Anatomy & Physiology I - midterm II

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  1. Name the functional classes of joints
    • synarthroses - immovable joints 
    • amphiarthroses - slightly loveable joints
    • diarthroses - freely moveable joints
  2. Name the structural classes of joints
    • fibrous joints
    • cartilaginous joints
    • synovial joints
  3. describe the general structure of fibrous joints
    • bones joined by dense fibrous connective tissue 
    • no joint cavity
    • most are synarthrotic
  4. 3 types of fibrous joints and an example of each!
    • Sutures
    • Syndemoses - tibiofibular joint
    • Gomphoses - peridontal ligament
  5. Describe the general structure of cartilaginous joints
    • bones united by cartilage
    • no joint cavity
    • not highly moveable
  6. 2 types of cartilaginous joints
    • synchondroses 
    • symphyses
  7. what defines a synchondroses joint?
    • bones connected by hyaline cartilage
    • synarthrotic (immovable)
  8. What defines a symphyses joint?
    • bones united by fibrocartilage
    • amphiartrotic (slightly moveable)
  9. synarthrotic joint
    immovable joint
  10. amphiarthrotic
    slightly moveable
  11. diarthrotic
    freely moveable
  12. general structure of synovial joint
    • bones separated by fluid-filled joint cavity 
    • all are diarthrotic
  13. 3 types of muscle tissue
    • skeletal muscle
    • smooth muscle
    • cardiac muscle
  14. 4 characteristics of muscle tissue
    • Excitability (ability to receive and respond to stimuli)
    • Contractility (ability to shorten forcibly when stimulated)
    • Extensibility (ability to be stretched)
    • Elasticity (ability to recoil tot resisting length)
  15. 4 important functions of muscle
    • movement of bones or fluids
    • maintaining posture and body position
    • stabilizing joints
    • heat generation
  16. list the levels of organization of skeletal muscle
    • (smallest) Myofibril 
    • muscle fiber
    • endomysium (areolar tissue)
    • Fascicle
    • perimysium (wraps Fascicle)
    • (Largest)Epimyusium (Dense CT)
  17. Each myofibril consists of repeating series of ________
  18. the smallest functional unit of a muscle fiber
  19. sarcomeres contain ___________
  20. describe the H Zone in the sarcomere
    region in the midsection of an A band where thick and thin filaments do no overlap
  21. describe the Z disc in the Sarcomere
    sheet of proteins that holds together the thin filaments
  22. describe the M line in the sarcomere
    sheet of proteins that hold together thick and thin filaments
  23. in the center of the sarcomere, thick filaments lack?
    • myosin heads 
    • myosin heads are only present in areas of myosin-actin overlap
  24. thin filaments consist of?
    two strands of actin subunits twisted into a helix
  25. describe the role of troponin and tropomyosin in the sarcomere
    • both a regulatory proteins 
    • Troponin anchors the tropomyosin into the actin filaments
    • tropomyosin coils around the actin filaments and blocks the myosin heads from attachment 
    • troponin's shape is altered by high [Ca++], and resumes its anchoring position in low [Ca++]
  26. Each thick filament consists of?
    many myosin molecules who's head protrude at opposite ends of the filament
  27. Each myosin head has ____ activity; both heads can act as _______ ______ during contraction
    • ATPase
    • cross bridges
  28. describe the 6 steps of the AP at the neuromuscular junction
    • AP arrives at the axon terminal of motor neuron
    • Voltage-gated Ca2+ channels open. Ca2+ enters the axon terminal moving down its electrochemical gradient  
    • Ca2+ entry causes ACh to be released by exocytosis 
    • ACh diffuses across the synaptic cleft and binds to its receptors on the sarcolemma 
    • ACh binding opens ion channels in the receptors that allow simultaneous passage of Na+ into the muscle fiber and K+ out of the muscle fiber. More Na+ ions enter than K+ ions exit, which produces a local change in the membrane potential called the end plate potential
    • ACh effects are terminated by its breakdown in the synaptic cleft by acetylcholinesterase and diffusion away from the junction
  29. Describe (Phase 2) of the excitation-contraction coupling in muscle fiber contraction
    • AP travels across the entire sarcolemma
    • AP travels along T tubules
    • SR releases Ca2+; Ca2+ binds to troponin;myosin-binding sites on actin are exposed
    • myosin heads bind to actin; contraction begins
  30. What happens what the E-C coupling phase 2 occurs in muscle contraction
    E-C is a sequence of events by which transmission of an action potential along the sarcolemma leads to the sliding of myofilaments
  31. After E-C coupling relaxation occurs
    describe the process of relaxation
    • when the AP ceases
    • Ca2+ release channels close in the SR
    • Ca2+ levels fall as Ca2+ is continually pumped back into the SR by active transport
    • Thus, the blocking action of tropomyosin is restored
    • myosin-actin interaction is inhibited
    • relaxation occurs
  32. define the cross bridge cycle in muscle contraction
    where myosin heads pull thin filaments toward the centre of the sarcomere
  33. list the sequence of events of the cross bridge cycle 
    • Cross bridge formation: energized myosin head attaches to an actin myofilament, forming a cross bridge
    • The power stroke: ADP and Pi are released and the myosin head pivots and bends, changing to its bent low-energy state. As a result it pulls the actin filament toward the M line 
    • Cross Bridge detachment: After ATP attaches to myosin, the link between myosin and actin weakens, and the myosin head detached 
    • Cocking of the myosin head: As ATP is hydrolyzed to ADP and Pi, the myosin head returns to its pre stroke high-energy position
  34. *For the cross bridge cycle to continue, what to factors are required?
    what happens when when one of the requirements is missing?
    • ATP is available
    • Ca2+ is bound to troponin

    when ATP is absent, myosin heads will not detach, causing robot mortis
  35. define isometric contraction
    • no muscle shortening 
    • muscle tension increases but does not exceed load
  36. define isotonic contraction
    muscles shortens because muscle tension exceeds load
  37. A motor unit consists of?
    one motor neuron and all the muscle fibers it innervates
  38. A graded muscle response is graded by these two factors
    • changing the frequency of stimulation
    • changing the strength of stimulation
  39. describe the muscles response to changes in stimulation frequency
    • at low frequency of simulation: temporal summation (another stimulus is applied before the muscle relaxed)
    • at high frequency of simulation: there is no relaxation at all between stimuli; complete tetanus
  40. define complete tetanus
    the muscle reaches maximal tension
  41. Describe the muscles response to changes in strength stimulus
    recruitement (multiple motor unit summation)
  42. List 3 ways ATP is regenerated in muscles and when they would be used
    • direct phosphorylation of ADP by creatine phosphate (short intense exercise)
    • anaerobic glycolysis (during  short-duration exercise)
    • aerobic respiration (during rest and pro-longed)
  43. factors that influence strength of muscle contraction
    • depends on the number of cross-bridges attached which depends on:
    • number of muscle fibers stimulated
    • relative size of fibers
    • frequency of stimulation
    • length-tension relationship (degree of muscle stretch)
  44. velocity and duration of muscle contraction are influenced by these factors:
    • muscle fiber type
    • load
    • recruitment of muscle fibers
  45. 3 types of muscle fibers
    • slow oxidative fibers
    • fast oxidative fibers
    • fast glycolytic fibers
  46. describe characteristics of slow oxidative muscle fibers
    • Speed of contraction: slow
    • Myosine ATPase activity: slow
    • ATP synthesis: aerobic
    • Myoglobin content: high 
    • Glycogen Stores: low
    • Activities suited for: endurance, posture
    • Mitochondria: many
    • Capillaries: many
  47. describe the characteristics of fast oxidative muscle fibers
    • Speed of contraction: fast 
    • Myosin ATPase activity: fast 
    • ATP synthesis: aerobic 
    • Myoglobin content: high 
    • Glycogen Stores: intermediate 
    • Activities suited for: sprinting, walking 
    • Mitochondria: many
    • Capillaries: many
  48. describe characteristics of fast glycolytic muscle fibers
    • Speed of contraction: fast
    • Myosin ATPase activity: fast
    • ATP synthesis: anaerobic glycolysis 
    • Myoglobin content: low 
    • Glycogen Stores: high
    • Activities suited for: short-term intense  or powerful movements
    • Mitochondria: few 
    • Capillaries: few
  49. contrast smooth muscle to skeletal muscle
    • no NMJ's, instead varicosities 
    • thick and thin filaments not organized into sarcomeres 
    • gap junctions connect adjacent fibers 
    • dense bodies are equivalent to Z discs
    • no troponin complex, instead Ca2+ binds to and activated myosin kinase
    • myosin kinase phosphorylates and activates myosin when high [Ca2+]
  50. two major types of smooth muscle cells
    • unitary smooth muscle 
    • multi unit smooth muscle
  51. describe the structure, function and location of unitary smooth muscle
    • structure: innervated by the ANS, neighbours are electrically coupled by gap junctions; function as a single unit 
    • location: walls of hollow organs albeit the heart
    • function: respond to chemical stimuli, responds to several hormones
  52. describe the structure, function and location of multi unit smooth muscle
    • structure: muscle fibers are independent of each other, innervated by the ANS, muscles contract independently 
    • location: walls of large airways, large arteries, arrector pili muscles, and the iris of the eye 
    • function: responds to several hormones
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Anatomy & Physiology I - midterm II
midterm II
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