1. The Musculoskeletal System Support, Protection, Movement and Locomotion

2. Characteristics of muscle tissue
Excitability – receive and respond to stimuli
Contractility – shorten and thicken
Extensibility – stretch and extend
Elasticity – return to original shape after contraction or extension

3. Functions Motion Maintenance of posture Heat production
Protection of internal organs

4. Origin of muscle tissue
Forms from the mesoderm germ layer
Triploblasts simplest: flatworms
Segmentation  annelids, arthropods, vertebrates

5. Types of muscle tissue Striated Smooth Invertebrate muscles
Skeletal
Attached to bones
Striated and voluntary
Cardiac
Heart wall
Highly branched
Striated and involuntary
Smooth
Walls of hollow internal structures
Nonstriated and involuntary
Striated
Voluntary movements
Longitudinal or circular in shape
Smooth
Involuntary movements
Invertebrate muscles
Vertebrate muscles

6. Muscle action Motion produced by action of muscles on bones  levers
Tendons  attach muscles to bones (e.g. Achilles tendon)
1 fixed point of attachment (origin) and 1 moving point of attachment (insertion)
Fascia  sheets that cover muscles
Muscles work in antagonistic or opposing pairs

7. Muscle movement Adduction Abduction Flexion Extension Rotation
Sphincters
Levators
Depressors
Supination
Pronation

8. Human skeletal muscle groups

9. Anatomy of skeletal muscles
epimysium
tendon
perimysium
Muscle Fascicle
Surrounded by perimysium
endomysium
Skeletal muscle
Skeletal muscle fiber (cell)
Surrounded by epimysium
Surrounded by endomysium

10. Organization of skeletal muscles

11. Overview of the Sliding Filament Theory
The muscle fiber is stimulated.
Ca2+ ions are released.
Thin filaments move to middle of sarcomere.
Muscle fiber contracts.
Muscle tension increases.

15. Muscle twitch
Cycle of contraction and relaxation generated from one stimulus
All or none response of muscle fibers
Force Summation
Increasing # and size of fibers contracting
Increasing frequency at which action potentials are sent to muscle fibers

16. Slow and Fast Twitch Fibers
Slow Twitch
More ATP from aerobic respiration
Continuous extended contractions over time
More myoglobin
Fast Twitch
Anaerobic metabolism (creatine phosphate and lactic acid fermentation)
Short bursts of speed
Fatigue quickly

17. Muscle and exercise

19. Cramps Painful sensations caused by contraction/
overshortening of muscles
Causes
Hyperflexion
Inadequate oxygenation
Changes in temperature
Dehydration
Low amount of electrolytes in blood
Treatment
Correct breathing
Increasing intake of water and electrolytes