Chapter 10

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

it would cause spastic paralysis / contracted muscles unable to relax

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

shortens

Which muscle types are voluntary, and which are involuntary?

skeletal is voluntary cardiac is not

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

skeletal muscle fibers

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

sliding filament theory

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

synaptic cleft

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

tendon

Define tendon and aponeurosis

tendon-projection of connective tissue beyond the end of the muscle that attaches to the bone aponeurosis- broad fibrous sheet of connective tissue that connects muscles to muscles

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

depolarization

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

During the Cori cycle, what happens in the liver?

glucose is produced from lactic acid

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

have many nuclei

Define motor unit

A motor neuron and all of the muscle fibers it innervates

.Identify three sources of stored energy utilized by muscle fibers.

Atp, creatine, phosphate and shygose

Define muscle hypertrophy and muscle atrophy

Hypertrophy-increase in muscle mass atrophy- decrease in muscle mass

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.

Define depolarization, and describe the events that follow it

a cell is depolarized when a threshold potential is reached and and Na + rushes into the cell.

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

a twitch

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

acetylchlorine

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

active transport of calcium into sacroplasmic reticulum

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

additional oxygen is required to restore energy reserves consumed during exercise

A resting muscle generates most of its ATP by

aerobic metabolism of fatty acids

Define oxygen debt (excess post exercise oxygen consumption

amount of oxygen used to aerobic activity minutes amount of oxygen actually used in aerobic activity of EPOC is elevated

What causes calcium to be released from the sarcoplasmic reticulum?

arrival of action potential

What molecule supplies the energy for a muscle fiber contraction?

atp

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

channel

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 muscle weakness of myasthenia gravis results from ...........

loss of acetylcholine receptors in the end plate membrane

The Na+ /K+ ion pump is responsible for

maintaining the sodium/potassium concentration gradients constant.

Cellular membrane potential is measured in

millivolts

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

most of lacatate enters the electron transport chain to produce more ATP

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

Skeletal muscle fibers are formed from embryonic cells called

myoblasts

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

myosatelites

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

polio

Membrane potential is

potential difference across the cell membrane

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

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

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

rigormortis

The plasma membrane of skeletal muscle is called the

sacrolemere

The repeating contractile unit of a skeletal muscle fiber is the

sarcomere

Describe the neuromuscular junction.

the synapse between the motor neuron and the muscle fiber that it controls

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

wave summetial

When do muscle fibers produce lactate?

when there's lack of oxygen