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 Smooth muscles (digestive tract, blood vessels) Cardiac muscle ( heart) 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 Lever 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