Module 1: Cellular And Molecular Neuroscience Flashcards
Population (aka global) cellular recordings have excellent ________ resolution, but poor ________ resolution.
Temporal : spatial
________ conduct action potentials away from the neuron cell body whereas ________ receive signals from other neurons which are carried towards the cell body.
Axons : dendrites
What are homogenizing factors that influence ionic concentration across neural membrane and contribute to RMP?
- electrostatic pressure
- ionic motion driven by concentration gradients
True or False. The concentration of positive ion species is greater inside of a neuron than outside.
False
RMP results from the ______ distribution of ion species across the neural membrane
unequal
How does diffusion of ions affect the RMP?
Each ion species has a differential permeability through the neural membrane which contributes to the unequal distribution of these ion species across the membrane.
Leak ion channels are primarily responsible for what?
Establishing resting membrane potential
True or false. The delay in synaptic transmission is shorter in electrical synapses than in chemical synapses.
True
True or false. Graded potentials of the sarcolemma are termed end-plate potentials (EPPs).
True
True or false. Neural activity at the NMJ always results in depolarization of the sarcolemma.
True
True or false. The NMJ is the synapses between multiple motor neurons and a single skeletal muscle fiber.
False
True or false. The NMJ contains nicotinic acetylcholine receptors located on the postynaptic membrane (sarcolemma).
True
True or false. The size of the synaptic cleft in chemical synapses is smalller than those of electrical synapses.
False
True or false. All chemical synapses utilize acetylcholine (ACh) are their main neurotransmitter.
False
True or false. Only electrical synapses require a change in membrane voltage in order to induce transmission.
False
True or false. Leak ion Chanel’s are primarily responsible for generating action potentials.
False, they establish RMP
Do resting membrane potentials require energy to maintain?
Yes, ATP for ion pumps
Type of neuron that has a single axon and contains multiple dendrites extending from the
soma (majority of CNS neurons)
Multipolar neuron
Type of neuron that contains a single process extending from the soma that can branch (peripheral and central portions) to form dendrites and axon terminals
Pseudounipolar/unipolar
Type of neuron that contains two processes, one axon and one dendrite, extending from the
soma
Bipolar neuron
Multiple neuron cell bodies in the CNS are called:
Nuclei
Multiple axonal processes that are anatomically or functionally distance in the CNS are called:
Tracts
Multiple neuron cell bodies in the PNS are called:
Ganglia
Multiple axonal processes that are anatomically or functionally distance in the PNS are called:
Nerves
What are the 5 principles of contact theory?
- neuron is elementary structural and signaling unit of nervous system
- dynamic polarization i.e. information received at one end, travels unidirectional to opposite end
- Synapses are specialized junctions where axon terminal (sending end) is in close contact to receptive end of another neuron
- connection specificity, meaning individual neuron will only communicate with synaptic contacts on specific regions of
specific cells - neural/synaptic plasticity is a phenomenon neuron connections can be modified by experience
Where do graded potentials occur?
At dendrites and the soma
Where do action potentials occur?
initiated at a region adjacent to the axon hillock (A-H) and travel along the axon toward the terminal button
What membrane voltages rely on the activity of ion channels located throughout the plasma membrane?
Both graded and action potentials
What type of neuron population recording detects the magnitude and gross location of electrical activity in cortical regions and is performed in conjunction with a cognitive task?
EEG, electroencephalography
What type of neuron population study measures muscle
response or electrical activity in response to a nerve’s stimulation of the muscle? Utilized to detect neuromuscular abnormalities.
EMG (electromyography) & nerve conduction studies
What type of neuron population recording reflects the activity of the brain in response
to a stimulus? I.e reflects summed postsynaptic potentials of multiple neurons that have been activated.
ERP (event-related potential)
What kind of electrical activity is recorded with an extracellular single-unit micro-electrode?
all-or-none action potentials (APs)
What kind of electrical activity is recorded with an intracellular single-unit micro-electrode?
resting membrane potential (RMP), graded potentials (EPSPs, IPSPs) and APs
What kind of electrical activity is recorded with “patch clamp” single-unit micro-electrode?
ionic current not voltage of either a single or a group of ion channels
What is the resting membrane poetical of neurons in millivolts?
~ -70 mV, although RMP is typically between -40mV to -90mV depending on neuron size
In resting state, neurons are considered to be _____.
Polarized
What are anti-homogenizing factors that influence ionic concentration across neural membrane and contribute to RMP?
- differential permeability of ions that utilize ion channels
- active membrane-bound transporters, mainly the sodium-potassium pump
Which passes more readily through ion channels in the neural membrane, sodium or potassium?
Potassium (and also chloride) readily passes through the membrane
Sodium passes with difficulty
How does the resting membrane potential arise and maintain?
by the differences between the intracellular and extracellular concentrations of Na+, K+, and Cl- ions, as well as the negative charges of the protein ions trapped inside the cell.
What is the electrostatic force on chloride through neural membrane?
negative internal potential drives Cl- ions out of the cell
How does concentration affect diffusion of chloride at the neural membrane?
Because electrostatic forces are driving Cl- out, they accumulate outside the cell and the concentration gradient forces them back in
How does concentration affect diffusion of sodium at the neural membrane?
The neural membrane is resistant to diffusion of Na+ so extracellular concentration is high and drives Na+ into the cell
How does electrostatic pressure affect the diffusion of Na+ at the neural membrane?
negative internal resting potential drives Na+ ions into the cell
How do transporters affect sodium and potassium concentrations?
sodium-potassium pumps maintain:
- high extracellular Na+ concentration by pumping out Na+ ions at the same rate that they move in
- high intracellular K+ concentration by pumping K+ ions into the
neuron at the same rate that they move out
How does electrostatic pressure affect the diffusion of K+ ions at the neural membrane?
internal negative potential drives K+ ions back into the cell
How does concentration affect the diffusion of K+ at the neural membrane?
High internal concentrations of K+ cause them to move out
Characteristics of leak/leakage ion channels:
- Open even in a resting state
- Selective for a single ion species
- Contribute to the RMP
- ions follow concentration gradient
Characteristics of gated ion channels:
- Closed until opened by stimulus (voltage, ligand, sensory
stimuli) - Can be selective for one or multiple ion species
- Necessary for graded and all-or-none action potentials
(APs) and neurosecretion - can have depolarizing and hyperpolarizing effects
Where are leak/non-gated channels located in the plasma membrane of neurons?
on the cell body, dendrites, and along
the axon.
Where are ligand-gated channels located in the plasma membrane of neurons?
on the cell body and dendrites of the neuron.
Where are voltage-gated channels located in the plasma membrane of neurons?
- on the axon hillock, all along unmyelinated axons,
and at the nodes of Ranvier in myelinated axons - terminal button
The target of a presynaptic neuron may be :
another neuron, a region of a muscle, or a secretory cell.
What are electrical synapses?
Communication that allows for direct cell to cell communication via the flow of electrical current through specialized membrane channels (pores) that connect two cells
The intercellular region between sending and receiving cell.
Gap junction
The center core of a gap junction is formed by six subunits called:
Connexins, which are integral membrane proteins
The hexameric complex that forms the center pore of a gap junction:
Connexon
What is the direction of transmission at gap junctions?
Bidirectional