A&P 1 Ch 9 & 10

25 July 2022
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question
What is the root word that means muscle?
answer
Myo
question
What are the three types of muscles? For each type of muscle, where do we find it? Is it striated or smooth? Is it voluntary or not? What is its function?
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Skeletal:muscles attached to skeleton; striated;voluntary;moves bones Cardiac:walls of the heart; striated; involuntary;contraction Smooth:walls of hollow visceral organs (except heart);smooth;involuntary
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What are the four special characteristics of muscle? What is the definition of each characteristic?
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Contractility - the ability of a muscle to shorten. Extensibility - the ability to lengthen. Elasticity - the ability to return to their original shape. Excitability - the ability to respond to stimulus
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What are the functions of muscle?
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Producing movement;maintaining posture and body position;stabilizing joints
question
Describe the gross anatomy of a skeletal muscle.
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Each skeletal muscle is a discrete organ made up of several kinds of tissue. Skeletal muscle predominate, but blood vessels, nerve fibers, and connective tissue are also present. Rich blood supply Connective tissue sheaths are found at various structural levels of each muscle: endomysium surrounds each muscle fiber, perimysium surrounds groups of muscle fibers, and epimysium surrounds whole muscles. 3. Attachments span joints and cause movement to occur from the movable bone (the muscle's insertion) toward the less movable bone (the muscle's origin). 4. Muscle attachments may be direct or indirect
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Is muscle an organ? Why or why not?
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Yes it is made up of several kinds of tissue
question
What are the names of the covering of the muscle belly, fascicles, and muscle fibers? Know the structural order from largest structure to smallest structure
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Epimysium Perimysium and fascicles Endomysium
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What are muscles attachments? What is the difference between an origin and an insertion? What is the difference between a director or indirect attachment? Which is more common? Why?
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Joints and other bones. Insertion is movable and origin is less or immovable. Direct(fleshy) attachment epimysium is fused to the periosteum. Indirect attachment connective tissue wrapping extend beyond the muscle. Indirect is more common because of its small size and durability.
question
What is fascia and aponeurosis?
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Flattened or expanded tendons, of a pearly-white color, iridescent and often glistening; they are only sparingly supplied with blood vessels.
question
Describe the microscopic anatomy of a muscle
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Each skeletal muscle fiber is a long cylindrical cell w/ multiple oval nuclei beneath the sarcolemma. Huge cells; diameters from 10-100um and 30 cm long.
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What are the parts of the muscle cell? What are the specialized names given to these parts (ie, sarcolemma...etc)?
answer
Sarcolemma Sarcoplasm Glycosomes Myoglobin
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What is the function of each of those parts?
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Sarcolemma: covers the cell Sarcoplasm: stores large amounts of glycosomes Glycosome: provide glucose (sugar) during periods of muscle cell activity Myoglobin: stores oxygen;Carry and store iron for muscle cells
question
Describe a myofibril
answer
A myofibril is a bundle of contractile filaments (myofilaments), 1-2 ฮผm in diameter, that are arranged in parallel groups in the cytoplasm of striated muscle cells.
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Why does a myofibril appear striated?
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Repeated presence of sarcomere on the myofibril.
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What is a sarcomere
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A sarcomere is the area between two Z discs.
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Describe a triad, and list the functions of the two structures within the triad
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Successive grouping of the 3 membranous (terminal cistern, T tubule, and terminal cistern) along the sarcoplasmic reticulum. T-tubules conduct impulses to the deepest regions of the muscle cell and every sarcomere. Terminal cistern produce energy during contraction
question
Explain how muscle fibers are stimulated to contract by describing the events at the neuromuscular junction
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Skeletal muscles are stimulated by somatic motor neurons Axons of motor neurons travel from the central nervous system via nerves to skeletal muscles Each axon forms several branches as it enters a muscle Each axon ending forms a neuromuscular junction with a single muscle fiber
question
Describe how an action potential is generated and moves from the motor neuron to the muscle fiber
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End plate potential spreads to adjacent membrane areas >Voltage-gated Na+ channels open >Na+ influx decreases the membrane voltage toward a critical threshold >If threshold is reached, an action potential is generated >Local depolarization wave continues to spread, changing the permeability of the sarcolemma
question
Follow and describe the events of excitation-contraction coupling that lead to cross bridge cycling
answer
Sequence of events by which transmission of an AP along the sarcolemma leads to sliding of the myofilaments > Latent period: > Time when E-C coupling events occur > Time between AP initiation and the beginning of contraction > AP is propagated along sarcomere to T tubules > Voltage-sensitive proteins stimulate > Ca2+ release from SR > Ca2+ is necessary for contraction
question
What is the role(s) of calcium, sodium (Na) and postassium (K) within a muscle contraction?
answer
Calcium-Muscle contraction is regulated by calcium ions, which will change thin filament into an activated state by binding to troponin. The binding of calcium to the troponin changes it's shape so the myosin binding sites on the actin (thin filament) are exposed Sodium-
question
What is the role of acetylcholine (Ach) within a muscle contraction?
answer
When released ACh binds to receptors on the motor end plate, changing its permeability to Na+ ions. Na+ ions (due to an increased electrochemical gradient) rush into the sarcolemma.
question
Be able to identify the function of any structure within the muscle contraction sequence?
answer
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question
What is the role of ATP?
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a. energizing the power stroke of the myosin cross bridge b. disconnecting the myosin head from actin c. actively transporting calcium back into the SR
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What prevents the myosin and actin to always to be binding together?
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question
An action potential is another name for what?
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Nerve Impulse
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What is the neuromuscular junction? What is the synaptic cleft?
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The area of contact between the axon terminal of a motor neuron and a portion of the sarcolemma of a muscle fiber. This is the junction between two neurons.
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What is the difference between the voltage gated channels and the ligand (chemical) gated channels? Where are each found?
answer
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question
What does depolarization mean?
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loss of polarity; loss of the difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell due to a change in permeability and migration of sodium ions to the interior
question
Define a motor unit and muscle twitch
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-A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that axon. -A small, local, involuntary muscle contraction and relaxation which may be visible under the skin
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Are all motor units the same size? Why or why not? Describe the differences between small and large motor units?
answer
No because larger muscles need larger units because there is more stress on the muscle. Small mortor units are more precise(fingers); Larger units hold more weight and are less precise.
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Are all motor units in one muscle stimulated at the same time? Why or why not? What does the all or nothing principal refer to?
answer
yes because stimulation of one motor unit causes weak contraction in the entire muscle.
question
Describe the events occurring during the three phases of a muscle twitch
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1) Latent period: events of excitation-contraction coupling 2) Period of contraction: cross bridge formation; tension increases 3) Period of relaxation: Ca2+reentry into the SR; tension declines to zero
question
Explain how smooth, graded contractions of a skeletal muscle are produced
answer
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question
What are two ways to change the grade of a muscle contraction?
answer
Increasing stimulus voltage calls more and more muscle fibers into play. Threshold stimuli produce the first observable contraction. As stimulus strength increases to maximal stimulus, all motor unit become recruited. Stimulus intensity beyond maximal does not produce further contraction.
question
Differentiate between isometric and isotonic (eccentric and concentric) muscle contraction
answer
isotonic: muscle length changes and moves a load isometric:muscle neither shortens nor lengthens eccentric: generates force as it lengthens concentris: muscle shortens and does work
question
What is muscle tone? How is it maintained?
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Maintained due to partial contraction of relaxed portions of skeletal muscle. There are ALWAYS a few muscle fibers within a muscle that are contracted while most are relaxed. This is ESSENTIAL in maintaining posture.
question
Describe three ways in which ATP is regenerated during skeletal muscle contraction
answer
ATP is regenerated by: 1) Direct phosphorylation of ADP by creatine phosphate (CP) (coupled reaction of creatine phosphate and ADP) 2) Anaerobic pathway (glycolysis and lactic acid formation) Aerobic respiration Produces 95% of ATP during rest and light to moderate exercise Fuels: stored glycogen, then bloodborne glucose, pyruvic acid from glycolysis, and free fatty acids
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Why is ATP important for muscle contractions
answer
It allows the myosin head to be released from the actin so that it can attach again. Without ATP, the myosin and actin would remain coupled for way too long and the contraction would suck so bad.
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For each method of regenerating ATP, indicate if it is aerobic or anaerobic, where the process occurs, how many ATP are produced, and which methods are from cellular respiration
answer
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question
Define EPOC and muscle fatigue. List possible causes of muscle fatigue
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EPOC-Excess post-exercise oxygen consumption-oxygen deficit -build up of lactic acid and anaerobic exercise
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Why and how much heat do muscles produce during exercise?
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60% so the body can maintain homeostasis.
question
Describe factors that influence the force, velocity, and duration of skeletal muscle contraction
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The four factors that influence contractile force are the number of muscle fibers stimulated, the relative size of the fibers, the frequency of stimulation and the degree of muscle stretch. Factors that influence the velocity and duration of contraction are the muscle fiber type, load and recruitment.
question
Describe three types of skeletal muscle fibers and explain the relative value of each type
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Fast: "white" majority of the muscle fibers (skeletal) -contract very quickly less than .01 seconds ex: money drop-fingers -larger in diameter -densely packed myofibrils (mechanism for generating power) -large glycogen reserve -few mitochondria (where you see the kreb cycle) -use alot of ATP through anaerobic glycolysis pathway- fatigue quickly-accumulate alot of lactic acid Slow: -Red fibers, fat is energy source -1/2 the diameter of the white fibers -less protein, less myofibrils -take 3x as long to contract -can contract for extended periods -a lot more mitochondria ( how we do aerobic respiration) -have molecule myoglobin (related to hemoglobin) bind oxygen and red pigment - keeps from oxygen depletion -glycogen reserves are relatively small Intermediate:have properties of both fast and slow look like fast fibers, but resist fatigue better
question
Compare and contrast the effects of aerobic and resistance exercise on skeletal muscles and on other body systems
answer
Increases capillaries, mitochondria, and myoglobin. Resistance exercise: muscle hypertrophy, increase size of muscle fibers, more mitochondria, more myofilaments and myofibrils, store more glycogen, more connective tissue.
question
What is an agonist, antagoists, and synergist and fixator?
answer
agonist means "producing an action antagonist opposes that action synergist aids another muscle by promoting the same movement. fixators prevents any unecessary movement,
question
Name the common patters of muscle fascicle arrangement and relate them to power generation
answer
Circular Fascicles arranged in concentric rings (e.g., orbicularis oris) Convergent Fascicles converge toward a single tendon insertion (e.g., pectoralis major) Parallel Fascicles parallel to the long axis of a straplike muscle (e.g., sartorius) Fusiform Spindle-shaped muscles with parallel fibers (e.g., biceps brachii) Pennate Short fascicles attach obliquely to a central tendon running the length of the muscle (e.g., rectus femoris)
question
Name the three types of lever systems and indicate the arrangement of effort, fulcrum, and load in each. Also note the advantages of each type of lever system.
answer
First class Fulcrum between load and effort Like scissors In the body: a first class lever system raises your head off your chest. The posterior neck muscles provide the effort, the atlanto-occipital joint is the fulcrum and the weight to be lifted is the facial skeleton. Second class Load between fulcrum and effort Like a wheelbarrow In the body : exerted when you stand on tip-toe. The effort is exerted by the calf muscles pulling upward on the heel; the joints of the ball of the foot are the fulcrum; and the weight of the body is the load. Third class Effort applied between fulcrum and load Like tweezers or forceps In the body : Flexing the forearm by the biceps brachii muscles exemplifies third-class leverage. The effort is exerted on the proximal radius of the forearm, the fulcrum is the elbow joint and the load is the hand and distal end of the forearm.
question
Define lever, and explain how a lever operating at a mechanical advantage differs from one operating at a mechanical disadvantage.
answer
1. A lever is a rigid bar that moves on a fixed point, or a fulcrum, when a force is applied to it. 2. The applied force, or effort, is used to move a resistance, or load. 3. In your body, your joints act as the fulcrums, the bones as the levers, and the muscle contraction as the effort. 4.There are three types of levers: first-class, second-class, and third-class.