Introduction to Musculoskeletal System 55
1 4
6 D
1 7
7 7
4 7
Neuromuscular Transmission & Mechanisms of Contraction
of Skeletal Muscle
1. 7 5
3 1
nerve 5 2
3 A
6 F
C 0
5 B
E B
5 2
3 0
muscle 65
3 6
7 E
2 E
1..i action potential arrive presynaptic terminal F0
E 0
Ca+
+ channel open F0
E 0
Ca++ rush in (electrochemical
gradient) F 0
E 0
release of Ach from synaptic vesicles into the
synaptic cleft by exocytosis F 0
E 0
diffuse to muscle membrane
(sarcolemma) and bind to its receptors’ α subunits)
receptor= nicotinic receptor F 0
E 0
Na+ and K+ ion channel
open F 0
E 0
produce end plate potential F 0
E 0
summate ~
threshold ~ action potential F0
E 0
action potential is
conducted along t-tubules F0
E 0
activate votage-gated Ca++
channel ,called dihydropyridine receptor ( in t-tubules) F 0
E 0
Ca++ release channel open (in SR, sarcoplasmic
reticulum) F 0
E 0
Ca++ release to sarcoplasm, bind to
troponin, stimulate contraction
2. 15 0
0 B
synaptic vesicle produce 76
8 4
potential 53
E B
miniature potential
3. Synthesis and of Ach:
Choline acetyltransferase
3..i Acetyle coenzyme A + choline --------------------------
> acetylcholine
4. Degradation of Ach:
Acetylcholinesterase
4..i Acetylcholine --------------------------------> acetyle
coenzyme A + choline
5. Properties of Muscle ( 3 5 0
0 B
“easy” F0
E 0
EC)
5..i Excitability
5..ii Extensibility
5..iii Elasticity
5..iv Contractility
6. Organization of skeletal muscle:
6..i Myofibrils F 0
E 0
Muscle fibers F 0
E 0
Muscle
fascicles F 0
E 0
Skeletal muscles
6..ii F0
E 0
Sarcolemma
+endomysium F 0
E 0
Perimysium F 0
E 0
Epimysium
7. 8 0
8 C
8 0
8 9
6 5
3 6
7 E
2 E
6 6
4 2
, A band 9 5
7 7
5 E
A 6
4 E
0 D
8 B
8 A
, Z lines 95
9 3
8 D
D D
9 6
E 2
7 E
2 E
7 7
E D
