Chapter 13

Arrange these events in transmission of an impulse from a motor neuron to the sarcolemma of a muscle cell according to the order that they occur, beginning with the arrival of a signal at the axon terminal.

1. A nerve signal arrives at the axon terminal. 2. Synaptic vesicles release acetlycholine (ACh). 3. ACh diffuses across the synaptic cleft. 4. ACh binds to receptors in the sarcolemma. 5. Electral signals spread down T tubules. 6. Calcium ions are realeased from the sarcoplasmic reticulum.

What supplies the energy for muscle contraction?

ATP

What ion is responsible for initiating muscle contraction?

Ca2+

What does the all-or-none law of muscle contraction state?

Muscle fibers will contract completely or not at all.

Select all of the following that are components of a muscle fiber.

T tubule sarcoplasm sarcolemma

In a skeletal muscle fiber, the sarcolemma forms _______ that penetrate into the cell and contact the sarcoplasmic reticulum.

T tubules

What do smooth, cardiac, and skeletal muscle all have in common?

The cells of these muscles are all called muscle fibers

When the nerve signal reaches the axon terminal, what happens next?

The synaptic vesicles release neurotransmitter.

Why are slow-twitch muscles darkly colored?

They contain myoglobin.

What is the deltoid muscle shaped like?

a triangle

According to the sliding filament model, which of these events occur during muscle contraction? Select all that apply.

actin filaments are pulled toward the center of the sarcomere myosin filaments break down ATP myosin filaments form cross bridges that pull on actin

Of the three pathways for supplying ATP to the muscle, which pathway(s) do slow-twitch fibers prefer?

aerobic respiration

The muscular system is made up of

all the muscles

What gives skeletal muscle its striated appearance?

arrangement of myofilaments

The synaptic cleft of a neuromuscular junction is the space between which two structures?

axon terminal sarcolemma

Select all of the following relationships between the skeletal and muscular systems that produce movement of the body.

bones store calcium needed for muscle contraction skeletal muscles contract and pull on bones contraction of jaw muscles and tongue allow you to grind food with the teeth

Match each type of muscle with the correct description of its structure.

cardiac - has intercalated disks; generally uninucleated skeletal - cells are multinucleated; fibers run the length of the muscle smooth - cells are spindle-shaped, each with a single nucleus

Match each type of muscle with the correct description of its function.

cardiac- involuntary pumping of blood skeletal- voluntary movement of body smooth- involuntary movement of substances in lumens of organs

The most efficient method of obtaining ATP for the activity of muscle cells is

cellular respiration

Select all of the body parts that contain smooth muscle.

colon stomach

Select all of the ways by which muscles help maintain body temperature.

constricting blood vessels shivering

What is the principle purpose of the muscular system?

create movement

From the outside of a muscle coming in, the first thing encountered would be

fascia

The type of muscle fibers that fatigue quickly, are light in color, and contain little or no myoglobin are ________-twitch fibers.

fast

Once a period of strenuous muscle activity has ended, about 80% of the accumulated lactate is converted back into

glucose

What is the biggest muscle (in terms of mass) in the body?

gluteus maximus

Match the muscle fiber structure with its function.

glycogen - energy storage for muscle contraction myoglobin - oxygen storage for muscle contraction sarcolemma - plasma membrane that forms T tubules sarcoplasm - contains organelles, including myofibrils sarcoplasmic reticulum - stores calcium needed for muscle contraction T tubule - extension of sarcolemma that conveys impulses

As members of the class of animals called vertebrates, humans have which characteristics?

jointed appendages internal vertebral column skeleton

Match the stages of a muscle twitch to the correct description.

latent period - time between stimulation and initiation of contraction contraction period - calcium leaves the sarcoplasmic reticulum and myosin-actin cross-bridges form. relaxation period - myosin-actin cross-bridges are broken, and calcium returns to the sarcoplasmic reticulum.

Muscle cells are most likely to obtain their ATP by cellular respiration during what type of exercise?

long, low intensity exertion

A nerve fiber with all of the muscle fibers it innervates is called a ______ unit.

motor

Select all correct descriptions of fast-twitch muscle fibers.

motor units contain many fibers helpful in sprinting or swinging a golf club usually anaerobic

What does the word sarco mean?

muscle

Select the four possible energy stores that can be used by muscles

muscle triglycerides blood glucose muscle glycogen plasma fatty acids

The cells that make up muscle tissue are called

myocytes

The long, cylindrical, contractile portions of a muscle fiber, which are composed of even smaller myofilaments, are called

myofibrils

The protein located in muscle cells that delivers oxygen directly to the mitochondria is

myoglobin

Of the three pathways for obtaining ATP for muscle contraction, which one requires oxygen?

only respiration

The ________of a muscle is on a stationary bone, and the_________ of a muscle is on a bone that moves.

origin, insertion

After muscle exertion, the continued increased intake of oxygen is called

oxygen debt

Select all of the following ways by which skeletal muscles protect the body.

pad and protect bones reinforce and cushion joints abdominal muscles protect internal organs

The sarcolemma of a muscle fiber is the

plasma membrane.

Which muscle provides protection to the abdominal organs?

rectus abdominus

The plasma membrane of a muscle fiber is called the _________.

sarcolemma

Within a myofibril, the distance from one Z line to the next is called a(n)

sarcomere

Which of the following stores calcium within a muscle fiber?

sarcoplasmic reticulum

What does the word brevis mean when referring to a muscle?

short

Of the three types of muscle tissue, which has multinucleated fibers?

skeletal

Of the three types of muscle tissue, which is voluntary?

skeletal muscle

Select the three types of human muscle tissue.

skeletal, smooth, and cardiac

Which type of muscle tissue contains fibers that are uninucleated and nonstriated?

smooth

Which type of muscle tissue is located in the walls of blood vessels and hollow internal organs?

smooth

When a person is cold they may develop "goose bumps" due to contraction of the arrector pili muscles, which are

smooth muscles that attach to hair follicles.

In good muscle tone, how many motor units are contracted?

some

What is the name of a sudden and involuntary muscular contraction, often accompanied by pain?

spasm

Select all of the functions of skeletal muscle.

support movement maintenance of constant body temperature

Match the function of skeletal muscles with the best description of how that function is provided.

support - contractions opposing force of gravity bone movement - contractions to make internal forces temperature - breakdown of ATP fluid movement - maintaining internal pressure protection - location of muscles

Fill in the blanks to complete the sentence. The small gap between the membrane of an axon terminal and the sarcolemma of a muscle fiber is called a _______ cleft.

synaptic

What is the name of the small gap that separates the axon terminal of a nerve from the sarcolemma?

synaptic cleft

Select all the components of a neuromuscular junction.

synaptic cleft axon terminal sarcolemma

What does the sliding filament model describe during muscle contraction?

the actin slide past the myosin

What information does the word rectus give you about a muscle?

the direction of the muscle fibers

What happens to the actin and myosin filaments when a muscle contracts?

they both stay the same length.

Select the two types of myofilaments that make up the myofibrils of a skeletal muscle fiber.

thick and thin

Match each type of myofilament that makes up the myofibrils of a skeletal muscle fiber with its major protein.

thick filament - myosin thin filament - actin

The origin of a muscle is the point of its attachment

to a stationary bone.

A muscle _______ is a single contraction of a motor unit.

twitch