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135 Cards in this Set
- Front
- Back
What are 3 types of Muscle Tissue?
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Skeletal
Cardiac Smooth |
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Define SKELETAL MUSCLES?
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Are organs composed primarily of skeletal muscle tissue, but they also contain connective tissue, nerve, and blood vessels.
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Each cell in skeletal muscle tissue is a single ____ _____.
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muscle fiber
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True or False: All skeletal muscle are directly attached to the bones of the skeleton?
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False some are directly while other are indirectly attached to the bones of the skeleton.
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Skeletal muscles perform 6 functions, what are they?
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Produce skeletal movements, where muscle contraction pull on tendons and move the bones of the skeleton.
Maintain posture and body position. Support soft tissues, support the weight of visceral organs and shield internal tissue from injury Guard entrances and exit: provide voluntary control over swallowing, urination Maintain body temperature: whenever energy is used in the body, some of it is converted to heat. Store Nutrients Reserves : inadequate protein can result in the breakdown of skeletal muscles. |
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There are 3 types of connective tissue for each muscle, what are these connective tissue called?
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Epimysium
Perimysium Endomysium |
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What are the differences between Epimysium, Perimysium, and Endomysium?
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Epimysium is a dense layer of collagen fibers and separates the muscle from the surround tissue and organs.
Perimysium divide the skeletal muscle into a series of compartments each containing a bundle of muscle fibers call fascicle. Endomysium surrounds the individual skeletal muscle cells or muscle fibers and loosely interconnects adjacent muscle fibers. |
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Between the three layers of connective tissues, which one is the most dense (Epimysium, Perimysium, and Endomysium)?
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Epimysium
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Of the 3 connective tissue (Epimysium, Perimysium, and Endomysium), which one possesses collagen and elastic fibers, blood vessels, and nerves?
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Perimysium
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Define FASCICLE?
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Bundles of Muscles
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Between the three layers of connective tissues, which one is the most delicate (Epimysium, Perimysium, and Endomysium)?
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Endomysium
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Between the three layers of connective tissues, which one is found within a fascicle (Epimysium, Perimysium, and Endomysium)?
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Endomysium
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Between the three layers of connective tissues, which one maintain blood flow and innervate the muscle fibers within the fascicles (Epimysium, Perimysium, and Endomysium)?
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Perimysium
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What does the endomysium connective tissue layer contain?
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Capillary networks that supply blood to the muscle fibers
Myosatellite cells Nerve fibers that control the muscle |
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What are MYOSATELITE CELLS?
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Embryonic stem cells that function in the repair of damaged muscle tissue
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Which two connective tissue layers will form interwoven and blend into another through the use of the collagen fibers?
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Perimysium
Endomysium |
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At each end of the muscle, the collagen fibers of the epimysium, perimysium, and endomysium come together to form either a bundle or a broad sheet, what are the terms?
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Tendon: bundle
Aponeurosis: Broad sheet |
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Between the three layers of connective tissues, which two contain the blood vessels and nerves that supply the muscle fibers (Epimysium, Perimysium, and Endomysium)?
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Endomysium
Perimysium |
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Skeletal muscles contract only under stimulation from the ____ ____ ____?
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Central Nervous System
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Skeletal muscles are involuntary or voluntary?
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Voluntary muscles because we have control over their contractions
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What are some distinctive features of skeletal muscles?
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Large in size
Multinucleate |
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Define SARCOLEMMA?
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Plasma membrane of a muscle fiber that surrounds the scarcoplasm.
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Define SCARCOPLASM?
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Cytoplasm of the muscle fiber
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Typically what the first step before muscle fibers contract?
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Change in the transmembrane potential
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In order for the skeletal muscle fiber to contract simultaneously, the signal to contract must be distributed quickly throughout the interior of the cell and this signal is conducted through what?
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Transverse tubules or T tubules
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What are Transverse Tubules?
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Narrow tubes that are continuous with the sarcolemma and extend into the sarcoplasm a the right angles to the cell surface
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What purpose does Transverse Tubules served?
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Filled with extracellular fluid, T tubules form passageways through the muscle fibers
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Impulses that triggers for muscle fiber contraction is called what?
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Action Potential
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Myofibrils are encircled by what structure?
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Transverse Tubules
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Myofibrils consist of bundles of protein filaments, called what?
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Myofilaments
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What are two types of Myofilaments?
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Thin filaments: are composed primarily of actins
Thick filaments: are composed primarily of myosin |
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Thick and thin myofilaments are organized into repeating function unit called what?
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Sarcomeres
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The structure of SARCOMERES contains what?
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Thick filaments
Thin filaments Proteins that stabilized the position of the thick and thin filaments Proteins that regulate the interaction between thick and thin filaments |
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Thick filaments and thin filaments are associated to which bands I or A?
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I bands - light bands - thin filam
A bands - dark bands - thick fila |
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Which bands includes all 3 of the following subdivisions, M line, H band, and zone of overlap?
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A band, which is the dark band, which is the thick filaments
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Purpose and location of M line?
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Located in the central portion of the each thick filaments
Stabilized the position of the thick filaments |
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Purpose and location of H bands?
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Located on either side of the M line.
Contain thick filaments, but no thin filaments |
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Purpose of the zone of overlap?
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Situated between the thick filaments
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Which bands composed of Z lines and Titin?
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I bands
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What purpose does Z lines serve?
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Mark the boundary between adjacent sarcomeres.
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What purpose does TITIN serves?
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Keep the thick and thin filaments in proper alignment and aids in restoring resting sarcomere length and also helps the muscle fiber resist extreme stretching that would otherwise disrupt the contraction mechanism
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Where would calcium ion generally wants to release?
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Calcium ions released by the SR enter the regions where thick and thin filaments can interact
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Thin filaments contain 4 different proteins, what are they?
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Actin
Nebulin Tropomysin Troponin |
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Describe the structure of thin filaments
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Filamentous actin is a twised strand compose of two rows of G actin with a long strand of Nebulin in between. Each G actin molecules contain an active site that can be bind. Strands of tropomyosin cover the active sites on G actin and prevent actin myosin interaction, in which will later bind to only one molecule of troponin. The troponin-tropomysin complex must change and exposed the F actin before a contraction can take place.
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What happens when skeletal muscle fibers contracts
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H bands and I bands get smaller
Zone of overlap get larger Z lines move closer together Width of A band remain constant |
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Skeletal muscle fibers contract under the stimulation of what system?
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Nervous system
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Communication between the nervous system and a skeletal muscle fiber occurs at a specialized intercellular connection known as what?
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Neuromuscular junction / myoneural junction
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The cytoplasm of the synaptic terminal contains mitochondria and vesicle filled with molecules of what?
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Acetylcholine
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What purpose does ACETYLCHOLINE served in the contraction of muscle fibers?
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Release of ACh from the synaptic terminal can alter the permeability of the sarcolemma and trigger the contraction of muscle fibers
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The synaptic cleft is a narrow space that separates the synaptic terminal of the neuron from the opposing sarcolemmal surface, what is the surface call?
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Motor end plate is a surface that contain membrane receptors tat bind ACh
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What enzyme break down acetylcholine?
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Acetylcholinesterase
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What signal stimulates the release of ACh?
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Arrival of an electrical impulse or action potential at the synaptic terminal
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Define ACTION POTENTIAL?
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An action potential is a sudden change in the transmembrane potential that travels along the length of the axon.
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What happens when action potential reach the synaptic cleft?
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Permeability changes in the membrane and trigger the exocytosis of ACh into the synaptic thru vesicles
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Once ACh diffuse through the synaptic cleft, where will it head to?
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Motor end plate, because there are receptors
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Once ACh binds to the receptor of the end motor plate, what will happen?
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ACh bindings changes he permeability of the motor end plate and allow a rush of Sodium ion to come through
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How would you stop the influx of Sodium ions?
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Acetylcholinesterase remove ACh from the cleft and eventually ACh will diffuse off the receptors and into the cleft
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The arrival of an action potential at the synaptic terminal thus leads to the appearance of an action potential in what?
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Sarcolemma
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What is EXCITATION-CONTRACTION COUPLING?
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This coupling occurs at the triad, in which an action potential triggers the release of calcium from the cisterne of the sarcoplasmic recticulum.
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Why is the effect of calcium release on the sarcomere almost instantaneous for contraction?
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Because the terminal cisternae are situated at the zone of overlap, where thick and thin filaments interact
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What blocks the active sites from being inaccessible?
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Tropinin
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How can the active sites become accessible?
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Calcium
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When troponin is only bind to actin and tropmyosin, and the binding site of calcium is empty, what is happening?
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Nothing, the muscle fiber is at rest
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At what point can contaction cycle begin?
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Binding of calcium, changes the shape of troponin molecule and weaken the bond between tropinin and actin, rolling the tropomysin strand away from the active sites
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During the contraction cycle, the myosin head function as _____ and at the start of the contraction cycle, each myosin head has already split a mole of _____.
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ATPase, an enzyme that can break down ATP
ATP |
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What is the breakdown product of ATP?
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ADP and phosphate
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Once the active sites are exposed, the energized myosin head binds to the active site forming what?
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Cross bridges
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True or False: Since cocking the myosin head requires energy, the breakdown of ATP. That both the ADP and phosphate are no longer bound to the mysoin head?
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False. both the ADP and phosphate are still bound to the myosin head
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The duration of contraction depends on what?
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The duration of stimulation at the neuromuscular junction
The presence of free calcium ions in the scaroplasm Availability of ATP |
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What is the primary energy source of muscle contraction?
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ATP
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What is the primary function of ATP?
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Transfer of energy from one location to another rather than the long term storage of energy
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At rest, a skeletal muscle fiber produces more ATP than it needs and then ATP transfers energy to what?
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Creatine
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What is creatine?
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Creatine is a small molecule that muscle cells assemble from fragments of amino acids
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By having ATP transferring energy to creatine, it created another high energy compound called?
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Creatine phosphate or phosphorylcreatine (CP)
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In previous chapters, we learned that during contraction, myosin heads break down ATP and produces ADP + phosphate group. How can ATP be restore again?
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The energy store in creatine phosphate is then used to recharged ADP converting it back to ATP.
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What is the enzyme utilize in the reaction of ADP and creatine phosphate to re-create ATP?
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Creatine Phosphokinase (CPK)
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What are 2 ways cells in the body generate ATP?
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Aerobic metabolism in the mitochondria
Glycolysis in the cytoplasm |
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For each molecule o pyruvic acid fed into the Kreb cycle, the cell gains how many ATP molecules?
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17
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Resting skeletal muscle fibers rely almost exclusively on the aerobic metabolism of ___ ____ to generate ATP?
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Fatty acids
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What source allows cell to continue to contract for an extended period, even without any external source of nutrients?
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Skeletal muscle fiber contain large amounts of glycogen that shift from fatty acid metabolism to glucose metabolism
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What is GLYCOLYSIS?
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Glycolysis is the breakdown of glucose to pyruvic acid in the cytoplasm of a cell.
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Is Glycolysis an aerobic or anerobic process?
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Anerobic
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What is the net gain of glycolysis?
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2 ATP molecules and 2 pyruvic acid molecules from each glucose molecules
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When comparing GLYCOLYSIS and AEROBIC METABOLISM (KREB CYCLE), which cycle is more sufficient in producing ATP?
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Aerobic metabolism (kreb cycle) because this cycle can generate a total of 17 ATP using one molecule of pyruvic acid, whereas Glycolysis which utilizes 2 pyruvic acid only to generate 2 ATP
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If AEROBIC METABOLISM is so much more efficient than Glycolysis, why is it use to produce ATP?
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Glycolysis is important only because it provides the substrate for aerobic metabolism and it can proceed in the absence of oxygen, glycolysis becomes an important source of energy when energy demands are high and the availability of oxygen is limited
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True or False: During period of recovery and oxygen is abundance, lactic acid can be recycled by converting it back to pyruvic acid?
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True
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Why is lactic acid so dangerous to the body?
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Lactic acid can lower the pH of the blood and tissue
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Define CORI CYCLE?
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The shuffling of lactic acid to the liver and glucose back to muscle cells
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Muscle performance can be considered in terms of two factors, what are they?
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Force
Endurance |
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Define FORCE?
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Force is the maximum amount of tension produced by a particular muscle or group of muscle
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Define ENDURANCE?
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Endurance is the amount of time during which the individual can perform a particular activity
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Identify the 3 types of SKELETAL MUSCLE FIBERS?
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Fast fibers
Slow fibers Intermediate fibers |
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Of the three types of skeletal muscle fibers, which one is more predominate in the body?
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Fast fibers
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What is MYOGLOBIN?
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Myoglobin is a globular protein that is structurally related to hemoglobin, in which they both reversibly bind to oxygen molecules
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Myoglobin is most found in which skeletal muscle fibers?
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Slow fibers
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What purpose does fast and slow skeletal muscle fibers serve?
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Fast Fibers: rapid activities
Slow Fibers: continue contracting for extended periods |
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What is an advantage of Fast fiber but is also consider a disadvantage of Slow fibers?
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Fast Fibers: faster peak tension; large glycogen reserves
Slow Fibers: slower peak tension; small glycogen reserves |
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What are the advantages of Slow fiber over Fast fibers
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Fast Fibers:
Slow Fibers: surrounded by more capillaries thus higher oxygen supply to support mitochondrial activity; Contain myoglobin resulting in substantial oxygen reserves that be mobilize during contraction |
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Fast fibers using which more anerobic or aerobic process?
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Anerobic
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What is the difference between HYPERTROPHY and ATROPHY?
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Hypertrophy is an enlargment of the stimulated muscle.
Atrophy: reduction in muscle size, tone, and power |
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What are ANAEROBIC ENDURANCE is supported by what kind of energy activity?
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Glycolysis
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What are AEROBIC ENDURANCE is supported by what kind of energy activity?
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Mitochondria activity
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Which two muscles are striated?
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Skeletal
Cardiac |
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Between CARDIAC AND SKELETAL muscle fibers, which one is smaller in diameter?
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Cardiac
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Between CARDIAC AND SKELETAL muscle fibers, which one has a central nuclei?
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Cardiac
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Between CARDIAC AND SKELETAL muscle fibers, which one contains TRIADS?
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Skeletal
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Between CARDIAC AND SKELETAL muscle fibers, which one lack terminal cisternae?
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Cardiac
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Between CARDIAC AND SKELETAL muscle fibers, which one is completely dependent on aerobic metabolism?
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Cardiac
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What is an intercalated disc and what happens at that connective site?
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Plasma membrane of two cardiac muscle are intertwined and bound together by gap junctions and demosomes. These connection help stabilize the relative position and maintain the 3D structures of the tissue
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What purpose does the GAP JUNCTION served?
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Allow ions and small molecules to move from one cell to another and creates a direct electrical connection between the two muscle cells
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What are 4 functions of CARDIAC Muscles?
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Cardiac muscle tissue contracts without neural stimulation (automaticity).
Innervation by the nervous system can alter the pace established by the pacemaker cells and adjust the amount of tension produced during a contraction Cardiac muscle cell contraction last roughly 10 times longer and have longer refractory periods and do not fatigue easily Cardiac muscle cannot produce tetanic contractions |
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Since cardiac muscle are considered automaticity, what cardiac specialize muscle cell is mainly responsible for it's contraction?
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Pacemaker Cells
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Between Smooth, Cardiac, and Skeletal muscles, which one has cells that is spindled in shaped?
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Smooth
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Between Smooth, Cardiac, and Skeletal muscles, which one have Tubules??
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Skeletal
Cardiac Smooth contains NO Tubules |
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Between Smooth, Cardiac, and Skeletal muscles, which one has non striated muscle?
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Smooth
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Between Smooth, Cardiac, and Skeletal muscles, which one have myofibrils and sacromeres?
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Skeletal
Cardiac |
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What are attach to the thin filaments in smooth muscle cells?
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Dense Bodies
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What are dense bodies?
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Structures distributed throughout the sarcoplasm in a network of intermediate filaments compose of the protein desmin.
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What function does dense bodies serve?
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The dense bodies are firmly attached to the sarcolemma and anchor the thin filaments the cell would shortens
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What triggers smooth muscle contraction?
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Free calcium ions in the cytoplasm
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Once there is an influx of calcium ion into the sarcoplasm, the calcium ions interact with what calcium binding protein?
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Calmodulin
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Calmodulin can activate what enzyme?
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Mysoin light chain kinase, enables attachment of myosin heads to actin
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What is the difference between excitation-contraction coupling of smooth muscle to cardiac or skeletal muscle fibers?
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In skeletal and cardiac, the trigger for contraction is the binding of calcium ions to troponin
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What is an important characteristics of smooth muscle when it comes in relation to length-tension relationship?
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Plasticity: the ability to function over a wide range of lengths and smooth muscle are able to acquire this characteristic is because thick and thin filaments are not organized into sarcomeres in smooth muscle
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What factors determine the number of cross bridges?
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Depends on the degree of overlap between thick and think filaments
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What factor can influence tension?
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Formation of Cross bridges
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Define TWITCH?
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A single stimulus contraction relaxation sequence in the muscle fiber
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A single twitch can be divided into 3 kinds of periods, what are they?
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Latent
Contraction Relaxation |
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What happens during the LATENT PERIOD?
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Action potential sweeps across the sarcolemma and releases calcium ions
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What happen during the CONTRACTION PERIOD?
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Calcium are bind to tropoinin, active sites are exposed and cross bridges are forming
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What is happening during the RELAXATION PHASE?
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Calcium level decrease as well as cross bridges
Active sites are covered by tropomyosin |
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What is the difference between isotonic and isometric contractions?
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Isotonic contraction is when tension rises and the skeletal muscle lengthen
Isometric: the muscle as whole doesn't lengthen and tension produced never exceeds the loads |
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What are two types of ISOTONIC CONTRACTION/
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Concentric
Eccentric |
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Give an example of Isotonic contraction
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Lifting an object, running and walking
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What is the difference between CONCENTRIC CONTRACTION and ECCENTRIC CONTRACTION?
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Concentric: The muscle tension exceeds the load and the muscle shortens.
Eccentric: tension is less than the load and muscle elongates |