1. Muscles

2. Function
a. Muscles contract or shorten
b. Provide motility
c. Move substances through body- heart, blood vessels & digestion

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

4. Types of muscles 1. Skeletal - Attached to bone a. Voluntary
b. Striated
c. Multinuclei
d. Bundled cells
e. Movement of body parts

5. 2. Smooth - internal organs
a. Involuntary
b. Not striated
c. Only 1 nucleus per cell
d. Regulates other systems

6. Ex. Peristalsis moves food through digestive system

7. 3. Cardiac - found only in heart
a. Striated
b. Involuntary
c. Can contract without nervous stimluation

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

9. Movement
1. Occurs when shortened
2. Work In pairs:
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
Myosin
Actin
Relaxed
Contracted

13. Caring for your muscles
1. Stretch before & after exercise; lactic acid can build up and cause soreness & possible injury
2. Without adequate exercise, muscles will atrophy.

14. Caring for your muscles
3. Without proper nutrition, muscles may spasm or become strained