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A & P Part 1
Muscular tissue
| Question | Answer |
|---|---|
| Skeletal muscle tissue | striated, alternating light & dark bands, voluntary |
| Cardiac muscle tissue | only in the heart, striated, involuntary |
| Smooth muscle tissue | walls of hollow internal structures, nonstriated, involuntary |
| Functions of muscle tissue | produce body movement, stabilize body position, storing and moving substances in the body, generating heat |
| Properties of muscle tissue | enable muscular tissue to contribute to homeostasis; electrical exciteability, contractility, extensibility, elasticity |
| Electrical exciteability | ability to respond to certain stimuli by producing electrical signals called action potentials (nerve impulses) |
| Contractility | ability of muscular tissue to contract forcefully when stimulated by an action potential |
| Extensibility | bility of muscle tissue to stretch without being damaged |
| Elasticity | ability of muscle tissue to return to its original length and shape after contraction or extension |
| Skeletal muscle histology | muscle tissue, connective tissue, blood vessels, lymphatic vessels, nerves, muscle fibers (cells) |
| Fascia | sheet or broad band of fibrous connective tissue that supports or surrounds muscles and other organs of the body (superficial, deep) |
| Superficial fascia | subcutaneous layer or hypodermis; areolar and adipose connective tissue; seperates muscle from skin; pathway for nerves, blood vessels, lymphatic vessels; storage of body fat; insulation, protection |
| Deep fascia | dense irregular connective tissue; binds muscles with similar function; epi-, peri-, endo- mysium layers |
| Epimysium | outermost layer, covers entire muscle, dense irregular connective tissue |
| Perimysium | surrounds fascicles (10-100), dense irregular connective tissue |
| Endomysium | surrounds individual muscle fibers, thin areolar connective tissue |
| Tendons | cords of dense regular connective tissue |
| Aponeurosis | broad, flat, tendon like sheets |
| Sarcolemma | plasma membrane of muscle cell |
| Sarcoplasm | cytoplasm of muscle cell |
| Transverse tubules | invaginations of sarcolemma, open to outside cell, action potentials spread to muscle cell |
| Triad | transverse tubule and two terminal cisterns |
| Sarcoplasmic reticulum | storage of calcium |
| Terminal cisterns | dilated ends of sarcoplasmic reticulum |
| Myofibrils | contractile organelles composed of thick & thin filaments |
| Muscle cell proteins | contractile, regulatory, structural |
| Contractile proteins of muscle cell | Actin and myosin; generate muscle contraction |
| Actin | main component of thin filament, myosin binding sites for attachment of muscle heads |
| Myosin | main component of thick filament, head & tail, converts chemical energy of ATP into mechanical energy of motion/force |
| Regulatory proteins | tropomyosin, troponin, regulate muscle contraction |
| Tropomyosin | covers myosin binding sites (on actin) in relaxed muscle cell; prevents attachment of myosin heads; thin filament |
| Troponin | holds tropomyosin in place; thin filament |
| Structural proteins | alignment of myofibrils, elasticity, integrity, strength of muscle cell, (titin, myomesin, nebulin, dystrophin) |
| Sarcomere | basic functional (contractile) unit of myofibril |
| Components of sarcomere | z-disc, m-line, thick & thin filaments, dark A & light I bands, h-zone (zone of overlap) |
| Sliding filament theory | 1) Myosin heads attach to Myosin binding sites on actin; 2) Myosin heads pull thin filaments toward center of sarcomere; 3) Length of thin & thick filaments don't change |
| Contraction cycle | 1) ATP synthesized to ADP and phosphate group and energy; myosin heads reorient and energize; 2) Attachment of myosin to actin (cross bridges); 3) rotation of crossbridge toward center of sarcomere (power stroke); 4) ATP attaches to myosin head (detaches) |
| Excitation-contraction coupling | 1) Muscle AP propagates sarcolemma t-tubules; 2) release of Ca from SR into cytosol; 3) Ca binds to troponin; 4) exposure of myosin binding sites on actin |
| Sarcoplasmic reticulum | Stores Ca (relaxation); releases Ca (contraction), Ca pumps replenish Ca in SR, T-TM complex covers myosin binding sites |
| Neuromuscular Junction | Synapse between motor neuron and skeletal muscle fiber, presynaptic membrane (synaptic end bulb), synaptic vesicles (carry ACh), synaptic cleft (between cells), postsynaptic membrane (motor end plate, ACh receptors) |
| Stimulation of muscle fiber | AP => exocytosis => release of ACh, diffusion across synaptic cleft; Activation of ACh receptors => inflow of Na => Change of membrane potential (muscle AP) => spreading along sarcolemma, ACh broken down by enzymes (termination) |
| Resting membrane potential | negative charge on the inside of it’s membrane and a positive charge on the outside of the membrane |
| Moving a muscle | polarization, depolarization, repolarization |
| Polarization | resting stage, positive ion charge outside, negative ion charge inside |
| Depolarization | Sodium pumps open, sodium swarms into cell changing charges |
| Repolarization | Potassium pumps open, potassium swarms out of cell, cell becomes positive outside and negative inside again |
| Reverse switch | Both potassium & sodium pumps open and particles switch back to original state |
| Mechanisms of generating ATP | 1) creatine phosphate 2) anaerobic cellular respiration 3) aerobic cellular respiration |
| Muscle fatigue | muscle inability to maintain force of contraction after prolonged activity |
| Contributing factors to muscle fatigue | low levels of Ca, creatine phosphate, oxygen, glycogen, ACh; buildup of lactic acid and ADP |
| Oxygen debt (recovery oxygen uptake) | Added O2 consumption above resting level after activity |
| How extra oxygen is used | metabolize lactic acid; renew creatine phosphate & ATP; replace oxygen in myoglobin; fuel higher metabolic rate; supply harder working respiratory muscles & heart; fuel tissue repair & processes |
| Force of muscle contraction | variable due to frequency of APs, number of contracting muscle fibers |
| Motor unit | somatic motor neuron and all skeletal muscle fibers innervated by it; all muscle fibers in a motor unit contract/relax together |
| Strength of contraction | depends on size of motor units, number of activated motor units |
| Twitch | brief contraction of muscle fibers in motor unit in response to single AP in its neuron |
| Fused (complete) tetanus | sustained contraction in which individual twitches cannot be detected |
| Muscle tone | Small amount of tension in muscle due to weak, involuntary, alternate contractions of different motor units |
| Flaccidity | loss of muscle tone due to motor neuron damage |
| Types of muscle contractions | isotonic, isometric |
| Isotonic muscle contraction | concentric, eccentric; constant tension, changes in length, movement occurs |
| Isometric muscle contraction | constant length; changes in tension (increase), no movement |
| Structural differences of skeletal muscle fibers | fiber diameter, blood supply, color, myoglobin & mitochondria content |
| Functional differences of skeletal muscle fibers | way of generating ATP, speed of contraction, resistance to fatigue |
| types of skeletal muscle fibers | 1) slow oxidative, 2) fast oxidative-glycolytic, 3) fast glycolytic |
| Myoglobin | red colored protein that binds oxygen in muscle fibers |
| Slow oxidative muscle fibers | use oxygen to generate energy, resistant to fatigue, and adapted for maintaining poster and aerobic and activities |
| Fast oxidative-glycolytic muscle fibers | intermediate diameter, contribute to activities such as walking and sprinting |
| Fast glycolytic muscle fibers | largest diameter, contracts strongly and quickly, fast twitch fibers adapted for intense anaerobic activities of short duration |
| Hypotonia | decreased or lost muscle tone, flaccid muscles appear flattened rather than rounded; affected limbs are hyperextended |
| Flaccid paralysis | characterized by loss of muscle tone, loss or reduction in tendon reflexes, and atrophy |
| Atrophy | wasting away, degeneration of muscles |
| Hypertonia | increased muscle tone, spasticity or rigidity |
| Spasticity | increased muscle tone associated with increase in tendon reflexes & pathological reflexes |
| Rigidity | increased muscle tone, reflexes not affected |
Created by:
rock-steady
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