Muscular System

Functions of the Muscular System Allows movement Maintains posture Stabilizes joints Gives the body shape Generates heat

2 Categories of Muscles Muscles you can control Voluntary Muscles Involuntary Muscles Muscles you can control Examples: muscles in your arms and legs Muscles you cannot control Examples: heart, stomach, diaphragm

3 Types of Muscle: Skeletal Skeletal: muscles that move bones Striated (striped) Voluntary Tires easily Found in bundles

3 Types of Muscle: Smooth Smooth: muscles that control internal organs No striations Involuntary Makes up internal organs (stomach, intestines) Does not tire

3 Types of Muscle: Cardiac Cardiac: muscle that makes up the heart Striated (striped) Involuntary Does not tire

Remember… What are ligaments? Strong bands of tissue that connect bones to each other at a joint

Tendons Strong bands of tissue that attach a muscle to a bone

Muscular Injuries Sprain: ligaments stretched or torn Strain: muscles stretched or torn Cramp: a muscle involuntarily contracted that will not relax

Fun Fact! Sartorius: longest muscle in the human body

How skeletal muscles work Muscles only contract They pull, they don’t push Skeletal muscles work in pairs Example in the arm: When the biceps contracts, the triceps relaxes When the triceps contracts, the biceps relaxes

Energy Muscles use energy to move When muscles run out of energy = muscle fatigue When true fatigue hits, a muscle cannot be contracted even when stimulated https://youtu.be/LKhkvSRQZYo

2 Types of Exercise Aerobic Exercise (air exercise) Jogging, biking, swimming Makes muscles stronger, more flexible, and more resistant to fatigue Increases metabolism Enlarges heart Lungs become more efficient DOES NOT increase muscle mass much

2 Types of Exercise Anaerobic Exercise (no air exercise) Weightlifting Increases muscle mass Does not increase endurance

Muscle Basics Myofibril: a muscle cell Sarcomere: a tiny contractile unit of a muscle A myofibril is made of many, many sarcomeres

Muscle Basics One sarcomere is made of interlocking actin and myosin