Untitled Flashcard Set

Movable end of a muscle

The end of a muscle that is not fixed in place during contraction.

Transverse (T) tubules

Extensions of the muscle cell membrane that penetrate into the cell, allowing for the spread of the action potential.

The width of the ___ remains constant during muscle contraction.

A band.

Myofibrils are composed primarily of

Actin and myosin proteins.

Myofibrils are surrounded by modified endoplasmic reticulum called the

Sarcoplasmic reticulum.

What collagen structure attaches skeletal muscle to bone?

Tendons.

Which of the following muscles has its insertion on the sternum?

Pectoralis major.

Muscle atrophy that progresses with aging is caused by reduction in

Muscle fiber size or number.

Which of the following muscles compresses the abdomen?

Rectus abdominis.

A muscle that assists the prime mover is called a(n)

Synergist.

Cardiac muscle

Involuntary muscle tissue found only in the heart.

The type of muscle cell that lacks transverse tubules, has one nucleus, and is involuntary is

Smooth muscle.

Age-related muscle atrophy involves a reduction in

Muscle mass.

A threshold stimulus is the

Minimal stimulus required to cause a contraction.

Skeletal muscles will contract

When stimulated by motor neurons.

The muscles that support, move, and brace the limbs are called

Skeletal muscles.

The linea alba is

A fibrous structure that runs vertically along the midline of the abdomen.

Acetylcholine release at a neuromuscular junction is triggered by

The arrival of an action potential.

The first event in muscle-fiber contraction is that

Calcium ions are released from the sarcoplasmic reticulum.

Increasing the number of active motor units in a contracting muscle is called

Motor unit recruitment.

A plank held in a fixed position primarily involves an contraction of the abdominal muscles.

Isometric.

Substances muscle cells create as energy reserves while at rest include

Glycogen.

Oxygen debt may develop because

Muscle demands exceed oxygen supply.

Compared with skeletal muscle, smooth muscle generally

Contracts more slowly and can sustain contractions longer.

Which of these phrases most aptly describes "muscle insertion"?

Attachment point of the muscle that moves.

The sternocleidomastoid originates on the

Sternum and clavicle.

The triangle of auscultation, commonly used to hear sounds of respiratory organs, is located near the border of the

Scapula.

A compartment (bundle) of muscle fibers is called a(n)

Fascicle.

What is the connective tissue that surrounds a muscle organ called?

Epimysium.

The cell membrane of a muscle cell is called the

Sarcolemma.

The boundaries between adjacent sarcomeres are marked by

Z lines.

During muscle contraction, the ___ become smaller.

Sarcomeres.

During muscle contraction, the ___ move closer together.

Z lines.

Transverse tubules and sarcoplasmic reticulum are especially well developed in

Skeletal muscle.

Which of the following is not a function of skeletal muscle?

Transporting oxygen in the blood.

Functions of muscles include

Movement, stability, posture, and heat production.

Skeletal muscles help maintain body temperature because

They produce heat during contraction.

The muscle primarily responsible for producing a movement is the

Agonist.

Which of the following is not an axial muscle?

Limb muscles.

The two major divisions of the skeleton are

Axial skeleton and appendicular skeleton.

The special functional connection between a motor neuron and a skeletal muscle fiber is the

Neuromuscular junction.

Axon terminals at neuromuscular junctions contain vesicles filled with

Acetylcholine.

The enzyme that inactivates acetylcholine is

Acetylcholinesterase.

At a neuromuscular junction, the folded muscle-fiber membrane forms the

Motor end plate.

Arrange these contraction events in the correct sequence: 1. The muscle impulse reaches the sarcoplasmic reticulum and calcium is released. 2. Thin filaments are pulled over thick filaments. 3. Calcium enters the sarcoplasm and binds to troponin, exposing active sites. 4. The impulse arrives at the synapse and travels through transverse tubules. 5. The muscle fiber shortens and contracts. 6. Tropomyosin moves away, allowing actin and myosin to link.

4, 1, 3, 6, 2, 5.

Wave summation with no relaxation phase is called

Tetanus.

A motor neuron and all the muscle fibers it innervates form a

Motor unit.

Strength of skeletal-muscle contraction depends mainly on how

Many motor units are activated.

A contraction that changes a skeletal muscle’s length is

Isotonic.

In a muscle-twitch recording, the delay between a stimulus and the beginning of muscle response is the

Latent period.

The brief time after stimulation when a muscle remains unresponsive to additional stimulation is the

Refractory period.

Creatine phosphate

Acts as an energy reserve in muscle cells.

Athletes tend to experience muscle fatigue less quickly than nonathletes because they

Have more efficient energy systems and better muscle conditioning.

Smooth muscle lacks

Striations.

Short muscle cells with centrally located nuclei are

Smooth muscle cells.

Structures that connect cardiac muscle cells are

Intercalated discs.

Which of the following is not a type of fascicle arrangement?

Striated.

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

Medial muscles.

Which muscle is named for shape and size?

Deltoid.

The ___ extends the neck.

Sternocleidomastoid.

Which of the following is not a muscle of mastication?

Sternocleidomastoid.

The sleus is a muscle that forms part of the

Obliques.