msd for pspd 2015

MUSCLE CONTRACTIONTRIGGER OF MOVEMENT

I Putu Gede ADIATMIKADept. of Physiology Faculty of Medicine – Udayana University

TEXT BOOK

TEXTBOOK OF MEDICAL PHYSIOLOGY

A.C. GUYTON

Musculoskeletal disorders

ATROPHYHIPERTROPHYCRAMPSEIZUREPARALIZEETC

HUMANMOVEMENT ?

What is the contribution of

Bone and joint

muscles

nerves

Human Movement ?

All of the systems must be in good condition

Stimulated by a stimulus from external or internal environment

Transferred as action potential by the nerves

Action potential is forwarded to the muscles through neuromuscular junction

Action potential within the muscles excite muscle contraction

Human movementRESPONSE TO ENVIRONMENT CHANGES

MOVEMEN

TSOMATIC

AUTONOMI

C

REFLEX

SYSTEM

NERVES

NEUROMUSCU

LAR JUNCTI

ON

MUSCLES

Action potential pathway

1. Central nerve system (CNS)

2. Peripheral nerve system (PNS)

Axon – skeletal muscles Somatic motor

neurons axon Neuromuscular

junction Muscle :

Skeletal muscles

Smooth muscles

Cardiac muscles

axon

Somatic neuron

neuromuscular junction

muscles

MEMBRANE POTENTIAL AND ACTION POTENTIAL

Cases If someone get an order to lift the upper

limb, what happen in the neuromuscular ?

Your hand touch the hot iron, what happen to your hand ? Why did happen ?

Neuron

Functional unit of nerves Surrounded by extracellular fluid Neuron has intracellular fluid

Membrane cell separated extra and intra cellular fluid membrane is permeable for ion Extra and intra cellular ion can pass the

membrane through the specific way

Neuron

Important ion for membrane potential : Sodium (Na) Potassium (K) Chloride (Cl)

Cause : a different electric potential between extra and intra cellular

Distribution of ION

IonIntra

cellular

Extra cellula

rResting condition

SodiumPotassiu

mChloride

121553,8

1454

120

- Permeability of K+ > Na+

- Resting membrane potential (-85 mV)

Bioelectric of extra and intra cellular Extra cellular : positive ( +++++++++++ ) Intra cellular : negative ( ----------------- )


Ion movement


Ion channel

Action Potential Cycle

duration : 2 – 4 msec. Action potential cycle consist of :

Depolarization Repolarization Hyperpolarization Refracter period: no response to stimulus

▪ Absolute refracter no action potential anymore▪ Relative refracter action potential occurred by

more adequate stimulus


Action potential

All or Nothing Principle

Action potential will occur if got optimum stimulation and will not occur if the stimulation is not enough MEMBRANE THRESHOLD

Action potential depend on : Stimulation intensity Point of membrane threshold Ion concentration

Which one is the action potential occurred ? WHY ?

Action potential conduction

Conduction on axon

Depend on type of axon : With myelin sheath Without myelin sheath

Axon surrounded by myelin sheath : Thicker than axon insulator Have node of Ranvier Wrapped by Schwann cells multiple

layer spingomyelin

Myelin sheath

- Increasing action potential conduction

- Conduction was done by jump at node of Ranvier (saltatory conduction)

Action potential conduction on axon

Without myelin sheath : Spread Slow

With myelin sheath : Jump within node of Ranvier saltatory

conduction Faster ( 50 x )

Benefits of saltatory conduction : Faster Save energy save space Suitable for high frequency impulse

SKELETAL MUSCLES CONTRACTION

Cases If someone get an order to lift the upper

limb, what process it occur within skeletal muscles ?

Two student sit on a different chair and in the some posture. On the next 30 minutes, one of them will change their posture cause of pain. Explain what did cause it ?

Cases

After run for marathon race, one runner felt down and scream that his leg cramped. Explain, why did happen ?

Muscle contraction

Initiated by action potential from terminal axon

MUSCLE TWITCH consist of : Contraction Relaxation

MUSCLE TWITCH

Skeletal Muscle

SarcolemmaSarcoplasmic

Reticulum▪ T-tubule▪ Terminal

cisternaeMyofilament▪ Actin▪ Myosin

Mitochondria

Components of muscle contraction

Actin Myosin Calcium Ion Troponin Tropomiosin ATP

Muscle contraction process

Calcium released from

cisternae

Calcium attach to TROPONIN

TROPOMYOSIN detach

from ACTINMyosin attach

to Actins

POWER STROKE of

MYOSIN

SLIDING MECHANISM (Contraction)

Calcium pumped back to Cisternae

Myosin actins detached

Actin back to initial position (Relaxation)

The role of Troponin Tropomyosin Complex

To regulate contraction and relaxation regularly

In turn with myosin when attach to actins

TYPE OF MUSCLES CONTRACTION

Based on endurance : Rapid muscles CEPAT (FAST TWITCH) Slow muscle (SLOW TWITCH)

Based on change of length : Isometric Isotonic

Muscle endurance

Muscle type affect to its endurance Red muscles – SLOW TWITCH

Slow contraction Long time Longer endurance Important for body posture

White muscles – FAST TWITCH Rapid contraction Short time Easy to fatigue – shorter endurance Important for trained movement

TYPE of MUSCLE CONTRACTION

Isotonic muscle shortening, muscle tone constant Ex : lifting

Isometric muscle length constant, muscle tone increased Ex : push the wall

Muscle change

ATROPHY : no action potential from the nerve Break of axon No activity of muscle : DISUSE ATROPHY

HYPERTROPHY : regular activity with maximal load (in sport) : Muscle cell getting bigger more ACTIN and

MYOSIN Circulation increased oxygen and food supply

increased

Staircase phenomenon

Repetitive and faster stimulation can change the contraction relaxation type

Type of contraction relaxation : Treppe Summation Incomplete tetanus Complete tetanus

Cause : Muscle temperature increased warming up Cumulative of metabolism waste product

STAIRCASE PHENOMENON

Energy resources

Energy resources 1st : PHOSPHOCREATINE 2nd : GLYCOGEN 3rd : OXYDATIVE METABOLISM

Waste product of metabolism 1st and 2nd : LACTIC ACID 3rd :▪ Carbondioxyde▪ Water

ENERGY METABOLISMFood substances

Oxygen (+) Oxygen (-)

Carbonic acid

Lactic acid

CO2 and H2O

ATP

AEROBIC ANAEROBIC

EXCITATION CONTRACTION OF SKELETAL MUSCLES

Cases

After got fever, the child couldn’t move the lower limb. He suspect to suffer from poliomyelitis. Where did the source of damage ? Why ?

MOTOR UNIT

UNIT OF SKELETAL MUSCLES AND ITS NERVES Important for excitation contraction

process Number of motor unit is depend on the

load of each muscles Affect to muscle tones

Motor unit

NEUROMUSCULAR JUNCTION

Axon terminal Vesicle

acetylcholine Synaptic cleft

Acetylcholine esterase

Motor end plate ACh receptor

ACTION POTENTION IN SKELETAL MUSCLE

Similar to nerve process

Result : release of Ca++ into myofibrils

Effect : muscle contraction

MOTOR END PLATE

SARKOLEMA

T – TUBULE

TERMINAL CISTERNAE

EXCITATION CONTRACTION

EXCITATION CONTRACTION OF SMOOTH MUSCLES

Action potential of smooth muscles

Easy to spread within muscles Cause : muscle interaction is very

thigh

Ion calcium movement into the cell is easier than sodium

Smoot muscle contraction process

Theory : Irregular actin myosin arrangement Extra cell and intracellular fibers contraction

Activator : Ca++ extra cell (caveola) and ATP Characteristic of contraction TONIC

CONTRACTION Longer and slower Dragging effect

STRONG CONTRACTION WITH MINIMAL ENERGY REQUIREMENT

SLIDING FILAMENT OF SMOTH MUSCLES

COMPARISON BETWEEN SKELETAL MUSCLES AND SMOOTH MUSCLES

1. Cross bridge cycle is slower2. Energy requirement to maintain

contraction is minimum3. Slower of initial contraction and

relaxation4. Strength of contraction is stronger5. Latch mechanism6. Stress-relaxation

Type of smooth muscles contraction

Cross sliding mechanism

Contraction cause change of cell to globular type

Drugs that affect to NEUROMUSCULAR JUNCTION

ACh-like action Drugs act as some as ACh Can’t be destroyed by ACh-esterase Cause local depolarization muscle spasm

Exp : Metacholine Carbachol Nicotine

Drug that affect to NEUROMUSCULAR JUNCTION

Inhibited ACh-esterase ACh can’t be separated

accumulation continued stimulation muscle spasm

Exp : Neostigmine Physostigmine Diisopropyl fluorophosphates

FATIGUE

Continued excitation can cause fatigue Classification :

Peripheral (Muscles) oxygen and energy decreased

Central (Nerve) impulse disturbation within CNS

Caused : activity Location :

Neuromuscular junction Nerve cell at cerebral cortex

Benefits : as body defense mechanism

FATIGUE

Prevention: Heavy workload short time Long time mild workload Avoid unnecessary movement Sufficient foodstuffs and oxygen

resources Sufficient rest Avoid to use drugs

THANK YOU

msd for pspd 2015

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