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Brain And Behaviour > Topic 4 > Flashcards

Topic 4 Flashcards

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1
Q

Electrical potential

A

Ability to do work using stored potential energy

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2
Q

Diffusion

A

Movement of ions from an area of high concentration to low concentration

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3
Q

Concentration vs. Electrical gradient

A

Concentration
- difference in concentration of a substance among regions in a container
Electrical
- difference in charge between 2 regions that allows a flow of current

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4
Q

3 types of neuronal signaling

A
  1. Resting membrane potential
  2. Graded potential
  3. Action potential
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5
Q

Resting membrane potential

A
  • there is a store of negative energy inside the cell compared to the outside
  • -70mV inside
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6
Q

Particles involved in resting membrane potential

A

Outside
- sodium Na+
- chloride Cl-

Inside
- potassium K+
- large proteins A-

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7
Q

Na+, Cl-, and K+ equilibrium potentials

A

Na+ is +60mV
Cl- is -70mV
K+ is -94mV

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8
Q

Equilibrium potential

A

The membrane potential where there is no net ion flow across open channels

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9
Q

Leak channels

A

Allow the passive diffusion of specific ions

Proteins are too large to pass

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10
Q

Selective permeability of ions

A
  • k+ diffuses freely out of the cell and down its concentration gradient
  • cell is more permeable to K+
  • very little Na+ leaks into the cell
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11
Q

Sodium-Potassium pump

A
  • moves Na+ and K+ against their concentration gradient, hence the ATP
  • 3Na+ out and 2K+ in
  • 1ATP
  • maintains the -70mV resting potential
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12
Q

Graded potentials

A

Small fluctuations across the membrane

Depolarization
- entry of Na+
- more positive
- decrease in membrane potential
- excitatory postsynaptic potential (EPSP)

Hyperpolarization
- entry of Cl- or exit of K+
- more negative
- increase in membrane potential
- inhibitory postsynaptic potential (IPSP)

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13
Q

EPSP vs. IPSP

A

EPSP
- depolarization in response to stimulation
- more likely to produce an action potential
- opening of Na+ channels

IPSP
- hyperpolarization in response to stimulus
- less likely to produce action potential
- opening if K+ and Cl- channels

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14
Q

Characteristics of IPSPS and EPSPS

A
  • amplitude is proportional to the intensity of the output
  • travel passively and rapidly
  • amplitude decreases with distance
  • effects can be summated to initiate action potential
  • synapses closest to the AIS have the most influence on neuronal firing
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15
Q

How do neurons integrate info?

A
  • impulses are excitatory or inhibitory
  • cell body integrates received inputs
  • net excitation must be equal to the threshold of excitation action to fire an action potential
  • higher EP does not mean stronger action potential
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16
Q

Types of summation

A

Temporal
- pulses occur at about the same time

Spatial
- pulses occur at about the same place on a membrane

17
Q

Threshold of activation

A

-50 mV

AP is initiated at the axon initial segment

18
Q

Action vs. Threshold potential

A

Action
- reversal in polarity of an axon
- all or none (not graded)
- non-decremental
- regenerated by the opening and closing of ion channels
- one way propagation

Threshold
- voltage on a neural membrane at which action potential is triggered
- opens voltage gated Na+ channels

19
Q

Phases of action potential

A
  1. Depolarization
  2. Repolarization
  3. Hyperpolarization
20
Q

Voltage gated ion channels

A
  • open and close at specific voltages
  • Na+ and K+
  • close at resting potential and open at threshold voltage
  • Na+ channels open and close faster than K+
21
Q

Toxins that block voltage gate channels

A
  • TEA blocks K+ channels
  • TTX blocks Na+ channels
22
Q

Refractory periods

A

Prevent the action potential from reversing directions and sets the maximum frequency of action potential firing

Absolute refractory
- new action potential cannot be elicited
- VG sodium channels are inactive

Relative refractory
- stronger stimulus is required to produce an action potential (in Hyperpolarization)
- K+ channels are open

23
Q

Stronger stimulus = larger action

A

False

It would produce higher frequency of action potential firing

24
Q

Myelin’s role in saltatory conduction

A
  • myelin increases conduction speed
  • nodes of ranvier allow for saltatory conduction
  • AP jumps from one node to the next
  • larger the axon diameter, faster the conduction
25
Q

Multiple sclerosis

A

Myelin formed by oligodendrocytes is damaged, disrupting the function of the neurons whose axons it encases

26
Q

Electrical synapse

A
  • Membranes are connected by gap junctions
  • small molecules pass through the cytoplasm freely
  • fast
  • glial and neuronal gap junctions
  • embryogenesis
  • synchronizes groups of cells
27
Q

Types of chemical synapses

A
  1. Axodendritic
    - axon buttons to dendrite
  2. Axosomatic
    - axon buttons to cell body
  3. Dendridendritic
    - dendrite to dendrite in either direction
  4. Axoaxonal
    - axon terminal to axon
    - presynaptic inhibition
28
Q

Steps of neurotransmitter release

A
  1. AP arrives at the terminal buttons
  2. Depolarization causes VG calcium channels to open
  3. Ca2+ enters
  4. Synaptic vesicles fuse, releasing neurotransmitters (exocytosis)
29
Q

Synthesis packing and transport of neurotransmitter molecules

A

Small
- synthesized in terminal buttons
- packaged in synaptic vesicles by the golgi complex
- Ca2+ causes exocytosis

Large
- synthesized in ribosomes in cell body
- packaged in cell body vesicles by the Golgi complex
- transported by microtubules to the terminals
- larger vesicles need larger stimulus so they are slowly released by increase in Ca2+
- vesicles fuse to presynaptic membrane prior to exocytosis

30
Q

Categories of neurotransmitters

A

Amino acids
- glutamate
- aspartate
- glycine
- GABA
Monoamines
Catecholamines
- dopamine
- epinephrine
- norepinephrine
Indolamines
- serotonin
Acetylcholine
- acetylcholine
Unconventional NTs
Soluble gases
- nitric oxide
- carbon monoxide
Endocannabinoids
- anandamide

Neuropeptides
- pituitary
- hypothalamic
- brain-gut
- opioid
- miscellaneous

31
Q

NT deactivation

A
  1. Reuptake
    - NT are reabsorbes by the presynaptic button and repackaged in vesic,es by Golgi complex
  2. Enzymatic digestion
    - NT broken down by specific enzyme
    - products are reabsorbed by presynaptic button

*neurons recycle synaptic vesicles

32
Q

Ionotropic receptor

A

Associated with ligand-activated ion channels
Directly alter membrane potential
ESPS - NT opens Na+ channels
ISPS - NT opens K+ or Cl- channels

33
Q

Metabotropic receptor

A

Associated with signal proteins and G-proteins
More prevalent
Effects are slower to develop but longer lasting and more varied

34
Q

7 steps of neurotransmitter release

A
  1. NTs are synthesized
  2. NTs are stored in vesicles
  3. Leaked NTs are destroyed by enzymes
  4. AP causes vesicles to fuse with the presynaptic membrane and release NTs into synapse
  5. NTs bind with autoreceptors to inhibit further NT release
  6. NTs bind to postsynaptic receptors
  7. Extra molecules are deactivated by reupatke or degradation

Brain And Behaviour (11 decks)

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