Anatomy and Physiology Chapter 7

A resting muscle generates most of its ATP by

aerobic respiration.

Which muscle is not part of the rotator cuff set of muscles?

biceps brachii

Which of the following acts to flex the elbow?

brachioradialis

The enzyme acetylcholinesterase causes acetylcholine to

break down.

In response to action potentials arriving from the transverse tubules, the sarcoplasmic reticulum releases

calcium ions.

Muscle cells

can only contract.

Active muscles generate

carbon dioxide and heat.

During which phase is the stimulus frequency so high that the relaxation phase is eliminated?

complete tetanus

Which of the following muscles is named for its shape? A) pectoralis major B) biceps brachii C) deltoid D) erector spinae E) tibialis anterior

deltoid

Which of the following muscles acts to flex the finger joints and wrist?

flexor digitorum

A muscle ________ contains a sarcolemma, sarcoplasm, myofilaments, and myofibrils.

fiber

The muscle that inserts on the iliotibial tract and gluteal tuberosity of the femur is the

gluteus maximus.

Regarding muscle fiber elongation,

gravity may help lengthen a muscle fiber after elongation.

Glycolysis

is an anaerobic process.

Calcium ions are released from the sarcoplasmic reticulum during the ________ phase of contraction.

latent

Which of the following inserts into the intertubercular groove of the humerus and acts to extend, adduct, and rotate the shoulder?

latissimus dorsi

The specialized sarcolemma that contains acetylcholine receptors is the

motor end plate.

The additional oxygen required during the recovery period to restore the normal pre-exertion levels is called the

oxygen debt.

Which of the following originates from the cartilages of ribs 2-6, the sternal body, and the clavicle?

pectoralis major

A sheath of connective tissue surrounding a bundle of striated muscle fibers is called

perimysium

Muscle fascicles are separated by

perimysium

Botulism

results from a bacterial toxin that prevents the release of acetylcholine at the axon terminals.

(Structural Components of a Skeletal Muscle Fiber) Structure C is the

sarcoplasmic reticulum.

Which of the following occurs when tension production rises to a peak and very brief periods of relaxation occur?

incomplete tetanus

"Anaerobic endurance"

is exemplified by contractions of fast muscle fibers.

Regarding lactic acid regulation, which cells in the body consume extra oxygen and produce ATP for the conversion of excess lactate absorbed from the blood back to glucose?

liver cells

Looking at the muscle name sternocleidomastoid, you would identify that this muscle is located in the area of the

neck.

The difference in the action when comparing the biceps brachii to the flexor carpi radialis, is

one muscle flexes the hand at the wrist and the other flexes the entire forearm.

(Structural Components of a Skeletal Muscle Fiber) Structure E is the

sarcolemma.

The active sites on actin molecules are usually covered up by other molecules. What is the critical material required to uncover the active sites on the actin molecules that will then bind to myosin heads?

calcium

(Structural Components of a Skeletal Muscle Fiber) The structures labeled F are the

mitochondria.

The less-movable end of a skeletal muscle is the

origin.

Which of the following inserts into a tendinous sheet, rather than a bone?

palmaris longus

Which muscle is not attached in some way to the scapula?

sternocleidomastoid

The ________ contains vesicles filled with acetylcholine.

axon terminal

Each myofibril consists of approximately ________ sarcomeres.

10,000

Place these steps of muscle contraction in the correct order. 1. Action potential is generated along the sarcolemma 2. Nerve impulse arrives at synapse 3. Calcium is released into muscle cell cytoplasm 4. Acetylcholine is produced 5. Actin and myosin molecules continuously cross-link, with actin molecules being pulled inward

2, 4, 1, 3, 5

The region of a sarcomere containing myosin, going from one end of the myosin molecules to the other end of the myosin molecules, is the

A band.

Choose the correct statement regarding motor units.

A motor neuron may control only two or three muscle fibers of the eye muscle(s).

Essay Questions. You have a large garden with a variety of fruits, vegetables, and flowers, and you have a problem with insects eating them. You decide to use Malathion, an organophosphate insecticide, but you are not terribly careful about protecting yourself as you are spraying. Worried, you decide to look up the action of Malathion and find that it is an acetylcholinesterase inhibitor. Explain how this chemical affects muscle contraction and include where it has its effect and why.

AChE is the enzyme that splits up acetylcholine or ACH. ACH is the neurotransmitter at the neuromuscular junction. If ACHE, or acetylcholinesterase, is blocked by the insecticide, it will no longer be at the synapse to break down ACH. The continued presence of ACH then causes continuous contractions until the muscle fatigues.

The stiffness that occurs at death, when actin and myosin molecules stay linked to each other in a contracted state, is due to a lack of

ATP.

Which of the following is one of the steps that ends a contraction?

Acetylcholine is broken down by acetylcholinesterase.

Essay Questions. While unloading the trunk of her car, Amy pulls a muscle. As a result, she has difficulty moving her arm. The attending physician in the emergency room tells her that she injured her latissimus dorsi muscle. Knowing that the latissimus dorsi was a back muscle, Amy doesn't understand what the muscle has to do with her injured arm. Explain the involvement of the muscle in Amy's injury.

Although the latissimus dorsi muscle is located across the back, it inserts on the humerus, the large bone of the upper arm. When the muscle contracts, it contributes to extension, adduction, and medial rotation of the humerus. All of these arm movements would be partially impaired if the muscle were damaged.

Essay Questions. Because Mary wants to enter a marathon, she decides to consult a trainer who happens to be a kinesiologist. The trainer advises her on what type of muscle fibers she needs to develop and how she should train for it. Which type of muscle fibers are involved? Briefly explain the anatomy and physiology of the trainer's advice.

As marathons require aerobic endurance, Mary would want to develop her slow fibers for long-term endurance. She would achieve this by engaging in activities that involve long-term mild to moderately intense workouts involving mostly leg and postural muscles, such as jogging, biking, swimming, and core exercises. Repeated long-term stimulation will help the slow fibers develop more mitochondria and a higher concentration of aerobic enzymes as well as slightly increase the size and strength of the muscles (hypertrophy).

Which of the following is characteristic of cardiac muscle?

Cardiac muscle cells are striated.

During moderate activity, which of the following is true regarding muscle metabolism?

Glucose and fatty acids are catabolized.

The area of the sarcomere that is the light region between two successive A-bands is the

I band.

Which of the following occurs when glycolysis produces pyruvate faster than it can be used by the mitochondria?

Lactic acid is produced.

Why do individual muscle twitches have to be added together, as in summation or tetanus?

Multiple twitches add up to an increase in muscle fiber tension, which increases the strength of the muscle.

Which of the following is true about red muscles?

Red muscles are slower than white muscles.

Which of the following is an accurate characteristic of slow fibers?

Resting slow muscle fibers contain oxygen reserves, bound to myoglobin.

Which of the following statements describes how muscles help maintain homeostasis?

Skeletal muscle contractions help maintain body temperature.

Which of the following is an effect of aging on the muscular system?

Skeletal muscle fibers become smaller in diameter.

The deltoid acts to

abduct the arm.

Upon the nerve impulse arriving at the axon terminal,

acetylcholine is released.

The striated appearance of skeletal muscle results from

actin and myosin arrangement.

(Structural Components of a Skeletal Muscle Fiber) Structure I is composed of

actin and myosin.

Myofibrils are made primarily of

actin and myosin.

Which of the following terms is a descriptive word for a muscle's action?

adductor

Which of the following is the origin of the pectoralis minor?

anterior surfaces of ribs 3-5

Smooth muscle cells

are spindle-shaped.

A muscle that inserts on the radial tuberosity or the ulnar tuberosity is most likely involved in

elbow flexion.

Which of the following describes the action of the trapezius?

elevates, adducts, depresses, or rotates the scapula

Which of the following is an origin of the pronator teres?

epicondyle of the humerus

A layer of collagen fibers that surrounds an entire muscle is called

epimysium.

Which muscle would not move the scapula?

erector spinae

Which of the following muscles functions to maintain an erect spinal column and head? A) erector spinae B) biceps brachii C) triceps brachii D) rectus femoris E) biceps femoris

erector spinae

Which muscle(s) would produce a twisting of the upper body?

external and internal oblique muscles

Fast fibers

have high glycogen reserves.

Skeletal muscle fibers differ from "typical cells" in that these muscle fibers

have many nuclei.

The term used to describe muscular growth in response to usage is

hypertrophy.

Exhaustion of energy reserves or decline in pH due to production and dissociation of lactic acid causes

muscle fatigue.

Which of the following occurs as a result of motor units in a particular muscle being always active, even though their contractions do not produce enough movement to cause contraction?

muscle tone

(Structural Components of a Skeletal Muscle Fiber) Structure J represents a

myofibril.

After death, rigor mortis lasts until

myofilaments are broken down.

(Structural Components of a Skeletal Muscle Fiber) Structure G is composed of

myosin.

The muscle that originates from the superior surface of the pubis around the symphysis is the

rectus abdominis.

Muscles comprising the quadriceps group include the

rectus femoris, vastus intermedius, vastus lateralis, and vastus medialis.

The insertion of the anterior part of the frontalis muscle is the

skin of the eyebrow and the bridge of the nose.

A person whose genetic makeup makes him or her a better marathon runner than a sprinter probably has more ________ in his or her leg muscles.

slow fibers

Nonstriated, involuntary muscle is

smooth

As a skeletal muscle contraction is initiated, acetylcholine binding alters the motor end plate membrane's permeability to

sodium ions.

The muscle that produces the action of standing on tip-toes is the

soleus.

(Structural Components of a Skeletal Muscle Fiber) Structure B

stores calcium.

Creatine phosphate serves to

supply energy to synthesize ATP.

Acetylcholinesterase is found within the

synaptic cleft.

The muscle that inserts on the coronoid process of the mandible is the

temporalis.

Which of the following is a muscle of the rotator cuff?

teres minor

(Structural Components of a Skeletal Muscle Fiber) The triad, seen as structure D, is composed of

the cisterna of the sarcoplasmic reticulum along with the T tubules.

The heart has to be able to regulate its contractions. Heart muscle, unlike skeletal muscle, cannot go into a tetanus. This is because

the heart muscle has to be able to consistently contract and pump blood in a controlled fashion.

Regarding a skeletal muscle fiber, wherever a T-tubule encircles a myofibril, the tubule is tightly bound to

the sarcoplasmic reticulum.

(Structural Components of a Skeletal Muscle Fiber) Structure H is the

thin myofilament.

Tom is having difficulty dorsiflexing and inverting his right foot. Which muscle is most likely involved in this problem?

tibialis anterior

The muscle that dorsiflexes the foot is the

tibialis anterior.

What is the function of the transverse tubule?

to transmit electrical impulses to the cell's interior

You are lying on the floor with your feet flat and your knees up practicing your abdominal crunches. You raise your upper body to the ceiling, up and down. What muscles are you using to the greatest extent?

transverse abdominis

Which muscle inserts on the clavicle and the acromion and spine of the scapula?

trapezius

Which muscle extends the elbow during the action of push-ups?

triceps brachii

Tropomyosin strands are held in position by which of the following?

troponin molecules

A single stimulus-contraction-relaxation sequence in a muscle fiber is known as a(n)

twitch.

Smooth muscle

uses primarily aerobic metabolism.

The muscle that originates along the entire length of the linea aspera of the femur is the

vastus medialis.

The muscle that would be used to blow air into a trumpet or a clarinet is the

buccinator.

Which statement regarding the relaxation phase of a muscle twitch is true? A) The phase begins at stimulation and typically lasts about two milliseconds. B) Muscle tension falls to resting levels. C) The action potential sweeps across the sarcomere during this period. D) Tension rises to a peak. E) Cross-bridges are interacting with active sites on actin filaments throughout this period.

Muscle tension falls to resting levels.

Which statement regarding isometric contractions is true? A) Tension rises during a contraction. B) The skeletal muscle's length changes. C) The tension produced never exceeds the load. D) Tension remains at a constant level until relaxation occurs. E) Examples are walking and running.

The tension produced never exceeds the load.

The area between Z lines is the

sarcomere

The terminal cisternae are structural features of the

sarcoplasmic reticula.

The skeletal muscles store calcium ions in the terminal cisternae of the

sarcoplasmic reticulum.

Which statement regarding skeletal muscle is true? A) Skeletal muscles are directly, but not indirectly, attached to bones. B) Skeletal muscles do not contain connective tissue. C) Skeletal muscles do not maintain body temperature. D) Skeletal muscles do not contain nervous tissue. E) Skeletal muscles contain blood vessels.

Skeletal muscles contain blood vessels.

(Structural Components of a Skeletal Muscle Fiber) Label A is pointing to

T tubules.

Which of the following is a muscle that originates from the zygomatic arch and functions in elevating the mandible?

masseter

During activities requiring aerobic endurance,

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

Neurotransmitters that cause skeletal muscle contraction are normally stored in

motor neuron axon terminals.

In infants, which muscle allows for the mouth to form a tight fit around the nipple during suckling at the breast?

orbicularis oris

Which statement regarding "heat loss" is true? A) Muscle activity does not generate heat. B) Shivering in a cold environment results in higher levels of heat loss. C) When skeletal muscles are contracting at peak levels, body temperature drops. D) Heat loss is reduced when blood flow to the skin increases. E) Muscle contractions play an important role in the maintenance of normal body temperature.

Muscle contractions play an important role in the maintenance of normal body temperature.