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Histologically identifying characteristics of 3 types of muscle
- 1) Skeletal:
- multinucleate; obvious striations
- 2) Cardiac:
- less obviously striated; intercalated discs
- 3) Smooth Muscle:
- dense bodies; kind of look like a pack of ghosts
What are the striations on skeletal muscles?
The dark bands (A-bands) are where the actin and myosin overlap one another
The light bands (I bands) are where there is only actin (off of the z lines)
What are the three types of CT associated with skeletal muscle?
1) Endomysium: Surrounds a muscle fibre (cell)
2) Perimysium: Surrounds a muscle fasicle
3) Surrounds muscle
All are connected with one another and extend beyond the muscle to the tendon. Makes tendons very deeply rooted.
What are the differences between red, white, and intermediate muscle fibres.
Red (type I): good for posturing, LOTS of myoglobin, many mitochondria, mostly oxidative phosphor., slow twitch
White (Type IIa, intermediate): 400m race, oxidative and anaerobic, the most mitochondria, fast twitch, intermediate
White (Type IIb): 10s sprint, anaerobic, low myoglobin, lots of glycogen, easily fatigable, fast twitch
What is the function and location of satellite cells in muscle? What happens if they run out?
They are myogenic stem cells located between basal lamina and plasma membrane. They either become new muscle nuclei or mother satellite cells. When depleted: patholigic conditions like muscular dystophy.
Skeletal muscle location and function.
Location: attached to skeleton; some visceral (e.g. tongue, diaphram, esophagus)
Function: Locomotion, heat, breathing, swallowing,
Describe the blood and nervous supply to muscle.
- Main artery is deep (with V and N) -> branch arteries go along perimysium -> these branch arteries send capillaries into endomysium (capp.'s are usually parallel to fibre)
Nerve: axon branches and supplies many fibres at the NMJs. One branch for each fibre.
Label Golgi tendon organ
- Uses the stretch of collagen fibres instead of intrafusal muscle
How do muscles regenerate?
following injury, the satellite cells start to rapidly divide and differentiate into new muscle cells.
Label the cardiac muscle.
Describe intercalated dics
- -Link the sarcolemmae of adjacent cells
- -Allow AP to spread from cell to cell
- -gap junctions
Where are Purkinje fibres found in the heart?
Close to the endocardium and substantially larger than the surrounding cardiac muscle cells.
Label the cross section of smooth muscle
Where is smooth muscle found and what is it function?
- -artery walls
- -ureter, intestines, uterus
- -regulates diameter
- -propels solids and liquids