Biophysics flashcards, diagrams and study guides
Study Biophysics sets on Quizlet for free. Learn what you need to get good grades in your classes. Memorize important Biophysics terms, definitions and concepts. Prepare for homework and exams with Quizlet’s free online flashcards, diagrams, study guides and practice tests. Discover Biophysics and other Biology sets on Quizlet.
Top 20 sets of about 15,340
used to study action potentials bc APs too fast for a voltmeter (100x faster than blinking)
Rapid depolarization (becomes positive) of the membrane. Continues until Vm reaches ~40 mV. Na in & K out
Inside of the neuron is positively charged compared to the outside. (0mV)
The resting membrane potential is the baseline potential that can be recorded across the plasma membrane of an excitable cell prior to excitation.
Leak channels for Na+ and K+ are ubiquitous, and they allow for the diffusion of these ions across plasma membranes.
The inside surface of the plasma membrane accumulates more negative charge because of the presence of Na+ and K+ gradients and the selective permeability of the membrane to Na+ and K+.
Gradient of electrical potential energy across a cell membrane.
Since the extracellular conectration of K is very important in determining the resting membrane potential and the rate at which K diffuses out of cells, changes in the concentration of this ion can have drastic consequences.
By placing an intracelluar electrode inside the cell and an extracellular electod in the ECF. A voltmeter could then mearuse the potental difference across the cell membrane. outside the cell is considered OmV inside of a cell at rest is always neg relative to the outside so the cell memrbane potential is a neg number.
the neuron that delivers a signal to the synapse is known as the presynaptic cell, and the cell that receives the signal is called the postsynaptic cell (Fig. 8.2f). The narrow space between two cells is called the synaptic cleft
C. Myelin sheath ( layer of Schwann cells wrapped around a neuron)
A (they are propagated down the length of the axon)
E (Active pumping moves ions against their chemical concentration gradients and the Nernst equation describes how membrane potentials can yield electrical gradients to motivate ion movement.)
Whenever there is permeability for an ion, there is constant movement of ions in both directions...but at equilibrium, there is no net movement of ions
K+ is higher inside the cell Cl- is higher outside the cell Na+is higher outside cell? CA2+ is higher outside the cell
K+ and proteins want to flow out Na+ and Cl- want to flow in
-membrane potential of neuron not sending signals -70mV
-if reached, action potential (massive depolarization) is generated at axon hillock
-changes in membrane potential -always reaches same number -all or nothing
A rapid change in the membrane potential depolarization followed by a return to the resting membrane potential.
Basis of signal transmission of excitable cells (nerve, muscle) and Initiation of muscle contraction
vary in size and shape between cells.
- only K+ permeable through membrane - negative membrane potential (-80 mV)
causes Na + channels to open
- Na+ channels close - inside of neuron is positively charged & outside of neuron is negatively charged
open/close in response to stimuli and alters the membrane's permeability to particular ions which allow a rapid flow of ions across the membrane, altering the membrane potential
Channels that open or close in response to a change in the membrane potential
increase in the magnitude of the membrane potential, makes inside of membrane more negative Ex. K+ channel opens which increases permeability to K+
gated - transition from open to closed states by changing their 3D configuration.; selective - Only certain ions permitted to pass. Selectivity arises from: • chemical properties (mainly charge state and distribution) of amino acid sequences lining the pore. • diameter of the pore when open. Passive - movement through open channels does not directly expend energy.;
Ion channels can be gated open in a number of ways: Random: open or close randomly, leakage channels Voltage gated: open or close depending on membrane voltage. Chemical/ligand gated: open or close by binding with a "ligand" often referred to as a "messenger" (extracellular messenger: "neurotransmitter"; intracellular messenger: "second messenger") Chemical AND voltage-gated: opened by binding transmitter only when membrane voltage is favorable Mechanical-gated ("stretch" channels): opened by membrane deformation.
a - outside b - outside c - inside d - outside
a phenomenon of excitable cells, such as nerve and muscle, and consists of a rapid depolarization (upstroke) followed by repolarization of the membrane potential. Action potentials are the basic mechanism for transmission of information in the nervous system and in all types of muscle.
process of making the membrane potential less negative. As noted, the usual resting membrane potential of excitable cells is oriented with the cell interior negative. Depolarization makes the interior of the cell less negative, or it may even cause the cell interior to become positive.
process of making the membrane potential more negative.
Makes up the cell membrane; Cluster so that their hydrophilic heads make up the inside and outside lining of the membrane, and their hydrophobic tails create the middle of the membrane
The cell membrane is very thin, and this makes it a great...
What is the role of proteins in the cell membrane?
differences in K+ and Na+ concentrations inside and outside cells differences in permeability of the plasma membrane to ions
is higher outside the cell
is higher inside the cell
corresponds to the period of repolarization of the neuron
process by which the resting potential is decreased as sodium ions move into the axon
state of unstimulated neurons membrane
Mechanically gated ion channels, Chemically gated ion channels, and Voltage-gated ion channels
current flow is directly proportional to the electrical potential difference between two points and inversely proportional to the resistance of the system to current flow. in other words, as resistance increases, current flow decreases.
a force that opposes flow
A separation of charge across a cell membrane (Em) (units Volts - V)
The difference in charge between the inside and outside of a cell at rest
A change in the membrane potential so that it is closer to zero