Anatomy and Physiology Ch. 10

The muscle weakness of myasthenia gravis results from

loss of acetylcholine receptors in the end plate membrane

In a sarcomere, thick filaments are linked laterally by proteins of the

M line

Which type of muscle tissue has the greatest effect on the body's heat production?

Skeletal

The action potential is conducted into a skeletal muscle fiber by

Transverse tubules

Sarcomere is best defined as ___________.

a repeating unit of striated muscle.

The rapid rise and fall in force produced by a muscle fiber after a single action potential is

a twitch

Skeletal muscle does each of these except __________. a.pump blood b.ventilate the lungs c.maintain posture d.produce movement

a. pump blood

During neuromuscular transmission, the axon terminals release __________.

acetylcholine

The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the neurotransmitter

acetylcholine

Triggering of the muscle action potential occurs after

acetylcholine binds to chemically gated channels in the end plate membrane

The biochemical reaction that consumes the majority of a muscle's ATP is the __________.

actin myosin cross-bridge cycle

The most important factor in decreasing the intracellular concentration of calcium ion after contraction is

active transport of calcium into the sarcoplasmic reticulum

Creatine phosphate

acts as an energy reserve in muscle tissue

During the recovery period the body's need for oxygen is increased because

additional oxygen is required to restore energy reserves consumed during exercise.

A resting muscle generates most of its ATP by

aerobic metabolism of fatty acids.

After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs.

an oxygen debt

Muscles are attached to bones by tendons or __________.

aponeuroses

Active sites on the actin become available for binding after

calcium binds to troponin

During anaerobic glycolysis.. a. ATP is produced b. Carbohydrate is metabolized c. oxygen is not consumed. d. pyruvic acid is produced d. All of the above

d. all of the above

Which of these is true of cardiac muscle fibers? a. Cardiac fibers branch b. cardiac fibers have a long twitch duration compated to skeletal fibers. c. Cardiac fibers have a single nucleus. d. all of the above

d. all of the above

To increase muscle tension, the nervous system can __________. a. increase the stimulation frequency b. recruit larger motor units c. increase the number of active motor units. d. all of the above

d. all of the above.

When a skeletal muscle fiber contracts.... a. the zones of overlap get larger b. the H bands and I bands get smaller c. the width of the A band remains constant. d. The Z lines get closer together. e. all of the above

e. all of the above

When comparing slow muscle fibers to fast muscle fibers, slow fibers a. have much smaller giver diameters b. are rich in red protein myoglobin c. generate much less tension d. take about three times as long to reach peak tension e. all of the above

e. all of the above

The dense layer of connective tissue that surrounds an entire skeletal muscle is the

epimysium

Synaptic vesicles contain neurotransmitters that are released by ________ when the action potential arrives.

exocytosis

The __________ type of muscle fiber has relatively few mitochondria.

fast

Which of the following is not a function of smooth muscle tissue?

forcing blood from the heart into the major arteries

During the Cori cycle, in the liver

glucose is produced from lactic acid

Fast fibers

have low resistance to fatigue and have quick twitches

Muscle fibers differ from "typical cells" in that muscle fibers

have many nuclei

All of the following are found in both skeletal and cardiac muscle fibers except __________.

intercalated disks

When a muscle contraction develops tension but doesn't shorten the muscle, the contraction is called __________.

isometric

How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?

it would cause spastic paralysis

Muscle fatigue occurs due to a buildup of __________ and __________ in pH.

lactic acid; decrease

When acetylcholine binds to receptors at the motor end plate, the end plate membrane becomes

more permeable to sodium ions

Receptors for acetylcholine are located on the

motor end plate

In an isotonic contraction,

muscle tension exceeds the load and the muscle lifts the load.

Skeletal muscle fibers are formed from embryonic cells called

myoblasts

Which thick filament binds to actin once its active binding sites are exposed?

myosin

Each skeletal muscle fiber is controlled by a motor neuron at a single

neuromuscular junction

Anaerobic glycolysis provides energy for muscle contraction when the supply of __________ is limited.

oxygen

A thin layer of connective tissue that surrounds a muscle fascicle is called the __________.

perimysium

The ability of smooth muscle to function over a wide range of lengths is called

plasticity

A patient takes a medication that blocks ACh receptors of skeletal muscle fibers. What is this drug's effect on skeletal muscle contraction?

reduces the muscles ability for contraction

Fast muscle fibers can adapt to aerobic metabolism by generating more mitochondria in response to

repeated, exhaustive stimulation

After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as

rigor mortis

The plasma membrane of a skeletal muscle fiber is called the

sarcolemma

In response to an action potential along the transverse tubules, the __________ release(s) calcium ions into the sarcoplasm.In response to an action potential along the transverse tubules, the __________ release(s) calcium ions into the sarcoplasm.

sarcoplasmic reticulum

The series of membranous channels that surround each myofibril is the

sarcoplasmic reticulum

Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber

shortens

The type of muscle fiber that is most resistant to fatigue is the ________ fiber.

slow

The narrow space between the synaptic terminal and the muscle fiber is the

synaptic cleft

The advantage of having many nuclei in the skeletal muscle fiber is

the ability to produce large amounts of the muscle proteins needed for growth and repair.

The muscle action potential penetrates into a fiber along the __________.

transverse tubules

At rest, active sites on the actin are blocked by

tropomyosin molecules

When calcium ion binds to troponin,

tropomyosin moves into the groove between the helical actin strands

In a sarcomere, cross-bridge attachment occurs specifically in the

zone of overlap