A&P Smartbook CH 10

Termination of the nerve impulse at an NMJ results in the passive sliding of ______ back to their original state.

myofilaments

After stimulation of ACh receptors, a muscle impulse spreads quickly along the _____ and into the muscle fiber along T-tubules

sarcolemma

The cytoplasm of a skeletal muscle cell has a specific name and is known as

sarcoplasm

The _____ filament theory explains how muscle fibers shorten during contraction.

sliding

Smooth muscle contraction is ___ , resistant to ___ , and usually sustained for an extended period of time.

slow; fatigue

A "step-wise" increase in the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation is called ____

summation

As a result of ACh stimulation, calcium ions are released from the ______ of the sarcoplasmic reticulum.

terminal cisternae

Slow-twitch and fast-twitch muscle fibers differ primarily in ______.

their ATPase which splits ATP

Single unit muscle cells contract ______.

together

As the troponin changes shape (due to binding calcium), it moves the ______ molecule to which it is attached, thus exposing the active sites on the G-actin molecules.

tropomyosin

Smooth muscle is found in which of the following locations?

- in wall of the uterus - in the wall of the small intestine - around blood vessels

Which can cause muscle fatigue?

- insufficient Ca2+ - build up of intracellular Pi - Na+ or K+ imbalances

-Body movement -Posture -Temperature regulation -Storage and movement of materials

-Muscles contract and pull on the tendons that attach the muscles to the bones. -Contraction of specific skeletal muscles stabilizes joints. -Heat is produced as a waste product of energy usage. -Voluntary sphincter muscles of the gastrointestinal and urinary tracts can be kept closed or opened.

1st 2nd 3rd 4th

-Nerve signal arrives at synaptic knob. -Calcium enters and binds synaptic vesicle. -ACh is released via exocytosis into the synaptic cleft -ACh bind receptors on the motor end plate.

In a motor unit, a single _____ neuron typically controls numerous muscle fibers in a muscle.

motor or somatic

Muscle cells are said to have what characteristic because they can respond to stimulation from the nervous system?

Excitability

Deep invaginations of sarcolemma are called ______.

T-tubules

True or false: Skeletal muscle is usually attached to the skeleton, but it is also found at the openings between the digestive tract and the external environment and the urinary tract and the opening to the external environment.

True

Sarcoplasm is another term for skeletal muscle ______.

cytoplasm

A motor unit is composed of a single ______ and all of the muscle fibers it controls.

motor neuron

Sarcolemma Muscle Fiber Sarcoplasm Sarcoplasmic Reticulum

-Plasma membrane of a muscle fiber. -A muscle cell. -Cytoplasm of a muscle fiber. -Smooth endoplasmic reticulum in a muscle fiber. -Narrow, tubular extensions of the sarcolemma into the sarcoplasm.

Smooth muscle cells are ______ in shape.

fusiform

The epimysium of a muscle is composed of ______ connective tissue.

dense irregular

Smooth muscle contraction is under ___ control of the nervous system.

involuntary, unconscious, or autonomic

In an isometric contraction, the muscle ______ body movement.

does not produce

True or false: A single myofibril runs the length of the muscle fiber.

True

True or false: Most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.

True - Reason: Most muscles contain all three muscle types but not in equal amounts.

The amount of additional oxygen that must be inhaled in order to restore pre-exercise levels is called oxygen

debt

If a muscle cell is stimulated to contract, allowed to partially relax, then stimulated again, its force of contraction the second time will be ______.

higher

Smooth muscle contraction is under ______ control.

involuntary

Match each stage of a muscle twitch with the amount of tension generated. Instructions

latent period - no tension contraction period - tension increases relaxation period - tension decreases

In order to predict how much tension a muscle can produce when contracting, it is important to consider the ______ relationship of thick and thin filaments.

length-tension

Slow fibers have a relatively large number of ______. This permits slow muscle fibers to produce a greater amount of ______ than fast muscle fibers while contractions are underway.

mitochondria; ATP

What is the force generated when a skeletal muscle is stimulated to contract called?

muscle tension

After the age of 30, the number of ______ in existing muscle fibers decreases.

myofibrils

The sarcoplasm of a skeletal muscle fiber contains hundreds to thousands of long, cylindrical structures called _____ that extend the length of the cell.

myofibrils

Myofibrils are made of ______.

myofilaments

The force generated when a skeletal muscle is stimulated to contract is muscle -_____

tension

The epimysium of a muscle surrounds ______.

the entire skeletal muscle

As you sit there reading this your muscles, even your relaxed ones are not completely relaxed and soft. This is because they have some background tension called resting muscle ______.

tone

A single contraction and relaxation of a muscle fiber is referred to as a muscle

twitch

Athletes have more defined muscles than non-athletes even while at rest because they have ______ motor units contracting all the time.

more

Myofibrils consist of bundles of short ______.

myofilaments

As you struggle to twist open a jar, more motor units are called into action until you finally generate enough force to open it. This is an example of ______.

recruitment

At the end of muscle contraction, calcium ions are moved back into the _____ reticulum by ATP-driven ion pumps.

sarcoplasmic

Attached to the skeleton and surrounding the openings of the urinary and gastrointestinal traces are locations of ______ muscle.

skeletal

Maintenance of posture and production of heat are functions of ______ muscle.

skeletal

Upon release from the terminal cisternae, some calcium ions bind to ______ causing it to change shape.

troponin

When smooth muscle is stretched, it responds by _____.

contracting then relaxing

Muscle tissue demonstrates the property of _____ when it is done contracting and returns to its resting length.

elasticity

Overall, as aging progresses, muscle strength and endurance are impaired, and the individual has a tendency to _____ quickly.

fatigue or tire

A skeletal muscle cell is also called a muscle

fiber

The diameter of a muscle fiber will predict ______.

how much power it will produce

You make a New Year's resolution to work out more and by March notice your muscles are getting bigger. This is a result of muscle ______.

hypertrophy

Smooth muscle is found where in the respiratory system?

around the bronchioles

After breaking your arm, you have a cast on it for three months. When the cast is removed, your arm looks much smaller than it did before. The process called ______ caused this to happen.

atrophy

A muscle fiber is what level of organization in the body?

cellular

During the development of skeletal muscle cells, some myoblasts do not fuse and instead become ______ cells.

satellite

If a skeletal muscle is injured, surrounding ______ cells may be stimulated to differentiate and assist in its repair and regeneration.

satellite

In which activities are muscles in an isometric contraction?

-holding a yoga pose. -sitting up very straight. -pushing on a locked door.

Identify each structure in the diagram of a muscle fiber.

A. mitochondrion B. nucleus C. sarcoplasmic reticulum D. T-tubule

True or false: A muscle fiber that is partially shortened can produce a contraction stronger than the contraction it can produce when at its resting length.

False - Reason: A muscle fiber at rest generates more force than one partially contracted because there is optimal overlap of thick and thin filaments.

The act of shivering is an example of skeletal muscle performing what function?

Heat production

Slow and intermediate fibers require oxygen to produce ATP, so the metabolic reactions within these fibers are termed ______.

aerobic

A piano player uses her hands for brief quick movements. Which muscle fiber type would you therefore predict to be predominant in these muscles?

fast glycolytic

In a normally functioning muscle, the inability to contract and produce tension is called muscle

fatigue

Multiunit smooth muscle cells are stimulated ______.

individually

When a nerve impulse reaches the end of an axon of a neuromuscular junction, calcium flows ______ the synaptic knob.

into

After you stop running, you notice that you keep breathing heavily for some time. This is because your body is in ______.

oxygen debt

As you hold a barbell and begin to flex your arm in a curl, your biceps brachii slowly lifts the weight by using more and more motor units. This phenomenon, which increases the strength of the contraction, is referred to as _____

recruitment

A contracting skeletal muscle fiber typically shortens as all of its ______ shorten in length.

sarcomeres

Identify the metabolic components pictured in the diagram. Instructions

A - glycolysis. B -decarboxylation of pyruvate to Acetyl CoA. C - citric acid cycle D - electron transport chain

Using the image of a muscle fiber, match each structure in the diagram with its name. Instructions

A - sarcolemma B - myofibril C - sarcomere D - myofilaments

Glycolysis and aerobic respiration are used to generate ______ in muscle fibers.

ATP