information

1. NEUROMUSCULARNEUROMUSCULAR
TRANSMISSIONTRANSMISSION
Secretion of acetylcholine, EffectSecretion of acetylcholine, Effect
of acetylcholine on muscle fiberof acetylcholine on muscle fiber

2. Secretion of acetylcholine on nerveSecretion of acetylcholine on nerve
terminalsterminals
• Nerve impulse reaches at neuromuscular
junction
• No. of released synaptic vesicles are 125
• NEURAL MEMBRANE
• On inside of neural membrane linear dense bars
• To each side of dense bars, protein particles are
present
• Voltage gated calcium channels
• Action potential

4. PRESYNAPTIC NERVE TERMINALPRESYNAPTIC NERVE TERMINAL
OR NEURAL MEMBRANEOR NEURAL MEMBRANE
• Channels opening
• Permission of calcium ions for diffusion
• From synaptic space of interior of terminal
• Calcium ions exert infuence on
acetylcholine vesicles
• Carrying and pushing them towards neural
membrane
• Fuse with neural membrane
• Exocytosis

6. EFFCTIVE STIMULUSEFFCTIVE STIMULUS
• Effective stimulus for causing
acetylcholine release is calcium ions
• Ach is emptied

7. Effect of acetylcholine onEffect of acetylcholine on
postsynaptic muscle fiberpostsynaptic muscle fiber
Sub-neural cleft
• Acetylcholine receptors
• Acetylcholine gated ion channels
• Location is at the mouth of sub-neural cleft
• Lying immediately below the dense bars
• Lying side by side in a circle
• Tubular channels

8. ACECTYLCHOLINE RECEPTORACECTYLCHOLINE RECEPTOR
• A Protein complex
• Five sub-unit proteins
• Two alpha, one beta, one
delta, one gamma
• Channel remain
constricted
• Two acetylcholine
molecules attach with two
alpha subunit

9. OPENINGOF CHANNELOPENINGOF CHANNEL
• Conformational change
• Opening of channels
• Opened acetylcholine channel has
diameter 0.65nanometer
• Permission to ions
• Na, K and Ca
• Negative ions cannot move such as Cl

11. OPENIN OF CHANNELOPENIN OF CHANNEL
• Strong negative charges in the mouth of
channel
• Repel the negative ions

12. Why Na ion rush insideWhy Na ion rush inside
• Why large amount of Na ions rush inside
• Two positive ions in large concentration
• Sodium and potassium ion
• Sodium ion in extracellular fluid
• Potassium ion in intracellular fluid

13. ACTION POTNTIALACTION POTNTIAL
Negative potential inside the membrane
• -80-------------90mv
• Pull sodium ions to inside of fiber
• Prevention of efflux of potassium ions

14. END PLATE POTENTIALEND PLATE POTENTIAL
• Large no of Na ions move inside of
muscle fiber
• Carrying with them large no of positive
ions
• Local positive potential change
• End plate potential
• Creates an action potential
• Initiation of action potential

15. ONSET OF ACTIONONSET OF ACTION
POTENTIALPOTENTIAL
• Action potential spreads along the muscle
fiber
• Cause muscle contraction

16. DESTRUCTION OFDESTRUCTION OF
ACETYLCHOLINEACETYLCHOLINE
• Ach is released in synaptic space
• Continues to activate the Ach receptor
• Destruction by two means
• Ach is destroyed by the action of
acetylcholinesterase
• Attached to spongy layer of fine
connective tissue
• Fill the synaptic pace between presynaptic
and postsynaptic terminal

17. DESTRUCTION OFDESTRUCTION OF
ACETYLCHOLINEACETYLCHOLINE
• Small amount of acetylcholine diffuses out
• Of the synaptic space
• No longer available
• To act on muscle fiber membrane
• Short time for ach stay is fewmillisec
• Sufficient to excite the membrane

18. END PLATE POTENTIALEND PLATE POTENTIAL
• Sudden insurgence of sodium ions
• Increase local potential
• Positive potential
• 50------------75mv
• Creating a local potential
• Sudden increase in nerve membrane
potential
• More than 20---------30mv

19. EXCITATION OF SKELETALEXCITATION OF SKELETAL
MUSCLE FIBERMUSCLE FIBER
• Sufficient to initiate more sodium channels
opening
• Initiation of action potential