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48 Cards in this Set

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what is the name of the plasma membrane of a muscle fiber?
sarcolemma
What is a isometric contraction?
a contraction in which the tension within the muscle changes, but the length of the muscle does not.
What would attempting to pick up an object too heavy result in?
It results in ISOmetric contraction.
What is myosin?
a protein within thick filaments that contain cross-bridges.
What ion is necessary for cross-bridging?
Calcium ions are nesscessary for what?
What are endomysium?
individual muscle fibers
What are skeletal muscles innervated by?
somatic motor neurons
What connective tissue sheath envelopes bundles of muscle fascicles?
epimysium
What are the major functions of muscles?
movement, protection, heat production, and posture
What is the plasma membrane of a muscle fiber?
sarcolemma
In the structure called the triad, the T-tubule is positioned where?
between the sarcoplasmic reticulum.
What is the function of the T-tubule?
to allow for electrical signals to move deeper into the cell.
The neurotransmitters secreted at the motor end plate of the skeletal muscle are called?
acetylcholine
What is acetylcholine?
neurotransmitters secreted at the motor end plate of skeletal muscle
A motor unit is most correctly described as a?
muscle fiber and a motor neuron.
What is the sarcoplasmic reticulum
an elaborate network of membranes in skeletal muscle cells that store calcium.
During muscle contraction, myosin cross bridges attach to what?
actin filaments.
What is a state of sustained muscle contraction called?
muscle tone
What do somatic motor neurons innvervate?
skeletal muscle
What is the most distinguishing characteristic of muscle tissue?
the ability to transform chemical energy
What is the major function of the sarcoplasmic reticulum?
to regulate intracellular calcium concentration
What is calmodulin?
the site of Calcium regulation in smooth muscle cells
What is treppe?
the warm-up period required by athletes in order to bring their muscles to peak performance.
What are white fibers?
fast fibers.
are also also known as what?
A lack of ATP, High levels of lactic acid, high levels of metabolic waste products, all may lead to what?
muscle fatigue.
What are the proteins associated with thin myofilaments?
Troponin, tropomyosin, actin.
The treppe effect is also termed as?
the staircase phenomenon
What is hypertrophy?
an increase in muscle size without an increase in the number of cells
What are the functional characteristics of skeletal muscles?
contractibility, extensibility, excitability
What do skeletal muscles look like?
they are long, cylindrical, and have many nuclei
In skeletal muscle, where do Calcium muscles bind to?
they bind to the TROPONIN molecule.
3 Characteristics of thin filaments are:
1.) composed of actin proteins
2.)contain regulatory proteins
3.)it is a helical structure that looks like a double strand of pearls.
What is troponin. Name 2 characteristics.
Troponin is a protein found on the actin filament.

It is calcium dependent, and if calcium binds to it, it will then expose the actin filament binding site.
What is influx?
the flow of sodium ions into the cell.
What is the synaptic cleft?
the space that separates the axonal ending and the muscle fiber.
What is excitability?
the ability of a muscle to receive and respond to a stimulus.
What happens in excitation-contraction coupling? 4
the actin potential travels along the muscle cell wall, calcium ions are released from the sarcoplasmic reticulum, calcium binds to troponin, and myosin heads bind to actin active sites.
What is tetanus:
the sustained state of muscle contraction
What is needed in order for the myosin head to bind to the actin active site?
calcium first binds to troponin

tropomyosin blocking actin needs to be removed,

ATP is required.
Give an example of typical skeletal muscle contraction.
moving your feet and walking.
What is absolute refractory period?
the period where a muscle will not contract irrespective of the rate or strength of the stimulus.
What is isometric contraction:
change in the muscle tension without a change in muscle length.
What system does Duchenne Dystrophy attack?
the muscular system
What is contractibility?
the ability of the muscle cell to shrink (contract) forcibly when adequately stimulated.
At -90 mV, the concentration of sodium is:
high in the extracellular
Three characteristics of Thick filaments:
1.composed of myosin protein.
2. has a rod like tail and 2 globular heads.
3.)the myosin head is the binding site for ATP
What does lack of ATP result in?
it results in locking of actin filaments to the myosin head, and this results when cells undergo respiration in the absence of Oxygen.
The resting membrane for a muscle cell is -90 mV with a threshold value of -60 mV. What would opening the K+ voltage gates result in?
Hyperpolarization.