The muscular system has three main functions - to facilitate movement, maintain posture, and produce heat. There are three types of muscles - skeletal, smooth, and cardiac. Skeletal muscle is striated and voluntary, attaching to bones to enable movement. Cardiac muscle is involuntary and found only in the heart. Smooth muscle is also involuntary, located in organs like the digestive tract. Muscles work in pairs through isotonic or isometric contractions - isotonic involves a change in length while isometric does not. Exercise strengthens muscles, improves tone, encourages good posture, increases size, and reduces risk of atrophy.

1. THE MUSCULAR SYSTEM

4. FUNCTIONS
•Facilitate Movement
•Maintain good posture
•Produce heat
THE MUSCULAR SYSTEM

5. TYPE OF MUSCLES
•Skeletal muscle
•Smooth muscle
•Cardiac muscle

6. SKELETAL MUSCLE
• Striated
• Voluntary control
• Attached to bone

7. CARDIAC MUSCLE
• Involuntary control
• Striated
• Found in the Heart

8. SMOOTH MUSCLE
• Involuntary control
• Found in the digestive tract and blood vessels

9. HOW MUSCLES WORK
• Over 600 muscles in the body.
• Muscles work in pairs to provide movement.
• One muscle contract while the other relaxes.
• Movement is produced when muscles contract.
• Muscles bulge and shorten when contracted and return to their
normal length when they are relaxed.

10. TYPES OF CONTRACTIONS
• Isotonic contractions
• Isometric Contractions

11. ISOTONIC CONTRACTIONS
• Occurs when there is a change in the length of a
muscle causes movement.
Two types
• Concentric contractions: which occurs when a
muscle shortens.
• Eccentric contractions: Which occurs when a
muscle is gradually released and returns to its
original length.

12. ISOMETRIC CONTRACTIONS
• Occurs when there is no change in the length of the muscle and do not
cause movement.
Examples:
• Pushing against a wall.

13. MOVEMENT
• Extensors – muscles that straighten.
• Flexors – muscles that bend a limb at a joint.
• Abductors – muscles that move limbs away
from the midline of the body.
• Adductors – muscles that move limbs
towards the body.

14. EFFECTS OF EXERCISE ON THE
MUSCULAR SYSTEM
• Makes muscles stronger and more efficient.
• Improves muscles tone. (readiness for a muscles to respond)
• Encourages good posture
• Increases muscle size (hypertrophy)
• Reduces the risk of muscle wasting away. (atrophy)

15. HOME WORK
1. What are functions of the Muscular system?
2. List the 3 types of muscles.
3. Identify 4 types of movement.
4. What type of muscle is found in the heart?
5. State 3 effects of exercise of the muscular system.
(15 Marks)