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
