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Phy Sci 111A - Exam 1
N/A
52
Physiology
Undergraduate 3
01/28/2010

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Term
What are the three classes of phospholipids?
Definition
Phosphoglycerides, sphingolipids, and sterols
Term
What is the model that describes how amphipatic molecules behave in the cell membrane?
Definition
Singer-Nicholson fluid-mosaic model
Term
What are two main types of molecules that make up the cell membrane?
Definition
Phospholipids and proteins
Term
What is Fick’s Law of Diffusion and what does it do?
Definition
dS/dt = Px(C1 – C2), describes the passive diffusion of a single substance across a barrier
Term
How do you calculate the permeability constant?
Definition
Px = DmK/a
Term
What is the Neuron Doctrine? Who proposed it?
Definition
The nervous system is not made of fibers, but rather discreet signaling elements (cells) called neurons, Santiago Ramón y Cajal (Spain)
Term
Who discovered a staining technique for neurons? How does the technique work?
Definition
Camillo Golgi (Italy), impregnating cell with silver grains.
Term
What are the components of a circuit? How are they manifested in the membrane?
Definition
Battery (voltage source) is the source of positive charge, usually the extracellular stimulation, current is the flow of ions, capacitor is the actual membrane, resistors can be membrane and cytoplasm (constant) and channels (variable)
Term
Why does the resting potential exist?
Definition
The cell membrane is semi-permeable, and has differing ionic concentrations on the inside and outside
Term
What is the name of the equilibrium that helps explain the resting potential?
Definition
Donnan equilibrium
Term
What are the three equations to determine resting potential?
Definition
Nernst equation, Goldman equation, and Ohm's Law
Term
Which one is least accurate, and how does it calculate the resting potential?
Definition
Nernst equation, approximates En as Vm
Term
What is the Nernst equation?
Definition
Fe = Fc, Fe = zFVm, Fc = RT ln([X]out/[X]in), set them equal and solve for Vm
Term
What was the experiment that supported the Nernst explanation of the resting potential?
Definition
Baker, Hodgkin, and Shaw (1961) squeezed our SGA cytoplasm, switched cytoplasm with extracellular fluid, saw Vm reverse back to ~+90 mV
Term
How do you calculate how many charges are needed to cross to develop resting potential?
Definition
C = Q/V
Term
What is the Goldman equation?
Definition
Vm = (RT/F) ln (Ptot[N]o/Ptot[N]i), make sure it is total out on top, total in on bottom
Term
What is Ohm's Law?
Definition
In = gn (Vm – En)
Term
Who was the proponent of the first primitive action potential theory, and what was the theory?
Definition
Bernstein (1917) described an event in which all the channels would open, making the membrane totally permeable, and Vm = 0 mV
Term
Who were the researchers to discovered how the action potential really occurs, and how did they do it?
Definition
Hodgkin, Huxley and Katz experimented on SGA
Term
What are the two general kinds of potentials?
Definition
Graded potentials and action potentials
Term
What are the basic traits of graded potentials?
Definition
Local, decremental, and non-propagating
Term
What are the basic traits of action potentials?
Definition
"All-or-none", non-decremental, and propagating
Term
What does "all-or-none" mean when referring to action potentials?
Definition
Increasing the stimulus to create an action potential does not increase the amplitude of the potenial, it only creates more action potentials
Term
Who invented the patch clamp, and what does it do?
Definition
Neher, Sackmann, and Sigworth, it records measurements of a single channel
Term
How many subunits does the voltage-gated Na+ channel have, and what are they?
Definition
Three; α, β1, and β2
Term
Which of the Na+ channel subunits is the largest?
Definition
α subunit
Term
What is the structure of the α subunit?
Definition
It has 4 transmembrane domains, each of which are made up of 6 transmembrane segments
Term
Which part of the α subunit is responsible for detecting voltage?
Definition
S4 transmembrane segment
Term
Who invented the voltage clamp, and what does it do?
Definition
K.C. Cole at Woods Hole, MA, allows experimenter to maintain Vm at a fixed value (Vcom)
Term
What cells produce myelin?
Definition
In the PNS, Schwann cells; in the CNS, oligodendrocytes
Term
What effect does myelin have on resistance and capacitance?
Definition
Capacitance is lowered, resistance is increased
Term
Who used the voltage clamp to illustrate how certain channels behave?
Definition
Hodgkin and Huxley
Term
Which ion has a higher selectivity through the Na+ channel than Na+?
Definition
Li+
Term
What is an inhibitor?
Definition
A drug or toxin that blocks the normal action of a protein or a biochemical process
Term
What is a receptor agonist?
Definition
A receptor agonist binds to a receptor and mimics the action of the naturally-occurring neurotransmitter
Term
What is a receptor antagonist?
Definition
A receptor antagonist binds to a receptor and blocks (antagonizes) the action of the neurotransmitter
Term
What is the difference between a receptor agonist and a receptor antagonist?
Definition
A receptor agonist mimics the action of the naturally-occurring neurotransmitter, while a receptor antagonist blocks it instead
Term
What is the difference between a receptor antagonist and an inhibitor?
Definition
A receptor antagonist is an inhibitor, but it is a specific kind
Term
What defines whether a synapse is excitatory or inhibitory?
Definition
Excitatory synapses depolarize, while inhibitory synapses hyperpolarize
Term
What is spatial summation?
Definition
Summing of simultaneous (or close to simultaneous) EPSPs and IPSPs from multiple synapses at the axon hillock
Term
What is temporal summation?
Definition
Summing of sequential EPSPs (or IPSPs) to create a single larger EPSP (or IPSP) to be sent to the axon hillock
Term
What is the average amplitude of an EPSP or IPSP?
Definition
About 1 mV
Term
What are the two types of neurotransmitter receptors?
Definition
Ionotropic and metabotropic
Term
What is an ionotropic receptor?
Definition
Receptors that are directly associated with the ion channel, faster and short-lasting
Term
What is a metabotropic receptor?
Definition
Receptors that induce changes in the cell membrane that lead secondarily to changes in ion channels, slower and long-lasting
Term
What is the end plate potential?
Definition
Same thing as a EPSP but in a muscle cell, brings muscle to threshold
Term
What is the reversable potential?
Definition
Vrev is the potential in a muscle cell in which the amount of Na+ flowing in and K+ flowing out is equal, Vrev = 1/2 (EK + ENa)
Term
What is the receptor density of a normal muscle at the neuromuscular plate?
Definition
About 10,000 receptors per μm2
Term
What happens to receptor density in denervated and hypersensitive muscle?
Definition
The receptor density spreads out across the entire muscle, and is around 1000-2000 receptors per μm2
Term
What is long-term potentiation and how does it occur?
Definition
LTP makes a neuron more sensitive to inputs as a response to rapid repeated stimulation, it occurs as a result of NMDA receptors responding to higher levels of stimulation
Term
What are trophic effects and how do they occur?
Definition
Trophic effects are long-term effects that do not involve the neurotransmitter, usually occur either by secretion of a substance other than the neurotransmitter, or mediation by the postsynaptic cell
Term
What are the numbers that should be remembered about a typical mammalian muscle cell?
Definition
Vm = -70 mV, EK = -90 mV, ENa = +63 mV
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