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NEUROMUSCULAR JUNCTION
• CONSISTS OF:
• 1. THE AXONAL TERMINAL OF A
SOMATIC MOTOR NEURON.
• 2. SYNAPTIC CLEFT
• 3. THE MOTOR END PLATE.
NEUROMUSCULAR JUNCTION
NEUROMUSCULAR JUNCTION
NEUROMUSCULAR JUNCTION
NEUROMUSCULAR JUNCTION
• FOR MORE INFORMATION
• SEE MODULE NUMBER 2
• OF THE MUSCULAR CD
ROM.
SLIDING FILAMENT THEORY
SLIDING FILAMENT THEORY
SLIDING FILAMENT THEORY
SLIDING FILAMENT THEORY
SLIDING FILAMENT THEORY
SLIDING FILAMENT THEORY
SLIDING FILAMENT THEORY
• FOR MORE INFORMATION
• SEE MODULE NUMBER 3
• OF THE MUSCULAR CD
ROM.
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.
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.
MUSCLE TWITCH
• THE RESPONSE, A CONTRACTION
• FOLLOWED BY RELAXATION, OF A
• MUSCLE TO A SINGLE BRIEF
• THRESHOLD STIMULUS.
MUSCLE CONTRACTION
• THERE ARE THREE
PHASES:
• 1. LATENT PERIOD
• 2. PERIOD OF
CONTRACTION
• 3. PERIOD OF RELAXATION
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.
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.
PERIOD OF CONTRACTION
• IF THE TENSION BECOMES GREAT
• ENOUGH TO OVERCOME THE
• RESISTANCE (WEIGHT BEING
• MOVED),THE MUSCLE SHORTENS.
PERIOD OF RELAXATION
• THE PERIOD OF RELAXATION
• FOLLOWS THE PERIOD OF
• CONTRACTION, AND IS THE RESULT
• OF Ca2+ ION CONCENTRATION
• RETURNING TO NORMAL LEVELS.
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.
THREE PHASES OF MUSCLE
CONTRACTION
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.
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
TREPPE
• A MUSCLE MUST HAVE
BEEN AT REST FOR A
PERIOD OF TIME.
TREPPE
• ALL PHASES OF
MUSCLE
CONTRACTION
• ARE PRESENT AND
HAVE
• NOT BEEN ALTERED.
TREPPE
• THE STIMULI ARE
EQUIDISTANCE APART.
TREPPE
• THE AMOUNT OF
TENSION IS INCREASING
DUE TO WARMING OF
THE MUSCLE. THE
INCREASE IN
TEMPERATURE CAUSES
ENZYMES TO BE MORE
EFFECTIVE.
TREPPE
• THE AMOUNT OF TENSION
DEVELOPED, WITH THE
SAME STRENGTH OF
STIMULUS, INCREASES
AND THEN REMAINS THE
SAME.
MYOGRAMS
INCOMPLETE TETANI
• IF THE STIMULUS
• STRENGTH IS HELD
• CONSTANT AND THE
• MUSCLE IS
STIMULATED AT AN
• INCREASINGLY
FASTER
• RATE, INCOMPLETE
• TETANI RESULTS.
INCOMPLETE TETANI
• ALL PHASE OF
MUSCLE
CONTRACTION ARE
PRESENT.
• HOWEVER, THE
PERIOD OF
RELAXATION IS
SHORTED.
INCOMPLETE TETANI
• THE STIMULI ARE
OF THE SAME
STRENGTH,
HOWEVER, THEY
ARE BECOMING
CLOSER
TOGETHER.
INCOMPLETE TETANI
• THE AMOUNT OF
TENSION IS
INCREASING DUE
TO AN INCREASE IN
THE NUMBER OF
Ca2+.
COMPLETE TETANUS
• WHEN ALL EVIDENCE
OF
• MUSCLE
• RELAXATION
• DISAPPEARS AND THE
• CONTRACTIONS FUSE
• INTO A SMOOTH,
• SUSTAINED
• CONTRACTION,
• COMPLETE TETANUS
• RESULTS.
COMPLETE TETANUS
• NOTICE THAT THE
PERIOD OF
RELAXATION HAS
• COMPLETELY
• DISAPPEARED.
COMPLETE TETANUS
• THE STIMULI ARE
BEING DELIEVED
ONE AFTER
ANOTHER, WITH NO
TIME ELAPSED.
COMPLETE TETANUS
• THE TENSION HAS
PLATEAUED,
BECAUSE ALL OF
THE
MYOFILAMENTS
ARE FORMING
BONDS. THERE IS A
MAXIMUM OF Ca2+
IN THE MYOFIBRIL.
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.
MUSCLE TONE
• MUSCLE TONE IS THE RESULT
• OF ASYNCHRONOUS MUSCLE
• MOTOR UNIT CONTRACTION.
ENERGY FOR CONTRACTION
•
•
•
•
1.
2.
3.
4.
ATP
CREATINE PHOSPHATE
GLYCOLYSIS
AEROBIC CELLULAR RESPIRATION
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.