Fundamentals of the nervous system Flashcards

1
Q

What are parts of the body and functions are in CNS and PNS

A

CNS
- brain and spinal cord
- Integration and control centre

PNS
- Cranial nerves & spinal nerves
- Communication between CNS & rest of body

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2
Q

What are the 2 principal cell types in the nervous system

A

Neurons: Excitable cells that transmit electrical signals
- Mass is far greater
Neuroglia: supporting cells (6 types)
- # is greater

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3
Q

What cells are in the CNS & PNS

A

CNS
- Astrocytes
- Microglia
- Ependymal Cells
- Oligodendrocytes

PNS
- Satellite cells
- Schwann cells

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4
Q

What are astrocytes (star-shaped)

A
  • guide the migration of neurons & formation of synapses
  • Tight junctions and basal lamina of the cerebral endothelial cells (cells line blood cells) play an important role in blood brain barrier
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5
Q

What are microglia

A
  • Migrate toward injured neurons
  • Phagocytize microorganisms & neuronal debris
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6
Q

What are ependymal cells

A
  • ciliated cells that circulate CSF
  • Produce CSF
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7
Q

What are oligodendrocytes

A

Forms myelins that gives impermeable membranes to axons

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8
Q

What are satellite cells (PNS)

A
  • Control microenvironment around cell body
  • Similar to astrocytes in CNS
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9
Q

What are schwann cells (PNS)

A

Most form myelin sheaths

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10
Q

What is the function of myelin sheaths

A
  • Protect and electrically insulate axon
  • Increase speed of nerve impulse
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11
Q

What is the neurilemma? which nervous system is it in?

A

Peripheral bulge of schwann cells in PNS

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12
Q

What are Nodes of Ranvier?
What effect does it have?

A

Gaps between the myelin sheaths
- Make AP go faster, also increasing diameter

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13
Q

Where are the voltage gated channels in a neuron

A

In the axon NOT cell body

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14
Q

What are clusters of cell bodies called in CNS and PNS? and processes in each?

A

CNS: nuclei; tracts
PNS: ganglia; nerves

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15
Q

What is the function of dendrites?

A

Receive input as graded potentials (short distance signals)

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16
Q

Where can graded potential be found? action potential?

A

GP: cell body + dendrites
AP: axon

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17
Q

What is the role of telodendria?

A

Synapses with synaptic terminals

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18
Q

What are the functions of axons? Name and explain the 2 directions in trafficking.

A

Anterograde: away from cell body
- Kinesin motor
- Mitochondria, enzymes

Retrograde: toward cell body
- dynein-dyactin motor
- viruses, toxins

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19
Q

Which type of neurons do not generate AP and are unmyelinated

A

Bipolar neurons

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20
Q

Which type of cell is mainly found in PNS

A

unipolar, function as sensory neurons

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21
Q

What are the functional classifications of neurons

A

SENSORY (afferent): transmit impulses from sensory towards CNS
MOTOR (efferent): carry impulses from CNS to effectors

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22
Q

What is Ohms law equation

A

Current = voltage/resistance

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23
Q

Contrast between the 3 gated channels

A

Chemically (ligand) gated channels
- open with binding of a specific NEUROTRANSMITTER

Voltage-gated channels
- open & close in response to changes in MEMBRANE POTENTIAL

Mechanically gated channels:
- open & close in response to physical deformation of receptors

24
Q

What are factors that influence RMP

A
  • Impermeable to negatively charged proteins
  • Slightly permeable to Na+ (Na+ leakage channels)
  • 25-100 times more permeable to K+ (K+ leakage channels)
  • Freely permeable to Cl-
  • Differences in ionic composition of ICF and ECF
  • Differences in PM permeability
25
Q

How do you generate a resting membrane potential?

A
  1. K+ ions diffuse in their leaky channels to outside: results in a negative charge in inner membrane
  2. K+ ions also move inside the cell as they are attracted to the - charge in the inner membrane
26
Q

What are the requirements for generating a resting membrane potential

A
  • Na+/K+ pump: pump more cations out
  • The concentration gradient of K+
  • Higher permeability to K+
  • Membrane impermeable to anionic proteins
27
Q

When does membrane potential change?

A
  • when concentrations of ions across membrane changes
  • membrane permeability to ions changes
28
Q

What is a graded potential? what is it triggered by? What sections of the graph does it result in?

A

-an incoming signal operating over a short distance
- triggered by stimulus that opens gated ions channels
- Results in depolarization and hyperpolarization

29
Q

What are long-distance signals called? What does it trigger to open?

A

Action potential
- triggers to open specific voltage gated channels

30
Q

What are the states of the 2 activation gates at rest? What causes them to change?

A

Activation gates:
- closed at rest
- open with depolarization to allow Na+ to enter

Inactivation gates:
- open at rest
- block channel once it is opened to prevent more Na+ from entering

31
Q

What occurs with the gates in depolarization

A
  • Activation and inactivation gates open
  • sodium enters
  • increases membrane potential
32
Q

What occurs with the gates in repolarization

A
  • Inactivation gates close
  • Activation gates stay open
  • Sodium stops entering
  • Potassium leaves
  • mV decreases
33
Q

What occurs with the gates in hyperpolarization

A

-Activation gates close
- Inactivation gates open
- Potassium is still exiting

34
Q

What is the absolute refractory period

A
  • time when Na+ channels open until channel resets (depolarization)
  • ensure all-or-none
35
Q

What is the relative refractory period

A
  • repolarization + hyperpolarization
  • threshold to get an AP is elevated in this period
36
Q

What is the role of the Na/K pump?

A

Ionic redistribution

37
Q

How does CNS determine stimulus intensity?
Frequency/height

A

by frequency

38
Q

What is the effect of large diameters in an axon?

A

Less resistance, faster impulse conduction

39
Q

What is the rate-limiting step in information transfer in chemical synapses

A

Synaptic delay

40
Q

What are the steps for info transfer across chemical synapses.

A
  1. AP arrives at axon terminal
  2. Ca2+ enters axon terminal via voltage gated Ca2+ channels
  3. Ca entry causes synaptic vessels containing neurotransmitters to exit via exocytosis
  4. Neurotransmitter diffuses into synaptic cleft and binds to specific receptors
  5. Binding of neurotransmitter opens ion channels resulting in GRADED POTENTIAL
  6. Neurotransmitter effects terminated by reuptake of transport proteins and enzymatic degradation
41
Q

For electrical synapses, how are neurons electrically coupled?

A

via gap junctions

42
Q

What is the role of EPSP

A
  • allow flow of Na+ and K+ in opposite directions
  • allows more + membrane potential (Na+ influx> K+ efflux) (net depolarization)
  • help trigger AP
43
Q

What is the role of IPSPs

A
  • Allow flow for either K+ out or Cl- in
  • Causes a hyperpolarization (more - mV)
  • reduces ability to produce an AP
44
Q

What is the difference between temporal and spatial summation

A

Temporal summation
- Impulses in rapid-fire order
- 1 entry

Spatial summation
- Impulses at the same time
- more than 1 entry

45
Q

What occurs in an axoaxonic synapse

A

release of an excitatory neurotransmitter may be inhibited by activity of another neuron

46
Q

What are the 6 neurotransmitter classes

A
  1. ACh
  2. Biogenic amines
  3. Amino acids
  4. Peptides
  5. Purines
  6. Gases (inhibitory or excitatory) & lipids (inhibitory)
47
Q

What neurotransmitter and class is involved in wakefulness

A

NE & E
Biogenic amine

48
Q

What are the neurotransmitters of excitatory and inhibitory of amino acids. 2 of each. Where does it work?

A

GABA (inhibitory) in brain
Glycine (inhibitory) in spinal

Glu: principal excitatory
Asp

49
Q

What is the role of neurotransmitter adenosine? Whats the class

A

Purines

Potent inhibitor in brain
(how caffeine works)

50
Q

Contrast between discharge zones and facilitated zones

A

Discharge zone:
- closest to incoming fibre
- immediate fast response

Facilitated zone:
- farther away from incoming fibre
- requires more stimulation

51
Q

Which receptors have an indirect action

A

G Protein-linked receptors

52
Q

Differentiate between diverging circuit and converging circuit

A

Diverging
- 1 input, many outputs
- Amplifying

Converging
- many inputs, 1 output
- concentrating

53
Q

Differentiate between serial processing and parallel processing

A

Serial
- 1 pathway
-Simple

Parallel
- multiple pathways
- higher level function

54
Q

What receptors have a direct action?
Which ions do the excitatory and inhibitory receptors allow in this receptor?

A

channel-linked receptors

Excitatory: Na+ influx
Inhibitory: Cl- influx, K+ efflux

55
Q

What is the neuron cell body called
What are the bodies called in this area

A

Perikaryon
Nissl bodies