Anatomy and Physiology I - Chapter 10 Learnsmart

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

A-band

if a skeletal muscle experiences markedly ______ _______, it loses both mass and tone

reduced stimulation

thick and thin filaments maintain their ______ whether the muscle is relaxed or contracted

same length

when you are cold or have a fever your muscles will often contract and relax rapidly to produce heat. this rapid relaxation and contraction can result in a phenomenon commonly known as ______

shivering

a nerve impulse travels through an axon to its _______

synaptic knob

the motor end plate has folds and indentations to increase the membrane surface area adjacent to the ______

synaptic knob

the H-band (or H-zone) is more lightly shaded because only ______ filaments are present

thick

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

thick/ thin

spread of a muscle impulse along the sarcolemma, then down the ______,causes calcium ions to leak out of the DR into the sacroplasm of the muscle fiber

transverse tubules

in smooth muscle cells, the sarcoplasmic reticulum is sparse, and ______ tubules are absent.

T

the ______ discs that anchor the sarcomere on either end in skeletal muscle are absent from smooth muscle cells

Z

ACh is an acronym for

acetylcholine

in a neuromuscular junction, what enzyme breaks down acetylcholine

acetylcholinesterase

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

a muscle cell obtains ATP in the short term via what process

anaerobic respiration

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

aponeurosis

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. what process caused this to happen?

atrophy

when smooth muscle is stretched, it responds by ______

contracting then relaxing

the shortening of muscle cells results in either a pull on bones of the skeleton or the movement of specific body parts. the process of shortening of muscle cells is called ______

contraction

a persons tolerance for exercise ______ with age

decreases

in smooth muscles cells, thin filaments are attached to ______

dense bodies

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

a sacromere is defined as the distance from one Z ______ to the next

disc

true or false: after diffusing across the synaptic cleft, ACh binds to receptors on the synaptic knob

false

which of the three skeletal muscle fiber has the largest diameter and provides both power and speed

fast glycolytic

intermediate fibers contract ______ than slows fibers and ______ than fast fibers

faster/slower

in a concentric isotonic contraction, the tension produced is ______ than the resistance

greater

an increase in muscle fiber size is called

hypertrophy

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

during an ______ contraction, the length of the muscle does not change

isometric

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

isometric

the motor neuron transmits the effect of a nerve impluse to the muscle fiber at a neuromuscular ______

junction

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

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

each muscle fiber is controlled by one _______ neuron

motor

in a motor unit, a single ______ neuron typically controls numerous muscle fibers in a muscle

motor

skeletal muscle contraction is controlled by ______ neurons

motor

skeletal muscle fibers are ______

multinucleate

thick myofilaments are composed of bundles of what protein molcules

myosin

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

neurotransmitter

smooth muscle cells have a single, centrally located

nucleus

aerobic respiration requires the presence of what molecule

oxygen

the immediate supply of ATP for use in muscle contraction is generated by the ______ system

phosphagen

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

an internal membrane complex in skeletal muscle cells that is similar to the smooth endoplasmic reticulum of other cells is called the sarcoplasmic ______

reticulum

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

sarcomeres

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

sarcromeres

the plasma membrane of a skeletal muscle fiber is called the ______

sarocloemma

at the end of contraction, when the stimulation form the nerve impulse ceases, calcium ions are pumped back into the ______

saroplasmic reticulum

type I muscle fibers contract more _____ than type IIa and IIb muscle fibers

slowly

what type of muscle forms the majority of the walls of the digestive tract

smooth

the muscle that surrounds the opening to your esophagus and opens reflexively to allow you to swallow food is what type of muscle

sphincter

cardiac muscle cells are ______ like skeletal muscle fibers

striated

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

terminal cisternae

slow-twitch and fast-twitch muscle fibers differ primarily in

their ATPase which splits ATP

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 ______

treppe

calcium ions bind to what protein in a thin myofilament

troponin

true or false: a single myofibril runs the length of the muscle fiber

true

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

twitch

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

debt

smooth muscle cells have a ______ mechanism that allows them to contract with more power and use less ATP than a skeletal muscle cell

latch bridge

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

true

true or false: smooth muscle cells lack transverse tubules

true

the ______ line is a thin, transverse, protein meshwork structure in the center of the H zone of a sarcomere

M

in a muscle there are concentric layer of connective tissue. from deep to superficial these connective tissue layers are the ______, the ______, and the _______

endomysium/ perimysium/ epimysium

the epimysium of a muscle surrounds the ______

entire skeletal muscle

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

excitability

what are characteristics of glycolytic fibers

-low concentration of myoglobin -white -good for a burst of power -use anaerobic respitation

in which activities are muscles in a isometric contraction

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

aerobic respiration requires the presence of what molecule

...

acetylcholinesterase in the synaptic cleft is needed so that ______ will not continuously stimulate the cell to contract

ACh