Lecture 9A

1. 1[blank_start]Chemically-gated[blank_end] channels open up to allow for movement of Na+ ions.
   As [blank_start]Na+ ions enter the ICF[blank_end], the membrane slightly depolarizes

   1. AChemically-gated
   2. BNa+ ions enter the ICF
2. 2At [blank_start]-70mV[blank_end], the membrane is at its resting potential and all of its chemically gated sodium channels are [blank_start]closed[blank_end]

   1. A-70mV
   2. Bclosed
3. 3At [blank_start]-65mV,[blank_end] the membrane is exposed to a chemical that opens the chemically gated sodium channels, sodium [blank_start]enters[blank_end] the cell. Any shift from the resting potential towards a more positive value is called [blank_start]depolarization.[blank_end]

   1. A-65mV,
   2. Benters
   3. Cdepolarization.
4. 4At -[blank_start]60mV[blank_end], the sodium ions now [blank_start]spread out[blank_end], attracted by the negative charges along the inner surface of the membrane. The extent of depolarization spreads as well. This movement of positive charges parallel to the inner and outer surfaces of the membrane is called a [blank_start]local current[blank_end]

   1. A60mV
   2. Bspread out
   3. Clocal current
5. 5read this

   

   1. AGraded potential graph
6. 6 Action potentials are [blank_start]propagated changes[blank_end] in the [blank_start]membrane potential[blank_end] that, once initiated, affect an entire excitable membrane.
   

   1. Apropagated changes
   2. Bmembrane potential
7. 7 Whereas the resting potential depends on [blank_start]leak channels[blank_end] and the graded potential depends on [blank_start]chemically gated channels,[blank_end] action potentials depend on [blank_start]voltage-gated channels[blank_end].
   

   1. Aleak channels
   2. Bchemically gated channels,
   3. Cvoltage-gated channels
8. 8 The stimulus that initiates an action potential is a [blank_start]graded depolarization[blank_end] large enough to open [blank_start]voltage-gated sodium channels.[blank_end] The opening of the channels occurs at a membrane potential known as the [blank_start]threshold.[blank_end]
   

   1. Agraded depolarization
   2. Bvoltage-gated sodium channels.
   3. Cthreshold.
9. 9 [blank_start]+30mV[blank_end] is when the inactivation gates of the voltage gated sodium channels close. And the voltage gated potassium channels [blank_start]open[blank_end]. Positively charged potassium ions move out of the cytosol, shifting the membrane potential [blank_start]back toward resting levels.[blank_end]
   

   1. A+30mV
   2. Bopen
   3. Cback toward resting levels.
10. 10 -90mV: The voltage-gated sodium channels remain [blank_start]inactivated[blank_end] until the membrane has [blank_start]repolarized to near threshold levels[blank_end]. At this time, they regain their normal status: [blank_start]closed but capable of opening[blank_end]. The voltage-gated potassium channels begin [blank_start]closing[blank_end] as the membrane reaches the normal resting potential (about [blank_start]–70 mV[blank_end]). Until all of these potassium channels have closed, potassium ions continue to leave the cell. This produces a brief [blank_start]hyperpolarization[blank_end].
    

    1. Ainactivated
    2. Brepolarized to near threshold levels
    3. Cclosed but capable of opening
    4. Dclosing
    5. E–70 mV
    6. Fhyperpolarization

11. 11[blank_start]-70mV[blank_end]: As the voltage-gated potassium channels close, the membrane potential returns to normal resting levels. The action potential is now over, and the membrane is once again at the [blank_start]resting potential.[blank_end]

    1. A-70mV
    2. Bresting potential.
12. 12ction potentials may affect adjacent portions of the plasma membrane through [blank_start]continuous propagation[blank_end] or s[blank_start]altatory propagation[blank_end]

    1. Acontinuous propagation
    2. Baltatory propagation
13. 13[blank_start]Continous propagation:[blank_end] the action potential appears to “move” along the axolemma of an axon in a series of tiny steps. [blank_start]Continuous propagation[blank_end] occurs along [blank_start]unmyelinated[blank_end] axons.

    1. AContinous propagation:
    2. Bunmyelinated
    3. CContinuous propagation
14. 14Continuous propagation cannot occur along a myelinated axon, because [blank_start]myelin blocks the flow of ions[blank_end] across the membrane. Ions can only cross the plasma membrane at the unmyelinated nodes ([blank_start]nodes of Ranvier[blank_end]). As a result, only the
    nodes can respond to a depolarizing stimulus. When an action potential appears at the initial segment of a myelinated axon, the local current skips the internode and depolarizes the closest node in a process called [blank_start]saltatory propagation[blank_end]

    1. Amyelin blocks the flow of ions
    2. Bnodes of Ranvier
    3. Csaltatory propagation
15. 15A [blank_start]skeletal muscle[blank_end] contains skeletal muscle tissue, connective tissues, blood vessels, and nerves.

    1. Askeletal muscle
16. 16What part of a muscle structure is this?

    

    1. AMuscle fascicle
17. 17 A [blank_start]myofibril[blank_end] is a cylindrical structure 1–2 μm in
    diameter and as long as the entire fiber. The sarcoplasm of a single skeletal muscle fiber may contain hundreds to thousands of [blank_start]myofibrils[blank_end].

    1. Amyofibril
    2. Bmyofibrils
18. 18 Myofibrils consist of bundles of protein
    filaments called [blank_start]myofilaments[blank_end]. The most abundant [blank_start]myofilaments[blank_end] are thin filaments composed primarily of [blank_start]actin[blank_end], and thick filaments composed primarily of [blank_start]myosin[blank_end].
    

    1. Amyofilaments
    2. Bmyofilaments
    3. Cactin
    4. Dmyosin
19. 19myofibril are arranged into repeating contractile units called [blank_start]sarcomeres[blank_end]. Each myofibril consists of approximately 10,000 [blank_start]sarcomeres[blank_end] aligned end to end.

    1. Asarcomeres
    2. Bsarcomeres
20. 20Label the structures in the sarcoplasm

    

    1. ASarcoplasmic reticulum
    2. BTransverse tubules
    3. CTerminal Cisternae
21. 21Skeletal muscle fibers contract only under the control of the nervous system. Each skeletal muscle fiber is controlled by the nervous system at a specialized site known as a [blank_start]neuromuscular junction[blank_end], located midway along the muscle fiber’s length.

    1. Aneuromuscular junction
22. 22 The NMJ is made up of an [blank_start]axon terminal[blank_end] (synaptic terminal) of a motor neuron, a specialized region of the sarcolemma called the [blank_start]motor end plate[blank_end] and, in between, a space called the [blank_start]synaptic cleft[blank_end].
    

    1. Aaxon terminal
    2. Bsynaptic cleft
    3. Cmotor end plate
23. 23A single axon may branch to control more than one skeletal muscle fiber, but each muscle fiber has only one [blank_start]NMJ[blank_end]. At the NMJ, the [blank_start]axon terminal[blank_end] of the neuron lies near the motor end plate of the muscle fiber.

    1. ANMJ
    2. Baxon terminal
24. 24 The cytoplasm of the axon terminal
    contains vesicles filled with molecules of [blank_start]acetylcholine[blank_end] .
    The stimulus for [blank_start]Ach[blank_end] release is the arrival of an electrical impulse, or [blank_start]action potential[blank_end], at the axon terminal.

    1. Aacetylcholine
    2. BAch
    3. Caction potential
25. 25An [blank_start]action potential[blank_end] is a sudden change in the membrane potential that travels along the length of the axon.
    When the action potential reaches the [blank_start]neuron’s axon terminal[blank_end], changes in the membrane permeability trigger the [blank_start]exocytosis of ACh[blank_end] into the synaptic cleft. Exocytosis occurs as the [blank_start]synaptic vesicles[blank_end] fuse with the [blank_start]neuron’s plasma[blank_end] membrane.
    

    1. Aaction potential
    2. Bneuron’s axon terminal
    3. Cexocytosis of ACh
    4. Dsynaptic vesicles
    5. Eneuron’s plasma
26. 26 [blank_start]ACh molecules[blank_end] diffuse across the synaptic cleft and bind to ACh
    receptors on the surface of the motor end plate. ACh binding alters the membrane’s permeability to Na+. Because the extracel- lular fluid contains a high concentration of Na+, and Na+ concentration inside the cell is very low, sodium ions rush into the [blank_start]sarcoplasm[blank_end]

    1. AACh molecules
    2. Bsarcoplasm
27. 27 The action potential generated at the motor end plate now sweeps across the [blank_start]entire membrane surface[blank_end]. The effects are almost immediate because an action potential is an electrical event that flashes like a spark across the [blank_start]sarcolemmal surface.[blank_end] The effects are brief because the ACh has been removed, and no further stimulus acts upon the motor end plate until another action potential arrives at the axon terminal.
    

    1. Aentire membrane surface
    2. Bsarcolemmal surface.
28. 28Read this. memorize it. Good.

    

    1. AChollinergic synpase
29. 29Cross- Bridge formation

    

    1. ACross bridge formation

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1 Fundamentals of human anatomy and physiology Quiz on Lecture 9A, created by Ada banana. on 08/11/2015.

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Ada banana.

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Created on 8 Nov 2015 · updated on 19 Feb 2016

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