H05&06: Muscle & Tendon Flashcards
What are the 3 types of muscle?
Skeletal/striated muscle
Smooth muscle
Cardiac muscle
Which muscle type is under voluntary control?
Skeletal muscle
Where is cardiac muscle found?
Around the heart
Where is smooth muscle found?
Around organs
What is the role of satellite cells in muscle?
They help with muscle cell repair
How is skeletal muscle formed?
1) Myoblasts fuse end to end to form myotubes.
2) Myotubes synthesise contractile proteins (myofibrils).
3) Myofibrils mature into muscle cells.
4) Nuclei of muscle cells is pushed into the periphery and the muscle cells become packed with contractile proteins.
What are particularities of skeletal muscle cells?
They are extremely long (can be up to cms long) & they are multinucleated.
What are the 4 layers of CT associated with skeletal muscle?
Tendons are rope-like CT that attaches muscle to bone.
Epimysium is the outermost layer of CT that surrounds many muscle fascicles.
Perimysium surrounds many myofibrils to form muscle fascicles.
Endomysium surrounds individual myofibrils, it is the innermost layer of CT.
Which band is the dark band and what is it made of?
The A band contains myosin filaments
Which band is the light band and what is it made of?
The I band contains actin filaments.
What is the sarcolemma?
The membrane of the myofibre
What is special about the sarcolemma?
It is highly invaginated to wrap around each myofibre and allow contact between T-tubules and sarcoplasmic reticulum.
What is the sarcoplasmic reticulum?
It is a specialised smooth ER that stores calcium.
State the 3 types of metabolism & explain how each works.
Creatinine phosphate involves using creatinine phosphate to phosphorylate ADP to produce ATP & creatinine
Aerobic metabolism involves hydrolysing ATP to provide energy.
Anaerobic metabolism is the breakdown of glycogen.
How does the life span of the 3 types of metabolism compare?
Creatinine phosphate and anaerobic metabolisms are short-lived while aerobic metabolism is long-lived.
Which metabolism is used by all types of muscle fibre?
Creatinine phosphate
State the 3 types of muscle fibres and the metabolism used by each.
Type I: uses aerobic metabolism
Type IIA: uses aerobic and anaerobic metabolism
Type IIB: uses anaerobic metabolism
What colour are each of the muscle fibres?
Type I is red
Type IIA is pink
Type IIB is white
What is the role of myoglobin?
It stores oxygen
What are type I muscle fibres used in?
Posture
What are type IIA muscle fibres used in?
Locomotion
Compare the twitch velocity, resistance to fatigue, rate of ATP hydrolysis and ATP generation capacity of the 3 types of muscle fibres.
Type I is slow twitching whilst type IIA & IIB are fast twitching.
Type I has a low rate of ATP hydrolysis while type IIA & IIB have high rates of ATP hydrolysis.
Type I has a high resistance to fatigue, type IIA has moderate resistance to fatigue and type IIB has low resistance to fatigue.
Type I has high ATP generation capacity while types IIA & IIB have low ATP generation capacity.
What are type IIB muscle fibres used in?
Rapid force
What are synergistic actions?
When muscles work together.
What are antagonistic actions?
When muscles oppose each other.
Which muscle primarily moves a limb?
The antagonist muscle
What are tendons made of?
Dense regular CT
What are aponeuroses made of?
Dense regular CT
How can muscles be attached directly to bone?
Using Sharpey’s fibres. They are dense tufts of collagen that directly extend from the periosteum into the endomysium of attaching muscles.
How is the musculotendinous junction adapted to withstand high impact?
It is not clear-cut and has finger-like projections to decrease the load on the membrane.
How does the last sarcomere of a muscle attach to the tendon?
It has long, projecting actin filaments so it is much larger than the usual sarcomere.
How are actin filaments attached to the tendon?
Integrins link the actin filament to the collagen-rich matrix. One set of integrins link the sarcolemma to the basement membrane and a second set of integrin proteins attach the basement membrane to collagen fibres.
How are tendons protected?
By sesamoid bones, synovial bursae, synovial tendon sheath, synovial membrane.
How do sesamoid bones protect tendons?
They prevent wear and tear as the tendon runs over the joint.
How do synovial bursae protect tendons?
They are fluid-filled sacs between bones, muscles & tendons that provide cushioning & reduce friction.
How do synovial tendon sheath protect tendons?
They protect tendons from abrasion as they move.
How does the synovial membrane protect tendons?
Some cells in the synovum secrete glycosaminoglycans (hyaluronic acid) and glycoproteins (lubricin) that lubricate tendons. There are also phagocytic cells that recycle & remove damaged parts of the synovial membrane.
How do tendons get their blood and nerve supply?
Through the mesotendon, a small gap that allows small blood vessels and single nerve fibres through.
