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Anatomy 20A > Neurons > Flashcards

Neurons Flashcards

1
Q

Dendrites

A

LOTS of little extensions off of the soma that recieve signals from other neurons

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1
Q

Soma

A

Body of a neuron
* Has a nucleus
* Protein synthesis
* Most of cells metabolism

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1
Q

Axon terminal

A

End of an axon that touches multiple other neurons

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1
Q

Axon

A

Long extension of the neuron covered with myelin

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2
Q

Synapses

A

Where the axon terminal of one neuron touches another neuron and signals it

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3
Q

Action Potential (AP)

A

Very fast electrical signal that travels down the axon from the soma to the axon terminal and can continue traveling far - When AP reaches the axon terminal → the 1st neuron fires the 2nd (at the synapse)

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3
Q

Myelin

A

Layers of fat wrapped (plasma membrane) around the axons of many neurons to Insulate and speed up AP.

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3
Q

Afferent

A

(A= ad = towards)
Sensory neurons carrying signals into the CNS from the PNS.

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4
Q

Efferent

A

(E= ex = exit)
neurons that carry info out from the CNS into the PNS

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4
Q

Motor Neurons

A

Efferent neurons that control muscles

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5
Q

Interneuron

A

Neurons that are between other neurons - almost all in the CNS

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6
Q

Multipolar Neuron

A

Most common neurons with many dendrites coming off the soma.
* Efferent neurons
* Most interneurons

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7
Q

Bipolar neuron

A

Bi-polar - 2 extensions - 1 dendrite + 1 axon
Neurons with only one dendrite coming off the soma at the end
Afferent in most of special senses:
Eyes, ears, nose

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8
Q

Pseudounipolar neurons

A

Sensory neurons where the soma is off to the side in the middle of the axon and the dendrites are at the start of the axon not coming off the soma.
AP starts where dentrites turn into axons
Somatic senses = senses of body: touch, pain, temp, tastes, etc

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9
Q

Anaxonic Neurons

A

Rare neurons only in CNS with many extensions and no clear axon.

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10
Q

Electrochemical Gradient

A

The difference in distribution of ions between 2 sides of membrane

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11
Q

Extracellular Fluid (ECF) Ions

A

Contains more Na+, Ca++, Cl-

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12
Q

Intracellular Fluid (ICF) makeup

A

More K+, amino acids + neucleotides.
Inside of the cell is negative relative to outside of the cell

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13
Q

Na+K+ Pump in relation to the electrochemical gradient

A

The most important protein for maintinaining the difference in ECF + ICF
Does active transport
Uses 1 ATP
Moves 3 Na+ from ICF → ECF
Moves 2 K+ from ECF → ICF

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14
Q

Resting membrane potential

A

The usual membrane potential of cell - when cell isn’t doing anything to change it. Has a charge of -70mV

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15
Q

Membrane potential effectors

A

Difference in concentration of ions between the fluids
Permeability of membrane to ions = how easily is if for ions to pass through the membrane

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16
Q

Open Ion Channels

A
  • Ions flow in + out of cell changing the membrane potential
  • Minimal effect on the concentration of ions on either side of the membrane
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17
Q

Leak Channels

A
  • Always open protein channels
  • Mostly responsible for a resting membrane potential
18
Q

Mechanically Gated Channels

A

Opens in response to some sort of force
Ex: sense of touch

19
Q

Ligand Gated Channel

A

Open when they bind a chemical
Allows cells to change membrane potential in response to a chemical signal
ex: Smell

20
Q

Voltage Gated Ion Channels

A

Open in response to a change in membrane potential
That allows changes in membrane potential to lead to more changes in the membrane potential –> Positive or negative feedback

21
Q

Effects of more Na+ & Ca++ in the ECF

A

Open Na+ & Ca++ ion channels
* Na+ & Ca++ flow into the cell
* Makes the cell more positive

22
Q

More K+ in the ICF

A

Opens K+ channels
* K+ flowing out
* cell is more negative

23
Q

Polarized Membrane

A

membrane at resting potential:
* Inside of cell is negative
* Na+ & K+ leak channels open
* More K+ channels open - the membrane is more negative

24
Q

Cell Membrane Depolarization

A

cell becomes more positive due to:
* Open Na+ or Ca+ channels
* Close K+ or Cl- channels

25
Q

Cell Membrane Repolarization

A

cell becomes negative again after depolarization due to:
* Open K+ or Cl- channels
* Close Na+ or Ca++ channels

26
Q

Cell Membrane
Hyperpolarization

A

Cell becomes even more negative than the resting potential (more - than -70) due to:
* Open K+ or Cl- channels
* Close Na+ or Ca++ channels

27
Q

Graded Potential

A

A change in membrane potential that can be big or small, positive or negative
Occurs in response to stimulus
Bigger stimulus → bigger change
Almost all cells are capable

28
Q

Action Potential (AP)

A

Wave of depolarization that travels down the axon
At each point down the axon - they become slightly depolarized
→ leads to a big depolarization
→ followed by a swift repolarization

29
Q

Voltage-Gated Na+ Channel

A

Composed of 2 gates:
1st gate opens in response to a slight depolarization
2nd gate closes in response to big depolarization

30
Q

Voltage-Gated K+ Channel

A

Opens in response to a big change (when very depolarized → repolarization)

31
Q

Action Potential Steps

A
  1. Resting potential
  2. Threshold Depolarization
  3. Depolarization
  4. Repolarization
  5. Hyperpolarization
  6. Return to resting membrane potential
32
Q

Resting potential for AP

A

Resting potential is -70mV
* Leak channels are open
* Voltage-gated Na+ & K+ channels are closed
Membrane’s ready for an action potential

33
Q

Threshold Depolarization

A

A small depolarization that’s sufficient to open volage-gated Na+ channel
Na+ moves down the axon from further up the axon
→ Slight depolarization → reaches threshold → Voltage-gated Na+ channels open
→ depolarization

34
Q

Depolarization

A

membrane becomes positive +40mV
Voltage gated Na+ channels open -> increased permeability of Na+ -> depolarization

35
Q

Repolarization

A

Membrane potential becomes negative again.
When the membrane reaches +40mV:
Voltage-gated Na+ channels closed
Voltage-gated K+ channels open
Both lead to repolarization

36
Q

Hyperpolarization

A

Membrane potential overshoots - more negative than -70mV
1. Voltage gated K+ channels open to make cell negative
2. Refactory period = a new AP can’t start

37
Q

Refactory period

A

A new AP can’t start
membrane cannot depolarize again, because K+ channels open and second gate of Na+ channel closed

38
Q

Voltage-gated Na+ channels
during action potential

A

Resting: Closed
Depolarization: Open
Repolarization: Closed
Hyperpolarization: Closed

39
Q

Voltage-Gated K+ channels
during action potential

A

Resting: Closed
Depolarization: Closed
Repolarization: Open
Hyperpolarization: Open

40
Q

Action potential propagation

A

how an AP moves down an axon
Soma → axon terminal
Have an AP → Na+ enters axon from AP → Na+ diffuses down axon → slight depolarization further down the axon → threshold → starts AP
Na+ will diffuse back up the axon too – further back up the axon is in Refractory period but AP can never go backwards

41
Q

Action potential frequency

A

How often a neuron has an AP
On any given neuron, all APs are:
1. Same size
2. Same speed
= APs are all or nothing - binary
Higher frequency APs = stronger signal

42
Q

Myelin sheath gaps

A

Spots along the axon where there’s no myelin
* APs happen only at gaps
* No APs between where there’s myelin

43
Q

Saltatory conduction

A

AP jumps from gap to gap
How:
1. AP at one gap - Na+ ions flow into the cell (depolarizes the membrane)
2. Na+ ions diffuse through myelin
3. Na+ ions lead to a threshold at the next gap

44
Q

Glial Cells

A

All cells in the nervous system that aren’t neurons
Develop from the same tissue as neurons
Located in the PNS & CNS

45
Q

Astrocytes

A

Glial cells in the CNS that maintain the environment in the CNS → ion concentrations in ECF
* Identifiable by the many long extensions coming off
* Feed neurons
* Provide structure to neurons

46
Q

Blood-brain burrier

A

Hard for substances to pass from blood into the CNS
Astrocytes wrap around blood vessels to help maintain the burrier

47
Q

Oligodendrocytes

A

Glial cells that make myelin in the CNS
Each one wraps the plasma membrane around the axons of multiple neurons

48
Q

Microglia

A

Glial immune cells of the CNS
* Not neural tissue
* They’re WBCs that live in the CNS
Phagocytes - Eat cells + large particles (Pathogens + old dead tissue)

49
Q

Ependymal

A

Glial cells of the CNS that line the inside of the dorsal cavity.
* Neural epithelial cells
* Cerebrospinal flood on one side / Nervous tissue on the other
* Cilia beat - moves Cerebrospinal fluid around the CNS
* Different than other glial cells

50
Q

Schwann cells

A

Glial cells that make myelin in the PNS.
Each one wraps around 1 axon.

51
Q

Satellite cells

A

Glial cells that wrap around cell bodies of neurons in the PNS + support them

Anatomy 20A (21 decks)

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