Term
|
Definition
| The more vital a parameter is, the more systems that the body mobilizes to regulate it. |
|
|
Term
| Compare equilibrium to steady state. |
|
Definition
Equil: state that does not involve energy consumption
SS: well-regulated parameter |
|
|
Term
|
Definition
| Study of the homeostatic mechanisms that allow an organism to persist despite the ever-changing pressures imposed by a hostile environment. |
|
|
Term
| What is the PM impermeable and semipermeable to? |
|
Definition
| Impermeable to large molecules such as proteins and NA; selectively perm to small molecules such as ions and metabolites. |
|
|
Term
| What must a cell be able to do if it wants to use a substance? |
|
Definition
| Able to accumulate it against a concentration gradient. |
|
|
Term
| PM is composed of what two main parts? |
|
Definition
|
|
Term
| What do phospholipids all have in common? |
|
Definition
| Glycerol backbone, two hydroxyl groups esterified to various FA or acyl groups. |
|
|
Term
| For glycerol-based phospholipids, what is the third glycerolic hydroxyl group esterified to? |
|
Definition
|
|
Term
| What do the physical characteristics of a lipid bilayer depend on? |
|
Definition
| Chemical composition of its constituent phospholipid molecules. |
|
|
Term
| Compare the sol and gel states. |
|
Definition
| When lateral diffusion can proceed rapidly in a membrane, it is sol state; when phospholipids diffuse slowly because they lack the energy to free themselves, it is gel state. |
|
|
Term
|
Definition
| Temp at which the bilayer membrane converts from the gel to the sol phase and vice versa. |
|
|
Term
| How does one increase or decrease transition temp? |
|
Definition
| Long, saturated FA chains increases; shorter chains with addition of double bonds decreases |
|
|
Term
| What subgroups make up sphingolipids? |
|
Definition
| sphingomyelins, glycosphingolipids and gangliosides |
|
|
Term
| When does cholesterol increase or decrease fluidity of membranes? |
|
Definition
| Increases at high concentrations but decreases at modest concentrations |
|
|
Term
| Why is a pure phospholipid bilayer extremely impermeable to any charged water-soluble substance? |
|
Definition
| Because they are insoluble in the hydrophobic membrane core. |
|
|
Term
| What are the two classes of membrane proteins? |
|
Definition
|
|
Term
| What are the three groups of integral membrane proteins? |
|
Definition
1) transmembrane proteins
2) proteins embedded without crossing it
3) lipid-anchored proteins attached by a covalent bond |
|
|
Term
| What are ways that integral proteins can be directly linked to membrane? |
|
Definition
| with a FA (myristyl gp), prenyl or glycosylphosphatidylinositol (GPI) |
|
|
Term
| What are characteristics of membrane-spanning segments of transmembrane proteins? |
|
Definition
| Composed of nonpolar AA, form alpha helices, can be single or several, can orient with either amino or carboxyl termini facing extracellular face |
|
|
Term
| What impedes the rate of diffusion of transmembrane proteins within the plane of the bilayer? |
|
Definition
| Attachment to cytoskeleton |
|
|
Term
| What do adhesion molecules do? |
|
Definition
| Form physical contacts with surround ECM or w/ cellular neighbors |
|
|
Term
| What do cell matrix adhesion molecules do? |
|
Definition
| Link cells to components of ECM at adhesion plaques, which produce conformational changes in integrin molecules transmitted to cytoplasmic tails. |
|
|
Term
|
Definition
| Glycoproteins with one membrane-spanning segment and large extracellular domain that binds Ca2+. |
|
|
Term
| What comprise the cell-cell adhesion molecules? |
|
Definition
| Ca-dependent cell adhesion molecules (cadherins) and Ca-independent neural cell adhesion molecules (N-CAMs). |
|
|
Term
| What do pores and channels serve as? |
|
Definition
| Conduits that allow water, ions or even very large proteins to flow passively through bilayer. |
|
|
Term
|
Definition
| Facilitate transport of specific molecule across the membrane or couple the transport of a molecule to that of other solutes. |
|
|
Term
|
Definition
| Use energy released through hydrolysis of ATP to drive the transport of substances into or out of cells against energy gradients. |
|
|
Term
| What is structure of amphipathic helices? |
|
Definition
| Hydrophobic AA alternate with hydrophilic residues at regular intervals of approximately 3-4 AA. |
|
|
Term
| Why are ion pumps enzymes? |
|
Definition
| bc they catalyze the hydrolysis of ATP and use energy released to drive ion transport. |
|
|
Term
| Where are integral membrane proteins located that participate in intracellular signaling? |
|
Definition
| Intracellular leaflet of bilayer |
|
|
Term
| Peripheral proteins can associate with the membrane in what two ways? |
|
Definition
| Ionic interactions with phospholipid head groups and direct binding to extracellular or cytoplasmic surfaces of integral membrane proteins |
|
|
Term
| What is the structure of the subcortical cytoskeleton? |
|
Definition
| Long, fibrillar molecule called spectrin, short polymers of cytoskeletal protein actin and ankyrind and band. |
|
|
Term
| What does the subcortical cytoskeleton do? |
|
Definition
| Provides RBC PM with strength and resilience; gives biconcave shape; forms scaffolding of peripheral membrane proteins for direct attachment to transmembrane proteins |
|
|
Term
| What is the major reservoir of Ca ions? |
|
Definition
|
|
Term
| Where are exosomes located? |
|
Definition
|
|
Term
| What is composition of nuclear double membrane? |
|
Definition
| Outer is studded with ribosomes and is continuous with RER; inner is smooth and faces intranuclear space. |
|
|
Term
| How do cytoplasmic proteins enter the nuclear interior? |
|
Definition
| Must be endowed with nuclear localization sequence, which have short stretches of 4-8 basic AA, under control of 2nd messenger systems |
|
|
Term
| What provides the nuclear pore's specificity? |
|
Definition
| nuclear pore complex (NPC), which is intricate matrix of proteins distributed in octagonal array |
|
|
Term
| How are chromosomes arranged? |
|
Definition
| packed densely as heterochromatin and loosely as euchromatin |
|
|
Term
|
Definition
| Organizes chromosomes into chain of rightly folded protein assemblies called nucleosomes |
|
|
Term
|
Definition
| Composed of lamins that provide structural support to nuclear envelope; orchestrates nuclear reassembly |
|
|
Term
| What component of lysosomes allows it it maintain acidic environment? |
|
Definition
| proton pump on its membrane |
|
|
Term
| What are intermediate filaments? |
|
Definition
| Polymers that are assembled from individual protein subunits. |
|
|
Term
| What are microtubules formed from? |
|
Definition
| Heterodimers of proteins alpha and beta tubulin. |
|
|
Term
| Describe function of plus and minus ends of tubules. |
|
Definition
| At plus end, heterodimers are added to growing polymers three times the rate that it occurs on minus end. |
|
|
Term
| What is dynamic instability wrt microtubules? |
|
Definition
| When MTs undergo rapid rounds of growth and shrinkage. |
|
|
Term
| Where do MTs originate from? |
|
Definition
| MTOC or centrosome, which consists of two centrioles |
|
|
Term
|
Definition
| ATPase that converts energy released through ATP hydrolysis into a conformational change that produces a bending motion. |
|
|
Term
| What direction does cytoplasmic dynein move? |
|
Definition
| plus to minus or retrograde direction |
|
|
Term
| How are thin filaments functionally similar to MTs? (2) |
|
Definition
1) Actin polymers are polar and grow at different rates at their two ends
2) Actin binds and then hydrolyzes a nucleotide |
|
|
Term
| What are thick filaments composed of? |
|
Definition
| Myosin, which have helical tails and globular head groups that hydrolyze ATP and act as motors to move along an actin filament |
|
|
Term
| What processes are actin and myosin involved with? |
|
Definition
| cytokinesis, contraction, locomotion, extension of processes |
|
|
Term
| Where do carrier vesicles pinch off and fuse to? |
|
Definition
| Moves from the transitional zone and fuses with Golgi stack. |
|
|
Term
| Describe the secretory pathway. |
|
Definition
| After synthesis in RER, proteins destined for PM move through cis, medial and trans Golgi then appear as secretory vesicles. |
|
|
Term
| Compare constitutive and regulated pathways. |
|
Definition
| First, vesicles fuse spontaneously with PM; in latter, vesicles fuse only when triggered by a signal such as hormone. |
|
|
Term
| What is fluid-phase endocytosis? |
|
Definition
| Uptake of materials that are dissolved in extracellular fluid and not specifically bound to receptors on cell surface. |
|
|
Term
| Describe secretory pathway of vesicles associated w/ clathrin? |
|
Definition
| Clathrin attaches to membrane via adaptin proteins, which adhere to cytoplasmic tail, membrane invaginates to form coated pit, vesicle detaches via membrane fission |
|
|
Term
| Describe receptor-mediated endocytosis. |
|
Definition
| Molecules to be internalized bind to cell surface receptors with high affinity. |
|
|
Term
| How do substrates increase the probability that they will be successfully internalized by cells? |
|
Definition
| Receptors cluster in regions of the membrane destined to be endocytosed. |
|
|
Term
| Where else are proton pumps located (besides lysosomes) to ensure low pH and why? |
|
Definition
| endosomes to separate the material that is destined for lysosomal destruction from those proteins that are to be recycled. |
|
|
Term
| What is iron bound to when it circulates in the plasma? |
|
Definition
|
|
Term
| What is structure of caveolae? |
|
Definition
| Rich in cholesterol and sphingomyelin; contain membrane proteins called caveolin which face the cytosol. |
|
|
Term
| What is the role of caveolae? |
|
Definition
| Transfer of large molecules across endothelial cells, uptake of substances |
|
|
Term
| What two features of epithelia permit them to function as useful barriers? |
|
Definition
1) connect to one another by tight junctions
2) provide boundary between apical and basolateral domain of PM |
|
|
Term
| Are surface membranes of epithelial cells polarized or non-polarized? |
|
Definition
|
|
Term
| Which side do apical membranes of epithelia face? |
|
Definition
| Lumen of a compartment that is continuous with outside world. |
|
|
Term
| Which side do basolateral membranes of epithelia face and rest? |
|
Definition
| extracellular fluid compartment and rest on basement membrane |
|
|
Term
| What is the basement membrane composed of? |
|
Definition
| Extracellular matrix proteins that are secreted by epithelia such as collagens, laminin and proteoglycans. |
|
|
Term
| What is a tight junction? |
|
Definition
| Complex structure that impedes passage of molecules and ions between cells of epithelial monolayer. |
|
|
Term
| What are the roles of tight junctions? |
|
Definition
| Act as barriers; act as selective gates to permit certain solutes to flow more easily; act as fences that separate polarized surfaces of epithelial PM into apical and basolateral domains. |
|
|
Term
| What is an adhering junction? |
|
Definition
| Belt that encircles entire epithelial cell just below level of tight junction. |
|
|
Term
| What is role of adhering junction? |
|
Definition
| Provide clues to epithelia about nature and proximity of neighbors for organizational purposes. |
|
|
Term
|
Definition
| channels that interconnect cytosols of neighboring cells to allow small molecules to diffuse freely |
|
|
Term
|
Definition
| Holds adjacent cells together tightly at a single, round spot. |
|
|
Term
| What is the characteristic morphology of desmosomes in electron micrographs? |
|
Definition
| Dense plaques of intermediate filaments. |
|
|
Term
| What increases the surface area of the apical and basolateral sides? |
|
Definition
| Brush borders and microvilli on apical; basal infoldings and lateral interdigitations on basolateral |
|
|
Term
|
Definition
| substance that is produced in one tissue or organ and released into blood and carried to other organs where it acts to produce specific response |
|
|
Term
| What are three targets that hormones act on? |
|
Definition
1) distant tissues (endocrine)
2) neighboring cell in same tissue (paracrine)
3) same cell that released signaling molecule (autocrine) |
|
|
Term
| What are four types of chemicals that serve as extracellular signaling molecules. |
|
Definition
| amines, peptides and proteins, steroids and small molecules |
|
|
Term
| What does the ability of a cell/tissues to respond to a specific signal depend on? |
|
Definition
| Complement of receptors it possesses and by chain of intracellular reaction that are initiated by binding of any one ligand to its receptor. |
|
|
Term
| What are 4 categories of receptors? |
|
Definition
1) ligand-gated ion channels
2) GPCR
3) catalytic receptors
4) nuclear receptors |
|
|
Term
| What are the 6 steps of signaling events? |
|
Definition
1) recognition of signal by receptor
2) transduction of extracellular message into intracellular signal
3) transmission of second messenger's signal to appropriate effector
4) modulation of effector
5) response of cell to initial stimulus
6) termination of response |
|
|
Term
| How is diarrhea divided by causative factor? |
|
Definition
| Osmotic diarrhea where dietary nutrient is not absorbed properly; secretory diarrhea where endogenous secretions of fluid and electrolytes from intestines |
|
|
Term
| What do secretory diarrhea causes all have in common? |
|
Definition
| Ability to increase cAMP, cGMP and Ca concentrations |
|
|
Term
| What does the constant-field equation tell us? |
|
Definition
| The ionic permeability changes underlying the action potential. |
|
|
Term
| What does conduction of APs allow? |
|
Definition
| Information from sensory organs to be transmitted along afferent nerves leading to brain. |
|
|
Term
| What 3 things does the duration of AP depend on? |
|
Definition
1. the gating and permeability properties of specific types of ion channels
2. intracellular and extracellular concentrations of ions that pass through these channels
3. membrane properties such as capacitance, resistance and geometry of cell |
|
|
Term
| What does the shape of the AP tell you? |
|
Definition
| Specialized functions of cell |
|
|
Term
| What is the shape of the AP subject to? |
|
Definition
| Hormonal modulation in certain cell types. |
|
|
Term
|
Definition
| Part of AP that lies above 0mV |
|
|
Term
| What does depolarization of the membrane above a certain threshold voltage trigger? |
|
Definition
| Spontaneous all-or-none response called AP. |
|
|
Term
| What are some electrophysiological characteristics of ion channels? |
|
Definition
| Selectivity for various ions, voltage dependence, kinetics of gating behavior |
|
|
Term
| What % of body weight is water for a young male and female? |
|
Definition
| 60% for males; 50% for females |
|
|
Term
| What is extracellular fluid consisted of? |
|
Definition
| blood plasma, interstitial fluid and transcellular fluid |
|
|
Term
| What are the cellular elements of blood? |
|
Definition
|
|
Term
|
Definition
| Fraction of blood volume that is occupied by RBCs. |
|
|
Term
| What are the smaller compartments within the interstitial fluid? |
|
Definition
| dense connective tissue and bone matrix |
|
|
Term
| What percent of the total body water is ICF and ECF? |
|
Definition
|
|
Term
| What do capillaries separate? |
|
Definition
| Intravascular and interstitial compartments |
|
|
Term
| Of the ECF, what % is plasma volume, interstitial fluid and transcellular fluid? |
|
Definition
| blood plasma is 20%, interstitial is 75% and transcellular is 5% |
|
|
Term
| What ions is intracellular fluid high and low in? |
|
Definition
|
|
Term
| What ions is extracellular fluid high and low in? |
|
Definition
|
|
Term
| What is the major difference and similarity between plasma and interstitial fluid? |
|
Definition
| Difference is the absence of plasma proteins from the interstitium but ion composition is similar. |
|
|
Term
| Can plasma proteins pass through capillary walls? |
|
Definition
|
|
Term
| How are ions in plasma reported? |
|
Definition
| meq per liter of plasma solution |
|
|
Term
| How are ions in interstitial fluid reported? |
|
Definition
| meq per liter of protein-free plasma solution |
|
|
Term
| What is the charge of plasma proteins and how does this affect presence of other ions? |
|
Definition
| Carry a net negative charge so plasma retains cations thus, cation concentration in interstitium is lower than plasma |
|
|
Term
| All body fluids have approximately the same WHAT? |
|
Definition
| same osmolality and equal numbers of positive and negative charges |
|
|
Term
|
Definition
| Describes total concentration of all particles that are free in a solution. |
|
|
Term
| Is the total solute concentration higher in the intracellular compartment or interstitium? |
|
Definition
|
|
Term
| How does one count in computing osmolality? |
|
Definition
| count each particle once whether it is a free ion, complex of two ions or several ions bound to a protein |
|
|
Term
| What is the principle of bulk electroneutrality? |
|
Definition
| number of pos charges in overall solution must be same as number of neg charges |
|
|
Term
|
Definition
| Difference between ignored cations and anions in blood plasma. |
|
|
Term
| What is the driving force of passive transport of solutes? |
|
Definition
| electrochemical gradient or electrochemical PE difference acting on solute between 2 compartments |
|
|
Term
| What are the two components of the electrochemical PE difference between 2 compartments? |
|
Definition
| Concentration gradient and voltage difference across membrane |
|
|
Term
| What determines the direction of net transport of X? |
|
Definition
| Direction of overall driving force acting on X. |
|
|
Term
| What is unidirectional flux? |
|
Definition
| Mvt of X across the membrane in one direction or other. |
|
|
Term
|
Definition
| Algebraic sum of the two unidirectional fluxes. |
|
|
Term
| When does net transport/net flux occur? |
|
Definition
| Only when unidirectional fluxes are unequal. |
|
|
Term
|
Definition
| When no net driving force is acting on X hence no net transport across membrane |
|
|
Term
|
Definition
| When conditions related to X do not change with time; both driving forces acting on a transport and rate of transport are constant with time. |
|
|
Term
| What is the relationship between equil and SS? |
|
Definition
| equil is a special case of SS. |
|
|
Term
| What is another term for voltage difference (Vm) across the membrane? |
|
Definition
|
|
Term
| What does the Nernst eq describe? |
|
Definition
| the conditions when an ion is in equilibrium across a membrane. |
|
|
Term
| What is another term for equil potential and what does it mean? |
|
Definition
| Nernst potential; value that the membrane voltage would have to have for X to be in equil. |
|
|
Term
| What is the equation expressing the net driving force? |
|
Definition
| Net driving force in volts = (Vm-Ex) |
|
|
Term
| What happens when the net driving force is negative aka when Vm is more negative than Ex? |
|
Definition
| Cations will enter the cell and anions will exit. |
|
|
Term
| What does flux (Jx) describe? |
|
Definition
| How fast X moves; the number of moles of X crossing a unit area of membrane per unit time. |
|
|
Term
| What three factors make up the permeability coefficient of X (Px)? |
|
Definition
| partition coefficient, diffusion coefficient and membrane thickness |
|
|
Term
| What will make the flux greater? |
|
Definition
| A greater difference in [X] between the two sides of the membrane. |
|
|
Term
| What parts can the net flux separate into? |
|
Definition
| unidirectional influx and unidirectional efflux |
|
|
Term
| What does Fick's Law describe? |
|
Definition
| Concepts governing the simple diffusion of an electrically neutral substance. |
|
|
Term
| What is unidirectional influx proportional to? |
|
Definition
|
|
Term
| What is unidirectional efflux proportional to? |
|
Definition
|
|
Term
| What is net flux proportion to? |
|
Definition
|
|
Term
| What are the three types of protein pathways through the membrane? |
|
Definition
| Pore, channel and carrier |
|
|
Term
| Describe characteristics of a pore. |
|
Definition
|
|
Term
| Describe characteristics of a channel? |
|
Definition
| Alternately open and closed (gating) because it has movable barrier or gate, ie all ion channels |
|
|
Term
| Describe the characteristics of a carrier. |
|
Definition
| Equipped with at least two gates that are never open at the same time. There is one or more binding sites for the solute; if both gates are closed, something is occluded in the compartment. |
|
|
Term
| What are large sized pores and what do they do? |
|
Definition
| porins, which allow very large solutes to diffuse passively from the cytosol |
|
|
Term
|
Definition
| Perforin monomers polymerize within the target cell membrane and assemble like staves of a barrel to form large channels; passive flow of molecules occurs |
|
|
Term
| What is a complement cascade? |
|
Definition
| Cascade of reactions that results in formation of doughnut-like structure |
|
|
Term
| What is nuclear pore complex (NPC)? |
|
Definition
| regulates traffic into and out of nucleus, very large, made of 30 different proteins, involves ATP hydrolysis |
|
|
Term
|
Definition
| Proteins that form channels on PM large enough to allow water molecules to pass through; contains membrane-spanning helices and requires single-file diffusion of water |
|
|
Term
| What are the functional components of gated ion channels? |
|
Definition
| A gate that determines whether channel is open or closed; sensors that respond to several different signal types (1. changes in memb voltage and 2. second messenger system and 3. ligands that bind to extracellular face); selectivity filter, which determines classes of ions that have access to channel pore; open-channel pore that provides continuous pathway between two sides of membrane for passive flow |
|
|
Term
| What causes the Na and K gradient on the cell membrane? |
|
Definition
| Active extrusion of Na from the cell and active uptake of K into the cell by the Na/K pump. |
|
|
Term
| How does the Na-K pump generate an inside-negative memb voltage (60mV)? |
|
Definition
| First, pump is electrogenic because it transports 3 Na out for ever 2 K in. Second, active K accumulation by the Na-K pump creates a concentration gradient that favors the exit of K. |
|
|
Term
| What is the MAIN cause of the inside-negative membrane voltage? |
|
Definition
| Tendency of K to exit through K channels with unmatched neg charges left behind |
|
|
Term
| What causes Na to enter the cell passively? |
|
Definition
| Inside-negative Vm with large concentration gradient for Na |
|
|
Term
| Energy of Na entry is used for what three purposes? |
|
Definition
1) transepithelial transport
2) excitable cells use it to generate AP
3) all cells use it to drive secondary active transport of nutrients and ions |
|
|
Term
| What keeps the intracellular Ca levels 4 orders of magnitude lower than extracellular Ca? |
|
Definition
| Ca pump and Na-Ca exchanger |
|
|
Term
| What do Ca pumps in organelles do? |
|
Definition
| Sequester cytosolic Ca in intracellular stores. |
|
|
Term
| How do Ca pumps on the PM extrude Ca? |
|
Definition
| When [Ca]i increases, it binds to calmodulin; this complex binds to the Ca pump which stimulates Ca extrusion. |
|
|
Term
| In most cells, why is [Cl] above equilibrium? |
|
Definition
| Because Cl uptake by the Cl-HCO3 exchanger and Na/K/Cl Cotransporter balances passive Cl efflux through channels |
|
|
Term
| What PM proteins are responsible for keeping intracellular pH and [HCO3] above their equilibrium values? |
|
Definition
| Na-H exchanger and Na-driven HCO3 transporters |
|
|
Term
| Is the transport of water across biological membranes ALWAYS passive? |
|
Definition
|
|
Term
| What are the two passive driving forces for water? |
|
Definition
| chemical potential energy difference from the difference in water concentration on two sides of the membrane and energy difference that results from the difference in hydrostatic pressure across the membrane |
|
|
Term
| Define osmolality and what are its units? |
|
Definition
| Concentration of osmotically active solutes; osmoles per kg H20 |
|
|
Term
| What is the osmotic pressure difference equal to at equilibrium? |
|
Definition
| Hydrostatic pressure difference. |
|
|
Term
| What is the hydrostatic pressure difference across a cell membrane? |
|
Definition
| Zero thus, it is not an active driving force for water transport. |
|
|
Term
| When is water at equilibrium across cell membranes? |
|
Definition
| When osmolality inside and outside the cell are the same. |
|
|
Term
| What is the driving force for driving fluid out across the walls of capillaries? |
|
Definition
| hydrostatic pressure difference |
|
|
Term
|
Definition
| Presence of a greater concentration of plasma proteins in the intravascular compartment than in interstitial fluid that sets up a difference in osmotic pressure, which pulls fluid back into the capillary. |
|
|
Term
|
Definition
| Movement of water out of capillary due to hydrostatic pressure difference exceeding the oncotic pressure. |
|
|
Term
| How can a cell prevent bursting from the negative charge on impermeant intracellular solutes (Gibbs-Donnan)? |
|
Definition
| Cell can do "osmotic work" to counteract the passive Donnan-like swelling. |
|
|
Term
| What is regulatory volume increase (RVI)? |
|
Definition
| When cells respond to shrinkage by activating solute uptake processes to increase cell solute and water content. |
|
|
Term
| What is regulatory volume decrease (RVD)? |
|
Definition
| When cell types respond to swelling by activating solute efflux pathways to decrease cell solute and water content. |
|
|
Term
| How do cells respond to long-term hyperosmolality? |
|
Definition
| By accumulating new intracellular organic solutes. |
|
|
Term
| What determines the osmotic flow of water across a cell membrane? |
|
Definition
| the gradient in tonicity aka effective osmolality |
|
|
Term
| Compare isosmolal and isotonic. |
|
Definition
| Isosmolal is when the osmolality of a solution is what is considered to be normal for that solution while isotonic is when two different solutions across a well-defined membrane have the same osmolality. |
|
|
Term
| What do shifts of water between the intracellular and interstitial compartments result from? |
|
Definition
| Alterations in effective ECF osmolality aka tonicity. |
|
|
Term
| What direction does oncotic pressure difference pull water? |
|
Definition
| From interstitium to the plasma. |
|
|
Term
| What direction does the hydrostatic pressure difference pull water? |
|
Definition
| From plasma into interstitium |
|
|
Term
| Define effective circulating volume. |
|
Definition
| Blood volume that is necessary to achieve adequate perfusion of key organs. |
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Term
| How can one measure how tightly an epithelium separates one compartment from another? |
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Definition
| Resistance to the flow of electrical current |
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Term
| What are the two distinct pathways by which substances cross epithelia? |
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Definition
1) transcellular, substance sequentially passes across apical and basolater memb
2) paracellular, substance bypasses cell and crosses epithelium |
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Term
| What are the 3 properties of ion transfer that all epithelia share? |
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Definition
1) Na-K pump is located exclusively on basolateral membrane
2) most of K taken up by Na-K pump recycles across basolateral memb through K channels
3) Na is much lower in an epithelial cell than in the ECF |
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Term
| How can epithelial cells absorb or secrete different solutes? |
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Definition
| By inserting specific channels or transporters at either the apical or basolateral memb |
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Term
| Define membrane potential (Vm) aka voltage difference across the cell membrane. |
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Definition
| Difference between electrical potential in the cytoplasm and electrical potential in extracellular space |
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Term
| What do cell membrane potentials depend on? |
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Definition
| ionic concentration gradients |
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Term
| What does the Nernst eq predict? |
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Definition
| the equilibrium membrane potential for any concentration gradient of a particular ion across a membrane |
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Term
| What is the Nernst-Planck electrodiffusion theory? |
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Definition
| Predicts how Vm will respond to changes in ion concentration gradients or membrane permeability. |
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Term
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Definition
| V=IR; the voltage and current are directly related to each other by the resistance |
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Term
| Given Ohm's Law, what pathway will ions with higher permeability or conductance move through? |
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Definition
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Term
| Given Ohm's law, what pathway will ions w/ low permeability or conductance move through? |
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Definition
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