Chapter 9 Flashcards
The consists of how many skeletal muscles
Over 600
Skeletal muscles are composed of (4 things)
Skeletal muscle tissue
Nervous tissue
Blood
Connective tissue
Thin covering of connective tissue around a muscle
Fascia
Cord-like mass of connective tissue that connects muscle to a bone
Tendon
Sheet-like mass of connective tissue that connects a muscle to bone, skin, or another muscle
Aponeurosis
Surrounds whole muscle; lies beneath fascia
Epimysium
Surrounds fascicles within a muscle
Perimysium
Surrounds muscle fibers(cells) within a fascicle
Endomysium
Cell membrane of muscle fiber
Sarcolemma
Cytoplasm of muscle fiber
Sarcoplasm
Consists of sarcomeres connected end-to-end
Myofibrils
Made by arrangement of myofilaments in myofibrils
Striation pattern
Composed of myosin protein, heads form cross-bridges with thin filament (filament)
Thick filament
Composed of actin protein, associated with troponin and tropomyosin, which prevent cross-bridge formation when muscle is not contracting (filament)
Thin filaments
Results from a movement within the myofibrils, in which the actin and myosin filaments slide past each other, shortening the sarcomeres. Muscle fiber shortens and pulls on attachment sites.
Skeletal muscle contraction
A type of synapse, also called “myoneural junction” site where an axon of motor neuron and skeletal muscle fiber interact. Skeletal muscle fibers contract only when stimulated by a motor neuron. (Junction)
Neuromuscular junction
Parts of motor neuron
Motor neuron
Motor end plate
Synaptic plate
Synaptic vesicles
Neurotransmitters
Neuron that controls skeletal muscle fiber
Motor neuron
Specialized folded portion of skeletal muscle fiber, where fiber binds to neurotransmitter.
Motor end plate
Membrane-bound sacs containing neurotransmitters
Synaptic vesicles
Chemicals released by motor neurons to deliver message to muscle fiber
Neurotransmitters
Neurotransmitter for muscle contraction
Acetylcholine (ACh)
Enzyme that rapidly decomposes ACH remaining in the synapse
Acetylcholinesterase
Glycolysis, occurs in cytoplasm, produces little ATP (phase of cellular respiration)
Anaerobic phase
Citric acid cycle and electron transport system, occurs in mitochondria, produces the most ATP, myoglobin stores extra oxygen in muscles
Aerobic phase
Inability to contract muscle; decreased blood flow, Ion imbalances across the sarcolemma, loss of desire to continue exercise, accumulation of lactic acid
Muscle fatigue
Sustained, involuntary muscle contraction, may be caused by changes in electrolyte concentration in extracellular fluids in the area
Muscle cramp
————— cells are a major source of body heat
Muscle cells
Transports heat throughout body core
Blood
Continuous state of partial contraction in resting muscles
Muscle tone (Tonus)
Muscle changes length but force is constant
Isotonic contraction
Constant length but force changes
Isometric contraction
Muscle contracts with force greater than resistance and shortens (type contraction)
Concentric contractions
Muscle contracts with force less than resistance and lengthen (type of contraction)
Eccentric contraction
Muscle contracts but does not change length (type of contraction)
Isometric contraction
Multinucleated, sacroplasmic reticulum- endoplasmic reticulum of muscle; stores calcium
Skeletal muscle
Covers binding sites on actin, prevents myosin and actin from binding, muscle fiber relaxes
Troponin-tropomyosin complex
Shorter, single, centrally located nucleus, elongated with tapering ends, lack striation, lack transverse tubules, sacroplasmic reticulum not well developed.
Smooth muscle
Two types of smooth muscle
Multi unit smooth muscle
Visceral smooth muscle
Cells less organized, function as a separate units, fibers function independently, found on IRIS of eye, walls of blood vessels, stimulated by neurons, hormones.
Multi unit smooth muscle
Single-unit smooth muscle; cells respond as a unit, sheets of spindle-shaped muscle fibers, fibers held together by gap junctions, exhibit rhythmicity, conduct peristalsis, walls of hollow organs, most common type of smooth muscle
Visceral smooth muscle
Smooth muscle contraction differs from skeletal because
Smooth muscle lacks troponin; uses calmodulin instead. Two neurotransmitters affect smooth muscle; Acetylcholine ACh and norepinephrine NE
Located only in heart
Striated muscle cells
Fibers branch, contain a single nucleus
Self-exciting and rhythmic
Longer refractory period than skeletal muscles
No sustained or tetanic contractions
Cardiac muscles
Action of muscle depends mainly on two factors
Type of joint it is associated with
Way muscle is attached on both sides of the joint
Muscle that causes an action
Agonist
Agonist primarily responsible for movement
Prime mover
Muscles that assist agonist/prime mover
Synergists
Muscles whose contractions cause movement in the opposite direction of the prime mover
Antagonist
