1. Muscles

2. Function
a. Muscles Contract-shorten and Relax-lengthen
b. Provide mobility
c. Move substances through body- heart, blood vessels & digestion

3. FUNCTIONS (cont.)
d. Muscle tone - maintains posture & keeps organs in place
e. Muscles generate heat when worked

4. Types of muscles 1. Skeletal - enables movement of body parts
a. Voluntary
b. Striated

5. 2. Smooth - internal organs
a. Involuntary
b. Not striated

6. Ex. Peristalsis moves food through digestive system

7. 3. Cardiac - found only in heart
a. Striated
b. Involuntary

8. d. Contracts & relaxes continuously
Does not fatigue!

9. Movement 1. Occurs when shortened 2. Work In pairs: that flexes bone
a. Flexor - muscle
that flexes bone
b. Extensor muscle that extends bone

10. 3. Tendons hold muscle to bone

11. Sliding Filament Theory
Muscles made of 2 filaments (actin & myosin) that slide over one another when they contract.

12. Sliding Filament Theory
Actin
Myosin
Relaxed
Contracted

13. Caring for your muscles 101:
1. Stretch before & after exercise; otherwise, lactic acid will build up and cause soreness & possible injury
2. Without adequate exercise, muscles will atrophy.
3. Without proper nutrition, muscles may spasm or become strained