Active & Passive Transport Flashcards
total body water (TBW)
extracellular fluid + intracellular fluid
extracellular fluid
interstitial fluid + plasma volume + transcellular fluid
transcellular fluid is _
completely surrounded by epithelial cell (e.g. joint synovial fluid, cerebrospinal fluid)
TBW in males
60% of body weight; usually around 42L
TBW in females
50% of body weight; usually around 35L
intracellular fluid makes up _
60% of total body water (males and females)
extracellular fluid makes up _
40% of total body water (males and females)
interstitial fluid makes up _
75% of ECF
plasma volume makes up _
20% of ECF
transcellular fluid makes up _
5% of ECF
blood volume equation
(PV)/(1-hematocrit)
Na+ in plasma
142mM
K+ in plasma
4.4mM
Ca++ in plasma
2.4mM total
Cl- in plasma
102 mM
Na+ in cell
15mM
K+ in cell
120mM
Ca++ in cell
0.0001mM
Cl- in cell
20mM
protein-free plasma
[ion] is raised because it was originally only in 93% of plasma (plasma is 7% proteins/lipids); so if protein/lipids are removed –> ion concentration will mM/0.93 which will go up
examples of passive transport
facilitated diffusion and simple diffusion
determinants of passive transport
size, charge, and lipid solubility
When is diffusion not random?
when some other force (gravity, pressure, electrical charge) influences the motion
simple diffusion occurs through _
channels/pores or lipid bilayer
pores are _
non-gated; always open
channels are _
gated
channel gates can be open due to
voltage difference across membrane or binding of ligand
facilitated transport requires _
a carrier protein but no energy
glucose used _
a uniporter to achieve facilitated diffusion
glucose transporter expression depends on _
insulin present in blood
GLUT1
in tissues
GLUT2
livers, kidneys, pancreas
GLUT3
tissues
GLUT4
muscle and fat
GLUT5
small intestine
active transport
movement of molecules/ions against their concentration gradient
active transport exhibits _
specificity and saturation
types of active transport
primary and secondary
primary active transport
directly uses ATP to move a molecule against its concentration gradient
secondary active transport
uses the movement of one molecule with its concentration gradient to move another molecule against its concentration gradient (indirectly uses ATP)
examples of primary active transport
Na+K+ pump, Ca++ pump, H+K+ pump, ABC transporters
secondary active transport examples
Na+/glucose co-transport, Na+/amino acid cotransport, Ca++/Na+, H+/Na+
ATP-powered pumps
P, V, C, ABC
P pump
moves only ions
F pump
moves only H+
V pump
moves only H+
ABC pump
moves ions and drugs
ATP binding sites on pumps are on the _ side
cytosolic; ATP is hydrolyzed to ADP and phosphate when ions/molecules are transported
Na+/K+ pump is an example of a _
P-type pump
Na+ is highest _
outside of the cell
K+ is highest _
inside of the cell
Na+/K+ pump
3 Na+ go out and 2 K+ come in
Na+/K+ pump cycle
E1 form of pump has ATP bound and IC gate open –> 3 Na+ bind –> ATP hydrolyzed –> E1 pump is phosphorylated (E1-P) and IC gate is closed –> changes to E2-P, causing EC gate to open –> Na+ exits and K+ binds the E2-P pump –> E2 loses its phosphate, closing the EC gate –> gate is opened intracellularly to release K+
ouabain
binds to E2-P version of pump and blocks the binding of K+
H-K pump is an example of a _
P type pump
H-K pump
found in the gastric glands of the stomach; takes up K+ and extrudes H+
Ca++ pump is an example of a _
P-type pump
ABC1 superfamily
mediates efflux of cholesterol and phospholipids
MDR subfamily
multidrug resistance transporters; found in liver, kidney, and GI tract; extrudes cationic metabolites and drugs
MDR1
pumps-anti cancer drugs out of cancer cells, rendering cells resistant to the drugs
2 major classes of secondary active transporters
cotransporters (symporters) and exchangers (antiporters)
Na+/glucose transporter
Na+ is passively leaking back into the intracellular fluid (high to low) and glucose piggy backs into the intracellular fluid with it (low to high)
Where does the energy to move glucose against its concentration gradient come from?
the Na+ electrochemical gradient maintained by the Na+/K+ pump
