Exam 1 Review Flashcards by Serena Mallavarapu

DNA is used to make RNA, which is used to make _______.

proteins

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What is translation?

Ribosomes read the genetic info in the RNA and use it as a template to produce amino acids that go in a chain of proteins

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What are some additional roles of Mitochondria besides producing ATP?

Recycling of proteins
Regulation of membrane potential
Regulation of calcium storage/release

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The ER and mitochondria have higher _________ levels compared to cytoplasm

calcium

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The ER has 2 different Ca2+ stores. Name the 2 cellular events that open them.

Activation of IP3 metabolism

Elevation of cytosolic Ca2+ itself

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Internal calcium regulates…?

Second messenger signaling, gating and kinetics of voltage/ligand gated channels, gene expression

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Motor proteins move organelles around the cell on _________ tracks

microtubular

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Kinesin proteins move toward the + end. What is the + designate?

toward periphery

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Dynein moves proteins toward -. What does - designate?

toward nucleus

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What kind of molecules are permeable to a phospholipid bilayer?

Gases, hydrophobic molecule, small polar molecules.

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Who postulated the theory that neurons were individual cells and not continuous to other neurons?

Santiago Ramon y Cajal, he called it the neuron doctrine

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What was the evidence for chemical transmission as discovered by Sherrington?

Nerve impulse delay
Unidirectional flow of info in neural chain
Synapse transmission is excitatory and inhibitory

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Microglia produce ________ that influence glia and can signal neurons.

cytokines

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Name 2 main functions of astrocytes.

Anchor neuron to blood supply for nutrients and expulsion of ions
Form BBB

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Describe a unipolar cell and its location

1 neurite, seen in primary sensory neurons

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Describe a bipolar cell and its location

1 dendrite and 1 axon, found in PNS

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Describe pseudo-unipolar cell and its location?

no dendrites, but 1 axon that branches off (PNS/spinal cord)

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Describe multipolar cells and its location

most common in CNS, multiple dendrites, 1 axon.

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Action potentials do not grow in amplitude with larger stimuli, rather they increase in ___________

Number/frequency

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Electrical potential is…?

amount of potential energy per unit of charge

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Potential difference is…?

difference in potential between 2 locations.

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Conductance is…?

ease of flow between 2 points

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Resistance is the ________ of conductance

inverse

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What is Ohm’s law

V= IR

V=voltage, I=current, R=resistance

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The resting membrane potential is due to 2 factors:

separation of ions across cell membrane (creates ion gradients) Permeability of the membrane to those ions

What does the Nernst equation do?

Predicts the voltage created by diffusion of a single ion type

The farther away from the equilibrium potential the membrane voltage is, the _________ for that ion

larger the current

Resting membrane voltage depends on ________.

potassium concentration gradient

What does the Goldman equation do that the Nernst equation neglected?

Includes the relative permeabilities of each ion

Resting membrane potential is not equilibrium potential because?

It relies on expenditure of ATP by ion pumps for maintenence

An action potential is the result of ________ permeability to Na+ and K+

increasing

What are the components that make up the action potential?

``` Threshold Rising phase Overshoot Falling Phase Undershoot (below RMP) ```

An action potential is the result of _________ in membrane's permeability to Na+ and K+

selective increases

What is the refractory period?

Depolarization that produces Na channel opening also causes delayed activation of K channels and Na channel inactivity. Is harder for APs to be produced at this time.

Question postulated by Hodgkin and Huxley: Do membranes have voltage dependent permeabilities?

current flow is observed in response to depolarization, not hyperpolarization. Effect is voltage dependent.

In neurons/dendrites, hyperpolarization can induce ______ flow.

current

Direction of current flow is described as what?

net movement of positive charge

Flow of positive charge into cell is ________.

inward current

_____ flowing into cell w/ concentration gradient brings more positive charge into cell (inward current)

Na+

If K+ flows out of cell, taking charge with it, it's ________

outward current

Na+ ions are very important for the _______ inward current

early

Tetrodotoxin, or blowfish poisoning is a ___________.

Na+ channel blocker

g(K+) is...?

slow and non-inactivating

gNa+ is...?

fast and inactivating

K+ is much slower to turn on that Na+, therefore, it requires more time to reach its peak. This is known as a...?

delayed rectifier

What are some other conclusions made by Hodgkin and Huxley besides delayed rectifier?

Na+ channels must inactivate, bc the current goes off even when it is depolarized K+ channel do not inactivate if the cell is depolarized. They are voltage dependent

Describe the phases of an Action potential (brace yourself, it's a long one)

- Rest potential(Vm): high resting K+ conduction - Generator potential: depolarizes cell bc of opening of ligand gated cation channels - Threshold(-50mV): voltage gated Na+ channels open - Rising Phase:approaches Na+ equilibrium potential, overshoots - Falling phase: K+ channels open, Na+ closes, membrane potential nears K+ equilibrium potential - Undershoot:MP becomes negative to rest potential - Return to rest potential - Refractory period: 2nd AP cant be evoked

What is the absolute refractory period?

Time in which it's impossible to get another AP

What's a relative refractory period?

Time in which a strong stimulus can evoke a AP. Na+ channels have recovered from inactivation but MP is below rest potential due to open K+ channels

Name 4 main characteristics of voltage gated ion channel (like Na+ and K+)

- show ion selectivity - both are voltage gated - have a voltage sensor - Na+ channel has mechanism for inactivation

Name steps in cycle of Na+ channel:

- fast response - 2 gates (activation/inactivation) - rapid opening followed by slower closing - refractory period

We know that impulse propagation is unidirectional. What does that mean for Na+ channels as the AP moves along the axon?

Na+ channels close as AP crosses them

A ______ length constant makes it easier for distant synapses to influence activity of neuron

large

Cells increase membrane resistance(Rm) by ___________, and decrease resistance inside axon(Ri) by increasing ___________

myelination, axon diameter

What is spatial summation.

Bigger length constant increases this--2 inputs far away from one another can sum together to reach threshold.

What kind of axons are better conductors?

Ones with an insulated large diameter

What do large diameter axone with lower resistance mean for propagation of an impulse?

less leak and longer conduction distances

Length constant is directly proportional to ________ and inversely proportional to axial resistance

membrane resistance

Time constant is defined as the time when the _________ rises to 63% of the steady state membrane

voltage response

Myelination decreases _________ because it increases effective thickness of the membrane. Which means there is a _______ time constant

capacitance, smaller *Important for axons

Resistance is the inverse of _________. This ________ time constant

conductance, decreases *important for dendrites

What is temporal summation?

Synaptic potentials generated in the same membrane patch as a result of successive stimulation are added together

A _____ time constant allows for more temporal summation

long

Describe Golgi's Reticular Network Theory

The entire nervous system was a huge net, and all neurons were connected to each other

Name the stains that stain neurons, astrocytes and microglia

NeuN, GFAP, OX-42 respectively

Where do radial glia arise from and what's the function?

neuroepithelial cells. Only present during early development. Guide growth of neurons using scaffolding technique

Sensory neurons are usually __________ neurons

pseudo-unipolar

Are interneurons excitatory or inhibitory?

inhibitory

Integration of synaptic input occurs at __________.

axon hillock

The knee-jerk reflex requires no effort from the brain, why?

It's a monosynaptic effort, it only utilizes the spinal cord for its function.

Where is electrical impulse initiated?

in the dendrites

Capacitance of a cell membrane increases with __________.

Surface area

What causes ionic seperation?

presence of pumps like Na+/K+ ATPase

What is the reversal potential of an ion?

There is no net flow of ions, number of ions going in and out is equal

Early inward current reverses around potentials more ________ than E(na)

depolarizes

In voltage clamp experiments, the flow of positive charge into the cell is shown as...?

downward deflection

In current clamp, which depict changes in ___________. APs are shown as upward deflection.

membrane potential

Exam 1 Review Flashcards

(77 cards)