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Physiology > Cell physiology, nervous system, CH4 > Flashcards

Cell physiology, nervous system, CH4 Flashcards

1
Q

A decrease in membrane potential where the membrane becomes less negative

A

depolarization

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2
Q

Cell membrane returns to resting potential after depolarization

A

repolarization

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3
Q

increase in membrane potential where the membrane becomes more negative

A

hyperpolarization

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4
Q

The ion flow usually associated with depolarization in action potentials

A

Net inward flow on Na+ through voltage gated sodium channels

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5
Q

Ion flow usually associated with repolarization in action potentials

A

Net outward flow if K+ through slow opening of K+ voltage channels

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6
Q

What causes hyperpolarization

A

Slow closing K+ channels allow the efflux of more than necessary K+

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7
Q

This type of potential dies out after a short distance, and the magnitude is directly correlated to the strength of the stimulus

A

Graded potential

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8
Q

This potential moves decrementally down the membrane by local current flow

A

graded potential

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9
Q

Leakage of ions across the membrane cause the strength of potential to decrease over a short distance and eventually die out

A

decremental spread of graded potential

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10
Q

Threshold potential

A

point of depolarization ususlly around -50mV for an action potential.

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11
Q

What occurs at threshold potential

A
  1. explosive depolarization due to a positive feedback loop opening more and more Na+ channels
  2. slow closing of Na+ inactivation gates which halts Na+ entry after a brief delay
  3. Slow opening K+ gates allow K+ to leave the cell which will bring the membrane potential back to resting
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12
Q

what is the change in membrane potential from resting to peak

A

-70mV to +30 mV

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13
Q

what are the confirmations for Na+ voltage gated channels?

A
  1. closed but capable of opening
  2. Open (activated)
  3. Closed and incapable of opening (inactivated)
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14
Q

What are the conformations for K+ voltage gated channels?

A

open or closed

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15
Q

What is the difference in triggering events between GP and AP?

A

GP: Stimulus
AP: depolarization to threshold

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16
Q

What is the difference in type ion movement between GP and AP?

A

GP: movement of Na+, Ca++, Cl-, or K+ through various means
AP: sequential movement of Na+ out then K+ into the cell through voltage gated channels

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17
Q

What is the difference in magnitude triggering events between GP and AP?

A

GP: magnitude of stimulus determines magnitude of potential
AP: all or nothing, larger trigger will lead to more APs in a shorter period of time, but not a larger potential

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18
Q

What is the difference in duration between GP and AP?

A

GP: varies based on trigger
AP: constant

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19
Q

What is the difference in potential change over distance between GP and AP?

A

GP: decremental
AP:undiminished, can travel much further

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20
Q

What is the difference in refractory period between GP and AP?

A

GP: none
AP: relative or absolute

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21
Q

What is the difference in summation between GP and AP?

A

GP: Temporal and spatial
AP: none

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22
Q

What is the difference in location between GP and AP?

A

GP: Specialized regions of membrane designed to respond to trigger events (pressure, heat, chemical changes, etc)
AP: regions of neural membrane with large concentration of voltage gated channels

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23
Q

What is the difference in direction of charge between GP and AP?

A

GP: depolarization or hyperpolarization
AP: always depolarization

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24
Q

What is the benefit of refractory period?

A

ensures the one way movement of a potential down the membrane

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25
Q

period of time when a patch of membrane cannot be re-stimulated no matter how strong the stimulus.

A

absolute refractory, Na+ gates are in their inactivated conformation

26
Q

period of time during which a patch of membrane can only be re-stimulated by a stronger than normal stimulus.

A

relative refractory

27
Q

All or None Law

A

Action potentials occur either maximally in response to stimulation or not at all. Variable strengths of stimuli are coded by varying the frequency of action potentials, not their size.

28
Q

two types of action potential propagation

A

Contiguous or Saltatory conduction

29
Q

what type of fibers are associated with Contiguous or Saltatory conduction

A

contiguous conduction has unmyelinated fibers

saltatory conduction has myelinated fibers

30
Q

Where are Schwann cells located

A

PNS

31
Q

Where are oligodendrocytes located

A

CNS

32
Q

what type of cells make Myelin

A

Schwann cells and oligodendrocytes

33
Q

What is the function of Myelin

A

to prevent leakage of ions across the membrane which allows for quicker signaling (50x faster) of an action potential

34
Q

What are the two types of synapses?

A

chemical or electrical

35
Q

How do electrical synapses communicate?

A

Through gap junctions. This communication occurs through adjacent cells and is unregulated.

36
Q

What type of cells use electrical synapses?

A

Widespread in CNS where synchronization is important, also in retina and pulp of tooth

37
Q

What type of synases are most common in the nervous system?

A

Chemical synapses

38
Q

What are the structures associated with a chemical synapse?

A

Presynaptic neuron with synaptic knob, synaptic clef, post synaptic neuron

39
Q

What are the steps in transmission of a signal in a chemical synapse?

A
  1. Action potential reaches axon terminal of presynaptic neuron.
  2. Ca2+ enters synaptic knob
  3. Neurotransmitter is released by exocytosis into synaptic cleft.
  4. Neurotransmitter binds to receptors that are an integral part of chemically gated channels on membrane of postsynaptic neuron.
  5. Binding of neurotransmitter to receptor-channel opens that specific channel
40
Q

If binding of Neurotransmitter opens Na+ and K+ channels the resulting in is a small depolarization (main examples)

A

excitatory post-synaptic potential (EPSP).

Acetylcholine and glutamate

41
Q

If binding of NT opens either K+ or Cl– channels that result in a small hyperpolarization (main examples)

A

inhibitory post-synaptic potential (IPSP).

Glycine and Gamma-aminobutyric acid, serotonin, and acetylcholine in the parasympathetic nervous system

42
Q

Temporal summation

A

EPSP or IPSP from a single, repetitively firing, presynaptic input that occur so close together in time that they add together

43
Q

Spatial summation

A

adding of EPSPs or IPSPs simultaneously from different presynaptic inputs

44
Q

grand post synaptic potential (GPSP)

A

domination of EPSP brings closer to threshold, domination of IPSP moves further away from threshold, summation of all IPSP and EPSP is called GPSP

45
Q

small, rapidly acting molecules, released from synaptic vesicles that trigger the opening of specific ion channels in milliseconds

A

neurotransmitters

46
Q

neuropeptides

A

large molecules (2-40 amino acids), synthesized in the ER and golgi, packaged in dense-core vesicles, act as neruomodulators

47
Q

Neuromodulators

A

They act slowly to produce long-term changes at the synapse.

48
Q

Direct intercellular communication

A

accomplished through gap junctions and the linkup of complementary surface markers (ie immune system cells)

49
Q

Indirect intercellular communication

A

Indirect communication is carried out through extracellular chemical messengers.

50
Q

local chemical messengers whose effect is only on neighboring cells and doesn’t enter the blood

A

paracrine

51
Q

very short-range chemical messengers released by neurons

A

neurotransmitter

52
Q

long-range chemical messengers secreted into the blood by endocrine glands

A

hormones

53
Q

long-range chemical messengers secreted into blood by neurons

A

neurohormones

54
Q

Two types of hormones

A

hydrophilic hormones; highly water soluble, low lipid solubility
lipophilic hormones; highly lipid solubility, poorly soluble in water

55
Q

Most common receptor protein for water soluble hormones

A

G-protein coupled receptor

56
Q

What is the difference in location of receptors for hydrophilic and Lipophilic hormones

A

lipophilic receptors are intracellular

hydrophilic are extracellular in the plasma membrane

57
Q

Difference in anatomic arrangement between NS and ES

A

NS: wired, structural arrangement between neuron and target cells
ES: wireless, glands are widely dispersed in relation to target cells

58
Q

Difference in chemical messenger for NS and ES

A

NS: synaptic cleft
ES: hormones release into the blood

59
Q

Difference in distance traveled by messenger, speed of response, and duration of action of the NS and ES

A

NS: short
ES: long

60
Q

Difference in specificity of action of the target cell between NS and ES

A

NS: dependent on close anatomical relationship between neuron and target cell
ES: Dependent on target cell specificity and sensitivity to the hormone

61
Q

Major functional difference between NS and ES

A

NS: rapid precise responses
ES: Activities that require a longer duration

Physiology (5 decks)

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