1. MUSCULAR SYSTEM

2. FUNCTIONS OF MUSCLE TISSUE
MOVEMENT
SUPPORT
HEAT PRODUCTION

3. PROPERTIES OF MUSCLES (p. 34 in Exercise Science)
Irritability
Contractibility
Elasticity
Extensibility
Conductivity

4. Types of Muscle Skeletal muscle Smooth muscle Cardiac muscle
The human body is comprised of 324 muscles
Muscle makes up 30-35% (in women) and 42-47% (in men) of body mass.
Three types of muscle:
Skeletal muscle
Smooth muscle
Cardiac muscle

5. TYPES OF MUSCLE TISSUE (p. 20 Exercise Science)
SKELETAL
 attach to bones by tendons
 striated appearance
 voluntary
SMOOTH
 involuntary
 non-striated; dense sheets
CARDIAC
 involuntary; controlled by the autonomic nervous system
 striated

7. ANATOMY OF A SKELETAL MUSCLE
3 layers of connective tissue:
EPIMYSIUM(FASCIA): envelopes the entire muscle; extends beyond the muscle and changes into a tendon
PERIMYSIUM: sheath of connective tissue that binds groups of muscle fibers
ENDOMYSIUM: surrounds each muscle fibers

8. Below the endomysium lies a plasma membrane called the SARCOLEMA which contains the cell’s cytoplasm (sarcoplasm)
Running along the muscle fibers length are thread-like structures called MYOFIBRILS. Within the myofibrils are two proteins: ACTIN (thin) AND MYOSIN (thick)
SACROMERE: repeating structural units of striated muscle containing actin and myosin

9. Sacromeres are separated by Z lines (discs)
Within a sacromere, the darker area, called the A band extends from one end to the other of the thick filaments and includes portions of the thin filaments (actin) where they overlap the thick filaments (myosin)
A lighter, less dense area called the I band contains only thin filaments (actin)
Z discs run through the centre of each I band
A narrow H Zone in the center of each A band contains only thick filaments (myosin)
Cross bridges are the projecting heads of mysoin (will be discussed with the sliding filament theory)

11. Components of skeletal muscle
d) myofibril c) muscle fibre b) muscle fibre bundle a) Muscle belly

13. THE NEUROMUSCULAR SYSTEM
The neuromuscular system is the general term referring to the linkages between the muscular system and the nervous system
Muscle contraction is under control of the CNS, which is made up of nerve cells called neurons
MOTOR UNIT is the term referring to the motor neuron, the axon (pathway) and the muscle fibers it stimulates
The point between the nervous and muscular system is called the NEUROMUSCULAR JUNCTION

14. Excitable cells (neurons and muscle fibers) make contact and communicate at specialized regions called SYNAPSES.
At most synapses, a small gap, called the SYNAPTIC CLEFT, separates the two excitable cells.
Because the cells do not physically touch, the neuron communicates with the muscle cell by releasing a chemical called a NEUROTRANSMITTER

15. Close to its target skeletal muscle fiber, the axon of a motor neuron branches into clusters of bulb-shaped AXON TERMINALS
The distal end of an axon terminal contains many membrane-enclosed sacs called SYNAPTIC VESSICLES which contain neurotransmitter molecules  acetylcholine (ACh)
When a nerve impulse (action potential) reaches the axon terminal, it triggers exocytosis of synaptic vessicles which liberate Ach into synaptic cleft

16. The region of the muscle fiber membrane (sarcolemma) that is adjacent to the axon terminals has what is called the MOTOR END PLATE
There are ACh receptors on the motor end plate
The binding of ACh to its receptor opens a channel that passes small cations, which trigger the action potential that leads to a muscle contraction
In most skeletal muscle fibres, there is only one NMJ located near the midpoint of the fiber  the muscle action potential spreads from the centre toward the ends

17. All-or-none Principle
The all-or-none principle stipulates that, when a motor unit is stimulated to contract, it will do so to its fullest potential
muscle fibre ALWAYS contracts entirely
the more fibres that are recruited determines the strength of the contraction
Every motor unit has a specific threshold that must be reached for such activation to occur

18. Types of Muscle Contraction
Forms and types of muscle contraction
Static
Dynamic

19. Types of Muscle Contraction
Forms and types of muscle contraction
Static
Isometric
Concentric
Eccentric

20. Types of Muscle Contraction
Concentric
Eccentric
Isometric
Static
Isotonic
Auxotonic
Isokinetic
Plyocentric
(overcoming,
accommodating)
(resistive)
Forms and types of muscle contraction
Dynamic

21. High microscope magnification of a single sarcomere within a single myofibril