Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
203 Cards in this Set
- Front
- Back
|
Six functions of skeletal muscle is? |
Skeletal movement, maintain position/posture, support soft tissue, guard openings, help maintain body temperature, and store nutrient Reserve. |
|
|
Common properties for muscle tissue? |
Excitability, contract ability, extend ability, and elasticity. |
|
|
Excitability |
The ability to receive and respond to a stimulus |
|
|
Contractility |
Ability of a muscle cell to shorten when it is stimulated |
|
|
Extensibility |
Stretching movement of a muscle |
|
|
Elatiticy |
Ability of a muscle to recoil to its resting length. |
|
|
Skeletal movement |
Skeletal muscle contraction pull on tendons to move our bones |
|
|
Maintain position/posture |
Tension in our skeletal muscle maintains body posture |
|
|
Support soft tissue |
Layers of skeletal muscle make up the abdominal wall and the pelvic floor cavity |
|
|
Guard openings |
Sphincters and circle the opening of Digestive and urinary tracts. Muscles give us voluntary control over swallowing pooping and urinating |
|
|
Help maintain body temperature |
Muscle contractions use energy and whenever energy is used in the body, some of it is converted to heat. |
|
|
Store nutrient Reserve |
When diet contains too few proteins or calories the contractile proteins in skeletal muscles are broken down, and there are amino acids released into the circulation. |
|
|
Epimysium |
Dense layer of collagen fibers that surrounds the entire muscle. It separates the muscle from nearby tissues and organs connected to the Deep fascia. |
|
|
Perimysium |
Divide skeletal muscles into a series of compartments. Each compartment contains a bundle of muscle fibers called fascicle. |
|
|
Fascicle |
Contains collagen and elastic fibers within the fascicle |
|
|
Endomysium |
Within fascicle the delicate connective tissue surrounds the individual skeletal muscle cells, called muscle fibers. |
|
|
Identify the three types of muscle tissues and cite their major functions |
The three types of muscle tissue are skeletal muscle, cardiac muscle, and smooth muscle. Skeletal muscle tissue moves the body for by pulling on our bones, cardiac muscle tissue pumps blood through the cardiovascular system, and smooth muscle tissue pushes fluid and solids along the digestive tract and other internal organs, and regulate the diameters of small arteries. |
|
|
Identify the common property shared by muscle tissues |
Muscle tissues share the common properties of excitability (the ability to receive and respond to a stimulus), contractility (the ability of a muscle cell to shorten when it is stimulated), extensibility (stretching movement of a muscle), and elasticity (the ability of a muscle to recoil to its resting length). |
|
|
Identify the primary functions of skeletal muscle |
Skeletal muscles produce skeletal movement, and maintain posture and body position, support soft tissue, guard body entrances and exits, maintain body temperature, and store nutrients. |
|
|
Skeletal muscles |
Are organs composed mainly of skeletal muscle tissue, but they also contain connective tissue, blood vessels, and nerves. |
|
|
Endomysium contains |
1. Capillary Networks (the smallest blood vessels) that Supply blood to the muscle fibers. 2. mayosatellite cells, stem cells that help repair damaged muscle tissues. 3. Nerve fibers that control the muscle. All these structures are in Direct contact with the individual muscle fibers. |
|
|
Myosatellite cells |
Stem cells |
|
|
Tendons or aponeurosis |
At the end of the muscle, the collagen fibers of the epimysium, perimysium, and endomysium come together to form either a bundle known as a tendon, or a broad she called aponeurosis. |
|
|
Describe the three connective tissue layers associated with skeletal muscle tissue. |
The epimysium is a dense layer of collagen fibers that surrounds the entire muscle. The perimysium divides the skeletal muscle into a series of compartments, each containing a bundle of muscle fibers called fascicles. And the endomysium surrounds individual skeletal muscle cells (muscle fibers). The collagen fibers of the epimysium perimysium and endomysium come together to form either bundles known as tendons, or broadsheets called aponeurosis. Tendons and aponeurosis generally attach skeletal muscle to bones. |
|
|
How would serving the tendon attached to a muscle affect the muscles ability to move a body part? |
Because tendons attach muscles to Bone, serving the tendon would disconnect the muscle from the bone, and so the muscle could not move a body part. |
|
|
Myoblasts |
Myo- muscle, blasts- formative cell |
|
|
Sarcolemma |
Sarco- flesh, lemma- husk |
|
|
Sarcoplasm |
The cytoplasm of a muscle cell |
|
|
Transverse (t) tubules |
Are narrow tubes Who services are continuous with the sarcolemma and extend deep into the sarcoplasm. |
|
|
Sacroplasmic reticulum (SR) |
Forms a tubular Network around each myofibrils, fitting over it like a lace sleeve shirt sleeves. The SR is similar to the smooth endoplasmic reticulum of other cells. |
|
|
Terminal cisternae |
Are large areas of the sarcoplasmic reticulum surrounding the T tubules |
|
|
Myofibrils |
Organized collections of myofilaments in skeletal and cardiac muscle cells. |
|
|
Myofilaments |
Find protein filaments composed primarily of the protein actin and myosin |
|
|
Thin filaments |
Actin |
|
|
Thick filaments |
Myosin |
|
|
Sarcomeres |
Sarco- flesh, meres- part |
|
|
Sarcomeres contain |
Thick filaments, thin filaments, proteins that stabilize the position of the thick and thin filaments, and proteins that regulate the interaction between thick and thin filaments. |
|
|
A single thin filament contains four main proteins |
F-actin, nebulin, tropomyosin, and troponin. |
|
|
Sliding filament theory |
1. The H bands and I bands of the sarcomeres narrow. 2. The zones of overlap widen. 3. The Z lines move closer together. 4. The width of the band remains constant. These observations make sense only if the thin filaments are sliding toward the center of each sarcomere, alongside the thick filaments. |
|
|
Describe the components of sarcomeres |
Sarcomeres, the smallest contractile units of a striated muscle cell, are segments of my referrals. Each circle Mirror Has a dark a band and a light Ivan the a band contains the M line in the H line in the zone of overlap. Each iban contains thin filaments, but not thick filaments. Z lines bisect the I bands and mark the boundaries between adjacent sarcomeres. |
|
|
Why do skeletal muscle fibers appear striated when viewed through a light microscope? |
Skeletal muscle fibers appear striated when viewed through a light microscope because the Z lines and the thick filaments of the myofribils within the muscle fibers are aligned. |
|
|
Where would you expect to find the greatest concentration of calcium ions in a resting skeletal muscle fiber? |
You would expect the greatest concentration of calcium ions in resting skeletal muscle fibers to be in the terminal cisternae of the sarcoplasmic reticulum. |
|
|
Excitable membranes |
Permit rapid communication between different parts of a cell. Membranes that are propagated action potentials, a characteristic of muscle cells and nerve cells. |
|
|
Action potential |
Appropriated change in the membrane potential for excitable cells, initiated by a change in the membrane permeability to sodium ions. |
|
|
Neuromuscular Junction |
A synapses between a neuron and a muscle cell |
|
|
Neurotransmitter |
A chemical compound released by one neuron to affect the membrane potential of another |
|
|
Excitation-contraction coupling |
Is the physiological process of converting an electrical stimulus to a mechanical response. Is the link between the action potential generated in the sarcolemma and the start of a muscle contraction. |
|
|
Contraction cycle |
Is a series of molecular events that enable muscle contractions |
|
|
Cross Bridges |
The Binding of a myosin head that projects from the surface of a thick filament at the active site of a thin filament in the presence of calcium ions. |
|
|
Powerstroke |
The connection between the head and the tail functions as a hinge that lets the head pivot. When it pivots using the energy released from the Hydrolysis of ATP, the head swings towards the end line, a movement known as the power stroke. |
|
|
Describe the neuromuscular Junction |
Neuromuscular Junction, is the Sim naps between a motor neuron and a skeletal muscle cell. This connection enables communication between the nervous system and skeletal muscle fiber. |
|
|
How would a drug that blocks acetycholine release affect muscle contraction? |
ACh released from the axon terminal is necessary for skeletal muscle contractions, because it serves as the first step in the process that leads to the formation of cross bridges in the sarcomeres. A muscle's ability to contract depends on the formation of cross Bridges between the myosin heads and the actin myofilaments. A drug that blocks ACh release would interfere with a cross Bridge formation and prevent muscle contraction. |
|
|
What would happen to a resting skeletal muscle if the sarcolemma suddenly became very permeable to calcium ions? |
If the sarcolemma of resting skeletal muscle suddenly became permeable of calcium ions, the cytosolic concentration of calcium ions would increase, and the muscle would contract. In addition, because the amount of calcium ions in the cytosol must decrease for relaxation to occur, The increased permeability of the sarcolemma to calcium ions might prevent the muscle from relaxing completely. |
|
|
Predict what would happen to a muscle if the motor end plate lacked acetycholinesterase (AChE) |
Without AChE the motor end plate would be stimulated continuously by ACh, locking the muscle in a state of contraction. |
|
|
Length tension relationship |
Is the observation that the isometric force exerted by a muscle is dependent upon its length when tested |
|
|
Twitch |
Is a single stimulus contraction relaxation sequence in a muscle fiber |
|
|
Latent period |
Begins at stimulation and last about 2 seconds. During this period, the action potential sweeps across the sarcolemma, and the SR releases calcium ions. The muscle fiber does not produce tension during the Latent period, because the contraction cycle has yet to begin. |
|
|
Contraction phase |
Tension increases to a peek. As the tension increases, calcium ions are binding to troponin, active sites on the thin filaments are being exposed, and cross Bridge interactions are occurring. For this muscle fiber, the contraction phase ends roughly 15 milliseconds after stimulation. |
|
|
Relaxation phase |
Last about 25 milliseconds. During this period the calcium ion level is decreasing as calcium ions are pumped back into the SR, active sites are being covered by tropomyosin, and the number of active cross Bridges is declining as they detach. As a result, tension decreases to the resting level. |
|
|
Treppe |
The graduated series of increasingly vigorous contractions that results when a corresponding series of identical stimuli is applied to a rested muscle. |
|
|
Why does a muscle that has been overstretched produce minimal tension? |
A muscle's ability to contract depends on the formation of cross Bridges between the myosin and the actin myofilaments in the muscle. In a muscle that is overstretched, the myofilaments would overlap very little, so very few cross Bridges between myosin and actin could form and, thus, the contraction would be week. If myofilaments did not overlap at all then no cross Bridges would form in the muscle could not contracted. |
|
|
Isotonic contractions |
The muscle length changes with a constant force |
|
|
Isometric contractions |
The length of the muscle does not change with a constant force |
|
|
Concentric |
Muscle shortens |
|
|
Eccentric |
Muscle lengthens |
|
|
Motor unit |
Is a motor neuron and all the muscle fibers that it controls. The size of a motor unit indicates how fine, or precise, a movement can be. |
|
|
Fasciculation |
Involuntary muscle twitch |
|
|
Recruitment |
When you decide to move your arm, specific groups of motor neurons in the spinal cord are stimulated. The contraction begins with the activation of the smallest motor unit in the stimulated muscle. These motor units generally contain muscle fibers that contract fairly slowly. As the movement continues, large motor units containing faster and more powerful muscle fibers are activated, and tension Rises steeply. The smooth but steady increase in the muscular tension produced by increasing the number of active motor units is called recruitment. |
|
|
Muscle tone |
In any skeletal muscle, some motor units are always active, even when the entire muscle is not contracted. Their contractions do not produce enough tension to cause movement but they do tents and firm the muscle. The resting tension in a skeletal muscle is called muscle tone |
|
|
Isotonic contractions |
Tension increases in the skeletal muscles length changes. |
|
|
Isotonic concentric contractions |
The muscle tension exceeds the load in the muscle shortens. |
|
|
Isotonic eccentric contractions |
The peak tension developed is less than the load, and the muscle elongates due to the contraction of another muscle or the pull of gravity. |
|
|
Isometric contraction |
The muscle as a whole does not change length, and the tension produce never exceeds the load. |
|
|
Can a skeletal muscle contract without shortening? Explain. |
Yes, a skeletal muscle can contract without shortening. The muscle can shorten (isotonic concentric contraction), elongate (isotonic eccentric contraction), or remain the same length (isometric contraction), depending on the relationship between the load (resistance) and the tension produced by Acton-myosin interactions. |
|
|
Normal muscle function requires |
1. Substantial intercellular energy Reserves. 2. A normal circulatory Supply. 3. A normal blood oxygen level. 4. A blood pH within normal limits. |
|
|
Creatine |
Is a small molecule that muscle cells Assemble from fragments of amino acid |
|
|
Creatine phosphate |
A high-energy compound in muscle cells. During muscle activity, the phosphate group is donated to ADP, regenerating ATP. Also known as phosphorylcreatine |
|
|
Creatine kinase |
Enzyme expressed by various tissue and cell types. |
|
|
Most cells in the body generate ATP through |
1. Glycolysis inside of plasma. 2. Aerobic metabolism in mitochondria. |
|
|
Glycolysis |
Is the anaerobic breakdown of glucose to pyruvate in the cytosol of a cell. |
|
|
Anaerobic process |
Without oxygen. Glycolysis is the anaerobic breakdown of glucose to pyruvate in the cytosol of a cell it is an anaerobic process because it does not require oxygen. Glycolysis provides a net gain of two ATP molecules and generates to pyruvate molecules from each glucose molecule. |
|
|
Glycogen |
Is a chain of glucose molecules |
|
|
Aerobic metabolism |
Normally provides 95% of the ATP demands of a resting cell. This process, mitochondria absorbed oxygen, ATP, phosphate ions and organic substrates (such as pyruvate) from the surrounding cytoplasm. |
|
|
Muscle metabolism in a resting muscle fiber |
The demand of ATP is low and sufficient oxygen is available for mitochondria to meet that demand. Fatty acids are absorbed and broken down into mitochondria creating a surplus of ATP. Some mitochondrial ATP is used to convert absorbed glucose to glycogen. Mitochondrial ATP is also used to convert creatine to creatine phosphate (CP). This result is the buildup of energy Reserves (glycogen and CP) in the muscle. |
|
|
Muscle metabolism during moderate activity |
The demand for ATP increases. There is still enough oxygen for the mitochondria to meet the increased demand, but no excess ATP is produced. ATP is generated primarily by aerobic metabolism of glucose from The stored glycogen. If the glycogen reserves are low, the muscle fiber can also break down other substrates, such as fatty acids. All of the ATP being generated is used to power muscle contraction. |
|
|
Muscle metabolism during Peak activity |
The demand for ATP is enormous. Oxygen cannot diffuse into the fiber fast enough for the mitochondria to meet that demand. Only a third of the cells ATP needs can be met by the mitochondria. The rest of the ATP comes from glycolysis, and when this produces pyruvate faster than the mitochondria can utilize it, the pyruvate built up in the cytosol. The pyruvate is converted to lactate. Hydrogen ions from ATP hydrolysis are not absorbed by the mitochondria. The build-up of hydrogen ions increase cytosol acidity, which inhibits muscle contractions, leading to Rapid fatigue. |
|
|
Recovery period |
The conditions in a muscle fibers are return to normal, pre exertion level. |
|
|
Cori cycle |
refers to the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose, which then returns to the muscles and is metabolized back to lactate. |
|
|
Oxygen debt or excessive post-exercise oxygen consumption (EPOC) |
The amount of oxygen required to restore normal, pre exertion conditions |
|
|
How do muscle fibers continuously synthesize ATP? |
Muscle fibers synthesize ATP continuously by utilizing creatine phosphate and metabolizing glycogen and fatty acids. Most cells generate ATP only through aerobic metabolism in the mitochondria and through glycolysis in the cytosol. |
|
|
Define oxygen debt |
Oxygen debt is the amount of oxygen required to restore normal, pre exertion conditions in muscle tissue. |
|
|
Force |
The maximum amount of tension produced by a particular muscle |
|
|
Endurance |
The amount of time during which a person can perform a particular activity |
|
|
Fast fibers |
They can reach Peak twitch tension in 0.01 seconds or less after stimulation. Fast fibers are large in diameter and contain densely packed myofibrils, large glycogen reserves, and relatively few mitochondria. Muscles dominated by fast fibers produce powerful contractions because the tension produced by a muscle fiber is directly proportional to the number of myofibrils. However, fast fibers fatigue rapidly because their contractions use ATP in massive amounts, and they have relatively few mitochondria to generate ATP. |
|
|
Slow fibers |
Have only about half the diameter of fast fibers and take three times as long to reach Peak tension after stimulation. These fibers are specialized in ways that enable them to continue Contracting long after a fast fiber would have become fatigued. Most important specialization support aerobic metabolism in thenumerous mitochondria. |
|
|
Intermediate fibers |
Are in between those of fast fibers and slow fibers. And appearance, intermediate fibers most closely resemble fast fibers because they contain little myoglobin and are relatively pale. They have an intermediate capillary Network in mitochondrial Supply around them and are more resistant to fatigue then are fast fibers. |
|
|
White muscles |
Muscles dominated by fast fibers appear pale |
|
|
Red muscles |
Extensive blood vessels in myoglobin give slow fibers a reddish color, some muscles dominated by slow fibers are known as red muscles |
|
|
Hypertrophy |
An increase in tissue size without cell division. |
|
|
Atrophy |
The wasting away of tissue from a lack of use, ischemia, or nutritional abnormalities |
|
|
The effects of aging on the muscular system |
Skeletal muscle fibers become smaller in diameter. Skeletal muscles become less elastic. Tolerance for exercise decrease. The ability to recover from muscular injury decrease. |
|
|
Fibrosis |
Makes the muscle less flexible, in the collagen fibers can restrict movement and circulation. |
|
|
Fatigued |
We can say and act of skeletal muscle is fatigued when it can no longer perform at the required level of activity. |
|
|
Muscle fatigue has been correlated with |
1. Depletion of metabolic reserves within the muscle fibers. 2. Damage to the sarcolemma and sarcoplasm reticulum. 3. A decline in PH within the muscle fibers and the muscle as a whole, with decrease calcium ion binding to troponin and Alters enzyme activities. 4. A sense of weariness and a reduction in the desire to continue the activity, due to the effects of low blood pH and sensation of pain. |
|
|
Anaerobic endurance |
Is the length of time muscular contraction can continue to be supported by the existing energy reserve of ATP and CP and by glycolysis |
|
|
Anaerobic endurance is limited by |
1. The amount of ATP and CP available. 2. The amount of glycogen available for breakdown. 3. The ability of the muscle to tolerate Lactaid and the buildup of hydrogen ions generated During the period of anaerobic metabolism. |
|
|
Aerobic endurance |
Is the length of time a muscle can continue to contract while supported by the mitochondrial activities. |
|
|
Improvements in Aerobic endurance results from two factors |
Alterations in the characteristics of muscle fibers. Improvement of cardiovascular performance. |
|
|
Identify the three types of skeletal muscle fibers. |
The three types of muscle fibers are: 1. Fast fibers (also called White muscle fibers, fast-twitch glycoltic fibers, type II-B fibers, and fast fatigue fibers). 2. Slow fibers (also called red muscle fibers, slow twitch oxidative fibers, type I fibers, and slow oxidative fibers). 3. Intermediate fibers (also called fast-twitch oxidative fibers type II-A fibers, and fast resistant fibers). |
|
|
Describe muscle fatigue |
Muscle fatigue is a muscles reduced ability to contract due to low ph (hydrogen ion buildup), low ATP levels, and other problems. |
|
|
Describe general age-related effects on skeletal muscle tissue |
General age-related effects on skeletal muscles include decreased skeletal muscle fiber diameters, diminished muscle elasticity, decreased tolerance for exercise, and a decreased ability to recover from muscular injuries. |
|
|
Why would a sprinter experience muscle fatigue before a marathon runner would? |
A sprinter requires a large amount of energy for a short burst of activity. To supply this energy, the sprinters muscles rely on anaerobic metabolism. Anaerobic metabolism is less efficient in producing energy than aerobic metabolism, and the process also produces acidic waste. This combination contributes to muscle fatigue. Conversely, marathon runners Drive most of their energy from aerobic metabolism, which is more efficient and produces fewer waste than anaerobic metabolism does. |
|
|
Which activity would be more likely to create an oxygen debt: swimming laps or lifting weights? |
Activities that require short periods of strenuous activity produce a greater oxygen debt, because such activities rely heavily on energy production of anaerobic metabolism. Because lifting weights is more strenuous over the short-term than swimming laps, which is an aerobic activity, weightlifting would likely produce a greater oxygen debt then would swimming laps. |
|
|
Which type of muscle fibers would you expect to predominate in the leg muscles of someone who excels at endurance activities, such as cycling or long distance running? |
People who excel at aderans activities have a higher than normal percentage of slow fibers. Slow fibers are physiologically better adapt to this type of activity then are fast fibers, which are less vascular and fatigue faster. |
|
|
Compare and contrast skeletal muscle tissue and cardiac muscle tissue |
Compared to skeletal muscle tissue, cardiac muscle tissue: 1. Has relatively small cells. 2. Has cells with a central located nucleus (some may contain two or more nuclei). 3. Has t tubules that are short and Broad and do not form Triads. 4. Has an Sr that lacks terminal cisternae and has tubules that contracted the plasma membrane as well as the T tubules. 5. Has cells that are nearly total dependent on aerobic metabolism as an energy source. 6. Contains intercalated discs that assist in stabilizing tissue structure and spreading Action potentials. |
|
|
What feature of cardiac muscle tissue allows the heart to act as a functional syncytium? |
Cardiac muscle cells are joined by Gap Junctions, which allows ions and small molecules to flow directly between cells. As a result, action potential generated in one cells spread rapidly two adjacent cells. Thus, all the cells contract simultaneously, as if they were a single unit (a synctium). |
|
|
Smooth muscle tissue forms |
Sheetz, bundles, or sheaths around other tissues in almost every Organ |
|
|
Smooth muscles play a variety of roles in various body systems |
Integumentary system, smooth muscles around blood vessels regulate the flow of blood to superficial dermis, smooth muscles of the arrector pili Elevate hairs. Cardiac muscle system coma smooth muscles around blood vessels control blood through through vital organs and help regulate blood pressure. Respiratory system, smooth muscles contract or relax to alter the diameters of the respiratory passageways and change the resistance to airflow. Digestive system, expensive layers of smooth muscle in the walls of the digestive tract play an essential role in moving materials along the track. Smooth muscle in the walls of the gallbladder contract to eject bile into the digestive tract. In both the digestive and urinary system, rings of smooth muscle called sphincters regulate the movement of material along internal passageways. Urinary system, smooth muscle tissue in the walls of small blood vessels Alters the rate of filtration in the kidneys. Layers of smooth muscle in the wall of the ureters transport urine to the urinary bladder, the contraction of the smooth muscle in the wall of the urinary bladder forces urine out of the body. Reproductive systems, in males, layers of smooth muscle help move sperm along the reproductive tract and cause the ejection of glandular secretion from the accessory glands into the reproductive tract. In females, layers of smooth muscle help move osteocytes (and perhaps sperm) along the reproductive tract, the contractions of the smooth muscle in the walls of the uterus expel the fetus at delivery. |
|
|
Internal organization of smooth muscle cells |
1. Smooth muscle cells are relatively long and slender. 2. Each cell is spindle shaped (tapered at both ends) and has a single, centrally located nucleus. 3. Smooth muscle cells lack Mayo for bills in Sacramento hours. As a result, the tissue also has no striation and is called non-striated muscle. 4. Thick filaments are scattered throughout the sarcoplasm of a smooth muscle cell. The myosin proteins are organized differently than the skeletal or cardiac muscle cells, and smooth muscle cells have more myosin heads per thick filament. 5. The thin filaments in a smooth muscle cell are attached to dense bodies, structures distributed throughout the sarcoplasm in a network of intermediate filaments composed of protein Desmin. Some of the dense bodies are firmly attached to the sarcolemma. The dense bodies and intermediate filaments anchor the thin filaments such that when sliding occurs between Thin and Thick filaments, the cells shorten. Dense bodies are not arranged in straight lines, so when a contraction occurs, the muscle cell twist like a corkscrew. 6. Adjacent smooth muscle cells are bound together in dense bodies, transmitting the contractile force from cell to cell throughout the tissue. 7. Although smooth muscle cells are surrounded by connective tissue, the collagen fibers never unite to form tendons or aponeuroses, as they do in skeletal muscles. |
|
|
Smooth muscle tissue differs from other muscle tissue in |
1. Excitation contraction coupling 2. Length tension relationships 3. Control of contractions 4. Smooth muscle tone. |
|
|
Calmodulin |
A calcium binding protein |
|
|
Identify the structural characteristics of smooth muscle tissue |
Smooth muscle cells lack sacrum years, and that smooth muscle tissues is non-striated. Additionally, the thin filaments are anchored to dense bodies. |
|
|
Which type of muscle tissue is least affected by change in extracellular calcium ion concentration during contraction? |
Skeletal muscle contractions are least affected by change in extracellular calcium ion concentration. In Skeletal muscle, most of the calcium ions come from the sarcoplasmic reticulum. Most of the calcium ions that trigger a contraction in cardiac and smooth muscles come from the extracellular fluid. |
|
|
Why can smooth muscle contract over a wider range of resting lengths than skeletal muscle can? |
The looser organization of actin and myosin filaments in smooth muscle allows smooth muscle to contract over a wider range of resting lengths than skeletal muscle. |
|
|
Connective tissue coverings of a skeletal muscle, listed from superficial to deep are |
Epimysium, perimysium, and endomysium. |
|
|
The signal to contract is distributed deep into the muscle fiber by the |
Transverse tubules |
|
|
The Detachment of myosin cross Bridges is directly triggered by |
The hydrolysis of ATP |
|
|
A muscle producing near Peak tension during rapid cycles of contraction and relaxation is said to be in |
Incomplete tetanus |
|
|
The type of contraction in which the tension Rises, but the low does not move is |
An isometric contraction |
|
|
An action potential can travel quickly from one cardiac muscle cell to another because the of the presence of |
Gap Junctions and tight junctions |
|
|
List the three types of muscle tissue in the body |
Skeletal muscle, cardiac muscle, and smooth muscle. |
|
|
What three layers of connective tissue are part of each muscle? What functional role does each layer play? |
1. Perimysium: surrounds bundles of muscle fibers (fascicles). 2. Epimysium: surrounds entire muscle. 3. Endomysium: surrounds individual skeletal muscle fibers (cells). |
|
|
The _______ contains vesicles filled with acetycholine. |
Axon terminal |
|
|
What structural feature of a skeletal muscle fiber propagates action potential into the interior of the cell? |
The transverse tubules propagate action potentials into the interior of the cell. |
|
|
What five interlocking steps are involved in the contraction process? |
1. Exposure to active sites. 2. Attachment of cross Bridges. 3. Pivoting of myosin heads (Powerstroke). 4. Detachment of cross Bridges. 5. Reactivation of myosin heads (recocking of myosin head). |
|
|
What two factors affect the amount of tension produced when a skeletal muscle contracts? |
Both the frequency of motor unit stimulation and the number of motor units involved affect the amount of tension produced when a skeletal muscle contracts. |
|
|
What forms of energy Reserve do resting skeletal muscle fibers contain? |
Resting skeletal muscle fibers contain ATP, creatine phosphate, and glycogen. |
|
|
What two mechanisms are used to generate ATP from glucose in muscle cells? |
Glycolysis anaerobic metabolism generate ATP from glucose in muscle cells. |
|
|
What is the calcium binding protein in smooth muscle tissue? |
The calcium binding protein in smooth muscle tissue is calmodulin. |
|
|
An activity that would require anaerobic endurance is |
A 50 meter dash, a pole vault, and a weightlifting competition. |
|
|
Areas of the body where you would not expect to find slow fibers include the |
Eye and hand |
|
|
During relaxation, muscles return to their original length because of all of the following. |
The contraction of the opposing muscles, the pull of gravity, the elastic nature of the sarcolemma, and elastic forces. |
|
|
According to the length tension relationship |
The greater the zone of overlap in the sacrum ear, the greater tension the muscle can develop. There is an Optimum range of actin and myosin overlap that will produce the greatest amount of tension. |
|
|
For each portion of a myelogram tracing a twitch in a stimulated calf muscle fiber, describe the events that occur within the muscle fiber. |
An initial latent Period (after the stimulus arrives and before tension begins to increase), an action potential generated in the muscle fiber triggers the release of calcium ions from the SR. In the contraction phase, calcium ions bind to troponin (cross Bridges) intention begins to increase. And the relaxation phase, tension decreases because cross-bridges have detached and because calcium ion levels have decreased. The active sites are once again covered by the troponin-tropomyosin complex. |
|
|
What three processes are involved in repaying the oxygen debt during a Muscle Recovery period? |
1. Oxygen for aerobic metabolism is consumed by litter, which must make a great deal of ATP to convert lactate to pyruvate, and pyruvate to glucose. 2. Oxygen for aerobic metabolism is consumed by skeletal muscle fibers as they restore ATP, creatine phosphate and glycogen concentration to their former levels. 3. The normal oxygen concentration in Blood and peripheral tissues is replenished. |
|
|
How does cardiac muscle tissue contract without neural stimulation? |
The timing of cardiac muscle contractions is determined by specialized cardiac muscle fibers called pacemaker cells. This property of cardiac muscle tissue is termed automaticity. |
|
|
Atracurium is a drug that blocked The Binding of ACh to ACh receptors. Give an example of a site where such binding normally occurs, and predict the physiological effects of this drug. |
Atracurium block The Binding of ACh to ACh receptors at the motor end plate of neuromuscular Junctions, the muscles ability to contract would be inhibited. |
|
|
Explain why a murder victim's time of death can be estimated according to the flexibility or rigidity of the body. |
In rigor mortis, the membranes of the dead cells are no longer selectively permeable. DSR is no longer able to retain calcium ions. As calcium ions enter the cytosol, a sustained contraction develops, making the body extremely stiff. Contraction persist because the dead muscle cells can no longer make the ATP required for cross Bridge Detachment from the active sites. Rigor mortis begins a few hours after death and ends after 1 to 6 days, or when decomposition begins. Decomposition begins when the lysosomal enzymes released by autolysis down the myofilaments. |
|
|
Which of the following activities would employ isometric contractions? |
Maintaining an upright posture |
|
|
Many potent insecticides contain toxins, called organophosphates, that interfere with the action of the enzyme acetycholinesterase. Ivan is using an insecticide containing organophosphates and is very careless. Because he does not use gloves or a dust mask, he absorbs some of the chemical through his skin and inhales a large amount as well. What signs would you expect to observe if Ivan as a result of organophosphate poisoning? |
Because organophosphates block the action of acetycholinesterase (AChE), ACh released in their somatic clef would not be removed. It would continue to stimulate the motor end plate, causing a state of persistent contraction (spastic paralysis). If the muscles of the respiration were affected (which is likely), Ivan would die of Suffocation. Prior to death, the most obvious sign would be uncontrolled to tetanic contractions of skeletal muscles. |
|
|
Linda's father suffers and apparent heart attack and is rushed to the emergency room at the local hospital. The doctor on call tells her that he has ordered some blood work and that he will be able to tell if her father actually had a heart attack by looking at the blood levels of CK and cardiac troponin in. Why would knowing the levels of CK and cardiac troponin help to indicate if a person suffered a heart attack? |
CK is the enzyme creatine kinase. It functions in the anaerobic reaction that transfers phosphate from creatine phosphate to ADP in muscle cells. the presence of cardiac troponin, a form found only in cardiac muscle cells, provides direct evidence that cardiac muscle cells have been severely damaged. |
|
|
Bill broke his leg in a football game, and after 6 week the cast is finally removed. As he steps down from the examination table, he loses his balance and Falls. Why? |
A skeletal muscle not regularly stimulated buy a motor neuron will lose muscle tone and mass and become weak (it will atrophy). Well his leg is immobilized, it did not receive sufficient stimulation to maintain proper muscle tone. It will take a while for bills muscles to regain enough strength to support his weight. |
|
|
Resting membrane potential |
Is the membrane potential of an unstimulated, resting cell. |
|
|
Graded potential |
The effects, which decreases with distance from the stimulus, is called graded potential |
|
|
Extracellular fluid (ECF) an intracellular fluid (cytosol) differ greatly in ionic composition |
The ECF contains high concentrations of sodium ions and chloride ions, whereas cytosol contains high concentration of potassium ions and negatively charged proteins. |
|
|
Cells have selectively permeable membranes |
It's a plasma membrane were freely permeable, diffusion would continue until all the ions were evenly distributed across the membrane and a state of equilibrium exists. But an even distribution does not occur, because cells are selectively permeable membranes. Ions cannot freely cross the lipid proportions of the plasma membrane. They can enter or leave the cell only through membrane channels. Many kinds of membrane channels exist, each with its own properties. At the resting membrane potential, a membrane potential of a undisturbed cell, ions move through leak channels --membrane channels that are always open. Active transport mechanisms, such as sodium potassium exchange pump , also move specific ions into or out of the cell. |
|
|
Membrane permeability varies by ion |
The cells passive and active transport mechanisms do not enter an equal distribution of charges across the plasma membrane, because membrane permeability varies by ion. For example, it is easier for potassium ions to diffuse out of the cell through potassium leak channels then it is for sodium ion to enter the cell through a sodium leak Channel. Additionally, negatively charged proteins inside the cell are too large to cross the membrane. As a result, the membranes inner surface has an excess AB negative charges with respect to the outer surface. |
|
|
Current |
A movement of charges to eliminate a potential difference is called a current |
|
|
Resistance |
The resistance of the membrane is a measure of how much the membrane restricts ion movement. If the resistance is high, the current is very small, because few ions can cross the membrane. If the resistance is low, the current is very large, because ions flood across the membrane. The resistance of a plasma membrane can change as ion channels open or closed. The changes result in current-carrying ions into or out of the cytosol. |
|
|
Electrochemical gradient |
The electric chemical gradient for a specific ion is the sum of the chemical and electrical forces acting on that ion across the plasma membrane. The electrical chemical gradient for potassium ions and sodium ions are the primary factors affecting the resting membrane potential for most cells, including neurons. |
|
|
Passive chemical gradient |
The intracellular concentration of potassium ions is relatively high so these ions tend to move out of the cell through potassium leak channels. Similarly, the extracellular concentration of sodium ions is relatively high so these ions move into the cell through sodium leak channels. Which ions movement is driven by a concentration gradient, or chemical gradient. |
|
|
Active sodium ions and potassium ion pumps |
Sodium and potassium ions exchange pumps maintain the concentration gradient of sodium and potassium ions across the potassium membrane. |
|
|
Passive electrical gradients |
Potassium ions leave the cytosol more rapidly than sodium ions enter Because the plasma membrane is much more preferable to potassium then to sodium. As a result, there are more positive charges outside the plasma membrane. Negatively charged protein molecules within the cytosol cannot cross the plasma membrane, so there are more negative charges on the side is all side of the plasma membrane. This result is an electrical gradient across a plasma membrane. |
|
|
Resting membrane potential |
Whenever positive and negative ions are held apart, a potential difference is arises. We measure the size of that potential differences in mini bolts. The resting membrane potential for most neurons is about -70 millivolts the minus sign shows that the inner surface of the plasma membrane is negatively charged with respect to the exterior. |
|
|
Potassium ion gradients |
1. At a neurons resting membrane potential, the chemical and electrical gradients are opposed for potassium ions. The net electrical chemical gradient tends to force potassium ions out of the cell. 2. If the plasma membrane were freely permeable to potassium ions, the outflow of potassium ions would continue until the equilibrium potential, -90 millivolts, was reached. Know how similar it is to the resting membrane potential. |
|
|
Sodium ion gradients |
1. At a neurons resting membrane potential, the chemical and electrical gradient of sodium ions are combined. The net electrochemical gradient forces sodium ions into the cell. 2. If the plasma membrane were freely permeable to sodium ions, the inflow of sodium ions would continue until equilibrium potential, +66 millivolts, was reached. Know how different it is from the resting membrane potential. |
|
|
Equilibrium potential |
The membrane potential at which there is no net movement of a particular ion across the plasma membrane is called the equilibrium potential for that ion. |
|
|
The resting membrane potential |
-because the plasma membrane is highly permeable to potassium ions, the resting membrane potential is approximately -70 millivolts is fairly close to -90 millivolts, the equilibrium potential for potassium ions. -the electrochemical gradient for sodium ions is very large, but the membranes permeability to these ions is very low. Consequently, sodium ions has only a small effect on the normal resting membrane potential, making it just slightly less negative than the equilibrium potential of potassium ions. -The sodium-potassium Exchange pump Age act 3 sodium ions for every two potassium ions that it brings into the cell it serves to stabilize the resting membrane potential when the ratio of sodium ion entry to potassium ion loss through passive channels is 3:2. -at the normal resting membrane potential, these passive and active mechanisms are in Balance. The resting membrane potential varies widely with this type of cell. A typical neuron has a resting membrane potential of approximately -70 millivolts. |
|
|
The resting membrane potential is the membrane potential of an undisturbed cell |
1. The cytosol differs from extracellular fluid in chemical and ionic composition. 2. The plasma membrane is selectively permeable. yet cells are Dynamic structures that continually modify their activities, either in response to external stimuli or to perform specific functions. |
|
|
Three classes of gated channels |
Chemically gated channels, voltage-gated channels, and mechanically gated channels. |
|
|
Chemically gated ion channels |
Open or closed when they bind specific chemicals, or acetycholine at the neuromuscular Junction are chemically gated ion channels. Chemically gated ion channels are most abundant on dendrites and cell body of a neuron, the area where most synaptic communication occurs. |
|
|
Voltage-gated ion channels |
Open or close in response to changes in the membrane potential. They are characteristics of areas of excitable cell membrane, a membrane capable of generating or propagating an action potential. Examples of excitable membranes are the axon 7 polar or multipolar neurons, and the sarcolemma (including T tubules) of skeletal muscle fibers and cardiac muscle cells. The most important voltage-gated ion channels, for our purpose are voltage-gated sodium ion channels, potassium ion channels and calcium ion channels. These sodium ion channels have to Gates that function independently: an activation gate that opens on stimulation, letting sodium ions into the cell, and an inactivation cage that closes to stop the entry of sodium ions. Therefore each channel can be in one of three states: close but capable of opening (activated), open, or closed and incapable of opening (inactivated). |
|
|
Mechanically gated ion channels |
Open or close in response to physical Distortion of the membrane surface, such as when pressure is applied due to the touch of a hand. Such channels are important in sensory receptors that respond to touch, pressure, or vibration. |
|
|
Graded potentials or local potentials |
Any stimulus that opens a gated Channel produces a graded potential. Graded potentials, or local potentials, are changes in the membrane potential that cannot spread far from the site of stimulation. |
|
|
Depolarization |
Sodium ions enter the cell and are attracted to negative charges along the inner surface of the membrane. As these additional positive charges spread out, the membrane potential shifts towards 0 millivolts. Any shift from the resting membrane potential toward a less negative potential is called depolarization. note that this term applies to both changes and potential form-70 millivolts to lesser negative values, as well as membrane potential above 0 millivolts. In all of these changes, the membrane potential becomes more positive. |
|
|
Local current |
As a plasma membrane depolarizes, sodium ions are released from its outer surface. These are ions, along with other extracellular sodium ions, then move toward the open channels, replacing ions that have already entered the cell. This movement of positive charges parallel to the inner and outer surfaces of a membrane that spreads the depolarization is called a local current. |
|
|
Repolarization |
When the chemical stimulus is removed and normal membrane permeability is restored, the membrane potential soon returns to the resting level. The process of restoring the normal resting membrane potential after depolarization is called repolarization. Repolarization typically involves a combination of ion movement through membrane channels and the activities of ion pumps, especially the sodium-potassium exchange pump. |
|
|
Hyperpolarization |
If a gated potassium ion Channel opens in response to a stimulus, the opposite effect occurs. The rate of potassium ions out flow increases, and the interior of the cell loses positive ions. In other words, the inside of the cell becomes more negative. The loss of positive ions produces hyperpolarization, an increase in the negativity of resting membrane potential, for example, from -70 volts to perhaps -80 volts or more. |
|
|
Graded potentials, whether depolarizing or hyperpolarizing, share four basic characteristics. |
-the membrane potential is most changed at the side of stimulation, and the effect decreases with distance. -the effect spreads passively, due to local currents. -the graded change in membrane potential may involve either depolarization or hyperpolarization. The properties and distribution of membrane channels involved determine the nature of the change. For example, in a resting membrane, the opening of sodium ion channels causes depolarization, whereas the opening of potassium ion channels causes hyperpolarization. That is, the change in membrane potential reflects whether positive charges enter or leave the cell. -the stronger the stimulus, the greater the change in the membrane potential in the larger the area affected. |
|
|
Define resting membrane potential |
The resting membrane potential is a membrane potential of a normal, unstimulated cell. |
|
|
What effect would a chemical that blocks the voltage membrane sodium ion channels in the plasma membrane of a neuron have on its ability to depolarize? |
If the voltage-gated sodium ion channels in the plasma membrane of a neuron could not open, sodium ions could not flood into the neuron and it would not be able to depolarize. |
|
|
What effect would decreasing the concentration of extracellular potassium ions have on the membrane potential of a neuron? |
If the extracellular concentration of potassium ions decreased, more potassium would leave the cell, and the membrane potential would become more negative. This condition is called hyperpolarization. |
|
|
Action potentials |
Are propagated changes in the membrane potential that, once initiated, affect the entire excitable membrane. Action potentials are dependent on the presence of both voltage-gated sodium and potassium ion channels. |
|
|
Depolarization to threshold |
The stimulus that initiates an action potential is a graded depolarization large enough to open voltage-gated sodium channels. The opening of the channels occur at the membrane potential known as the threshold |
|
|
Activation of sodium ion channels and rapid depolarization |
When the sodium Channel activation gates open, the plasma membrane become too much more permeable to sodium ions. Driven by the large electrochemical gradient, sodium ions rush into the cytosol, and Rapid depolarization occurs. The inner membrane surface now has more positive ions than negative ones, and the membrane potential has change from -60 millivolts to a positive value. |
|
|
Inactivation of sodium ion channels in activation of potassium ion channels starts repolarization |
As a membrane potential approaches to + 30 millivolts, the inactivation Gates of the voltage-gated sodium channels close. This step is known as sodium channel inactivation, and it coincides with opening of voltage-gated potassium channels. Positively charged potassium ions move out of the cytosol, Shifting the membrane potential back toward that the resting level. Repolarization now begins. |
|
|
Time lag in closing all potassium ion channels leads to temporary hyperpolarization |
The voltage-gated sodium channels remain inactivated until the membrane has repolarized to near threshold level. At this time, they regain their normal status: closed but capable of opening. The voltage-gated potassium channels begin closing as the membrane reaches the normal resting membrane potential (about -70 millivolts). Until all these potassium channels have closed, potassium ions continue to leave the cell. This produces a brief hyperpolarization. |
|
|
Steps in generation of an action potential in the initial segment of an axon. |
1. Depolarization threshold. 2. Activation of sodium ion channels and Rapid depolarization. 3. Inactivation of sodium ion channels and activation of potassium ion channels start repolarization. 4. Time lag in closing all potassium ion channels leads to temporary hyperpolarization. |
|
|
Action potentials or nerve impulses |
Are changes in the membrane potential that, once initiated, affect an entire excitable membrane. That is, Action potentials are not graded potentials. An action potential is propagated (spread) along the surface of the axon and does not diminish as it moves away from the its source. This impulse travels along the axon to the axon terminals. |
|
|
Threshold |
The membrane potential at which an action potential begins. |
|
|
All or none principle |
The properties of the action potential are independent of the relative strength of the depolarizing stimulus, as long as the stimulus exceeds the threshold. |
|
|
Refractory period |
The plasma membrane does not respond normally two additional depolarizing stimuli from the time an action potential begins until the resting membrane potential has been reestablished. This period is known as the refractory period of the membrane. From the moment the voltage-gated sodium ion channels open at threshold until sodium ion channels in activation and, the membrane cannot respond to further stimulation because all the voltage-gated sodium ion channels either are already open or are inactivated. |
|
|
Absolute refractory period |
The first part of refractory period and last 0.4 to 1.0 milliseconds. |
|
|
Relative refractory period |
Begins when the sodium ion channels regain their normal resting condition, and continues until the membrane potential stabilizes at the resting level. |
|
|
Continuous propagation along an unmyelinated Axon |
In an unmyelinated axon, and action potential moves along by continuous propagation. The action potential spreads by depolarizing the adjacent region of the axon membrane. This process continues to spread as a chain reaction down the Axon. 1. As an action potential develops at the initial 1 segment, the membrane potential at this site depolarizes to +30 millivolts. 2. A local current then develops as the sodium ions entering at 1 spread away from the open voltage-gated channels. A graded depolarization quickly brings the axon membrane (axolemma) in segment 2 to threshold. 3. An action potential now occurs in Segment 1 while segment 2 begins repolarization. 4. As a sodium ions entering at segment to spread laterally, a graded depolarization quickly brings the membrane and segment 3 to threshold and the cycle is repeated. |
|
|
Saltatory propagation along myelinated Axon |
Because myelinated limits the movement of ions across the axon membrane, the action potential must jump from node to node during propagation. This result is much faster propagation along the Axon. 1. An action potential has occurred at the initial Segment 1. 2. A local current produces a graded depolarization that brings the axon membrane (axolemma) at the next node to threshold. 3. An action potential develops at nude 2. 4. A local current produces a graded depolarization that brings the axolemma at Node 3 to threshold. |
|
|
Type A fibers |
Are the largest Myelinated axons, with diameters ranging from 4 to 20 um. These fibers carry action potentials at speeds of up to 120 meters per second or 268 miles per hour. |
|
|
Type B fibers |
Are smaller myelinated axons, with diameters of 2- 4 um. Their purgation speed averages around 18 meters per second or 40 miles per hour. |
|
|
Type c fibers |
Are unmyelinated and less than 2 um in diameter. These axons propagate action potential at the leisurely pace of 1 meter per second or two miles per hour. |
|
|
Define action potential |
An action potential is appropriated change in the membrane potential of excitable cells, initiated by a change in the membrane permeability to sodium ions. |
|
|
Identify the steps involved in the generation and propagation of an action potential. |
The four steps involved in the Regeneration of action potentials are: 1. Depolarization to threshold 2. Activation of voltage-gated sodium ion channels in Rapid depolarization. 3. Inactivation of voltage-gated sodium ions and activation a voltage gated potassium ion channels. 4. Closing of voltage-gated potassium ion channels and return to normal permeability. |
|
|
What is the relationship between myelin and the propagation speed of action potentials? |
The presence of Myelin greatly increases the propagation speed of action potentials. |
|
|
Which of the following axons is myelinated: one that propagates action potentials at 50 meters per second, or one that carries them at 1 meter per second? |
Action potentials travel along myelinated axons (By saltatory propagation) a much higher speeds than a long unmyelinated axons. The axon with propagation speed of 15 meters per second must be than myelinated Axon. Temple propagation speed for unmyelinated axons are about 1 meter per second. |
