CH 9 : MUSCLES AND MUSCLE TISSUSES, FINAL REVIEW

Describe the events occurring during the three phases of a muscle twitch.

1) Latent period: events of excitation-contraction coupling 2) Period of contraction: cross bridge formation; tension increases 3) Period of relaxation: Ca2+reentry into the SR; tension declines to zero

What protein makes up thin filaments? actin

actin

What type of neurons Smooth muscle?

autonomic

The sequence of events for muscle contractions?

motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments or Nerve impulse 1. Activation of Muscle by Ach at neuromuscular junction: (wave "jumps" from neuron to muscle) Muscle impulse 2. Excitation-contraction coupling: Link between electrical event (impulse) and mechanical event (sliding of myofilaments) Contraction (Increase in intracellular Ca2+ signals "go" )

a motor neuron and all the muscle cells it stimulates motor unit

motor unit

The response of a muscle to a single brief threshold stimulus. muscle twitch

muscle twitch

What protein makes up thick filaments? myosin

myosin

Do smooth muscle fibers have sarcomeres? Myofibrils? Myofilaments?

no sarcomeres or myofibrils, but does contain myofilaments

the sheath of connective tissue surrounding a bundle of muscle fibers. perimysium

perimysium

the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wavelike movements that push the contents of the canal forward.

peristalsis

the fine transparent tubular sheath that envelops the fibers of skeletal muscles. sarcolemma

sarcolemma

a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band. The smallest unit of muscle.

sarcomere

Myofilaments are arranged in repeating, functional units called __________. sarcomeres

sarcomeres

the cytoplasm of striated muscle cells. sarcoplasm

sarcoplasm

a specialized type of smooth ER that regulates the calcium ion concentration in the cytoplasm of striated muscle cells.

sarcoplasmic reticulum

Which is the only muscle conscious (voluntary) control? skeletal

skeletal

What are the 3 types of muscle in the human body? skeletal, cardiac, smooth

skeletal, cardiac, smooth

Would motor units serving eye movement be large or small? small

small

The walls of hollow organs and large blood vessels contain this type of muscle tissue. smooth

smooth

What type of neurons innervate skeletal muscle?

somatic

Muscles attach to bone via rope-like dense regular connective tissues called ________. tendons

tendons

The four factors that influence contractile force are

the number of muscle fibers stimulated the relative size of the fibers the frequency of stimulation the degree of muscle stretch

What is the primary function of the sarcoplasmic reticulum in skeletal muscle?

Regulate intracellular calcium concentration

Compare and Contrast the basic types of muscle tissue

(1) Skeletal Muscle-is associated with the bony skeleton, and consists of large cells that bear striations and are controlled voluntarily. somatic (2) Cardiac Muscle-occurs only in the heart, and consists of small cells that are striated and under involuntary control autonomic (3) Smooth Muscle-is found in the walls of hollow organs, and consists of small elongated cells that are not striated and are under involuntary control. Autonomic

Describe the sliding filament model of contraction.

In the relaxed state, thin and thick filaments overlap only slightly During contraction, myosin heads bind to actin, detach, and bind again, to propel the thin filaments toward the middle of myosin (filaments overlap more) Sarcomeres shorten, muscle cells shorten, and the whole muscle shortens

Define muscle tone.

Maintained due to partial contraction of relaxed portions of skeletal muscle. There are ALWAYS a few muscle fibers within a muscle that are contracted while most are relaxed. This is ESSENTIAL in maintaining posture. or A continuous passive partial contraction of muscles

What structures make up a "triad" and what is its role in muscle contraction?

Triad are successive groupings of two terminal cisterns and IT-Tubule. Triads help to ensure every myofibril in the muscle fiber contracts at virtually the same time.

meaning within the muscle, is a wispy layer of areolar connective tissue that ensheaths each individual myocyte (muscle fiber, or muscle cell). It also contains capillaries and nerves. It overlies the muscle fiber's cell membrane: the sarcolemma. endomysium

endomysium

a sheath of fibrous elastic tissue surrounding a muscle. epimysium

epimysium

Describe factors that influence the velocity and duration of contraction are the muscle

fiber type, load and recruitment.

Muscle cells are referred to as ________.

fibers

What feature in single-unit smooth muscle tissue allows cells to contract as a sheet (in unison)? gap junctions

gap junctions