-
characteristics of muscle
- -contractibility
- -muscle tissue is derived from mesoderm
- -classifications:
- -skeletal
- -cardiac
- -smooth
-
skeletal muscle
- -has striations
- -fibers
- -multinuclei
- -has sarcoplasmic reticulum
- -voluntary
- -located in muscles of arms, legs, ect
-
cardiac muscle
- -has striations
- -cells
- -1-2 nuclei
- -has sarcoplasmic reticulum
- -involuntary
- -spontaneous
- -found in heart
-
smooth muscle
- -no striations or cells
- -1 nuclei
- -involuntary
- -spontaneous
- -found in internal organs
-
function of skeletal muscle
- –SUPPORT
- –MOVEMENT
- –HOMEOSTASIS
- –PROTECTION
- –RESPIRATION
- –CIRCULATION
-
Muscle CT
(from largest to smallest)
- 5.Muscle ~ Epimysium
- 4.Fascicle ~ Perimysium
- 3.Fiber ~ Endomysium
- 2.Fibril (intracellular0
- 1.Filament (intracellular)
-
sarcomere
basic contractile unit
-
striations
-due to overlap of actin and myosin
-bands change in length during stretch & relaxation
-
Sarcomere: Z – Z
I-band – only actin
A-band – length of mysin
H-band – only myosin
-
- Myofibrils->
- Myofilaments
- •Actin (thin)
- -troponin
- -tropomyosin
- •Myosin (thick)
-
•Membrane systems:
•Sarcolemma
•Transverse (“T”) Tubule
•Sarcoplasmic Reticulum (SR)
•Triads
-
•Sarcoplasmic Reticulum
–Ca++ sequestration
-
Neuromuscular Junction
- Nerve terminal
- • Synaptic vesicles
- • Neurotransmitter
- -(acetylcholine)
- Motor end plate:
- Synaptic clefts
- Acetylcholinesterase
- Acetylcholine receptors
-
Mesenchyme - Myoblasts - Myotubes - Myofibers - Reserve Myoblasts - Satellite Cells
-
•Individual cells can divide
•Multi-nucleate fibers cannot
•Satellite cells can divide
•DNA is added to multi-nucleate muscle fibers by fusion of satellite cells
RAHHHHHHH =[)
-
smooth muscle
- -single cells, no striations
- -contraction:
- -actin, myosin present
- -contractile filaments anchored by "dense bodies" (act similar to z-bands)
- -spontaneuosly active
- -connected by gap juntions
- -located in internal organs, blood vessels
- -often arranged in logitudinal and circular groupings
-
cardiac muscle
- -striated
- -single cells
- -central nuclei
- -branching fibers
- -spontaneously active
- -intercalated discs
- -gap juntions
- -tight junctions
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