A&P Chapter 10 Connect

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

excitability

In which activities are muscles in an isometric contraction?

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

In an isotonic contraction, the muscle fibers ______, resulting in movement.

shorten or lengthen

The two types of muscle contraction are: a. _____ contraction (when a muscle contracts but does not change in length) and b. _____ contraction (when a muscle contracts and does change in length.)

a. isometric
b. isotonic

a tendon that forms a thin, flattened sheet is called a/an ______

aponeurosis

The neurons that stimulate muscle contraction are called _____ neurons.

motor

A neuromuscular junction contains a

-synaptic cleft
-motor end plate
-synaptic knob

The vascular supply to slow muscle fibers is _____ than the network of capillaries around fast muscle fibers.

more extensive

contraction period

tension increases

body movement

Muscles contract and pull on the tendons that attach the muscles to the bones

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

TF a byproduct of anaerobic respiration is lactic acid.

TRUE

skeletal

voluntary

The superficial fascia, composed of _____ and adipose connective tissue, separates muscle from skin.

areolar

The endomysium is composed of what type of connective tissue?

areolar

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

tension

actin

double-stranded contractile protein

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

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

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

isometric contraction

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

motor end plate

TF After diffusing across the synaptic cleft, ACh binds to receptors on the synaptic knob.

FALSE

The sarcoplasmic reticulum stores ______ ions needed to initiate muscle contraction.

calcium

The narrow space separating the synaptic knob and the motor end plate is called the

synaptic cleft

During an ____ contraction, the length of the muscle does not change.

isometric

Calcium ions bind to what protein in a thin myofilament?

Troponin

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

tropomyosin

Myosin head attachment and pivoting do not require energy, but ATP is needed for the myosin head cross bridge to ______ from actin and re-cock.

detach

After a contraction, muscle returns to its original relaxed position due to it's natural

elasticity

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

sarcomeres

ACh is an acronym for

acetylcholine

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

closer together

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

Match the duration of a single muscle contraction with the source of ATP

Immediate - creatine phosphate
Short term - anaerobic respiration
Long term - aerobic respiration

Energy to drive the myosin movement in the sliding filament process is provided in the form of

ATP

The plasma membrane of a skeletal muscle fiber is called the

sarcolemma

During development, many groups of ______ fuse to form single skeletal muscle fibers.

myoblasts

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

TF A single myofibril runs the length of the muscle fiber.

TRUE

Parts of the sarcoplasmic reticulum that appear as blind sacs perpendicular to the fiber's length are called ________

terminal cisternae

Thick myofilaments are composed of bundles of _______ protein molecules.

myosin

A sarcomere is defined as the distance from one Z ______ to the next.

disc

within a myofibril, Z discs separate the functional units known as

sarcomeres

In a sarcomere , the __ zone (or band) is the light , central region of the A band ?

H

In a sarcomere, the M-line serves as an attachment site for the ______ filaments and keeps them aligned during contraction and relaxation.

thick

Under the light microscope, the dark (A) bands observed in skeletal muscle contain ________ filaments

thick and thin

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

motor neuron

although muscle fibers obey the all-or-none principle, the force of muscle contraction can be varied depending on how many ______ units are used

motor

The motor neuron transmits the effect of a nerve impulse to the muscle fiber at a

neuromuscular junction

The synaptic knob of the neuron is a ____ of an axon.e

expanded tip

The motor end plate has folds and indentations to increase the membrane surface are adjacent to the

synaptic knob

Acetylcholinesterase in the synaptic cleft is needed so that ____ will not continuously stimulate the cell to contract.

ACh

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

sarcoplasm

Myofibrils are made of

myofilaments

Within a myofibril, each _____ shortens as the muscle fiber contracts.

sarcomere

The striated appearance in skeletal muscle cells is due to size and density differences between ______ and ______ filaments.

thick and thin

Which is not a connective tissue component of a muscle?

skeletal muscle fibers

muscle

multiple bundles housing many muscle fibers

fascicle

a bundle of muscle fibers

muscle fiber

elongated, multinucleate, cylindrical cell

myofibril

long, cylindrical contractile element within muscle cell

myofilament

short contractile proteins of two types: thick and thin

the epimysium of a muscle surrounds

entire skeletal muscle

in muscle contraction, as increasing numbers of motor units are recruited _____ force is exerted

greater

The point where a motor neuron meets a skeletal muscle fiber is called the

neuromuscular junction

When a muscle fiber contracts, which parts of the sarcomere maintain a constant length throughout contraction?

A band

which are characteristics of oxidative fibers?

-high concentration of myoglobin
-good for endurance
-use aerobic respiration
-red

For longer contractions, muscle cells obtain ATP by which process?

aerobic respiration

An individual has better proficiency in performing repeated contractions under aerobic conditions if he or she as a greater percentage of ____ fibers in specific muscles.

slow

slow and intermediate fibers require oxygen to produce ATP, so the metabolic reaction within these fibers are termed

aerobic

The majority of skeletal muscle fibers in the body are ____ fibers.

fast glycolytic

TF most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.

TRUE

If used repeatedly for endurance events, _____ fibers can develop the appearance and functional capabilities of _____ fibers.

fast; intermediate

The diameter of a muscle fiber will predict

how much power it will produce

With endurance training, it is possible for fast _____ fibers to take on characteristics of fast _____ fibers.

glycolytic; oxidative

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 "step-wise" increase in the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation without an increase in intensity or frequency of stimulation is called ______

summation

In ___ tetany, a muscle cell is stimulated so frequently that it is not allowed to relax at all between stimuli

incomplete

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

latent period

there is no tension

relaxation period

tension decreases

The filaments in smooth muscle cells contain which proteins

actin and tropomyosin

smooth muscle contraction is under _____ control

involuntary

The _____ mechanism allows smooth muscle to maintain muscle contraction without the use of additional ATP

latchbridge

Smooth muscle shows a different length-tension relationship than skeletal muscle because

-it lacks z discs but has dense bodies
-the arrangement of the thick and thin filaments allows for contraction even when stretched

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

involuntary

autonomic motor neurons that control smooth muscle contraction have bulbous swellings called ______ that contain synaptic vesicles.

varicosities

Multiunit smooth muscle cells are stimulated

individually

Smooth muscle is found where in the respiratory system?

around the bronchioles

TF Smooth muscle retains its mitotic ability.

TRUE

TF smooth muscle cells lack transverse tubules.

TRUE

Cytoskeleton network

intermediate filaments

Anchoring point between intermediate filaments and the sarcoplasm

dense body

anchoring between intermediate filaments and the sarcolemma

dense plaque

The wall of the heart is composed of

cardiac muscle

posture

contraction of specific skeletal muscles stabilizes joints