Details Title: 111A Lecture 1 Description: January 5, 09 Total Flash Cards: 38 Created: 01/11/2009 20:08:06		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Physiology Flashcards
Cards in this set: Term The membrane is a highly selective filter that... Definition 1. maintains unequal concentrations of ions 2. allows nutrients to enter and waste the cell Term What does a membrane consist of? Definition 1. phosholipid bilayer 2. proteins Term What are the three different classes of phospholipids? Definition 1. phosphoglycerides 2. sphingolipids 3. sterols Term What is a phosphoglyceride? Definition Amphipatic (polar head, apolar tail) molecule with a glyceride backbone Term What is a sphingolipid? Definition Amphipatic molecule with a sphingosine backbone Term What is a sterol Definition Nonpolar molecule Term What is our phospholipid bilayer referred to as? Definition Singer-Nicolson Fluid Mosaic Model Term What is the purpose of having proteins in the membrane? Definition To allow the passage of ions since the membrane is impermeable to them Term What are some functions of proteins? Definition 1. enzymes 2. receptors for hormones 3. passive channels/pores 4. pumps for active transport 5. carriers for passive transport 6. recognition of molecules Term What are the two main functions of the membrane? Definition 1. To control solute concentrations 2. To store energy to do work Term How does the membrane set up a membrane potential? Definition 1. By establishing a concentration (electrochemical) gradient using chemical energy 2. By establishing charge separation using electrical energy Term What is permeation? Definition The passive diffusion of solutes across a barrier Term What is Fick's Law of Diffusion? Definition dS/dt=Px(C1-C2) Term What does Fick's Law tell us? Definition That the amount of a substance crossing a unit area per time is equal to the product of the permeability constant and the change in concentration across the membrane Term Does every cell carry a membrane potential? Definition Yes, but only excitable cells can modify it Term What is the permeability constant (Px)? Definition Depends on how soluble a solute is in the membrane Term How does the permeability constant apply to nonpolar substances? Definition Nonpolar substances have a higher permeability constant therefore they are more permeable Term What is the equation for permeability? Definition Px=(DK)/a where D is the diffusion coefficient, K is the partition coefficient, and a is the membrane thickness (usually ~70A Term What does the partition coefficient mean? Definition It is the ratio of the concentration of a solute in oil and water (oil:water), thus the higher the K the more soluble it is in oil and the more nonpolar it is Term What does the diffusion coefficient say? Definition As viscosity and molecular size increase, D decreases Term Who was Santiago Ramon Y Cajal? Definition Spanish neuroscientist who discovered that the nervous system is made up of neurons, discrete signaling elements ("Neuron Doctrine") Term Who was Camillo Golgi? Definition Italian neuroscientist who discovered histological staining techniques by impregnating the cell with silver grains Term How much charge can a capacitor store? Definition C=EA/d where E is the dielectric constant, A is the area of the plates, and d is the distance between the plates Term What does a capacitor do? Definition Although DC current cannot flow through a capacitor, it can store charge and such charge buildup can push charges to circulate Term How does capacitance relate to the plasma membrane? Definition The plasma membrane is like a capacitor because it can store charge and channels could be seen as resistors Term What kind of channels are there? Definition 1. Open (leakage) channels 2. Gated channels (voltage gated, ligand gated, mechanosensory) Term What is meant by active transport? Definition Requires ATP (energy) to sustain pumps that will maintain the voltage inside (eg: Na/K ATPase pumps 2K in and 3Na out) Term What could block the active transport mechanism of the pumps? Definition Cardiac glycosides (eg: those found in some toad poisons) Term How is a membrane potential measured? Definition As the difference in voltage across the membrane; the potential of the inside relative to the outside (~70mV) Term At resting potential what is the state of the K and Na ions? Definition There is more K in than out and more Na out than in Term What does the Nernst equation say? Definition At equilibrium, the chemical force of an ion equals its electrical force Term What is the equation for the chemical force? Definition Fc=RTln([Kout]/[Kin]) Term What is the equation for electrical force? Definition Fe=zFV Term What are the equilibrium potentials for a cell only permeable to K or Na, respectively? Definition K: -90mV, Na: +63mV Term What is the relationship between resting potential and temperature? Definition RP is directly proportional to temperature Term What did Baker, Hodgkin, and Shaw discover in 1961? Definition When they switch the axoplasm of a squid giant axon with its extracellular fluid, the voltage across the membrane reversed to ~+90mV Term How much capacitance is usually found across a membrane per square cm? Definition 1 microF (10^-6) per square cm Term What is the Goldman equation (Constant-Field equation)? Definition It takes into account the permeability of the membrane to more than one (monovalent) ion (an expansion of the Nernst equation