Exam 1 Review Flashcards
DNA is used to make RNA, which is used to make _______.
proteins
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
What are some additional roles of Mitochondria besides producing ATP?
Recycling of proteins
Regulation of membrane potential
Regulation of calcium storage/release
The ER and mitochondria have higher _________ levels compared to cytoplasm
calcium
The ER has 2 different Ca2+ stores. Name the 2 cellular events that open them.
Activation of IP3 metabolism
Elevation of cytosolic Ca2+ itself
Internal calcium regulates…?
Second messenger signaling, gating and kinetics of voltage/ligand gated channels, gene expression
Motor proteins move organelles around the cell on _________ tracks
microtubular
Kinesin proteins move toward the + end. What is the + designate?
toward periphery
Dynein moves proteins toward -. What does - designate?
toward nucleus
What kind of molecules are permeable to a phospholipid bilayer?
Gases, hydrophobic molecule, small polar molecules.
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
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
Microglia produce ________ that influence glia and can signal neurons.
cytokines
Name 2 main functions of astrocytes.
Anchor neuron to blood supply for nutrients and expulsion of ions
Form BBB
Describe a unipolar cell and its location
1 neurite, seen in primary sensory neurons
Describe a bipolar cell and its location
1 dendrite and 1 axon, found in PNS
Describe pseudo-unipolar cell and its location?
no dendrites, but 1 axon that branches off (PNS/spinal cord)
Describe multipolar cells and its location
most common in CNS, multiple dendrites, 1 axon.
Action potentials do not grow in amplitude with larger stimuli, rather they increase in ___________
Number/frequency
Electrical potential is…?
amount of potential energy per unit of charge
Potential difference is…?
difference in potential between 2 locations.
Conductance is…?
ease of flow between 2 points
Resistance is the ________ of conductance
inverse
What is Ohm’s law
V= IR
V=voltage, I=current, R=resistance
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
