NEUROMUSCULAR JUNCTION

1
(No Transcript)
2
NEUROMUSCULAR JUNCTION

• CONSISTS OF
• 1. THE AXONAL TERMINAL OF A SOMATIC MOTOR
  NEURON.
• 2. SYNAPTIC CLEFT
• 3. THE MOTOR END PLATE.

3
NEUROMUSCULAR JUNCTION
4
NEUROMUSCULAR JUNCTION
5
NEUROMUSCULAR JUNCTION
6
NEUROMUSCULAR JUNCTION

• FOR MORE INFORMATION
• SEE MODULE NUMBER 2
• OF THE MUSCULAR CD ROM.

7
SLIDING FILAMENT THEORY
8
SLIDING FILAMENT THEORY
9
SLIDING FILAMENT THEORY
10
SLIDING FILAMENT THEORY
11
SLIDING FILAMENT THEORY
12
SLIDING FILAMENT THEORY
13
SLIDING FILAMENT THEORY

• FOR MORE INFORMATION
• SEE MODULE NUMBER 3
• OF THE MUSCULAR CD ROM.

14
MOTOR UNIT

• A MOTOR UNIT IS A SOMATIC MOTOR NEURON AND ALL
  OF THE MUSCULE CELLS IT INNERVATES.
• THE NUMBER OF MUSCLE FIBERS PER MOTOR UNIT MAY BE
  AS HIGH AS SEVERAL HUNDRED OR A FEW AS FOUR.

15
MOTOR UNIT

• AS A RESULT, STIMULATION OF A
• SINGLE MOTOR UNIT CAUSES A WEAK
• CONTRACTION OF THE
• ENTIRE MUSCLE, OR A NUMBER OF MOTOR UNITS MAY
  CAUSE A STRONG CONTRACTION OF THE ENTIRE MUSCLE.

16
MUSCLE TWITCH

• THE RESPONSE, A CONTRACTION
• FOLLOWED BY RELAXATION, OF A
• MUSCLE TO A SINGLE BRIEF
• THRESHOLD STIMULUS.

17
MUSCLE CONTRACTION

• THERE ARE THREE PHASES
• 1. LATENT PERIOD
• 2. PERIOD OF CONTRACTION
• 3. PERIOD OF RELAXATION

18
LATENT PERIOD

• THE PERIOD TIME, USUALLY A
• FEW MILLISECONDS, AFTER THE
• DECISION TO CONTRACT A SKELETAL
• MUSCLE AS BEEN MADE AND THE
• ACTUAL SHORTING OF THE MUSCLE
• HAS OCCURRED.

19
PERIOD OF CONTRACTION

• THE PERIOD OF CONTRACTION IS
• WHEN CROSS BRIDGES ARE ACTIVE,
• FROM THE ONSET TO THE PEAK OF
• TENSION DEVELOPMENT, AND THE
• MYOGRAM TRACING RISES TO A PEAK.

20
PERIOD OF CONTRACTION

• IF THE TENSION BECOMES GREAT
• ENOUGH TO OVERCOME THE
• RESISTANCE (WEIGHT BEING
• MOVED),THE MUSCLE SHORTENS.

21
PERIOD OF RELAXATION

• THE PERIOD OF RELAXATION
• FOLLOWS THE PERIOD OF
• CONTRACTION, AND IS THE RESULT
• OF Ca2 ION CONCENTRATION
• RETURNING TO NORMAL LEVELS.

22
PERIOD OF RELAXATION

• THE MUSCLE TENSION DECREASES TO
• ZERO AND THE TRACING
• RETURNS TO THE BASELINE. IF THE
• MUSCLE HAS SHORTENED DURING
• CONTRACTION, IT NOW RETURNS TO
• ITS INITIAL LENGTH.

23
THREE PHASES OF MUSCLECONTRACTION
24
GRADED MUSCLE RESPONSES

• MUSCLE CONTRACTION CAN BE GRADED
• IN TWO WAYS
• 1. BY CHANGING THE SPEED OF STIMULATION.
• 2. BY CHANGING THE STRENGTH OF THE STIMULUS.

25
GRADED MUSCLE RESPONSES

• MUSCLE RESPONSES TO AN INCREASE IN THE NUMBER OF
  STIMULI
• 1. TREPPE
• 2. TEMPORAL (WAVE) SUMMATION
• 3. INCOMPLETE TETANI
• 4. COMPLETE TETANI

26
TREPPE

• A MUSCLE MUST HAVE BEEN AT REST FOR A PERIOD OF
  TIME.

27
TREPPE

• ALL PHASES OF MUSCLE CONTRACTION
• ARE PRESENT AND HAVE
• NOT BEEN ALTERED.

28
TREPPE

• THE STIMULI ARE EQUIDISTANCE APART.

29
TREPPE

• THE AMOUNT OF TENSION IS INCREASING DUE TO
  WARMING OF THE MUSCLE. THE INCREASE IN
  TEMPERATURE CAUSES ENZYMES TO BE MORE EFFECTIVE.

30
TREPPE

• THE AMOUNT OF TENSION DEVELOPED, WITH THE SAME
  STRENGTH OF STIMULUS, INCREASES AND THEN REMAINS
  THE SAME.

31
MYOGRAMS
32
INCOMPLETE TETANI

• IF THE STIMULUS
• STRENGTH IS HELD
• CONSTANT AND THE
• MUSCLE IS STIMULATED AT AN
• INCREASINGLY FASTER
• RATE, INCOMPLETE
• TETANI RESULTS.

33
INCOMPLETE TETANI

• ALL PHASE OF MUSCLE CONTRACTION ARE PRESENT.
• HOWEVER, THE PERIOD OF RELAXATION IS SHORTED.

34
INCOMPLETE TETANI

• THE STIMULI ARE OF THE SAME STRENGTH, HOWEVER,
  THEY ARE BECOMING CLOSER TOGETHER.

35
INCOMPLETE TETANI

• THE AMOUNT OF TENSION IS INCREASING DUE TO AN
  INCREASE IN THE NUMBER OF Ca2.

36
COMPLETE TETANUS

• WHEN ALL EVIDENCE OF
• MUSCLE
• RELAXATION
• DISAPPEARS AND THE
• CONTRACTIONS FUSE
• INTO A SMOOTH,
• SUSTAINED
• CONTRACTION,
• COMPLETE TETANUS
• RESULTS.

37
COMPLETE TETANUS

• NOTICE THAT THE PERIOD OF RELAXATION HAS
• COMPLETELY
• DISAPPEARED.

38
COMPLETE TETANUS

• THE STIMULI ARE BEING DELIEVED ONE AFTER
  ANOTHER, WITH NO TIME ELAPSED.

39
COMPLETE TETANUS

• THE TENSION HAS PLATEAUED, BECAUSE ALL OF THE
  MYOFILAMENTS ARE FORMING BONDS. THERE IS A
  MAXIMUM OF Ca2 IN THE MYOFIBRIL.

40
MUSCLE TONE

• MUSCLE TONE KEEPS THE MUSCLES
• OF THE BODY FIRM, HEALTHY, AND
• READY TO RESPOND TO STIMULI.
• IN ADDITION, MUSCLE TONE HELPS
• STABLIZE JOINTS AND MAINTAIN
• POSTURE.

41
MUSCLE TONE

• MUSCLE TONE IS THE RESULT
• OF ASYNCHRONOUS MUSCLE
• MOTOR UNIT CONTRACTION.

42
ENERGY FOR CONTRACTION

• 1. ATP
• 2. CREATINE PHOSPHATE
• 3. GLYCOLYSIS
• 4. AEROBIC CELLULAR RESPIRATION

43
MUSCLE FATIGUE

• TRUE MUSCLE FATIGUE IS THE
• RESULT OF BUILD UP OF ACIDIC
• COMPOUNDS, MAINLY LACTIC ACID,
• A REDUCTION IN THE AMOUNT OF ATP, AND ELECTROLYTE
  IMBALANCES.