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PNB 2XB3 (Neuroanatomy) > Lecture 3 + Assignment 3 > Flashcards

Lecture 3 + Assignment 3 Flashcards

1
Q

A.P. speed compared to electricity

A
  • electricity = 1/2 speed of light
  • A.P. speed slower
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2
Q

Leaky, sticky, and thin

A
  • all make a.p.s move slower

Leaky = low membrane resistance
Rm

Sticky = high membrane capacitance
Cm

Thin = high axial resistance
Ra

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3
Q

Membrane resistance / Rm

A
  • leakiness
  • like a balloon with a hole

Rm = resistance of the membrane

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4
Q

Membrane capacitance / Cm

A
  • stickiness
  • ability of membrane to store charge
  • if it can’t store charge well, sticks to ions on the outside due to attraction
  • makes them travel slower

Cm = capacitance of the membrane

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5
Q

Axial resistance /Ra

A
  • thin = hard to flow through
  • how easy it is for ions to flow through

Ra = resistance of the axon

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6
Q

Invertebrates avoiding leaky/sticky/thin

A
  • evolved wider axons
  • they take up more space
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7
Q

Vertebrates avoiding leaky/sticky/thin

A

myelin
- reduces axon leakiness and stickiness

saltatory conduction
- jumping between nodes of Ranvier
- makes conductance speed faster

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8
Q

Myelin in CNS vs. PNS

+ Nervous system path

A

Oligodendrocytes
- in CNS
- connect to multiple axons

Schwann cells
- in PNS
- connect to one axon

myelin -> glial cells -> oli -> multiple axons

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9
Q

Theodor Schwann

A

Discovered schwann cells

supported cell theory
“all living things are composed of cells and cell products”

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10
Q

Multiple sclerosis

A
  • autoimmune disorder where virus with an antigen that looks like myelin gets degraded as well
  • Epstein-Barr virus
  • myelin attacked/degraded by immune system
  • slow action potentials
  • also forms sclerosis scar tissue which slows a.p.s
  • lose feeling then it comes back
  • nervous system fights back to repair glial cells/myelin
  • first symptoms vision, tactile, balance, speech
  • 20-40 years old
  • 2x prevalence in women
  • genetic factors (twin studies)

1/1000 ppl

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11
Q

Guillain-Barre syndrome

A
  • similar to MS but in PNS
  • antibodies attack myelin schwann cells

1/100 000 ppl

  • symptoms: paresthesia, paralysis, loss of sensation
  • movement difficulty starting in the legs moving up
  • rapid onset, recovery after weeks or years
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12
Q

Neuron doctrine vs. reticular theory

A

Golgi
- reticular theory
- neurons all connected through giant network

Santiago Ramon y Cajal
- neuron doctrine
- separate by nearby neurons

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13
Q

Synaptic cleft

A

20-40 nm wide

beneath the resolution of conventional light microscopy

1nm = 10^-9 m

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14
Q

Otto Loewi - heart in a jar

A
  • do heartbeat in one jar
  • slow heartbeat
  • makes heart in other jar also slow down
  • indicates chemical transmission through synapses

bc vagus nerve releases something into the saline fluid

  • did this experiment
  • used frog hearts
  • dreamt it up then scribbled it down but couldn’t read the stuff
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15
Q

Evidence of quantal transmission

A
  • smallest possible depolarization of 0.4 mV
  • quantal packages during synaptic release
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16
Q

Bernard Katz

A
  • found evidence of quantal transmission
  • 1911-2003
17
Q

Resting synapse

A
  • neurotransmitters in synaptic vesicles
  • presynaptic axon connects to postsynaptic dendrite

axon terminal = synaptic bouton

  • voltage-gated calcium ion channel closed
18
Q

Active synapse

A

neurotransmitters in vesicles leave the cell (exocytosis)

bind to ligands

opens ligand-gated ion channels when they bind

  • opens voltage-gated calcium ion channels
    Ca goes OUT
19
Q

Calcium leaving the axon terminal

A

Ca pump lets it out of the cell as 2H enters
- uses ATP hydrolysis

Na/Ca exchanges one for another

20
Q

Mechanisms of transmitter exocytosis

A
  1. vesicle docks
  2. SNARE complexes form to pull membranes together - vesicle to axon terminal membrane
  3. exiting Ca binds to synaptotagmin on vesicle
  4. Ca-bound synaptotagmin catalyzes membrane fusion and teurotransmitter releae
21
Q

Gruber prize in neuroscience - 2012

+ how many neurotransmitters discovered

A

Lily Jan and Yuh Nung Jan

  • discovered that peptides can be neurotransmitters

over 100 neurotransmitters discovered

22
Q

Small molecule amino acid neurotransmitters

A

Glutamate
- most common excitatory nt

GABA
- most common inhibitory nt in cerebral cortex

Glycine
- common inhibitory nt in brainstem/spinal cord

23
Q

Glutamate receptor channel

A
  • glutamate binds
  • channel opens and lets Na in

= excitatory

has same permeability of K out as Na in (g=g)

Na has a larger driving force in so net current inward = negative current

24
Q

GABA receptor channel

A
  • GABA binds
  • channel opens and lets Cl in
  • selectively permeable to Cl

= inhibitory

25
Q

Driving force equation

A

I = g(Vm - E)

I = current of ion
g = membrane conductance
Vm = membrane potential
E = equilibrium potential

Vm - E = driving force on ion

26
Q

+/- Current

A

(+) current
= outward (+)
- cell loses (+) charge or gains (-) charge
GETTING MORE (-)

(-) current
= inward (+)
- cell loses (-) charge or gains (+) charge
GETTING MORE (+)

27
Q

Axon hillock

A

where axon attaches to the cell body

28
Q

EPSP

A
  • glutamatergic
  • depolarization
29
Q

IPSP

A
  • GABAergic
  • hyperpolarizaion
30
Q

Spatial integration of EPSPs

A

lambda = length constant = √rm/ra

Vx = Voe^-(x/lambda)

Vx = membrane potential
x = distance

31
Q

Temporal integration of EPSPs

A

tau = time constant = rmxcm

Vt = Voe^-(t/tau)

Vt = membrane potential
t = time

32
Q

Spatiotemporal integration

A
  • spatial and temporal EPSPs
33
Q

Patch clamp - nobel prize

A

Nobel prize in physiology or medicine - 1991

Neher and Sakmann

  • invented patch clamp
  • discovered opening and closing of single ion channels
34
Q

Patch clamp - technique

A
  • pipette over ion channel
  • suction doesn’t allow other ions to enter

Cell-attached recordings
- just take recordings with suctioned separate environment
=microscopic currents
- reveals characteristics of different channels

Whole-cell recordings
- strong pulse of suction to make cytoplasm continuous with pipette (breaks membrane)

Inside-out
- take a chunk and membrane closes behind it
- cytoplasm facing out
- can change medium inside cell

Outside-out
- take a chunk and membrane closes behind it
- rips twice and folds back together in pipette
- membrane facing out

35
Q

Fast vs. slow axonal transport

A

Fast axonal transport occurs at a rate of up to 400 mm/day.
- uses molecular motors like kinesin, dynein

Slow axonal transport occurs at a rate of 0.5–5.0 mm/day.

36
Q

Anterograde vs. retrograde transport directions

A

Anterograde axonal transport towards axon terminal.

Retrograde axonal transport towards cell body.

37
Q

Glutamate = not axonal transport

A
  • synthesized in presynaptic cytoplasm
  • packaged into synaptic vesicles by vesicular glutamate transporters, aka VGLUTs
  • vesicles are then transported into cells by excitatory amino acid transporters, aka EAATs

PNB 2XB3 (Neuroanatomy) (5 decks)

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