Energy for Muscle Contraction Direct Phosphorylation Aerobic Respiration Anaerobic Glycolysis

Vocabulary Aponeurosis: A sheetlike fibrous membrane that binds muscles together or as a means of connecting muscle to bone. Motor Unit: A single motor neuron and all the muscle fibers it stimulates. Ligament: A sheet or band of tough, fibrous tissue connecting bones or cartilages at a joint

Vocabulary Epimyusium: The external sheath of connective tissue surrounding a muscle. (outermost) Perimysium: The fibrous sheath enveloping each of the primary bundles of skeletal muscle fibers. (Middle) Endomysium: The connective tissue layer surrounding an individual skeletal muscle fiber. (Innermost)

Direct Phosphorylation Uses Creatine Phosphate –Found only in muscle –Regenerates ATP from ADP –CP exhausted in 20 seconds –No Oxygen Used

Aerobic Respiration Generates ATP in mitochondria Uses Oxygen Oxidative Phosphorylation Glucose is broken down to CO 2 and H 2 O –36 ATP per 1 glucose –Slow process –Lasts for hours

Anaerobic Respiration Glycolysis uses no oxygen Occurs in cytosol Broken down to pyruvic acid which is converted to lactic acid when oxygen cannot keep up to demand 2 ATP per glucose seconds

Energy Sources First: Glucose Second: Pyruvic Acid Third: Fatty Acids stored in adipose tissue Fourth: Amino Acids from protein catabolism

Muscle Fatigue Muscle cannot contract even when stimulated Weaker and weaker until it stops Results from Oxygen debt Build up of lactic acid and lack of creatine phosphate and ATP reserves

Oxygen Debt Prolonged workouts Oxygen uptake can no longer keep up Results in rapid or deep breathing Muscle may quit entirely

Hitting the Wall Bonk Glycogen depletion Extreme fatigue Remedied by carbohydrates

Movements Flexion Extension Hyperextension

Movements Abduction Adduction Circumduction

Movement Plantar Flexion Dorsiflexion

Movement Rotation Medial Rotation Lateral Rotation

Movement Supination Pronation

Movement Inversion Eversion

Review Sarcomere

More Vocabulary: Sarcolemma: Plasma membrane of a muscle cell Myofibril: Long organelles that fill the cell and are composed of myofilaments Myofilaments: threadlike protein fibers –Thick filaments = Myosin –Thin Filaments = Actin

Muscle Characteristics Skeletal: Multinucleate, Striated, Long Thin Cells. Attached to bones. Voluntary Cardiac: Branched, Uninucleate, Striated, Intercalated discs. Walls of Heart. Involuntary Smooth: Fusiform (tapered), Uninucleate, No striations. Involuntary.

Vocabulary A Bands = Dark bands of a myofibril I Bands = Light bands of a myofibril Z Disc or Z Band= Interruption in the center of the I Band M Line: Holds thick filaments together and can be seen in the center of the H zone H Zone: Light central area of sarcomere that lacks actin (also bare zone) this disappears during contraction when fibers overlap

Muscle Contraction Review 1.Motor neuron is stimulated and the action potential travels along the neuron.

Muscle Contraction 2. Acetylcholine is released from the neuron end plate into the neuromuscular junction

Muscle Contraction 3.Acetylcholine diffuses across the neuromuscular junction gap

Muscle Contraction 4. The muscle fiber membrane is stimulated, impulse travels through transverse tubules to sarcoplasmic reticulum

Muscle Contraction 5. Sarcoplaspic reticulum releases Ca +2 into the sarcoplasma

Muscle Contraction 6. Calcium binds to troponin on the actin (thin) filaments allowing myosin (thick) filaments to form cross- bridges

Muscle Contraction 7&8 Power Stroke occurs and repeats as long as calcium is present and the muscle shortens

Muscle Contraction 9. Motor neuron stimulation stops. Cholinesterase causes the breakdown of acetylcholine

Muscle Contraction 10. Calcium ions are pumped out into the sarcoplasmic reticulum using active transport

Muscle Contraction 11& 12 Linkages between actin and myosin are released. The muscle relaxes to its pre-stimulated length

Quiz Tuesday – Muscle Physiology