Home > Flashcards > Print Preview
The flashcards below were created by user
on FreezingBlue Flashcards. What would you like to do?
What is the difference in composition of extracellular fluid versus intracellular fluid in regards to Na+, K+, Ca2+, Cl-, and HCO3-?
- Na+ Extra: 142 mEq/L Intra: 10 mEq/L
- K+ Extra: 4 mEq/L Intra: 140 mEq/L
- Ca2+ Extra: 2.4 mEq/L Intra: 0.0001 mEq/L
- Cl- Extra: 103 mEq/L Intra: 4 mEq/L
- HCO3-Extra: 28 mEq/l Intra: 10mEq/L
Plasma versus Interstital Fluid
The concentration of ions between the blood plasma and the interstitial fluid is the same, except in regards to proteins; there should be no proteins in the interstitial fluids, whereas there will be ~7 g% in the blood plasma
What is Fick’s First Law?
The net rate of diffusion (flux;mmol/sec) is equal to the permeability (cm/sec) times the area (cm6) of the membrane times the concentration difference across the membrane (mmol/ml) divided by the membrane thickness (cm); J=PA (CA-CB)/ΔX
What factors affect permeability?
Lipid solubility, size and shape of diffusing molecule, temperature, and membrane thickness
What does the reflection coefficient (σ) tell you?
If σ = 1, then the solute is completely reflected and is impermeable; if σ = 0, then the solute is not reflected at all and is highly permeable
What is Lidocaine and how does it work?
Blocks voltage-gated Na+ channels and prevents the occurrence of nerve action potentials
Ca2+ channel blockers
Epithelial Sodium Channels (ENaC)
Found in Kidney, lung, and gut; aldosterone increases incorporation of ENaC into renal tubular cell membranes; Amiloride blocks ENaC and causes diuresis
What are uniporters?
Transport proteins; often called this because they transport a single substance down its concentration gradient during facilitated diffusion; has a Vmax
What are the features of carrier-mediated diffusion?
Takes place more rapidly than simple diffusion for that solute; shows saturation kinetics; high degree of chemical specifity; competitive and non-competitive mechanisms can limit binding to the carrier; works in both direction, but always down a concentration gradient; requires binding and conformational change in the carrier protein
What is the difference between primary and secondary active transport?
Primary directly moves molecule with ATP energy (Na+/K+ ATPase), while secondary uses cotransport of molecule moving down a concentration gradient set up by primary active transport
Why is the Na+/K+ ATPase pump so important?
There is a concentration gradient where Na+ is outside the cell and K+ is inside the cell, but this gradient is so great they leak across the cell membrane; the pump keeps this gradient because it is so important to other molecules who get across the membrane via specialized co-transporters
What are some examples of primary active transport and what do they do?
Na+/K+ ATPase pumps Na+ out and K+ in to balance the leak; Ca2+ pump in plasma membrane pumps Ca2+ out of the cell to lower cystolic Ca2+ levels; Ca2+ pump – SR or mitochondria pumps ca2+ into the SR to lower cytosolic Ca2+ levels
How do glycosides control cardiac contractility?
- Via an antiport; inhibit the Na+/K+ ATPase which helps keep cellular Ca2+ low by running the Na+/Ca+ exchanger off the
- Na+ gradient; blocking the Na+/K+ ATPase indirectly decreases the Na+/Ca+ exchanger which increases intracellular Ca2+
What is osmolarity?
Concentration of osmotically active particles; 1mM of NaCl contains 1mM Na+ and 1mM Cl-, and therefore have 2 milliosmoles; 2mOsmoles/liter = 2mOsmolar
What does D5W demonstrate?
5% dextrose in water, is isosmotic but is hypotonic; glucose enters the cell and the water follows the glucose, swelling the cell; saline by contrast is isosmotic and isotonic