Body Compartments And Drug Movement Flashcards
Compartments define:
Location, separated by physical barrier, usually refers to fluids
Cavities define:
Space is that contain organ surrounded by a thin layer of fluid
Pleura
Finley of tissue that covers the lungs and lines, the anterior wall of the chest cavity
Mediastinum
space in your chest that holds your heart and other important structures
Pericardium
Protective fluid filled sac that surrounds your heart and helps it function properly
Peritoneum
Membrane a sheet of smooth tissue that lines, your abdominopelvic cavity and surrounds your abdominal organs
Meninges
Serious membranes that protect the brain and spinal cord
Lumen define:
Channels within hollow organs or tissues, filled with or lined by fluid
Endothelial vs epithelial
Endothelial cells cover the blood vessel in a surface while epithelial cells cover outer surface of the internal organs in the body.
Interstitial fluid define:
Fluid found in the spaces around cells, electrolytes to have leaked out of blood
4 Main barriers
Lumen
Epithelium
Serous membrane
Lipid membrane
Serous membrane define:
Sheet of cells connected by connective tissue That line is your body cavities.
Epithelium classification:
Simple
Stratified ( multiple layers e.g skin is squamous stratified)
Gap junctions can be tight or loose
Simple/stratified epithelium can be either?
Squamous
Cuboidal
Columnar
Paracellular movement
Drugs move between cells
Transcellular movement
Drugs move through cells
Drug molecules move around the body in two ways. How?
Bulk flow
Diffusion
Factors affecting the rate of diffusion
Surface area to volume ratio
Thickness
Concentration gradient
Temperature
Particle size
Lipid solubility is?
Partition coefficient between membrane and aqueous environment
Diffusivity is?
Mobility of molecules within the lipid
Diffusion coefficient - Depends on particle size
Ka
Acid dissociation constant
Smaller the pKa= stronger/weaker acid?
Stronger the acid
PKa value
-10log of Ka
pKa value defined:
Is the hydrogen ion concentration (pH) at which 50% of the drug is ionised and 50% is un-ionised
Ionised vs unionised : which diffuse across the membrane? And why?
Unionised drug = is lipid soluble so diffuses across the membrane
How to trap a drug in body compartment?
Increase ionisation.
Endogenous define:
Natural to the body
Uniporter
Proteins that transport substrates across the cellular membrane by soley using chemical potential of the substrates as their driving force
Antiporter
Transports 2 molecules at the same time in oppose directions
Symporter
Proteins that simultaneously transport 2 molecules across a membrane in the same direction
Organic cation transporters OCTs
Transport drugs that are weak bases
Organic anion transporters OATs
Transport drugs that are weak acids
OCTSs and OATs are examples of what transporters?
SLC carriers
P-gp transporters are examples of what transporters?
Efflux pumps
P- glycoprotein (P-gp) pumps??
Pumps many foreign substances out of cells: reduces drug concentration at treatment target, reducing efficacy
P-gp function can be impaired by?
- drugs that block transporter function (causing drug interactions)
- mutations that change transporter function
Drug transporters in action : In the gut
P-gp stops the body from absorbing some drugs? Protective
Drug transporters in action : In the brain
P-gp and OAT mostly move drugs out of the brain into the bloodstream
Drug transporters in action : In the placenta
P-gp is protecting the fetas from drugs by pumping them into the maternal blood
Drug transporters in action : In the liver
P-gp is the main transporter pumping drugs from the liver into bile for excretion
Drug transporters in action : In the kidney
Anion and cation transporters extract drugs from the blood into the kidney cells. P-gp pump drugs from the cells into urine for excretion
