The muscular system chapter 10

Muscles with fibers that run parallel to the long axis of the body are called

rectus

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

shortens

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

synaptic cleft

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

Active transport of calcium into the sarcoplasmic reticulum.

What happens to the lactate produced by skeletal muscle during peak activity?

Most of the lactate diffuses into the bloodstream and enters the liver where it is converted to pyruvate.

Define muscle hypertrophy and muscle atrophy

Muscle atrophy is the decrease in muscle strength due to a decrease in musclemass, or the amount of muscle fibers. Muscle hypertrophy is an increase in the size of a muscle through an increase in the size of its component cells.

When do muscle fibers produce lactate?

Muscle fibers produce lactate when there is a lack of oxygen.

Membrane potential is

a potential gradient that forces ions to passively move in one direction: positive ions are attracted by the 'negative' side of the membrane and negative ions by the 'positive' one.

Na+ and K+ both use ________ to passively diffuse across the plasma membrane.

diffusion

Individual muscle cells are surrounded by what connective tissue?

endomysium

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

epimysium

List the muscles of the tongue

genioglossus, the hyoglossus(often including the chondroglossus) the styloglossus, and the palatoglossus.

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

have many nuclei

Muscles including the term "capitis" would be found within or attached to the

head

The ________ muscle allows you to look down.

inferior rectus

Muscles located entirely within an organ are called

intrinsic

Describe the neuromuscular junction

is a synaptic connection between the terminal end of a motor nerve and a muscle

Identify three sources of stored energy utilized by muscle fibers.

ATP, creatine phosphate, and glycogen

The function of the appendicular muscles is to

support, move, and brace the limbs.

What is the function of the axial muscles?

1. Support and move head and spinal column 2. Function in nonverbal communication by affecting facial features 3. Move lower jaw during mastication 4. Assist in food processing and swallowing 5. Aid in breathing 6. Support and protect the abdominal and pelvic organs.

Define tendon and aponeurosis.

A tendon is a projection of connective tissue beyond the ends of the muscle that attaches to the bone. An aponeurosis is a broad fibrous sheet of connective tissue that connects the muscle to adjacent muscles.

During the ________ phase of action potential development, voltage-gated sodium channels are open.

Depolarization phase

Compare incomplete tetanus with wave summation.

Incomplete tetanus refers to a muscle producing near-peak tension during rapid cycles of contraction and relaxation. Wave summation refers to the addition of one twitch to another.

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

It would cause muscles to stay contracted

Muscle A abducts the humerus and muscle B adducts the humerus. What is the relationship between the two muscles.

Muscles A and B are antagonists, because they perform opposite actions.

________ are stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue.

Myosatellite

Muscular walls of the thorax and abdomen are composed of ......

Oblique and rectus muscles

The muscle that medially rotates and flexes (unlocks) the knee joint is the

Popliteus

The plasma membrane of skeletal muscle is called the

Sarcolemma

Which muscle types are voluntary, and which are involuntary?

Skeletal muscle is voluntary and striated, cardiac muscle is involuntary and straited and smooth muscle is involuntary and non-striated.

What causes calcium to be released from the sarcoplasmic reticulum

The inward flow of calcium from the L-type calcium channels activates ryanodine receptors to release calcium ions from the sarcoplasmic reticulum.

The structural explanation of how a muscle fiber contracts is called the

Sliding Filament Theory

The muscle that elevates the tongue is the

Styloglossus

Name the extrinsic eye muscles.

Superior rectus, Inferior rectus, Lateral rectus, Medial rectus, Superior obliqueand Inferior oblique

At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a

Tendon

Define depolarization, and describe the events that follow it.

a cell is depolarized when a threshold potential is reached and Na+ rush into the cell. The depolarization peaks at +30mV. Na+ inflow then abruptly stops and repolarization begins at K+ rush out of the cell. This loss of positive ions causes the membrane potential to become negative again.

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

acetylcholine

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

additional oxygen is required to restore energy reserves

What molecule supplies the energy for a muscle fiber contraction?

adenosine triphosphate (ATP)

A resting muscle generates most of its ATP by

aerobic metabolism of fatty acids

What are the divisions and functions of the muscular system?

axial and appendicular divisions

When a muscle is stimulated repeatedly at a high rate, eliminating a relaxation phase, the amount of tension gradually increases to a steady maximum tension. This is called

complete tetanus

Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for

contraction

The zygomaticus major muscle acts to

controls facial expression, drawing the mouth's angle upward and outward. The zygomaticus major muscle starts at the cheekbone and extends to the corner of the mouth. This muscle causes the corners of a person's mouth to rise when they smile.

A fan-shaped muscle with a broad origin and fascicles that attach to a common site is a

convergent muscle

The muscle weakness of myasthenia gravis results from

loss of acetylcholine receptors in the end-plate membrane.

Define motor unit

made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals.

The Na+/K+ ion pump is responsible for

maintaining the sodium/potassium concentration gradients constant.

Pam's daughter is born cross-eyed. As she grows, the problem does not improve. Her physician suggests cutting an eye muscle to bring the eyes into a more normal position. Which muscle will the doctor cut?

medial rectus

Muscles located close to the midline of the body may be called

medialis

Cellular membrane potential is measured in

millivolts

During activities requiring aerobic endurance,

most of the muscle's energy is produced in mitochondria.

Receptors for acetylcholine are located on the

motor end plate

Neurons and ________ have electrically excitable membranes that propagate action potentials.

muscle cells

Define the term synergist as it relates to muscle action.

muscle that helps a larger agonist (or prime mover- a muscle that is responsible for a specific movement) perform its actions more efficiently.

Skeletal muscle fibers are formed from embryonic cells called

myoblasts

Muscles with fibers that run at an angle to the long axis of the body are called

oblique

The "kissing muscle" that purses the lips is the

orbicularis oris muscle

The end of a muscle that remains stationary when the muscle contracts is called the

origin

Name the clinical condition affecting skeletal muscle, which is caused by a virus?

polio

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 repeating contractile unit of a skeletal muscle fiber is the

sarcomeres

Medial rotation of the eyeball is performed by the ________ muscle.

superior oblique muscle

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

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

Define oxygen debt (excess postexercise oxygen consumption).

the amount of oxygen intake required to produce the ATP needed to restore the body after strenuous activity.

During the Cori cycle, what happens in the liver

the liver absorbs lactate and converts it to pyruvate and glucose is distributed back to the muscle cells

A muscle whose name ends in the suffix "-glossus" would be found within or attached to the

tongue

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

twitch

If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called

wave summation