Chapter 10 RA

Place the events at a neuromuscular junction in order.

1. arrival of nerve signal synaptic knob 2. calcium entry into synaptic knob 3. exocytosis of ACh into synaptic cleft 4. binding of ACh to motor end plate

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 stage of cross bridge cycling in the picture.

A - Ca2+ binds troponin; myosin-binding sites uncovered B - cross-bridge formation C - power stroke D - release of myosin head by ATP E - reset of myosin head

Using the image of a muscle, match the structure with its label in the diagram.

A - blood vessel B - epimysium C - perimysium D - endomysium

According to the sliding filament theory, the length of the ______ band remains constant, but the ______ zone disappears.

A; H

The connective tissue layers in muscle provide protection, distribution sites for blood vessels and nerves, and a means of ______ to the skeleton.

Attachments

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.

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

Cellular

Muscles are considered organs because they are composed not only of muscle tissue but also ______ tissue and nervous tissue

Connective

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

Excitability

A skeletal muscle cell is also called a muscle

Fiber

Match each muscle unit with the connective tissue layer that surrounds it.

Muscle - epimysium Fascicle - perimysium Muscle Cell - Endonysium

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

Skeletal

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

Skeletal

Somatic motor neurons innervate ______ muscle.

Skeletal

______ distribute the muscle impulse throughout the inside of the muscle fiber.

T-tubules

When calcium ions bind to troponin, which of the following then occurs?

The myosin-binding sites on actin are exposed

When a muscle fiber is in a relaxed state, the ______ molecules cover the G-actin active sites, preventing interaction between thick filaments and thin filaments.

Tropomyosin

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

Your biceps brachii muscle in your arm is an organ.

True

Match each event at a neuromuscular junction with its location.

a nerve signal arrives at this structure - synaptic knob ACh is released into this space - synaptic cleft ACh binds to receptors on this surface - motor end plate

To start a muscle contraction, a nerve impulse causes ______ release at a neuromuscular junction.

acetycholine

ACh is an acronym for

acetylcholine

The arrival of a nerve impulse at the synaptic knob of a motor neuron causes synaptic vesicles to release _____ into the synaptic cleft.

acetylcholine, ACh, or neurotransmitter

Contraction of a muscle fiber requires that the myosin heads in the thick filament bind to active sites on ______ molecules within the thin filaments

actin

The cyclic events of "attach, pivot, detach, return" continue as long as ions remain bound to the troponin.

calcium

When a nerve signal arrives at a synaptic knob, what type of channels open in the membrane?

calcium voltage-gated

As a result of muscle fiber contraction, thick filaments in neighboring sarcomeres move ______.

closer together

In a muscle, the perimysium is composed of what type of connective tissue?

dense irregular

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

dense irregular

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

elasticity

The connective tissue layer that surrounds individual muscles fibers is called ______.

endomysium

In a muscle there are concentric layers of connective tissues. From deep to superficial these connective tissue layers are the _____ , the ____ , and the ___.

endomysium perimysium epimysium

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

epimysium

The three connective tissue layers surrounding the individual components of a muscle are the: ____ , ____ , and ____ .

epimysium perimysium endomysium

There is a(n) ______ network of blood vessels delivering blood to muscle tissue.

extensive

In a transverse section of a muscle, you can see that each skeletal muscle is actually composed of many_____ , which are bundles of muscle fibers.

fascicles

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

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

into

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

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

Neurons that stimulate muscle contraction are called ______ neurons.

motor

Upon release from the synaptic knob, acetylcholine attaches to receptors on the ______.

motor end plate

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

muscle tension

After the cross bridges are formed, ATP is required to detach the ______ and complete the sequence of cyclic events.

myosin heads

Muscle fibers contain cylindrical structures called myofibrils, which are composed of ______.

mysofilaments

An extensive network of blood vessels and nerve fibers extends through both the epimysium and the _____ of a muscle.

perimysium

The connective tissue layer that surrounds each muscle fascicle is called ______.

perimysium

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

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

The endomysium contains ______ fibers to help bind together neighboring muscle fibers.

reticular

Thick and thin filaments maintain their ______, whether the muscle is relaxed or contracted.

same length

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

sarcolemma

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

sarcomeres

according to the sliding filament theory, when a muscle contracts, thick and thin filaments _____ past each other, and the _____ shortens.

slide sarcomere

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

sliding

The attachment of ACh to the receptor on the motor end plate causes the receptor to open, allowing _____ ions to enter the muscle fiber.

sodium

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

Once started, a muscle impulse will travel along the sarcolemma and into the muscle fiber via the ______.

t-tubules

A thick cordlike structure that attaches a muscle to a bone is called a(n) ______.

tendon

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

T-tubules are located adjacent to ______, which are reservoirs storing the calcium ions required for muscle contraction.

terminal cisternae

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

Calcium ions bind to what protein in a thin myofilament?

troponin

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

Within a synaptic knob, synaptic _____ contain the neurotransmitter ACh.

vesicles