1. The Skeletal and Muscle System

2. Overview of Muscles Types of Muscles :
Voluntary or Skeletal Muscles-Muscles attached to the skeleton allow body movement and are under conscious control by the brain
Involuntary Muscles-They are not under conscious control. For examples : the heart muscle .
How muscles work:
-When a muscle is relaxed the muscle appears long and thin.
-When a muscle is contracted the muscle appears short and thick.
-Muscle work together in Antagonistic pairs (muscles that opposes the action of another) Ex: the biceps muscle at the front of your upper arm contracts to lift the forearm while the triceps muscle at the back of your upper arm relaxes.

3. Flexor and Extensor :
Flexor : is the muscle in each pair which contracts to bend the joint Ex. Biceps
Extensor: is the muscle in each pair which contrast to straighten the joint Ex. Triceps
Sources of Energy :
-Muscles uses energy from glucose for contraction. ( Respiration )
- Aerobic Respiration : is where muscles are receiving a flow of oxygen and glucose to the muscles
-Anaerobic Respiration: When the body does rapid strenuous activity
- Small amounts of Energy (rich ATP) are made when very little oxygen is available for a short time.
Three types of Muscles :
-Cardiac
-Skeleton
-Smooth

4. Muscular Growth and Repair
Muscle cells become damaged when they're forced to take on stress beyond their normal level.
This leads to the appearance of larger muscles and can develop strength as well.
When trauma begins to tear down portions of the muscle, it must be repaired before growth can occur and to avoid further injury.
Having stronger muscles helps in avoiding some injuries.
Muscle growth and repair are meant to keep the muscle cells throughout the body healthy.

5. Continued.....
Muscle growth comes about because of hypertrophy or hyperplasia
Hypertrophy: Sarcomere & Sarcoplasmic
Sarcomere hypertrophy allows growth of the muscle contractile machinery, composed of actin and myosin filaments, which make up about 80% of each muscle cell.
Sarcoplasmic hypertrophy, on the other hand, allows growth of the ATP-producing cell components that can provide energy to the muscle; these components make up the other 20% of muscle cells.
Muscles grow as the human grows, which is normal growth. But muscle growth can be increased by exercises

7. Cardiac Muscles Functions :
Cardiac muscle - is an involuntary muscle that its action generates within the heart to allow contraction to the entire muscle .
-The striated and involuntary muscle of the vertebrate heart
-Consists of single heart muscle cells (cardiomyocytes) that have to be connected by intercalated discs to work as a functional organ
-Found in the walls and in a muscular tissue of the heart (myocardium)
-Cells that comprises cardiac muscle are mononuclear
- Cardiac muscle cells resembles Skeletal muscle in which both are Striated and each cell contains sarcomeres with sliding filaments of actin and myosin.
-Cardiac Muscles cells like the body rely on blood supply to deliver oxygen and nutrients also removes waste products (Carbon dioxide )
-Dependent on cellular respiration

8. Cardiac Muscles Damage:
- When anything interrupts the flow of oxygenated blood to the heart
-Any form of blockage can cause a heart attack and leads to damage or death

9. Smooth Muscles
-Smooth muscles do not depend on motor neurons to be stimulated
-Smooth muscles lacks calcium
-They are a single-unit variety that is either the whole muscle contracts or the whole muscle relaxes
-Smooth muscle lines blood vessels the urinary-tract and digestive.
-Multi-unit smooth muscle , occurs in the trachea , (the large elastic arteries and iris of the eye

10. Skeletal Muscle
Skeletal muscles are made of Muscle fibers (long tube like fibrous proteins) that slide across each other when expanding and contracting.
Skeletal muscles are controlled by the somatic nervous system, which means its voluntary movements
When you think about moving, your brain sends a signal to contract your muscle which pulls on the tendon which pulls on the bone
Skeletal muscles tire a lot faster than Cardiac muscles because you won't die if you stop moving your skeletal muscles

11. Muscle Contractions -Brain sends signal to motor neurons to move.
-MYOSIN FILAMENTS and MYOSIN HEADS attach to the ACTIN FILAMENTS
-MYOSIN HEADS (still attached to ACTIN FILAMENTS) moves and flexes back and forth
-When MYOSIN HEADS flex it brings the ACTIN FILAMENTS together, and brings the muscle tissue together
-Use ATP to release MYOSIN HEADS form ACTIN FILAMENTS
_rigga mortis

12. ANIMATIONS

13. Skeletal System
Hinge joints: are found at the elbow and knee. It only allows movement in one direction.
Ball and Socket joints: are found at the shoulder and hip. It allows movement in three different directions

14. Skeletal System
Tendons: a connective tissue attaching muscle to bone when a muscle connects to move a joint.The tendon pulls on the bone.
Ligaments: they are bands that connect bones to other bones at the joint.They are elasticated to allow movement, but strong enough to withstand movement outside its normal range.
Cartilage: Soft cushioning substance that covers the ends of bones. It acts as a shock absorber and reduces rubbing on the bones.