The PRESENCE (but not hydrolysis) of ATP is required for myosin to release actin after the power stroke.
- ATP hydrolysis is used to reset the myosin head to a “high energy conformation”
Does the power stroke of actin-myosin binding require ATP?
NO!
When you run out of ATP, your muscles can’t _________.
Relax! This is why rigor mortis occurs.
Do myosin head groups act synchronously or asynchronously?
Asynchronously
What does tropomyosin do?
Covers up the myosin binding sites so that actin and myosin cant interact
What does troponin do?
When calcium is released, it binds to troponin, tugging tropomyosin out of the way so that it no longer blocks the myosin binding sites -> myosin can bind to actin -> filaments slide (contraction)
What causes release of calcium from the sarcoplasmic reticulum?
Depolarization of the cell (SR) -> opens voltage-gated calcium channels and calcium floods the cytosol, binds to troponin
What is a motor unit? How would you describe contraction at this level?
A motor neuron and all the muscle cells it controls.
Contraction at this level is all or none.
In what is the first energy used by muscle cells?
Phosphocreatine
What molecule stores oxygen in the muscles?
Myoglobin
What things cause the oxyhemoglobin saturation curve to shift to the right?
- Increased CO2
- Increased temp
- Decreased pH
What are the characteristics of Type II muscle fibers? Which is the fastest?
White Contract fast Contract strongly Fatigues easily Low myoglobin Low mito Low blood supply
Type IIB = the fastest of all
What are the characteristics of Type I muscle fibers?
Red Contract slowly but for longer Not as strong High myoglobin High mito Highly vascular
What are the regions of a long bone and what are they made of?
long shaft called diaphysis made of compact bone and yellow marrow (fat). The innermost region that contains the marrow is called the medullary cavity.
+ 2 collagenous growth plates at each end
The knobs at the ends are made of spongy bone and are called epiphysis
