A & P CH 6 (12th) —— The Muscular System

Where is the epimysium locate?

Outside of muscle.

Which of these muscles is located on the ventral (anterior) side of the body?

Pectoralis major.

Muscle development in babies occurs in a _____________________________ direction.

Superior/inferior proximal/distal

A skeletal muscle twitch differs from a tetanic contraction in that _____________________.

The muscle twitch is a brief and "jerky" movement, while the tetanic contraction is prolonged and continuous.

Which facial muscle is considered the "smiling" muscle since it raises the corners of the mouth?

Zygomaticus.

Which of the following muscles are antagonists?

biceps brachii and triceps brachii

Cardiac muscle fibers are joined by special gap junctions called ________________________.

intercalated discs.

Contractions in which muscles shorten and produce movement are known as ________.

isotonic contractions

Describe the events that occur from the time that a motor neuron releases acetylcholine at the neuromuscular junction until muscle cell contraction occurs.

- Acetylcholine diffuses across synaptic cleft - Acetylcholine attaches to receptors along the folded sarcolemma - Sodium and Potassium moving in a out like usual prior - Sodium channels open and sodium floods in - More sodium is moving in than Potassium is moving out, causing a change in charges and thus, depolarization - Once depolarization occurs, action potential (or nerve impulse) can move across muscle cell - Calcium ions released and attach and cause protein to change shape - Cross bridges form and slide past one another (muscle cell contracts)

Identify the four quadriceps muscles. (bonus)

- rectus femoris - vastus medialis - vastus lateralis -vastus intermedius

What creates the alternating light and dark bands that provide the striation pattern on skeletal muscle tissue?

A bands and I bands.

What does the perimysium wrap?

A fascicle of muscle cells.

The mechanical force of contraction is generated by _________________.

A sliding of thin filaments past thick filaments.

The movement of a limb away from the body midline.

Abduction.

What is released by axon terminals into the synaptic cleft to stimulate a muscle to contract?

Acetylcholine.

What enzyme breaks down acetylcholine into acetic acid and choline to prevent continued contraction of the muscle fibe?

Acetylcholinerase.

What is the unstoppable electrical current that travels down the length of the entire surface of a sarcolemma?

Action potential

Which movement is opposite to abduction?

Adduction.

Which method of regenerating ATP during muscle contraction can produce lactic acid?

Anaerobic fermentation.

Muscles that perform opposite actions to one another are termed

Antagonists.

Which of the following is NOT a function of the muscular system?

Blood cell formation. Functions ARE: - production of movement - maintenance of posture - stabilization of joints - generation of heat

Like the biceps brachii muscle, which muscle is a prime mover in elbow flexion?

Brachialis.

Why are calcium ions necessary for skeletal muscle contraction?

Calcium ions trigger the binding of myosin heads to actin filaments.

The sarcoplasmic reticulum wraps like a sleeve around the myofibril and stores and releases _____________________.

Calcium.

Striated involuntary muscle tissue is classified as ________ muscle.

Cardiac

The arrangement of fascicles in orbicularis oris is

Circular

What term is used when the fascicles of a muscle come together at a single insertion tendon? It produces a muscle that is triangular or fan-shaped. (bonus)

Convergent.

The heads of the myosin myofilaments are called ________ when they link the thick and thin filaments together during skeletal muscle contraction.

Cross bridges

The prime mover of arm abduction is the _____________________ muscle.

Deltoid.

The fastest mechanism for producing ATP is ______________________.

Direct phosphorylation (CP).

________________ and _________________________ refer to up and down movements of the foot at the ankle.

Dorsiflexion and plantarflexion.

Which muscle forms the curved calf of the posterior leg?

Gastrocnemius.

A smooth, sustained contraction, with no evidence of relaxation, is called __________.

Fused, or complete, tetanus

Anaerobic glycolysis requires _______ to make ATP.

Glucose only.

Skeletal muscle, as a whole, can generate different amounts of force, and different degrees of shortening, in response to stimuli. What is this concept called?

Graded response.

What is the endomysium?

It surrounds muscle fibers.

What is the main function of the quadriceps group?

Knee extension.

Which of the following consists of two large, flat muscles that cover the lower back?

Latissimus dorsi.

Which one of the following is NOT a criterion generally used in naming msucles?

Method of attachment of the muscle to bone.

One neuron and all the skeletal muscles it stimulates is known as a ________.

Motor unit

An inherited disease that causes muscles to degenerate and atrophy is known as ______________________.

Muscular dystrophy.

The gap between the axon terminal of a motor neuron and the sarcolemma of a skeletal muscle cell is called the ____________________.

Neuromuscular junction.

The point of muscle attachment to an immovable or less movable bone is known as the ________.

Origin

Which muscle helps compress the abdominal contents during defecation or childbirth?

Rectus abdominis.

Explain what meaning is inferred in the muscle name rectus femoris. (bonus)

Rectus: vertical, or straight up and down, muscle. Femoris: located on the femur.

The plasma membrane of a skeletal muscle cell is called the ________________________.

Sarcolemma.

What organelle wraps and surrounds the myofibril and stored calcium?

Sarcoplasmic reticulum

Which term does NOT describe smooth muscle cells?

Skeletal. NOT: - visceral - nonstriated - involuntary

The type of muscle tissue that is shown in figure (nonstriated, involuntary, and uninucleate).

Smooth muscle.

What must rush into a muscle cell to promote its depolarization?

Sodium ions.

Depolarization of a skeletal muscle cell leads to the opening of more channels that only allow _______________.

Sodium.

Creatine phosphate (CP) functions within the muscle cells by ________________.

Storing energy that will be transferred to ADP to resynthesize ATP as needed.

The muscle fiber is also referred to as the muscle _____.

The muscle cell.

Which of the following is composed mostly of the protein myosin?

Thick filaments. (thin filaments are actin)

Jason injured his hamstring muscle group during football practice. He will be unable to perform ___________________.

Thigh extension and knee flexion.

Which of these muscles is the prime mover of the elbow extension?

Triceps brachii.

Muscle tissue has the ability to shorten when adequately stimulated, a characteristic known as

contractility

The striations seen in skeletal muscle are actually alternating _____________________________.

dark A and light I bands.

type of movement that points the toes.

plantar flexion.

The movement of a bone around its longitudinal axis.

rotation.

A sarcomere is _________________.

the contractile unit between two Z discs

The condition of skeletal muscle fatigue can be best explained by __________________.

the inability to generate sufficient quantities of ATP due to feedback regulation of synthesis.