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Physiology > Exam 2 Slides > Flashcards

Exam 2 Slides Flashcards

1
Q

Action Potential

A

Triggered by stimulus exceeding threshold potential/ gated ion channels open and close

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2
Q

Absolute Refractory Period:

A

No stimulus of any strength can produce an action potential
- Due to inactivated Na+ channels

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3
Q

Relative Refractory period:

A

Strong stimulus can produce another AP, but with smaller amplitude
- Due to still open K+ channels

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4
Q

What happens to membrane potential during continuous stimulation?

A

Excitability of membrane decreases with time (threshold increases)
- Is Due to changes in sensitivity of membrane channels to depolarization
- This physiological change is called accommodation

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5
Q

Length constant:

A

distance over which a graded potential shows a 63% drop in amplitude.

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6
Q

Spreading of electrical signal is due to?

A

cable properties of nerve membrane.

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7
Q

The larger the length constant?

A

the further away a new AP will be generated, and the faster the propagation of APs.

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8
Q

Synapse:

A

connection between two neurons or a neuron and an effector cell

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9
Q

Electrical Synapse

A

Rapid transmission of signals. Faster than in chemical synapses!
- Used to synchronize electrical activity in groups of cells: e.g. vertebrate heart, oscillations and brain rhythms.

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10
Q

Chemical synapse: fast transmission

A
  1. NT release close to receptors.
  2. Receptors directly open ion channels (ionotropic).
  3. Small vesicles
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11
Q

Chemical synapse: slow transmission

A
  1. NT release distant from receptors.
  2. Receptors indirectly open ion channels (metabotropic).
  3. Large vesicles
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12
Q

Active zone:

A

area of NT release

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13
Q

Acetylcholine

A

Primary neurotransmitter at vertebrate neuromuscular junction

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14
Q

If depolarization exceeds threshold

A

Yes AP

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15
Q

If depolarization does not exceed threshold

A

No AP

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16
Q

Change in membrane potential is a

A

graded potential

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17
Q

If ion current depolarizes the membrane?

A

excitatory
- stimulates an AP in the postsynaptic cell

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18
Q

If ion current hyperpolarizes the membrane?

A

inhibitory
- prevents an AP in the postsynaptic cell

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19
Q

Opening Na+ or Ca2+ channels results in a graded depolarization called an?

A

excitatory postsynaptic potential

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20
Q

Opening K+ or Cl− channels results in a graded hyperpolarization called an

A

inhibitory postsynaptic potential

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21
Q

EPSPs move membrane potential

A

closer to threshold
- EPSPs from several neurons may be needed to actually produce action potential

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22
Q

IPSPs move membrane potential

A

farther from threshold
- Can counter EPSPs from other neurons

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23
Q

Summation of EPSPs and IPSPs at initial segment of axon dose what?

A

determines whether action potential occurs.

24
Q

Presynaptic Inhibition

A

Inhibitory synapse on top of an excitatory synapse

25
Q

Strychnine dose what?

A

binds to and blocks glycine receptors in the spinal cord.

26
Q

Function of Sensory System

A
  1. Signal detection
    2.Discrimination of some aspects of the sensory input
27
Q

Receptor cell sends

A
  • intensity of stimulus
    frequency of APs
  • location of stimulus
    receptive field
28
Q

Receptive Field

A

Area of skin that, when stimulated, changes the firing rate of a neuron

29
Q

The more receptors, the

A

smaller the field, the larger the brain area for processing.

30
Q

Sensory Acuity

A

Ability to detect details

31
Q

Degree of convergence of primary neurons on secondary neurons determines?

A

size of receptive field.

32
Q

Range fractionation:

A

different cells with different but overlapping sensitivities, extending dynamic range

33
Q

Phasic response:

A

Firing activity only when stimulus strength changes (on/off)

34
Q

Tonic response:

A

Firing activity continues for the duration of the stimulus

35
Q

Lateral Inhibition can occur with?

A

a group of adjacent receptor cells, such as found in the eye.

36
Q

Olfactory

A

pathways from the nose project directly to the cortex

37
Q

More brain area means

A

more information processing and relatively more important

38
Q

Stimulus energy is “converted” to

A

action potential energy.

39
Q

Signals are interpreted as sight, sound, taste, depending on

A

which sensory cells send the signal and which tissue in CNS receives it!

40
Q

GUSTATION is what sense

A

Taste

41
Q

Salty

A

Na+ entry: depolarization: NT release

42
Q

Sour

A

H+ entry: depolarization: NT release.

43
Q

Sweet and umami

A

Sugar or glutamate binds to receptor: closing K+ channels: depolarization: NT release.

44
Q

Bitter

A

Quinine binds to receptor: Ca2+ entry : NT release

45
Q

Labeled-Line Coding:

A

each receptor responds to limited range of stimuli and sends direct line to brain.

46
Q

Across-Fiber Pattern or Ensemble Coding:

A

each receptor responds to wider range of stimuli and contributes to perception of each of them.

47
Q

Cone cells:

A

less sensitive, distinguish colors.

48
Q

Neural pathways for vision

A

Object on right goes to brain on left: Information crosses over!

49
Q

Hair cells modulate release of NT:

A

Change in AP frequency above spontaneous frequency.

50
Q

Actin

A

thin filament

51
Q

Myosin

A

thick filament

52
Q

Sarcomere:

A

functional unit of contraction
Z disk to Z disk

53
Q

Sliding Filament Theory

A

Thin actin filaments slide past the thick myosin filaments
- More overlap, shorter sarcomere

54
Q

Myosin structure

A
  • Myosin heads stick out from the thick filament.
  • Myosin connect with actin and sliding of the filaments occurs.
55
Q

Cross bridge function

A
  • Myosin cross bridge binds to actin
  • Power stroke slides actin past myosin
  • Cross bridge releases actin
56
Q

T tubules

A

Narrow tunnels formed from the plasma membrane (sarcolemma)
Extend into center of cell

57
Q

Muscle relaxation

A

Nerve action potentials stop
Muscle action potentials stop
Calcium-release channels close
Ca2+ pumps move Ca2+ back into SR (active transport)
No more Ca2+ is available to bind to troponin complex
Tropomyosin moves over myosin-binding sites on actin, no cross-bridges possible.

Physiology (6 decks)

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