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A&P Lecture 6

Muscle tissue, muscular system

Types of muscle tissue skeletal, cardiac, smooth
Muscular system includes only skeletal muscles
Function of skeletal muscles produce skeletal movement, maintain body position, support soft tissues, guard openings, maintain body temperature, store nutrient reserves
Structures in skeletal muscle muscle fibers, connective tissues, nerves, blood vessels
Three layers of connective tissue within muscles epimysium, perimysium, endomysium
Epimysium an exterior collagen layer connected to deep fascia; separates muscle from surrounding tissues
Perimysium connective tissue that surrounds fascicles; contains blood vessel and nerve supply to fascicles
Fascicle a bundle of muscle fibers
Endomysium connective tissue that surrounds individual muscle fibers, and contains capillaries and nerve fibers contacting muscle cells; also contains myosatellite cells that repair damage
Myosatellite cell a muscle stem cell
Muscle attachment connective tissue at the end of muscles made of the combined epimysium, perimysium, and endomysium that forms a connective tissue attachment to the bone matrix, either as a tendon or an aponeurosis
Tendon bundle of connective tissue that attaches muscle to bone matrix
Aponeurosis sheet of connective tissue that attaches muscle to bone matrix
Function of nerves in the muscular system connect muscles to the central nervous system, allowing voluntary control
Nomenclature of skeletal muscles a descriptive name followed by a location name
Function of blood vessels in the muscular system form an extensive vascular network that supplies nutrients and large amounts of oxygen, and carries away waste products
Properties of skeletal muscle fibers are very long; develop through fusion of myoblasts; contain hundreds of nuclei
Myoblast mesodermal stem cell that forms skeletal muscle cells
Sarcolemma cell membrane of a muscle fiber; maintains transmembrane potential to allow contractions
Sarcoplasm cytoplasm of a muscle fiber
T tubule transverse tubule; transmits action potential through the muscle fiber; allows entire fiber to contract simultaneously, and has same properties as the sarcolemma
Myofibril lengthwise subdivision within muscle fiber made up of myofilaments
Myofilament a protein filament responsible for muscle contractions
Types of myofilaments thin filaments made up of actin; thick filaments made up of myosin
Sarcoplasmic reticulum membranous structure surounding each myofibril that helps transmit action potential and forms terminal cisternae attached to the T tubule; similar structure to smooth endoplasmic reticulum
Terminal cisterna concentrates calcium ions via ion pumps, and releases them into sarcomeres to begin muscle contraction
Triad internal structure of a muscle fiber formed by one T tubule and two terminal cisternae
Sarcomere contractile unit of muscle that forms the structural unit of a myofibril, and forms visible patterns within the myofibril
Muscle striations a pattern of light (I band) and dark (A band) filaments within myofibrils
A band a dark, thick filament within the myofibril
I band a light, thin filament within the myofibril
M line the center of the A band, at the midline of the sarcomere
Z line the center of the I band, at the ends of the sarcomere
Zone of overlap the darkest area visible in the myofibril, where the A and I bands overlap
H band area around the M line that has thick filaments but no thin filaments
Titin a strand of protein that reaches from the tips of the thick filaments to the Z line, stabilizing the filaments
Function of sarcomeres contracts when calcium ions released by the sarcoplasmic reticulum cause the thin and thick filaments to interact
Four proteins of thin filaments F-actin, nebulin, tropomyosin, troponin
Mnemonic for remembering thick and thin filaments the "tin" in actin corresponds to the thIn filaments, which look lIght and form the I band; the A band looks dArk
Types of fascicle organization parallel, convergent, pennate
Types of attachment sites for convergent muscles tendon, aponeurosis, raphe
Types of pennate muscles unipennate (extensor digitorum), bipennate (rectus femoris), multipennate (deltoid)
Sphincter circular muscles that open and close to guard entrances of the body
Orbicularis oris the muscle that closes and opens the mouth
Orbicularis oculis the muscle that closes and opens the eye
Lever rigid, moving structure
Fulcrum fixed point
Three functions of levers changes direction of applied force, distance and speed of movement, effective strength of applied force
First-class lever fulcrum is in the center between the applied force and the resistance; for example, nodding yes
Second-class lever centers resistance between fulcrum and applied force, to move a large weight with a small force; for example, tiptoeing
Third-class lever centers applied force between resistance and fulcrum, to maximize speed and distance traveled; for example, flexion of the elbow
Types of muscle functions agonist, antagonist, synergist, fixator
Agonist muscle produces a particular movement
Antagonist muscle opposes movement of a particular agonist
Synergist muscle smaller muscle that assists a larger agonist
Fixator muscle stabilizes point of attachment of an agonist muscle
Only two muscles without the word "muscle" in their correct names platysma, diaphragm
Platysma flat muscle of the lower jaw
Diaphragm umbrella-shaped muscle that separates the thoracic and abdominal cavities
Ways muscles are named location in the body, origin and insertion, fascicle organization, relative position, structural characteristics, action
Muscles of the eye six extrinsic muscles (sclera), two intrinsic
Six extrinsic muscles of the eye superior rectus, medius rectus, inferior rectus, lateral rectus, superior oblique, inferior oblique
Intrinsic muscles of the eye ciliary, iris
Ciliary muscle of the eye controls the shape of the lens to focus vision
Iris muscle controls the size of the pupils
Divisions of the muscular system axial (60% of muscles), appendicular (40%)
Six muscle groups of the head and neck facial expression, extrinsic eye muscles, mastication, muscles of the tongue, muscles of the pharynx, anterior muscles of the neck
Process of initiating contraction Ca2+ ion binds to receptor on troponin molecule; troponin-tropomyosin complex changes, expressing the active site of F-actin
Sliding filament theory thin filaments slide along thick filaments toward the M line at the center of the sarcomere; width of the A zone stays the same, Z lines move closer together
Five steps of the contraction cycle exposure of active sites; formation of cross-bridges; pivoting of myosin heads; detachment of cross-bridges; reactivation of myosin
Process of relaxation Ca2+ concentrations fall; Ca2+ ions detach from troponin; active sites are re-covered by tropomyosin; tension gradually falls to resting levels; titin proteins recoil after stretching
Neuromuscular junction location of neural stimulation; action potential causes release of neurotransmitters into the synaptic cleft
Action potential electrical signal that travels along the nerve axon and ends at synaptic terminal
Synaptic terminal part of the neuron that releases acetylcholine into the synaptic cleft
Acetylcholine neurotransmitter that transmits action potential from a motor neuron to a muscle fiber by binding to membrane receptors on the sarcolemma, making it more permeable to sodium ions
Synaptic cleft gap between the synaptic terminal and motor end plate, where acetylcholine is released by the neuron and attaches to the motor end plate
Motor end plate portion of the sarcolemma that receives acetylcholine
Cardiac muscle tissue striated muscle tissue found only in the heart, notable for containing intercalated discs
Intercalated discs specialized contact points between cardiocytes made up of gap junctions and desmosomes that enhance molecular and electrical connections and conduct action potentials
Smooth muscle tissue nonstriated tissue with different functional characteristics from skeletal muscle; causes involuntary movement in the body, mainly in the cardiovascular (regulating blood pressure and flow), digestive (peristalsis, sphincters), and integumentary systems
Muscles of the shoulders and upper limbs position the pectoral girdle, flex and extend the shoulder and elbow, abduct and adduct the shoulder, and rotate the shoulder
Muscles that position the pectoral girdle trapezius, rhomboid, levator scapulae, serratus anterior, subclavius, pectoralis minor
Muscles that abduct the shoulder deltoid (agonist), supraspinatus (synergist)
Muscle that adducts the shoulder coracobrachialis
Muscles that rotate the shoulder subscapularis and teres major (medial), infraspinatus and teres minor (lateral)
Muscle that extends the shoulder latissimus dorsi
Muscle that flexes the shoulder pectoralis major
Muscles of the rotator cuff supraspinatus, subscapularis, infraspinatus, teres minor
Muscles that flex the elbow biceps brachii (agonist), brachialis and brachioradialis (synergists), triceps and anconeus (antagonists)
Muscles that extend the elbow triceps brachii (agonist), anconeus (synergist), biceps and brachioradialis (antagonists)
Muscles that move the thigh gluteal, lateral rotators, adductors, iliopsoas
Gluteal muscles gluteus maximus, gluteus medius and minimus, tensor fasciae latae
Lateral rotators of the thigh piriformis, obturator
Adductors of the thigh adductor magnus, adductor brevis, and adductor longus; pectineus, gracilis
Hip flexors psoas major, iliacus
Extensors of the knee four muscles of the quadriceps femoris
Quadriceps femoris vastus medialis, vastus intermedius, and vastus lateralis; rectus femoris
Flexors of the knee hamstring
Hamstring muscles biceps femoris, semitendinosus, semimembranosus
Created by: ekolmus



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