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Chapter 9 Muscles and Muscle Tissue
Terms in this set (52)
What are the three types of muscle tissue?
skeletal, cardiac, smooth
Skeletal , Cardiac, and Smooth tissue Differ
In cell structure, body location, function, and the means by which they are activated to contract.
Skeletal , Cardiac, and Smooth tissue are Similar
In that all are elongated and contraction depends on 2 kinds of myofilaments
Skeletal Muscle Tissue
Packaged into the skeletal muscle that attach to and cover the bony skeleton. (STRIATED & VOLUNTARY)
Cardiac Muscle Tissue
Found only in the heart. STRIATED & VOLUNTARY). Gap junctions allow rapid communication between cells which synchronizes cell contractions.
Smooth Muscle Tissue
In walls of hollow organs-- stomach, bladder, respiratory tract. (NON STRIATED). (INVOLUNTARY CONTROL). Contractions are slow and sustained. Found in sheets of alternating circular and longitudinal layers.
List the functions of muscle
Movement, Maintenance of Posture, Joint Stability, Heat Generation.
Just about all movements result from muscle contraction. Skeletal muscles are responsible for all locomotion and manipulation. Skeletal muscles enable the body to respond quickly to changes in the external environment.
Maintenance of Posture
Muscles function almost continuously making small adjustments to maintain an erect or seated posture despite the effects of gravity.
Generate heat as the muscles contract. Vitally important in maintenance of normal body temperature. Skeletal muscles are most responsible.
Skeletal muscles help stabilize joints with poor reinforcement or noncomplementary articular surfaces--shoulder, knee.
Ability to receive and respond to stimuli
Ability to shorten and thicken forcibly. Unique to muscles.
Ability to STRETCHED or EXTEND. Muscle fibers shorten when contracting. They can be stretched beyonng their resting length when relaxed.
Ability of muscle fibers to recoil and resume their resting length after being stretched.
Functional Characteristics of Muscle
Excitability, Contractility, Extensibility, Elasticity
Each muscle fiber is seen to contain large numbers of rodlike myofibrils that run parallel to its length. Myofibrils are the contractile elements of SKELETAL MUSCLE. Contains 3 types of smaller structures call MYOFILAMENTS. (Thick, Thin, and Elastic)
Thick and Thin Myofilaments
Thick and Thin Myofilaments overlap one another. The pattern of theit overlap causes the cross striations seen in muscle fibers. Filaments inside a myofibril do not extend the entire length of a muscle fiber. They are arranged in compartments called SARCOMERES.
Nerve and Blood Supply
Each muscle receives a NERVE, ARTERY, and VEINS.
Consciously controlled skeletal muscle has nerves supplying EVERY fiber to control activity.
Contracting muscle fibers require huge amounts of oxygen and nutrients.
Also need waste products REMOVED QUICKLY.
Surrounds entire muscle
Connective tissue surrounding a fascicle
Surrounding each muscle fiber
Attachment to movable bone
Attachment to immovable or less movable bone
Epimysium fused to periosteum of bone or perichondrium of cartilage
connective tissue wrappings extend beyond muscle as ropelike tendon or sheetlike aponeurosis
Muscle fiber plasma membrane
Muscle fiber cytoplasm
Densely packed, rodlike elements. Single muscle fiber can contain 1000's. Accounts for 80% of muscle cell volume
The smallest contractile unit of muscle fiber. Contains A band with half an I band at each end. (CONSISTS OF AREA BETWEEN Z DISCS)
A bands (DARK)- I bands (LIGHT)- Z disc line-- Coined shaped sheet of proteins on midline of LIGHT I bands.
Striations, Sarcomeres, Myofilaments, Molecular composition of myofilaments
Thin filaments/ Extend across (LIGHT) I bands and partway in A band. Anchored to Z discs
Thick filament/ Extend length of (DARK) A bands
Intertwine to form myosin tail
Form myosin globular head
Composed of protein myosin that contains two heavy and four light polypeptide chains
Heads link thick and thin filaments together, forming cross bridges
Each THIN FILAMENT is composed of
Actin, Tropomyosin, and Troponin
Cross bridge attachment
Activated myosin heads are strongly attracted to the exposed binding sites on actin.
Myosin head pivots pulling on the thin filament, sliding it toward the center of the sarcomere. ENERGY REQUIRING step.
Cross bridge detachment
As new ATP binds to the myosin head, the myosin cross bridge is released.
Cocking of myosin head
Splitting of ATP provides the energy needed to return the head to its high-energy upright or cocked position
Formed by protrusion of sarcolemma deep into cell interior.
When an electrical impulse passes by, T tubule proteins change shape, causing SR proteins to change shape, causing release of calcium into cytoplasm
Pulled toward M line & become closer
Move closer to each other
Covers myosin binding sites on the actin molecules
A protein of muscle that together with tropomyosin forms a regulatory protein complex controlling the interaction of actin and myosin and that when combined with calcium ions permits muscular contraction
Sliding filament theory of contraction
During contraction, myosin cross bridges pull on the thin filaments, causing them to slide inward
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