Homework: Chapter 10 Muscle Fiber Physology

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 in which of the following locations?

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

Multiunit smooth muscle cells are stimulated _________.

individually

Cardiac muscle cells form Y-shaped branches and join to adjacent muscle cells at junctions called _______ discs.

intercalated

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

into

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

into

Smooth muscle contraction is under _______ control.

involuntary

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

involuntary

If you strain to push on a wall that does not move, your muscles are in a type of ________ contraction.

isometric

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

latent period --> there is no tension contraction period --> tension increases relation 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

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

more

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

motor neuron

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

Myofibrils consist of bundles of short _______.

myofilaments

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

myofilaments

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 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

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 ___________.

recuitment

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

sarcolemma

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

sarcolemma

The plasma membrane of a skeletal muscle fiber is called the __________.

sarcolemma

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

sarcomeres

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

sarcoplasmic

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

sarcoplasmic

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

Cardiac muscle cells are ________ and thicker than skeletal muscle cells, and they have only _______ nuclei.

shorter; 1-2

Approximately 40-50% of your body weight is ________ muscle.

skeletal

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

The force generated when a skeletal muscle is stimulated to contract is muscle __________.

tension

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

terminal cisternae

The epimysium of a muscle surrounds _________.

the entire skeletal muscle

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

their ATPase which split ATP

Single unit muscle cell contract _________.

together

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 muscles ________.

tone

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

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

troponin

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

twitch

Match each function of skeletal muscle with its description.

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

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

Heat production

Match the name of the muscle cell component with its function.

Muscle fiber --> metabolic activities; contraction Sarcolemma --> regulates entry and exit of materials Sarcoplasm --> site of metabolic processes for normal muscle fiber activities Sarcoplasmic Reticulum --> stores calcium ions needed for muscle contraction T-tubule --> transports the action potential from the sarcolemma throughout the entire muscle fiber

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

Muscle tension

Deep invaginations of sarcolemma are called _________.

T-tubules

Smooth muscle cells retain their mitotic ability.

True

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

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

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

aerobic

Smooth muscle is found where in the respiratory system?

around the bronchioles

Which can cause muscle fatigue?

build up of intracellular P1; insufficient Ca2+; Na+ or K+ imbalances

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

cellular

When smooth muscle is stretched, it responds by _______.

contracting then relaxing

Sarcoplasm is another term for skeletal muscle ________.

cytoplasm

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

debt

In an isometric contraction, the muscle ________ body movement.

does not produce

The connective tissue layer that surrounds an entire muscle is called ________.

epimysium

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

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

fatigue

A skeletal muscle cell is also called a muscle _________.

fibers

Smooth muscle is composed of short cells that have a _______ shape.

fusiform

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

The diameter of a muscle fiber will predict ________.

how much power it will produce

An increase in the number of mitochondria can be observed in ________.

hypertrophy

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

ATP

Place the events that occur at a neuromuscular junction in order.

1st --> nerve signal arrives at synaptic knob 2nd --> calcium enters and binds synaptic vesicle 3rd --> ACh is released via exocytosis into the synaptic cleft 4th --> ACh binds receptors on the motor end plate

Identify each structure in the diagram of the muscle fiber.

A --> Mitochondrion B --> Nucleus C --> Sarcoplasmic reticulum D --> T-Tubule

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

A --> Sarcolemma B --> Myofibrils C --> Sarcomere D --> Myofilaments

Identify the metabolic components pictured in the diagram.

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

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

Elasticity

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

Excitability

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