CH 9 & 11 Flashcards
What is the characteristic that allows muscles to pull on bones and organs to create movement called?
Contractility
When muscles stretch and recoil, they recoil to a shorter length. What is this property called?
Elasticity
Skeletal muscle exhibits alternating light and dark bands called
Striations
Muscles that arenotunder conscious control are said to be?
Involuntary
Muscle fibers are bundled together into fascicles by which connective tissue layer?
Perimysium
Which property allows muscle cells to stretch to as much as three times their contracted length?
Extensibility
Because skeletal muscle is under the conscious control it is said to be?
Voluntary
When a muscle lengthens, the collagenous components protect the muscle because they resist?
Stretching
Which muscles are not attached to bones?
Involuntary muscles
Glycogen
a starch-like carbohydrate found in muscle cells that provides energy during intense exercise
The innermost layer of connective tissue that surrounds each muscle fiber
endomysium
Muscle and nerve cells have developed which characteristic more than other cells?
Excitability
The protein found in muscle cells that stores and then releases oxygen when needed
Myoglobin
Which prevents muscle cells from becoming too slack?
Elasticity
Which stem cells fuse to form a muscle fiber?
Myoblasts
When a muscle relaxes, elastic recoil of the collagen helps to return the muscle to its?
resting tension
Which connective tissue layer surrounds the entire muscle?
Epimysium
when a muscle is injured these cells can multiply and help repair the damage
Satellite Cells, stem cells located between a muscle fiber and the endomysium
What is the function of T-tubules?
to stimulate the terminal cisternae to release calcium
What happens to the sarcoplasmic reticulum when a skeletal myofiber is first stimulated?
Calcium is released into the sarcoplasm through gated channels
Infoldings of the sarcolemma that are associated with two terminal cisternae
Transverse Tubules (T-Tubules)
Which protein makes up the thick filaments of a myofibril?
Myosin
4 Components of Thin Filaments
Fibrous (F) actin , Globular (G) actin, Tropomyosin, and Troponin
Which membranous structures conduct impulses through the sarcoplasm to stimulate the release of calcium?
T-tubules
Elastic filaments in a myofibril are made of which protein?
Titin
What are the end-sacs of the sarcoplasmic reticulum called?
Terminal Cisternae
Which is found in thin filaments but is not a regulatory protein?
Actin
A thick filament is composed of pairs of this molecule, intertwined together
Myosin
What happens when calcium ions bind to troponin?
Tropomyosin moves off the active site on actin
Thin filaments are primarily composed of which protein?
F actin
What is the function of T-tubules?
To stimulate the terminal cisternae to release calcium / carry the action potential through the sarcoplasm
Which protein links actin fibers to the inner face of the sarcolemma?
Dystrophin
What stabilizes thick filaments and prevents over-stretching?
Elastic filaments
In a thin filament, each tropomyosin molecule has a small calcium-binding protein bound to it called
Troponin
What are two regulatory proteins found in a myofibril?
Tropomyosin and Troponin
Under the microscope, muscle that has alternating light and dark regions is said to be
Striated
Within a sarcomere, the overlap of actin and myosin produce what bands?
A Bands (anisotropic) , dark bands
A genetic condition in which an abnormal form of the dystrophin protein is produced
Muscular Dystrophy
Within a sarcomere, what is the region within the A band that lacks thin filaments?
H band
What is the portion of a myofibril from one Z disc to another called?
Sarcomere
Which type of neuron controls a skeletal muscle cell?
Somatic motor neuron
What causes skeletal muscle cells to be striated?
the alternating light and dark regions of the sarcomeres
What do all the muscle fibers innervated by a single nerve fiber constitute?
a Motor Unit
When are large motor units used?
Where physical strength is needed
What are light bands in skeletal muscle called?
I bands that are bisected by Z discs
A synapse is the point where a nerve fiber meets a target cell. When the target cell is a muscle fiber, what is this synapse called?
Neuromuscular Junction (NMJ)
Each muscle fiber is innervated by how many motor neurons?
Only one motor neuron per muscle cell
A neuromuscular junction is a type of what?
Synapse
What is a motor unit?
All of the muscle fibers innervated by a single motor nerve fiber
Within a synapse, a neuron ends in a swelling called?
an axon terminal
What are smaller motor units used for?
Fine motor control
What is the neurotransmitter used in a neuromuscular junction?
Acetylcholine (ACh)
I bands are composed primarily of which protein?
Actin (thin filaments)
What is a neuromuscular junction?
A site where a nerve fiber communicates with a muscle fiber
What is the indented region of the sarcolemma that participates in the neuromuscular junction called?
Motor end plate
What are the folds in the sarcolemma at the neuromuscular junction called?
Junctional folds
The synaptic knob does not touch the muscle fiber but is separated by which structure?
Synaptic cleft
What do neurons and muscle cells have in common?
Their membranes undergo voltage changes when stimulated
What is acetylcholine?
The neurotransmitter released at a neuromuscular junction
What is the difference in electrical charge from one point to another called?
electrical potential or voltage
What is the change in membrane potential with the entry of sodium ions called?
Depolarization
During an action potential, the loss of potassium ions from the cell results in what?
Repolarization