CSCS Chapter 1 Study Guide 1. Skeleton consists of: A. Axial Skeleton - Cranium (Skull) - Vertebral Column (C1- Coccyx): o Neck: 7 Vertebrae: Atlas (C1), Axis (C2), C3-C7 o Mid to Upper Back: 12 Thoracic Vertebrae: T1-T12 o Lower Back: 5 Lumber Vertebrae: L1-L5 o Rear Pelvis: 5 Sacral Vertebrae o Vestigial Internal Tail extending downward from Pelvis: 3-5 Coccygeal Vertebrae - Ribs - Sternum B. Appendicular Skeleton - Shoulder/ Pectoral - Girdle (Left and Right Scapula and Clavicle) - Bones of Arm, Wrist and Hand - Pelvic Girdle - Bones of Leg, Ankle and Feet C. Joints - Uniaxial: Rotating only on 1 axis and acts as hinges - Biaxial: Allows movement on 2 perpendicular axes - Multiaxial: Allow movement about all 3 perpendicular axes - Fibrous Joints: allows no movement (e.g. sutures of skull) - Cartilaginous Joints: allows limited movement (e.g. intervertebral disks) - Synovial Joints: allows considerable movement (e.g. elbow and knee) D. Hyaline Cartilage: Is smooth and covers ends of articulating bones. E. Synovial Fluid: fluid that entire joint is capsulated in. CSCS Chapter 1 Study Guide 2. Fibrous Connective Tissue covering 430 muscles of body A. Epimysium: Outer Layer B. Perimysium: Surrounds each Fasciculus (group of Fibers) C. Endomysium: Surrounds each individual Fiber 3. Parts of the Heart A. Left and Right Atrium: Delivers Blood to left and right ventricles. B. Left and Right Ventricle: Supplies main force for delivering blood though pulmonary and peripheral circulations. C. Valves: - Atrioventricular (AV) Valves: Tricuspid Valve and Mitral Valve o Function: Prevents flow of blood from ventricle back into atria during ventricular contraction (Systole) - Semilunar Valves: Aortic Valve and Pulmonary Valve o Function: Prevent backflow from aorta and pulmonary arteries into ventricles during ventricular relaxation (Diastole) D. Conduction System: - Sinoatrial (SA) Node: Intrinsic Pacemaker – where rhythmic electrical impulses are initiated. o Located at upper lateral wall of Right Atrium and spreads into Atria. - Internodal Pathways: Conducts impulses from SA node to AV node. o Located in posterior septal wall of Right Atrium - Atrioventricular. (AV) Node: Where impulses delayed slightly before passing into ventricles. - Atrioventricular (AV) Bundle: Conducts impulses to ventricles and: o Left and Right Bundle Branches: divides further into Purkinje Fibers and conducts impulses to all parts of ventricle. CSCS Chapter 1 Study Guide E. Blood Vessels: Arterial System (Carries Blood away from Heart) and Venous System (Returns blood towards Heart) - Arteries: rapidly transports blood pumped from heart o Arterioles: Small branches of arteries that act as control vessel through which blood enters capillaries. Plays major role in regulation of blood flow to capillaries. Has strong, muscular walls capable of closing arteriole wall completely or allowing it to be dilated many times their size. - Capillaries: facilitates exchange of oxygen, fluid, nutrients, electrolyte, hormones, and other substances between the blood and the interstitial fluid in various tissues of the body. Capillary walls are thin and permeable to these, but not all, substances. - Veins: o Venules: collects blood flow from the capillaries and gradually converge into larger Veins. Has thin, muscular walls allowing them to constrict or dilate to a greater degree and thereby act as a reservoir for blood, either in small or large amounts. o Veins: Transport blood back into heart F. Blood - Functions: Transport of oxygen from lungs to tissues for cellular metabolism and removal of CO2. - Hemoglobin: iron-protein molecule carried by red blood cells. Transport of oxygen is accomplished by this. Acts as acid-base buffer, a regulator of hydrogen ion concentration. - Red Blood Cells (RBC): major component of blood. Has many functions such as catalyzing reaction between CO2 and water to facilitate CO2 removal because RBC contain large quantities of carbonic anhydrase. CSCS Chapter 1 Study Guide 4. Skeletal Muscle Pump: The assistance that contracting muscles provide to the circulatory system. It works with the venous system, which contains one-way valves for blood return to the heart. The contracting muscle compresses the veins, but since the blood can only flow in the direction of the valves, it is returned to the heart. This mechanism is one reason why individuals are told to keep moving around during exercise to avoid blood pooling in lower extremities. It is also important to periodically squeeze muscles during prolonged sitting to facilitate blood flow to heart. 5. All-or-None Principle: When a motor unit receives a stimulus of sufficient intensity to bring forth a response. All muscles fibers within unit contracts at the same time and at maximum extent. 6. Anatomical Planes A. Sagittal Plane: Divides body into left and right portions. B. Coronal (Frontal) Plane: Divides body into anterior and posterior portions. C. Transverse Plane: Divides body into superior and inferior. D. Proximal: closer to the trunk. E. Distal: farther from trunk. F. Superior: closer to the head. G. Inferior: closer to the feet. 7. Contraction Types A. Concentric Contractions: Muscle tension rises to meet resistance then remains stable as muscle shortens. B. Eccentric Contractions: Muscle lengthens as resistance becomes greater than the force the muscle is producing. o Produces largest amount of force. o Precedes countermovement jump. C. Isometric Contractions: muscle contraction without motion. 8. Myofibril: bundles of interconnected protein filaments in striated muscles. Myofilaments: organized longitudinally in Sarcomere (smallest contractile unit of skeletal muscle) 1. Myosin: thick filaments (~ 16 nm is diameter) consisting of 200 myosin molecules that contain a globular head, hinge point and fibrous tail. - Globular head protrudes away from myosin filament at regular intervals, and a pair of myosin filaments forms a cross-bridge which interacts with actin. 2. Actin: thin filaments (~6 nm in diameter) consisting of two strands arranged in a double helix. Sliding Filament Theory: states that the actin filaments at each end of the sarcomere slide inward on myosin filament, pulling Z-Lines toward center on sarcomere and thus shortening the muscle fiber. As actin filaments slide over myosin filaments, both H-zone and I-Band shrink. - Sarcolemma: muscle fiber membrane, surrounding each muscle fiber. - Sarcoplasm: cytoplasm of muscle fiber. - Fasciculi: muscle fibers groups in bundles - Sarcomere: Z-line to Z-Line o I-Band: only actin filaments o Z-line: splits I-band and separates sarcomere. o H-Zone: middle of sarcomere; contains only myosin filaments. o A-Band (length of myosin filament). During a muscle contraction (concentric or eccentric), it’s not the length of the filaments that change but the amount of sliding or overlap between the two. No matter what, A-band stays the same. H and I Bands length decrease also causing Z-line to approximate. A. Resting Phase: muscle at rest because no muscle tension, so most Calcium stored in SR. Very few Myosin cross-bridges attached to Actin. - Even with Actin binding site covered, Myosin and Actin still interact in a weak bond, which becomes strong (and muscle tension is produced) when actin binding site is exposed after release of stored calcium. B. Excitation-Contraction Coupling Phase: SR releases calcium ions (due to Acetylcholine) and calcium attaches to Troponin (a protein situated at regular intervals along actin filament) causing s shift in Tropomyosin (in relaxed state, blocks attachment site for myosin crossbridge) that runs along the length of the actin filament in the groove of the double helix. The myosin crossbridge not attaches CSCS Chapter 1 Study Guide much more rapidly to the actin filament, allowing force to be produced as the actin filaments are pulled toward the center of the Sarcomere. - Sarcoplasmic Reticulum (SR): network of T-tubules and vesicles; provides structural integrity of muscle fiber, stores and releases calcium (Ca pump) when AP arrives. o When AP is no longer present and released. Ca not utilized is sequestered back into SR. - Troponin: Ca binds to troponin causing tropomyosin complex to move off actin. - Myosin cross-bridge heads bind more rapidly to actin allowing cross-bridge flexion to occur. - The number of cross-bridges formed between actin and myosin at any given instance in time dictates the force production of a muscle. C. Contraction Phase: The energy for power stroke comes from hydrolysis (breakdown) of ATP to ADP and phosphate, catalyzed by the enzyme ATPase. Another molecule of ATP must replace ADP on the myosin crossbridge globular head for the head to detach from active actin site and return to original position. This allows the contraction process to continue or relaxation to occur. - Calcium and ATP are necessary for crossbridge cycling with actin and myosin filaments. D. Recharge Phase: Muscle contraction/muscle shortening occurs in this sequence of events: 1. Binding of calcium to Troponin. 2. Coupling of myosin crossbridge with actin. 3. Crossbridge flexion 4. Dissociation of actin and myosin 5. Resetting of crossbridge head is repeated over and over again. E. Relaxation Phase: Muscular relaxation occurs when stimulation of motor nerve stops. Calcium returns to SR, stopping binding process between actin and myosin. Body builders produce 2/3 amount of force as powerlifters due to neuromuscular adaptations, rather than myofibril hypertrophy. 9. Muscle Fiber Types A. Type 1: Slow Twitch (Slow Oxidative) a. Metabolically have large capacity for aerobic energy supply, relatively resistant to fatigue. b. Limited availability to rapidly generate force, slower calcium- handling abilities, reduced glycolytic capacity. c. Numerous large mitochondria. d. Endurance Activities and sports. B. Type IIa: Fast Twitch/ Fast Oxidative/ Glycolytic Fibers a. Energy insufficient, easily fatigable, lower aerobic power. b. Moderate capacity for aerobic and anaerobic energy production. c. Able to rapidly generate force due to high myosin ATPase activity and anaerobic power. d. Surrounded by a greater number of capillaries than Type IIx fibers, allowing for greater aerobic metabolism. C. Type IIx: Fast Twitch/ Fast Glycolytic Fibers a. Less capacity for aerobic energy production, making them more fatigable than Type IIa fibers. b. Greater capacity for anaerobic energy production, and the fastest shortening velocity, so are able to generate significant force. Most common muscle type transition: Type IIx -> IIa via combination of resistance and aerobic training. Chronic endurance (e.g. LSD) training causes transition for IIx -> I Type IIx fibers are most likely to be utilized by a sprinter. 10. What are some ways athletes can improve their force production? Adaptations to resistance training the improve force production include both increased twitch frequency and increased number of activated motor units. Muscle force production in athletes can be improved by the following: o Incorporating phases of training with heavier loads. o Increasing muscle CSA through resistance training. o Focusing on explosive, muti-muscle, multi-joint exercises. 11. Proprioceptors: specialized sensory receptors that provide CNS with information needed to maintain muscle tone and perform complex coordinated movements. Located in: joints, muscles and tendons. - Muscle Spindle is the primary proprioceptive feedback structure in the muscle and the most important component in the stretch reflex response. CSCS Chapter 1 Study Guide o As the muscle lengthens, the MS are stretched, activating a sensory neuron in the spindle that sends signal to the spinal cord → synapses with motor neurons → innervate extrafusal fibers → activate muscle fiber causing reflexive muscle action called stretch reflex → causes spindles to shorten, and sensory impulses stop o After the signal is sent from the muscle spindle to the motor neuron of the spine, the motor neuron then generates a muscular action of the stretched muscle. o Increasing loads cause spindles to stretch more; the muscle force and power and potentiated by this reflexive contraction. o Senses when rapid strength is applied to a muscle and reflexively contracts, which serves to potentiate the force-generating capacity of the muscle as well. o Stimulation of MS induces a contraction of stretched muscle. o Static stretching decreases MS stimulation. o Spindles indicate the degree of muscle activation needed to overcome resistance. o Activation of muscle spindle increases activation of motor unit. o muscle spindles respond to eccentric muscle action. o Reciprocal Inhibition - relaxation that occurs in the antagonist muscle to the muscle experiencing tension. Occurs when one simultaneously contracts the opposite muscle of the muscle being stretching (i.e. quads contracted during hamstring stretch) - Golgi Tendon Organs (GTO) are mechanoreceptors located within the musculotendinous junction that are sensitive to o activated when the tendon attached to an active muscle is stretched. As tension increases within a muscle, discharge of the GTOs increases. o Autogenic Inhibition - relaxation that occurs in the same muscle experiencing tension. Can be accomplished via active contraction of a muscle immediately before a passive stretch of that same muscle. Tension built up during active contraction stimulates the GTO, causing reflexive relaxation of muscle during subsequent passive stretch. o Stimulation of GTO is graded based on the amount of tension that develops, such as low forces, the effect of GTOs is minimal, but with increasing loads, the GTOs mediate more significant reflexive inhibition. o GTOs protect the muscle/tendon from injury from excessive tension & loads. o Motor cortex signals can override GTO response - possibly an adaptation to heavy resistance training that increases force development. o During PNF stretching, stimulation of GTO allows the relaxation of the stretched muscle by its own contraction. o GTO activation decreases activation of motor unit. o GTO responds to concentric muscle action. Fleshy muscular attachments are often found at the proximal end of muscle.
