Lecture 2:
-physiology-= study of chemical and physical functions present in a living system
-mass balance= everything must be constant, for every gain, must be a loss
-gain= consumption and production
-loss= metabolic activity: catabolism (break down) & anabolism (make up)
3 compartments/homeostasis:
-intracellular fluid= fluid inside cells
-extracellular fluid= fluid outside of cells
-interstitial= fluid surrounding cells
-plasma= fluid portion of blood
–homeostasis= stability of body’s internal environment
-osmotic equilibrium= total amount of solute per volume of fluid
-chemical disequilibrium= solutes more concentrated than other
–bodies electrically neutral, due to ionic imbalances they’re in electrical disequilibrium
-dynamic state= moving back and forth between 2 compartments
-steady state=there is no net movement or change
Plasma membrane:
-physical isolation= barrier between components inside the cell and environment
-regulation= entry of nutrients & ions, removal of waste, and release of cellular products
-communication= monitor changes & respond to signals
-structural support= cytoskeleton to maintain cell shape, junctions between cell and
extracellular matrix which stabilizes cells in tissues
Fluid Mosaic Model:
-lipids and proteins, more metabolic activity=more proteins
-phospholipids arranged in bilayer: hydrophilic heads face aqueous side & hydrophobic tails
hidden in center of membrane
3 types of lipids in plasma membranes:
-phospholipids=arranged to exclude water from hydrophobic regions
-polar phosphate/glycerol head (hydrophilic)
-nonpolar fatty acid tail (hydrophobic)
-sphingolipids=fatty acid tail attached to sphingosine
-cholesterol=stiffening membrane, hydrophobic
-plasma membrane impermeable to H2O soluble molecules
-improves membrane flexibility over wide temperature ranges
Membrane proteins:
-peripheral= loosely attached to integral proteins
-enzymes, structural binding proteins
-integral/transmembrane= extend across membrane
-hydrophobic segments
-cytoskeletal proteins make them immobile
-lipid-anchored= covalently bound to fatty acid tails & inserted in bilayer
-associated sphingolipids forming lipid rafts
-sometimes considered integral protein
-ligand binding receptors=vesicular transport, receive & respond to chemical messages,
hydrophobic
-structural proteins= cells form physical contact with its environment
Transport proteins:
-channel proteins= water filled passages (pores & channels)
-carrier proteins= bind to substrates & carry them from one side of membrane to next
-carriers= facilitate movement of molecule across membrane down concentration grad
-pumps=energy from hydrolysis of ATP to move solutes into/out of cell
-intracellular signaling= relay signals received at cell surface, ex) G proteins, kinases
-enzymes= catalyze reactions on inner side of plasma membrane
-submembranous c.s.= integral & peripheral proteins, organize plasma mem into diff domains
Membrane permeability:
-highly soluble= uncharged O2/CO2 & nonpolar (fatty acids)
-not soluble= charged Na/K & polar (glucose)
-passive= no ATP needed for movement
-active= ATP needed for movement
Membrane transport:
-diffusion= high to low concentration, passive
-faster at higher concentration grad., shorter distances, higher temperatures, smaller
molecules.
–fick’s law of diffusion= magnitude of concentration gradient, permeability of membrane
to substance, surface area, & thickness of membrane
Pores/channels/carriers:
-pores=always open, no gate
-channels= a gate that exists in opened or closed state
-open= leak channels, water pores
-closed= gated channels, regulate movement of ions through them
-chemically gated= intra message or extra ligand
-voltage gated= electrical state
– mechanically gated= physical forces
-carriers= bind to substrates and carry them across membrane by changing shape
-carrier mediated transport= what kind and amount of material to be transported
-specificity= each carrier protein specific to molecule its supposed to transport
-competition= carrier can bind more than one substance, rate of transport dependent
on presence of number of molecules
-saturation= limited number of carrier binding sites
Active transport:
-primary= energy in form of ATP
-secondary= potential energy stored in concentration grad to push other molecules against
concentration gradient
-Na/K pump= Na out & K into cell
-regulates cell volume by controlling solute
-potential energy stored serve as energy for cotransport of glucose & amino acids
-secondary active transport= indirectly used to facilitate transportation of substance against
concentration grad.
-cotransporters= solutes move in same direction
-exchangers= antiporters, opposite direction
Lecture 3:
-secretory pathway= soluble, secretable proteins and transmembrane made in RER
-soluble= organelles/vesicles, membrane= in membrane
-constitutive= made continuously & secreted in unregulated fashion
-regulated= made continuously, regulatory control
Vesicular transport:
-large macromolecules & particles too big to enter or leave cells through protein
channels/carriers
-clathrin= release from receptors
-coatamers= coat proteins, help form round shape
–SNARE= promote docking, “attracted to”
-SNAPS= dissemble SNARE after fusion, energy dependent
-endocytosis= intake
-fluid phase= cell drinking
-receptor mediated= high concentration of coat proteins, receptor ligand interaction,
transports hormones, growth factors, & binding proteins into cell
-calveolae= capillaries, internalize small molecules, transfer of macromolecules across
capillary epithelium
-phagocytosis= intake
-cell eating, ATP requires to move cytoskeletal elements & intracellular transport
Osmosis:
-H2O across concentration gradient
-permeable to H2O and solute= diffuse across membrane & equilibrate
-permeable to H2O and not solute= H2O diffuses to higher solute concentration until
hydrostatic pressure blocks flow
-osmolarity=number of particles in a given volume of solution
Na/K pump:
-ouabain & Na-K inhibition, passive leakage disrupts osmotic equi. Water goes in, cell swells
-shrinking= increase in extracel. osmolality, water leaves/shrinks cell. Ions&water enter, normal
-swelling= decrease in extracellular osmolality, water enters/swells, ions & water leave, normal
Tonicity:
-hypertonic= water moves out
-hypotonic= water moves in
Epithelial transport:
-absorption= moving material from lumen
-secretion= moving material into lumen
-paracellular (adjacent cells) or transcellular (through)
Cell to cell communication:
-electrical= changes in cells membrane potential
-chemical=molecules secreted into ECF
-4 basic methods of cell to cell communication: gap junctions, contact dependent signaling,
local signaling, long distance signaling
-gap junctions=cytoplasmic bridge between cells, small molecules including ions, ATP, amino
acids, and chemical messages to be passed freely b/w connected cells
-contact dependent= adjacent cells to communicate (direct), CAMs act as receptors
-local signaling= external environment
-autocrine= cell releases factor on same cell
