Muscular System

1. Muscular System Madi Larson & Kylei Hunter

2. FunFacts There are muscles in the roots of your hair that give you Goosebumps It takes 17 muscles to smile and 42 muscles to frown The hardest working muscle is the eye Muscles account for about 40% of your body weight

3. Function • Provide muscle tone • Propel body fluids and food • Generate heartbeat • Distribute heat Three types: • Skeletal • Smooth • Cardiac

4. Structure of a Skeletal Muscle • Voluntary • Striated • Many nuclei • Well developed transverse tubule system

5. ) Structure of Muscle Fiber (cell) • Tendon • Fascia : connective tissue that separates skeletal muscle from other muscle types and holds it in position • Epimysium: closely surrounds skeletal muscle • Perimysium: Separates muscle tissue into small compartments • Endomysium: thin covering of connective tissue in which each muscle fiber within a fascicle lies • Sarcolemma: cell membrane itself • Sarcoplasm: cytoplasm of the muscle fiber. • Many nuclei • Mitochondria • myofibrils

6. Structure of Muscle Fiber (cell) • Sarcomere: extension of myofibrils from one Z-line to the next Z-line • Sarcoplasmic reticulum: (endoplasmic reticulum) contain transverse tubules that lie between two enlarged portions of sarcoplasmic reticulum near where the actin and myosin overlap • Myofibril: inside sarcoplasm that lie parallel to one another • Play role in muscle contraction • Contain 2 proteins. Myosin and Actin • Produces light and dark striations or bands • Filaments: Actin and Myosin filaments create cross-bridges that are important to sliding filament theory A-Band: thick myosin filaments, overlapping with actin filaments I-Band: thin actin filaments. directly attached to Z-line

7. Relations

8. Description • Neuromuscular Junction: • Connection between motor neuron and muscle fiber • Motor End Plate: • Specialized portion of muscle fiber membrane at a neuromuscular junction • Neurotransmitter: • Chemical that an axon end secretes on effectors (muscle or gland) • Muscle Contraction: Shortening or tensing

9. Role of Actin & Myosin • Myosin: • Composed of 2 twisted protein strands • Cross-bridges • Thick filament • Contain ATPase, which catalyzes the breakdown of ATP and ADP and Phosphate; releasing energy that puts the myosin in a “cocked” position • Actin: • Binding site to which myosin cross-bridges can attach • Twist into double strand(helix) • Troponin & Tropomyosin • Thin filament • Provides site for attachment of myosin; which pulls filament causing contraction

10. Stimulating Muscle Contraction • Neurotransmitter stimulates • Acetylcholine • In cytoplasm of motor neuron • Stored in vesicles of the motor neuron

11. Energy Supply • ATP molecules • Must be regenerated from ADP and Phosphate • Creatine Phosphate aids regeneration • High energy phosphate bonds • Cannot directly supply energy • As ATP decomposes the energy from creatine phosphate can be transferred to ADP molecules, converting them back into ATP http://howmed.net/physiology/skeletal-muscle/

12. Roleof Oxygen • Oxygen Debt: occurs as a result of the building up of lactic acid • Oxygen amount = amt. of oxygen liver cells require to convert the accumulated lactic acid into glucose + amt. muscle cells require to restore ATP and creatine phosphate • Oxygen Supply • Blood carries oxygen required for respiration from lungs to cells • Oxygen is loosely bound to molecules of hemoglobin (brings out red color)

13. Oxygen Supply • Cramping: occur when changes in extracellular fluid surrounding the muscle fibers • Motor neurons trigger uncontrolled stimulation • Contraction: during strenuous exercise; used to synthesize the ATP the muscle fiber needs to contract • Fatigue: mostly to arrisefom accumulation of lactic acid • Lowered amount of lactic acid results in build up in oxygen

14. Major Anterior Muscles • Lower Body: • VastusLateralis • Rectus Femoris • VastusMedialis • Tibialis Anterior • Gastrocnemius • Soleus • Adductor Longus • Adductor Magnus • Extensor DigitorumLongus • Upper Body: • Temporalis • Sternocleidomastoid • Trapezius • Deltoid • Bicep • Tricep • Pectoralis • LatissimusDorsi • Rectus Abdominis • Obliques • Flexors • Brachioradialis

15. Major Posterior Muscles • Lower body: • Gluteus maximus • Gluteus medius • Biceps femoris • Semitendinosus • Semimembranosus • Gracilis • Vastuslateralis • Vastusmedialis • Sartorius • Gastrocnemius • Soleus • Fibularislongus • Calcaneal tendon • Upper body: • Splenius capitis • Semispinaliscapitis • Temporalis • Occipitalis • Trapezius • Teres major • Teres minor • Infraspinatus • Brachialis • Phomboideus • Latissimusdorsi • Triceps brachii • Deltoid • External oblique • Brachioradialis

16. Anterior and Posterior Views

17. Distinguishing • Synergist: muscles that contract and assist the prime mover • Antagonist: Resist a prime movers action and cause a movement in the apposite direction • Origin: immovable end of muscle • Ex: Biceps brachii= 2 heads • Insertion: moveable end • Attachment of biceps along radius • Prime movers: muscle that provides most of the movement • Ex: upper limb is lifted horizontally; “deltoid” is prime mover

18. Distinguish difference • Recruitment: Increase in the amount of motor units being activated • As intensity of stimulation increases, recruitment continues until all possible motor units are activated • Summation: The force of individual twitches combined • Force that muscle fiber can generate is not limited to maximum force of single twitch

19. Distinguish differences • Muscle Tone: Muscle appears to be at rest; its fibers undergo some sustained contraction known as this • response to nerve impulses that originate repeatedly from the spinal cord and stimulate a few muscle fibers • Sustained Contractions: summation and recruitment together can produce this of increasing strength • Smaller motor units are most easily stimulated and respond earlier in a series • Larger motor units respond later and more forcefully