HUMAN SYSTEMS Muscular System MUSCLE Muscle cells have

HUMAN SYSTEMS: Muscular System

MUSCLE � Muscle cells have contractile proteins � Contract and relax � Help in movement � Heart muscles � Blood vessels � Stomach

TYPES OF MUSCLES � 3 types of muscles 1. Smooth muscles (digestive tract, blood vessels) 2. Cardiac muscle ( heart) 3. Skeletal muscle (attached to bones) � Muscle action could be voluntary or involuntary � Smooth and cardiac muscles are involuntary � Skeletal muscles could be voluntary or involuntary (e. g. blinking of eyes)

TYPES OF MUSCLES

MOVEMENT � Muscles are attached to bones through tendons � When muscle shortens (contracts), the bones are pulled closer � When muscle relaxes, bones move away � Musculoskeletal system - movement

MOVEMENT Muscles work in pairs � Flexor (Biceps) - bends a part of the body � Extensor (Triceps) – straightens a part of the body � Bicep is flexor Tricep is extensor

LEVERS IN HUMAN BODY � � � Levers increase the amount of work done by a force (mechanical advantage) Three types of levers

LEVERS IN HUMAN BODY

MUSCLE AND EXERCISE Resistance exercise (increases muscle strength) � Aerobic exercise (strengthens heart) �

MUSCLE INJURY AND PROBLEMS � Strain – muscle or tendon over stretched or torn � Tendinitis – inflammation of tendons � Anabolic steroids – can be helpful in increasing muscle strength but may be associated with causing other problems � Muscle fatigue and lactic acid