muscle tissue learnsmart

what can cause muscle fatigue?

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

smooth muscle is found in what locations?

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

list the events that occur at a neuromuscular junction in order (4 steps)

1. nerve signal arrives at the synaptic knob 2. calcium enters and bind synaptic vesicle 3. ACh binds receptors on the motor end plate 4. ACh is released via exocytosis into the synaptic cleft

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

A band

glycolysis and aerobic respiration are used to generate ________ in muscle fibers

ATP

in a relaxed muscle fiber there are no thin filaments overlapping the thick filaments in the ____________

H zone

lighter region in the middle of an A band

H zone

light band containing thin filaments only

I band

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

M

appears as a dark protein disc in the center of the H zone

M line

made of dark proteins that create a zig zag line

Z disc

each myosin head in a thick filament can ind to the protein in a thin filament called ___________

actin

in a muscle cell, the short term energy is supply by _______________ respiration, where as long term energy is supplied by ______________.

anaerobic, aerobic

where is smooth muscle found in the respiratory system?

around the bronchioles

the sarcolemma of smooth muscle cells have small invaginations called ______________

caveolae

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

cellular

muscle tissue demonstrates the property of ____________ when it is done contracting and returns to its resting length

elasticity

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

excitability

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

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 ___________

fiber

what part of a myosin molecule does ATP bind to?

head

an increase in the number of mitochondria can be observed in _________________

hypertrophy

multiunit smooth muscle cells are stimulated ______________

individually

cardiac muscles 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 flows (into or out of) the synaptic knob

into

smooth muscle contraction is under (voluntary or involuntary control)

involuntary

smooth muscle contraction is _____________, resistant to _______________, and usually sustained for an extended period of time

involuntary, fatigue

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

isometric

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

because muscle cells require a huge amount of ATP in order to contract, they have a large number of which organelles

mitochondria

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

neurons that stimulate muscle contraction are called __________ neurons

motor

a motor unit is composed of a single ____________________ and all of the muscle fibers it controls

motor neuron

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

myofibrils

muscle cells store oxygen bound to a _______________ molecule

myoglobin

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

sarcolemma

plasma membrane of muscle fiber

sarcolemma

the plasma membrane of a skeletal muscle fiber is called the

sarcolemma

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

sarcomere

within a myofibril, each ____________ shortens as the muscle fiber contracts

sarcomere

cytoplasm of muscle fiber

sarcoplasm

cardiac muscle cells are _________ and thicker than skeletal muscle cells, and they have only ________ nuclei

shorter; 1-2

function of sarcoplasm

site of metabolic processes for normal muscle fiber activities

attached to the skeleton and surrounding the openings of the urinary and gastrointestinal traces are locations of _______ muscle

skeletal

if a skeletal muscle is injured, surrounding __________ cells may be sitmulated to differentiate and assist in its repair and generation

stem

function of sarcoplasmic reticulum

stores calcium ions needed for muscle contraction

a "step wise" increase the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation is called ________________.

summation

a neuromuscular junction contains a (3 parts)

synaptic cleft synaptic knob motor end plate

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 cistern

the epimysium of a muscle surrounds

the entire skeletal muscle

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

their ATPas which splits ATP

in a sarcomere, the M line serves as an attachment site for the ______________ filaments and keeps them aligned during contraction and relaxation

thick

the H band (H zone) is more lightly shaded because only _________ filaments are present

thick

function of T-tubule

transports the action potential from the sarcolemma throughout the entire muscle fiber

the deep invaginations of the sarcolemma that extend into the sarcoplasm of skeletal muscle fibers as a network of narrow membranous tubules are called

transverse tubules (T-tubules)

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

if the sarcoplasm of a muscle cell is flood with calcium ions, to which protein will they bind?

troponin

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

twitch

each myosin protein molecule in a thick filament consists of ___ strands

two

function of sarcolemma

regulates entry and exit of materials