1. Muscular System

2. My muscles are important because they…
Hold my organs in place
Hold my bones together so that I can move
Help me chew my food
Open and close my eyelids
Pump my blood
Allow me to run and play
Help me to smile!

3. What are muscles made of?
Stretchy, elastic cells and fibers
What else is stretchy like a muscle?

4. Did you know that ?
more than 50% of body weight is muscle !
more then 60% of your body heat is generated by muscle contractions – maintain body temperature
-You have over 650 muscles
-It takes more muscles to frown then it does to smile

5. Three types of muscle
Skeletal
Cardiac
Smooth

6. Classification of muscle
Voluntary – choice to contract
Involuntary – contracts automatically
Skeletal
Cardiac
Smooth
Limbs
Heart
Viscera
organs
Striated- look striped
Non-striated – not striped
Note: Control, Location and Structure

7. Skeletal muscle Large muscles Maintain posture Facilitate locomotion –
PULL ON BONES
Move jointed bones
Found in antagonistic pairs
Attached to bones by tendons

8. Structure of skeletal muscle
Each cell (fibre) is long and cylindrical
Muscle fibres are multi-nucleated = more then one nucleus
Have large number of mitochondria = organelle that produces ATP (energy)

9. Skeletal muscle - Summary
Voluntary movement of skeletal parts
Spans joints and attached to skeleton
Multi-nucleated, striated, cylindrical fibres

10. Cardiac muscle Main muscle of heart Pumping mass of heart
Critical To Life
Heart muscle cells behave as one unit
Heart always contracts to it’s full extent

11. Structure of Cardiac Muscle Cells
(fibres) are short, branched and interconnected
striated & multi-nucleated
Adjacent cells joined via electrical synapses (gap junctions)

12. Cardiac muscle - Summary
Found in the heart
Involuntary rhythmic contraction
Branched, striated fibre with single nucleus and intercalated discs

13. Smooth muscle Lines walls of viscera (organs)
Found in longitudinal or circular arrangement
Alternating contractions of muscles in the digestive system leads to peristalsis

14. Structure of Smooth Muscle Cells
uni-nucleated (one nucleus) cells
Striations not observed
Actin and myosin filaments are present
Ratio of thin-to-thick filaments is 16:1 (in striated muscle this is 2:1)
Myosin filaments are attached to dense bodies at the end of each cell

15. Smooth muscle - Summary
Found in walls of hollow internal organs
Involuntary movement of internal organs
Elongated, spindle shaped fibre with single nucleus

16. Muscle Control Type of muscle Nervous control Type of control Example
Skeletal
Controlled by CNS
Voluntary
Lifting a glass
Skeletal
Cardiac
Regulated by ANS
Involuntary
Heart beating
Smooth
Controlled by ANS
Involuntary
Peristalsis