Exam 3 part one

Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber strengthens. shortens. weakens . lengthens. There is insufficient information to determine the answer.

shortens

Which muscle types are voluntary, and which are involuntary? skeletal muscle is voluntary, and cardiac and smooth muscles are involuntary skeletal and smooth muscles are voluntary, and cardiac muscle is involuntary cardiac and smooth muscles are voluntary, and skeletal muscle is involuntary smooth muscle is voluntary, and cardiac and smooth muscles are involuntary skeletal and cardiac muscles are voluntary, and smooth muscle is involuntary

skeletal muscle is voluntary, and cardiac and smooth muscles are involuntary

The narrow space between the synaptic terminal and the muscle fiber is the motor end plate. motor unit. synaptic knob. M line. synaptic cleft.

synaptic cleft.

At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a ligament. satellite cell. tenosynovium. sheath. tendon.

tendon

The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called a(n) myofibril. ligament. fascicle. tendon. epimysium.

tendon

Within a resting skeletal muscle fiber, where is the greatest concentration of Ca2+? inside the transverse tubules Z lines between adjacent sarcomeres bound to troponin zone of overlap of the sarcomere terminal cisternae of the sarcoplasmic reticulum

terminal cisternae of the sarcoplasmic reticulum

Which statement about the microscopic anatomy of skeletal muscle fibers is not true? Tubular extensions of the sarcolemma penetrate the fiber transversely. Each fiber has many nuclei. Cross striations result from the lateral alignment of thick and thin filaments. Multiple myofibrils link end-to-end along length of the muscle cell. Muscle fibers are continuous from tendon to tendon.

Multiple myofibrils link end-to-end along length of the muscle cell.

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

depolarization

Individual muscle cells are surrounded by what connective tissue? myofibrils perimysium sarcomere endomysium sarcolemma

endomysium

The delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent muscle fibers together is the endomysium. perimysium. superficial fascia. epimysium. periosteum.

endomysium

The dense layer of connective tissue that surrounds an entire skeletal muscle is the endomysium. fascicle. tendon. perimysium. epimysium.

epimysium

Muscle fibers differ from "typical cells" in that muscle fibers have many nuclei. are very small. lack a plasma membrane. lack mitochondria. All of the answers are correct.

have many nuclei

Each skeletal muscle fiber contains ________ myofibrils. 50 to 100 100 to 150 150 to 200 200 to 500 hundreds to thousands

hundreds to thousands

If the membrane potential of a neuron is -80 mV, it is depolarized. at resting potential. repolarized. at threshold. hyperpolarized during the refractory period

hyperpolarized during the refractory period

Identify the structure where ATP is produced. Image showing a three-dimensional cross-section representation of a skeletal muscle cell. Figure 9-1 2 7 1 3 6

1

Where is ATP is consumed? Image showing a three-dimensional cross-section representation of a skeletal muscle cell. Figure 9-1 Where is ATP is consumed? 2 1 7 3 8

3

Where are the myosin molecules located? Image showing a three-dimensional cross-section representation of a skeletal muscle cell. Figure 9-1 4 5 6 7 8

5

Where would calcium ions be predominately found? Image showing a three-dimensional cross-section representation of a skeletal muscle cell. Figure 9-1 1 2 4 8 9

9

The region of the sarcomere containing the thick and thin filaments is the I band. A band. Z line. M line. H band.

A band

Define tendon and aponeurosis. A tendon is a bundle of collagen fibers that connects a skeletal muscle to a bone, whereas an aponeurosis is a broad collagenous sheet that connects skeletal muscle to a broad area on one or more bones. A tendon is a broad collagenous sheet that connects skeletal muscle to a broad area on one or more bones, whereas and aponeurosis is a bundle of collagen fibers that connects a skeletal muscle to a bone. A tendon is a bundle of collagen fibers that connects bones together, whereas an aponeurosis is a dense layer of collagen fibers surrounding an entire muscle. A tendon is a bundle of collagen fibers that connects bones together, whereas an aponeurosis is a thin layer of areolar connective tissue that surrounds each muscle fiber. A tendon is a dense layer of collagen fibers surrounding an entire muscle, whereas an aponeurosis is a fibrous layer that divides the skeletal muscle into fascicles.

A tendon is a bundle of collagen fibers that connects a skeletal muscle to a bone, whereas an aponeurosis is a broad collagenous sheet that connects skeletal muscle to a broad area on one or more bones.

Define depolarization, and describe the events that follow it. Depolarization is the when the inside of the cell becomes positive due to potassium ions rushing in. After depolarization, repolarization occurs when sodium ions rush out of the cell causing the inside of the cell to become negative again. Depolarization is the when the inside of the cell becomes positive due to sodium ions rushing in. After depolarization, repolarization occurs when potassium ions rush out of the cell causing the inside of the cell to become negative again. Depolarization is when the inside of the cell becomes neutral due to an equal amount of sodium ions entering the cell and potassium ions leaving the cell. Depolarization is the when the inside of the cell becomes negative due to sodium ions rushing out. After depolarization, repolarization occurs when potassium ions rush into the cell causing the inside of the cell to become positive again. Depolarization is the when the inside of the cell becomes negative due to potassium ions rushing out. After depolarization, repolarization occurs when sodium ions rush into the cell causing the inside of the cell to become positive again.

Depolarization is the when the inside of the cell becomes positive due to sodium ions rushing in. After depolarization, repolarization occurs when potassium ions rush out of the cell causing the inside of the cell to become negative again.

What is the general function of an excitable membrane? Excitable membranes function in slow, endocrine cell-cell communication. Excitable membranes function when the intracellular fluid and extracellular fluid compositions match. Excitable membranes permit rapid communication between different parts of a cell. Excitable membranes allow ions to leak across ion channels. Excitable membranes are on cells with extracellular receptors for binding chemicals.

Excitable membranes permit rapid communication between different parts of a cell.

Compare F-actin with G-actin. F actin binds myosin during muscle relaxation and G actin binds myosin during muscle contraction. F actin binds myosin during muscle contraction and G actin binds myosin during muscle relaxation. F actin is a twisted strand made up of two rows of G actin subunits where myosin heads can bind. G actin is a twisted strand made up of two rows of F actin subunits where myosin heads can bind. F actin is functional actin that contains myosin binding sites and G actin covers the binding sites on F actin to prevent actin-myosin interaction.

F actin is a twisted strand made up of two rows of G actin subunits where myosin heads can bind.

The area in the center of the A band that contains no thin filaments is the I band. zone of overlap. H band. M line. Z line.

H band

The region of the sarcomere that always contains only thin filaments is the A band. I band. H band. Z line. M line.

I band

Summarize the sliding filament theory. It is the theory that sarcomeres lengthen during the sliding of the thin and thick filaments past each other. It is the process that causes an action potential to travel down the T tubules into the sarcolemma. It is the theory that Z lines will move further from each other when the thin and thick filaments slide past each other. It is the process of sarcomere shortening caused by the sliding of thin and thick filaments past another. It is the theory that excitation-contraction coupling leads to muscle fiber relaxation.

It is the process of sarcomere shortening caused by the sliding of thin and thick filaments past another.

In a sarcomere, thick filaments are linked laterally by proteins of the H band. A band. M line. I band. Z line.

M line

________ are stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue. Myosatellite cells Myofilaments Myoblasts Multinucleate cells Myofibrils

Myosatellite cells

When a skeletal muscle fiber contracts, which of the following does not occur? The width of the A band remains constant. The Z lines get closer together. The H bands and I bands get smaller. The zones of overlap get larger. Myosin and actin filaments decrease in length.

Myosin and actin filaments decrease in length

Name the three types of muscle tissue, identify where they are found, and list their functions. Skeletal muscle is directly or indirectly attached to bones and enables movement of the body. Cardiac muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels. Smooth muscle forms the heart and propels blood. Skeletal muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels. Cardiac muscle forms the heart and propels blood. Smooth muscle is directly or indirectly attached to bones and enables movement of the body. Skeletal muscle forms the heart and propels blood. Cardiac muscle is directly or indirectly attached to bones and enables movement of the body. Smooth muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels. Skeletal muscle is directly or indirectly attached to bones and enables movement of the body. Cardiac muscle forms the heart and propels blood. Smooth muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels. Skeletal muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels. Cardiac muscle is directly or indirectly attached to bones and enables movement of the body. Smooth muscle forms the heart and propels blood.

Skeletal muscle is directly or indirectly attached to bones and enables movement of the body. Cardiac muscle forms the heart and propels blood. Smooth muscle is found throughout the body and moves substances through hollow tubes, such as in the digestive tract and regulates the diameter of blood vessels.

Which of the following statements is incorrect? The contractions of skeletal muscles pull on tendons and move bones of the skeleton. Skeletal muscle contractions help maintain body temperature. Skeletal muscles store nutrient reserves. Skeletal muscles are responsible for the pumping action of the heart. Skeletal muscles support the weight of some internal organs.

Skeletal muscles are responsible for the pumping action of the heart.

Describe the connective tissue layers associated with skeletal muscle tissue. The epimysium divides the skeletal muscle into fascicles; the perimysium surrounds individual muscle fibers; the endomysium surrounds the entire muscle. The epimysium surrounds individual muscle fibers; the perimysium divides the skeletal muscle into fascicles; the endomysium surrounds the entire muscle. The epimysium surrounds the entire muscle; the perimysium divides the skeletal muscle into fascicles; the endomysium surrounds individual muscle fibers. The epimysium divides the skeletal muscle into fascicles; the perimysium surrounds the entire muscle; the endomysium surrounds individual muscle fibers. The epimysium surrounds the entire muscle; the perimysium surrounds individual muscle fibers; the endomysium divides the skeletal muscle into fascicles

The epimysium surrounds the entire muscle; the perimysium divides the skeletal muscle into fascicles; the endomysium surrounds individual muscle fibers.

What would happen if there were no AChE in the synaptic cleft? The motor end plate could not be stimulated and continuous muscle contraction would occur. The motor end plate could not be stimulated and no muscle contraction could occur. The motor end plate would be unaffected because epinephrine not ACh stimulates the contraction of skeletal muscles. The motor end plate would be continuously stimulated and no muscle contraction could occur. The motor end plate would be continuously stimulated and continuous muscle contraction would occur.

The motor end plate would be continuously stimulated and continuous muscle contraction would occur.

Describe the neuromuscular junction. The neuromuscular junction is where the axon terminals of a motor neuron interact with the skeletal muscle fiber midway along the fiber's length. The neuromuscular junction is where the cell body of a motor neuron interact with the skeletal muscle fiber at one end. The neuromuscular junction is where the axon terminals of a sensory neuron receive inputs from a skeletal muscle fiber. The neuromuscular junction is where the dendrites of a sensory neuron receive inputs from a skeletal muscle fiber. The neuromuscular junction is where the dendrites of a motor neuron interact with the skeletal muscle fiber midway along the fiber's length.

The neuromuscular junction is where the axon terminals of a motor neuron interact with the skeletal muscle fiber midway along the fiber's length.

What special terms are used to describe the plasma membrane and cytoplasm of a skeletal muscle fiber? The plasma membrane is called the endomysium and the cytoplasm is called the soma. The plasma membrane is called the neurolemma and the cytoplasm is called the neuroplasm. The plasma membrane is called the epimysium and the cytoplasm is called the myoplasm. The plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm. The plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasmic reticulum.

The plasma membrane is called the sarcolemma and the cytoplasm is called the sarcoplasm.

Explain why the propagation of action potentials along electrically excitable membranes occurs in only one direction. All electrically excitable membranes have two poles, a positive and a negative pole, and the action potential can only travel towards the negative pole. The refractory period prevents it from propagating back in the direction from which it began. All electrically excitable membranes have two poles, a positive and a negative pole, and the action potential can only travel towards the positive pole. The repolarization period prevents it from propagating back in the direction from which it began. The stimulation of electrically excitable membranes by neurons occurs on only one side of the membrane so it will travel to the other side.

The refractory period prevents it from propagating back in the direction from which it began.

Explain the function of sodium-potassium ion pumps. The sodium-potassium ion pump allows facilitated diffusion of potassium during the repolarization of a muscle cell. They generate ATP for the cell during the electron transport chain when hydrogen ions move in a process known as chemiosmosis. The sodium-potassium ion pump maintains the resting membrane potential of a cell by exporting three sodium ions out in exchange for two potassium ions entering the cell. The sodium-potassium ion pump binds acetylcholine across the synaptic cleft to generate an action potential at the sarcolemma. The sodium-potassium ion pump allows facilitated diffusion of sodium during the depolarization of a muscle cell.

The sodium-potassium ion pump maintains the resting membrane potential of a cell by exporting three sodium ions out in exchange for two potassium ions entering the cell.

Why is the zone of overlap an important region of the sarcomere? The zone of overlap is important because it is where one sarcomere ends and another sarcomere begins. The zone of overlap is important because it is where myosin filaments are anchored to and overlap titin proteins. The zone of overlap is important because it is where the myosin heads can interact with the thin filaments. The zone of overlap is important because it is where actin filaments are anchored to and overlap nebulin proteins. The zone of overlap is important because it is where the troponin proteins bind acetylcholine to generate an action potential that can cause muscle contraction to occur.

The zone of overlap is important because it is where the myosin heads can interact with the thin filaments.

Which of the following statements is not true about action potentials? They end in repolarization. They can travel in two directions. They occur in neurons. They can be generated in less than 2 msec. They can travel long distances within cells.

They can travel in two directions.

Define transverse tubules. Transverse tubules are composed primarily of actin filaments. Transverse tubules are tubular extensions of the sarcolemma that extend deep into the sarcoplasm contacting the terminal cisternae of the sarcoplasmic reticulum. Transverse tubules are composed primarily of myosin filaments. Transverse tubules are tubular proteins that bind calcium within the sarcomeres. Transverse tubules forms a tubular network around each individual myofibril and is similar to the smooth endoplasmic reticulum of other cells.

Transverse tubules are tubular extensions of the sarcolemma that extend deep into the sarcoplasm contacting the terminal cisternae of the sarcoplasmic reticulum.

The skeletal muscle complex known as the triad consists of actin, myosin, and sarcomeres. filaments, myofibrils, and muscle fibers. a terminal cisterna and two transverse tubules. A bands, H bands, and I bands. a transverse tubule and two terminal cisternae.

a transverse tubule and two terminal cisternae.

The cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with molecules of the neurotransmitter acetylcholinesterase. epinephrine. antidiuretic hormone. acetylcholine. norepinephrine.

acetylcholine.

What is released from the structure labeled "9"? Image showing a three-dimensional cross-section representation of a skeletal muscle cell. Figure 9-1 proteins acetylcholinesterase calcium ions acetylcholine sodium

calcium ions

What physiological process occurs in the structure labeled "7"? Image showing a three-dimensional cross-section representation of a skeletal muscle cell. Figure 9-1 acetylcholinesterase breakdown of acetylcholine the sliding of actin and myosin filaments conduction of the action potential toward the triad release of proteins into the muscle fiber release of acetylcholine

conduction of the action potential toward the triad

Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for contraction. peristalsis. conduction. cushioning. None of the answers is correct.

contraction

Which of the following is not a recognized function of skeletal muscle? produce movement maintain body temperature maintain posture guard body entrances and exits controlled involuntarily

controlled involuntarily

Physical evidence that supports the sliding filament theory of muscle contraction includes constant distance between Z lines during contraction. decreased width of the A band during contraction. increased width of the I band during contraction. decreased width of the H band during contraction. the I band and H band distance is constant during contraction.

decreased width of the H band during contraction.

Na+ and K+ both use ________ to passively diffuse across the plasma membrane. leak channels exocytosis facilitated diffusion carrier-mediated transport voltage-gated channels

leak channels

The Na+/K+ ion pump is responsible for amplifying signals using ATP. initiating action potentials. transferring messages from enzyme-linked receptors to the cell nucleus. diffusing chloride across the plasma membrane. maintaining the sodium/potassium concentration gradients constant.

maintaining the sodium/potassium concentration gradients constant.

Cellular membrane potential is measured in milliseconds. millivolts. amperes. Hertz. micrometers.

millivolts.

Identify the structures labeled "1." Image showing a three-dimensional cross-section representation of a skeletal muscle cell. Figure 9-1 myofibril glycogen ATP synaptic vesicle mitochondria

mitochondria

Which of the following is not found in the structure labeled "3"? Image showing a three-dimensional cross-section representation of a skeletal muscle cell. Figure 9-1 myosin tropomyosin actin mitochondria titin

mitochondria

Receptors for acetylcholine are located on the sarcomere. synaptic knob. motor end plate. synaptic cleft. transverse tubule.

motor end plate

Neurons and ________ have electrically excitable membranes that propagate action potentials. epithelial cells muscle cells proteins osteocytes dense connective tissue

muscle cells

Interactions between actin and myosin filaments of the sarcomere are responsible for the conduction of neural stimulation to the muscle fiber. muscle relaxation. muscle fatigue. muscle contraction. the striped appearance of skeletal muscle.

muscle contraction

Skeletal muscle fibers are formed from embryonic cells called myomeres. myofibrils. fascicles. myoblasts. sarcomeres.

myoblasts

Name the proteins that make up a thick filament. myosin and nebulin myosin and titin actin and dystrophin actin and titin actin and nebulin

myosin and titin

Cross-bridges are portions of tropomyosin molecules. calcium ions. myosin molecules. troponin molecules. actin molecules.

myosin molecules

Each skeletal muscle fiber is controlled by a motor neuron at a single transverse tubule. synaptic knob. synaptic cleft. sarcomere. neuromuscular junction.

neuromuscular junction.

Nerves and blood vessels that service the muscle fibers are located in the connective tissues of the sarcolemma. sarcomere. myofibrils. sarcoplasm. perimysium.

perimysium

Which of the following is an ion that is more concentrated inside the cell than outside? chloride sodium potassium hydrogen calcium

potassium

The advantage of having many nuclei in a skeletal muscle fiber is the ability to contract. store extra DNA for metabolism. produce large amounts of the muscle proteins needed for muscle contraction. produce more ATP with little oxygen. All of the answers are correct.

produce large amounts of the muscle proteins needed for muscle contraction.

If potassium channels were blocked, the ________ phase of the action potential would not occur normally. threshold repolarization depolarization refractory

repolarization

The plasma membrane of skeletal muscle is called the sarcoplasm. sarcolemma. sarcomere. sarcosome. sarcoplasmic reticulum.

sacrolemma

The repeating contractile unit of a skeletal muscle fiber is the myofilament. sarcomere. sarcoplasmic reticulum. sarcolemma. myofibril.

sarcomere

The structural explanation of how a muscle fiber contracts is called the sliding filament theory. myosin spiral theory. cross-bridge connection. thin filament theory. active site rule.

sliding filament theory.

Which of the following best describes the sarcoplasmic reticulum? thin filaments are anchored here largely made of myosin molecules protein that accounts for elasticity of resting muscle repeating unit of striated myofibrils storage and release site for calcium ions

storage and release site for calcium ions.

Which of the following best describes the term titin? where thin filaments are anchored repeating unit of striated myofibrils largely made of myosin molecules storage site for calcium ions substance that accounts for elasticity of resting muscle

substance that accounts for elasticity of resting muscle

Membrane potential is a chemical signal that has not yet bound to a receptor. the electrical gradient of a cell. the site of signal transfer between two cells. a cell's capacity to respond to a chemical signal. the period when the membrane cannot respond to another stimulus.

the electrical gradient of a cell.

Which of the following proteins is not found as a part of thin filaments? actin troponin tropomyosin titin nebulin

titin

The complex of a transverse tubule and two adjacent terminal cisternae is known as a(n) M line. triad. free head. zone of overlap. sarcomere.

triad

At rest, active sites on the actin are blocked by tropomyosin molecules. myosin molecules. calcium ions. troponin molecules. ATP molecules.

tropomyosin molecules.

At rest, the tropomyosin molecule is held in place by calcium ions. myosin molecules. ATP molecules. actin molecules. troponin molecules.

troponin molecules.

Each thin filament consists of chains of myosin molecules. a rod-shaped structure with "heads" projecting from each end. two protein strands coiled helically around each other. six molecules in a rod-like structure. a double strand of myosin molecules.

two protein strands coiled helically around each other.

Which of the following best describes the term "Z line"? storage site for calcium ions largely made of myosin molecules protein that accounts for elasticity of resting muscle repeating unit of striated myofibrils where thin filaments are anchored

where the thin filaments are anchored