1. Muslces
Group 4

3. Classification Agonist: prime mover Antagonist: reverses agonist
Synergist: prevents rotation
Fixator: stabilizes the origin of the prime mover

4. Naming (LADSNOR!) Direction of the muscle fibers
Ex) transverse, rectus, oblique
Relative size of muscles
Ex) major, minor
Location
Number and location of origin
Shape
Action of the muscle
Ex) extensor, flexor

5. Origin and Insertion
Origin: immovable end
Insertion: movable end

6. Characteristics Muscle cells are elongated
Contractions are due to the movement of microfilaments

7. Structure (skeletal muscle)

8. Structure (cont.) From outermost to innermost
Muscle>Fascicles>Muscle fibers>Myofibril>Thick and thin filaments
Fascia>Epimysium>Perimysium>Endomysium

9. Tissue layers of a skeletal muscle
Fascia: covering the whole muscle
Epimysium: lies beneath the fascia
Perimysium: separates cells of fascicle
Endomysium: separates individual muscle fibers

10. Fascicle Collection of muscle fibers
Covered by blood vessels and axon of motor neurons
Each muscle fibers is separated by endomysium
It is surrounded by sarcolemma
Contains nucleus and sarcoplasmic reticulum
Each muscle fibers is composed of myofibril

11. Myofibril & Sarcomere

12. Sarcomere
It is a repeating pattern formed by striations

13. Sarcomere (cont.)
Troponin: protein that works with tropomyosin to block muscle contraction until calcium ions are present
Transverse tubule: set of membranous channels that contain extracellular fluid

14. Smooth muscle
It is shorter than skeletal muscle, and has single centrally located nuclei
It lacks troponin
It alternates between a state of relaxation and contraction

15. Cardiac muscle Composed of striated cells, containing a single nucleus
It has a well developed sarcoplasmic reticulum
Its transverse tubule is larger than skeletal muscle’s

16. Contraction
Acetylcholine(ACh) is the neurotransmitter that contracts skeletal muscles
ACh binds with receptors on the motor endplate, which causes muscle impulse
Calcium ions diffuse from sarcoplasmic reticulum to sarcoplasm and binds to troponin

17. Contraction (cont.)
Tropomyosin moves, which allows actin and myosin to link
Actin is pulled to the center of the sarcomere, which allows muscle fibers to shorten

18. Threshold

19. Respiration Anaerobic breaks down glucose and releases ATP
Aerobic requires oxygen to produce ATP

20. Oxygen debt
When cellular respiration is not able to sustain the muscle, lactic acid diffuses into the blood stream
This creates an oxygen debt, that must be repaid later

21. Muscle fatigue When a muscle loses its ability to contract
Most likely occurs from accumulation of lactic acid

22. Types of contraction