Lectures 3 & 4 JUST Terms Flashcards
Fluid Compartment
2 main fluid compartments:
(1) the EXTRAcellular fluid (ECF) outside the cells &
(2) the INTRAcellular fluid (ICF) within the cells
- the dividing wall b/t ECF & ICF is the cell membrane
- the extracellular fluid subdivides further into PLASMA, the fluid portion of the blood, & INTERSTITIAL FLUID, which surrounds most cells of the body
Extracellular
outside the cells
Intracellular
within the cells
Interstitial
which surrounds most cells of the body
Plasma
the fluid portion of the blood
Butter Sandwich
early model of the cell membrane structure
- a clear layer of lipids sandwiched b/t 2 dark layers of protein
- NOT accurate b/c it implies that it is homogenous
Fluid Mosaic
present day model of the cell membrane structure
- proteins are afloat on a sea of lipid
- membrane composed of phospholipid bilayer with proteins inserted wholly or partially into the bilayer
Glycolipids
molecule that is a combination of carbohydrate & lipid
Phospholipids
diglycerides with phosphate attached to the single carbon that lacks a fatty acid
- a derivative of glycerides
- are amphipathic molecules
- several different varieties: (R-group, saturation)
- polar head groups towards aqueous sides, non-polar fatty acid tails inside
Cholesterol
flat molecule, slips b/t fatty acid tails
- a steroid that serves as the basis for steroid hormones; also a key component of membranes
what it does:
- regulates membrane fluidity
- slows diffusion of molecules across membranes
Sphingolipids
- have fatty acid tails (like phospholipids) but their heads may be either phospholipids or glycolipids
- have longer tails than phopholipids
- tend to aggregate together = lipid rafts
Integral
are permanently attached (tightly bounded) to the cell membrane
- can be polytopic, bitopic, or monotopic
Peripheral
attached to one side of membrane by non-covalent interactions; weak
- associate non-covalently with integral proteins, or polar heads of phospholipids
Lipid-anchored
some of these proteins are covalently bound to lipid tails that insert themselves into the bilayer
Cytoskeletal
not a membrane protein, but often interact with membrane proteins
- flexible skeleton of fibrous proteins throughout the cytoplasm (give physical strength)
Extracellular Matrix
membrane proteins & secreted protein found on the extracellular side of membranes
- forms a “husk” around cells
- highly variable glycosylation
- contribute to physical strength of cells
Lipid Raft
sphingolipids tend to aggregate together = lipid rafts
- rafts also have a high density of cholesterol
- some proteins associate ONLY with lipid rafts, leading to areas of SPECIALIZATION on cell membranes
- for ex: some G-protein coupled receptors
Transmembrane Domain (=membrane spanning domain)
are regions of a protein that are hydrophobic, so that they prefer to be inserted into the cell membrane such that the parts of the protein on either side of the domain are on opposite sides of the membrane. ?
Diffusion/Osmosis
diffusion: process of moving solute molecules away from an area of high concentration towards area of low concentration
osmosis: is the diffusion of water
Protein Mediated Transport
the vast majority of solutes cross membranes with the help of membrane proteins, a process we call mediated transport
Vesicular Transport
the resulting vesicle attaches to microtubules in the cell’s cytoskeleton & is moved across the cell by this process
- don’t go into it in class
Concentration gradient
a difference in the concentration of a substance b/t 2 places
Kinetic Energy
the energy of motion
Electrochemical Gradient
the combined concentration & electrical gradients for an ion
Osmotic Pressure
is the pressure that must be applied to oppose osmosis
Hyperosmotic
if solution A has a higher osmolarity (contains more particles per unit volume, is more concentrated) than solution B, we say that solution A is hyperosmotic to solution B
Hypoosmotic
solution B, with fewer osmoles per unit, is hyposmotic to solution A
Isoosmotic
if 2 solutionss contain the same # of solute particles per unit volume, we say that the solutions are isosmotic
Hypertonic
if the cell loses water & shrinks at equilibrium
Hypotonic
if a cell placed in the solution gains water at equilibrium & swells
Isotonic
if the cell in the solution does not change size at equilibrium
Penetrating Solute
if the solute particles (ions or molecules) can enter the cell
Non-Penetrating Solute
particles that cannot cross the cell membrane
Channel
is a water filled pore
- can open to both sides (directly link intracellular & extracellular compartments)
Pore
both membranes of the envelope are pierced here & there by round holes
Carrier
NEVER form an open channel b/t the 2 sides of the membrane
- bind to the substrate that they carry
Symport
2 molecules are transported across the membrane simultaneously across the cell membrane in the same direction
- type of carrier protein
Antiport
moving more than 1 solute molecule, but is moving them in opposite directions
- using ATP
- type of carrier protein
Uniport
allows a single molecule of glucose to move across a membrane (in 1 direction)
- type of carrier protein
Facilitated Diffusion
is defined as moving a molecule across the cell membrane via a carrier protein, & the transport does not require energy other than the concentration gradient
Primary Active Transport
- uses ATP
- establishes gradients
- sometimes called pumps
- Na+/K+/ATPase is the most widely known ex, but there are others
- Ca2+ ATPase
- H+ ATPase
- H+/K+ ATPase
Secondary Active Transport
- does NOT directly utilize ATP as a source of energy
- instead, uses the concentration gradient of 1 molecule/ion to move another against its gradient (acts as energy source)
- Na+-glucose secondary active transporter is a good ex: SGLT-protein
ATPase
- b/c primary active transport uses ATP as its energy source, many primary active transporters are known as ATPases
- the suffix -ase signifies an enzyme, & the stem (ATP) is the substrate upon which the enzyme is acting
- these enzymes hydrolyze ATP to ADP & inorganic phosphate (Pi), releasing usable energy in the process
Epithelial Transport of Glucose
movement of material from one side of an epithelium to the other
- utilizes:
- facilitated diffusion
- primary active transport
- secondary active transport
Specificity
the ability of an enzyme or receptor to bind to a particular molecule or a group of closely related molecules
Competition
the property of competition is closely related to specificity
- a transporter may move several members of a related group of substrates, but those substrates compete with one another for binding sites on the transporter
- ex:
- GLUT transporter has a “preference” for one or more hexoses, based on its binding affinity
Saturation
all active sites on a given amount of protein are filled with substrate & rxn rate
Affinity
the degree to which a protein is attracted to its ligand
Agonist
a ligand that binds to a protein binding site & ALTERS the state of the protein, resulting in a biological response
- a hormone or neurotransmitter or a drug for example
- can be a drug that mimic a neurotransmitter & in that case consider it an agonist
Antagonist
a ligand that REDUCES the action of an agonist (i.e. binds but causes NO biological response)
- also called inhibitors, blockers
Tight Junction
cell-to-cell junction in epithelia that does not allow much movement of material b/t the cells
Absorption
transfer of substances from the lumen of the kidney or gastrointestinal tract to the extracellular space
Active Transport
is the process of moving molecules across a cellular membrane through the use of cellular energy.
Apical
the edge of the epithelial tissue facing the lumen or the external environment is called the apical surface. ?
Aquaporin
family of membrane water channels
- can aid in moving H20 (a small uncharged polar molecule) across cell membrane
ATP-Gated K+ Channel or KATP Channel
channel that closes when the ATP/ADP ratio increases
Basolateral (membrane/surface)
the sides of transporting epithelial cells that face the extracellular fluid
Blood Plasma
the liquid matrix of blood, is 25% of the ECF volume
Carrier Proteins
membrane protein that binds to the molecule it transports
- NEVER form an open channel b/t the 2 sides of the membrane
Channel Proteins
a membrane protein that forms water-filled channels to link intracellular & extracellular compartments
- a water filled pore - can open to both sides
Chemical Disequilibrium
although the overall concentrations of the ECF & intracellular fluid (ICF) are =, some solutes are more concentrated in one of the 2 body compartments than in the other
- this means the body is in a state of chemical disequilibrium
Chemical Gradient
AKA concentration gradient
- a difference in the concentration of a substance b/t 2 places
Chemically Gated Channels
channels whose open gate is controlled by binding to a chemical ligand
Competitive Inhibitor
molecules that bind to the active site of the enzyme, preventing substrate binding
Concentration Gradient
a difference in the concentration of a substance b/t 2 places
Conductor
when separated positive & negative charges can move freely toward each other, the material through which they move is called a conductor
Cotransporter
a protein that moves more than one kind of molecule at one time
Depolarized
more +
Diffusion
process of moving solute molecules away from an area of HIGH concentration towards are of LOW concentration
- “down the concentration gradient”
- passive (no external energy, just kinetic energy of molecules)
- process continues until equilibrium is reached
Dynamic Steady States
A system that is in a steady state remains constant over time, but that constant state requires continual work. ?
Electrical Disequilibrium
the inside of cells is slightly (-) relative to the ECF
- this ionic imbalance results in a state of electrical disequilibrium
Electrical Gradient
uneven distribution of electrical change, especially across a membrane
Electricity
the rate of flow of negative charges of the conductor. ?
Electrochemical Disequilibrium
N/A
Electrochemical Gradient
the combined concentration & electrical gradients for an ion
Electrodes
a conductor that is used to make contact with a nonmetallic part of a circuit. ?
Electrogenic
producing a change in the electrical potential of a cell. ?
Epithelial Transport
movement of material from one side of an epithelium to the other
- utilizes:
- facilitated diffusion
- primary active transport
- secondary active transport
Extracellular Fluid (ECF)
includes all fluid outside the cells
- the ECF is 1/3 of the body fluid volume
- consists of:
- interstitial fluid (IF)
- plasma
Facilitated Diffusion
is defined as moving a molecule across the cell membrane via a CARRIER PROTEIN, & the transport does NOT require energy other than the concentration gradient
- does NOT require ATP, or other solutes
- also sometimes called passive transport
Fick’s Law of Diffusion
diffusion through a membrane is directly proportional to the surface area & concentration gradient & inversely proportional to the thickness of the membrane & its resistance
Fluids
both gases & liquids are considered fluids b/c they flow
Gated Channels
a channel that opens & closes in response to stimuli
GLUT Transporters
family of facilitated diffusion carriers for glucose & other hexose sugars
Ground (Electrical)
s a reference point in an electrical circuit from which voltages are measured ?
Hexoses
a 6-carbon sugar
Impermeable
not allowing fluid to pass through.
Interstitial Fluid
which lies b/t the circulatory system & the cells, is 75% of the ECF volume
Intracellular Fluid (ICF)
is 2/3 of the total body water volume
- material moving into & out of the ICF must cross the cell membrane
Ion Channels
may be specific for 1 ion or may allow ions of similar size & charge to pass
Leak Channels or Pores
ion channels that spend most of their time in
Lipophobic
molecules that cannot diffuse through the phospholipid bilayer
Mechanically Gated Channels
a channel that opens in response to mechanical stimuli such as pressure & heat
Mediated Transport
movement across a membrane with the aid of a protein transporter
Membrane Enzymes
catalyze chemical reaction that take place either on the cell’s external surface or just inside the cell
Membrane Receptor Proteins
are part of the body’s chemical signaling system
Membrane Transporters
moves molecules across membranes
Molarity (M)
solution concentration expressed as moles of solute per liter of solution
Mole
6.02 x 10^23 atoms, ions, or molecules of a substance
Monovalent
having a valence of one. ?
Mucosal
The moist, inner lining of some organs and body cavities (such as the nose, mouth, lungs, and stomach). ?
Na+-K+-ATPase
- pumps 2 K+ ions into cell, removes 3 Na+ ions
in order to do this:
- hydrolyses ATP
- several conformational changes
Open Channels
channel proteins form an open channel but carrier proteins do NOT
Osmolality
is concentration expressed as osmoles of solute per kg of water
Osmolarity
describes only the # of solute molecules in a cell (units of Osm)
Osmoles
(osmol/L or OsM)
Osmometer
an instrument for measuring osmolarity of a fluid ?
Osmosis
is the diffusion of water
Osmotic Equilibrium
b/c of this free movement of water, the ECF & ICF compartments reach this state
Ouabain
cardiac glycoside that specifically inhibits the Na+-K+-ATPase ?
Paracellular Transport
through the junctions b/t adjacent cells
Passive Transport
AKA facilitated diffusion
- moving a molecule across the cell membrane via a carrier protein, & the transport does not require energy other than the concentration gradient
Permeable
allowing liquids or gases to pass through it.
Pressure Gradient
The difference in hydrostatic pressure on either side of a membrane. ?
Selectively Permeable
cell membranes are selectively permeable, which means that some molecules can cross them but others cannot
Serosal Membrane
membranes lining closed internal body cavities. ?
SGLT (Na+-Glucose Secondary Active Transporter)
uses the potential energy stored in the Na+ concentration gradient to move glucose against its concentration gradient
Simple Diffusion
diffusion across the phospholipid bilayer of a cell
Steady States
a state or condition of a system or process (as one of the energy states of an atom) that does not change in time
Structural Proteins
maintain cell shape, akin to a skeleton, and they compose structural elements in connective tissues like cartilage and bone ?
Tonicity
is a physiological term used to describe a solution & how that solution would affect the cell volume if the cell were placed in the solution & allowed to come to equilibrium
Total Body Water
body water is the water content of an animal body that is contained in the tissues, the blood, the bones and elsewhere. ?
Transepithelial Transport
epithelium whose primary function is the movement of solutes & water b/t 2 compartments
Transport Maximum (Tm)
the maximum transport rate that occurs when all carriers are saturated
Transport Proteins
moves molecules across membranes
Uniport Carriers
a membrane transport protein that moves only one kind of molecule
Voltage-Gated Ca2+ Channel
the route for Ca2+ entry into cells, particularly excitable cells, in response to depolarization. ?
Voltage-Gated Channels
a gated channel that opens or closes in response to a change in membrane potential
Water Channels
most cells have water channels made from a protein called aquaporin
- water channels are an example of channel proteins
