Cell Membrane, Membrane Transport, and Membrane Potential 4 Flashcards
How of the body is water?
60% of body weight in kg
What percentage of the body’s weight in kg is in the extracellular fluid?
20%
-5% blood plasma
-15% interstitial fluid
What percentage of the body’s weight in kg is in the interstitial fluid?
40%
What is the osmolarity difference between the extracellular and intercellular space?
none
-the osmolarity is equal inside the cells and outside of the cells most of the time
300 Osm
What is active transport?
the movement of something across the cell membrane the requires the input of energy
What are the two types of active transport?
- active transport with membrane proteins
- bulk (vesicular) transport
What are active transporter?
transmembrane proteins that move ions and hydrophilic building blocks across the plasma membrane against the concentration gradient
What are active transporters classified by?
- number of substances being transported
- direction substances are being transported
- source of energy for transport
What are active transporters that only move one substance across the membrane?
uniporter
What are active transporters that move more than one substance in the same direction across the membrane?
symporter
What are active transporters that move more than one substance in opposite directions across the membrane?
antiporter
What is primary active transport?
when the energy needed to move the substance against the concentration gradient comes directly from the breakdown of ATP
What is secondary active transport?
when the energy needed to move substance against the concentration gradient comes from one substance moving down its gradient is used to move a second substance against its concentration gradient
What is an example of a primary active transporter?
ATPase pumps
(Na-K pump)
What are the functions of the Na-K pump?
-maintain Na and K concentration differences
-establish negative membrane potential
How does the Na-K pump create a negative membrane potential?
3 positive sodiums are leaving the cell for every 2 positive K entering the cell
-more positive leaving than entering
What is an example of a symporter?
Na/Glucose symporter
-Na move down gradient
-glucose move against gradient
What is an example of an antiporter?
Na/Ca exchanger
-Na move down gradient
-Ca move against gradient
What is vesicular transport?
move large substances across the plasma membrane
What are characteristics of vesicular transport?
-gradient independent
-requires energy
What is Endocytosis?
process of bringing something large into the cell
-forms vesicle
-removes a part of the cell membrane
What is exocytosis?
process of bringing something large out of the cell
-vesicles fuse to membrane
-adds membrane to the plasma membraneH
How does vesicular transport alter the plasma membrane?
endocytosis removes a portion of the membrane
-could remove receptors, proteins, sugars, and many other
exocytosis add to the membrane
-could bring receptors, fats, steroids
What is pinocytosis?
form of endocytosis
-nonspecific drinking
-nonspecific substances brought into the cell
What is phagocytosis?
endocytosis that only phagocytes do
-foreign substance brought into the cell
-part of the immune system
What is receptor mediated endocytosis?
happens in all cells all the time
-ligands bind to specific receptors and specific substances brought into the cell
What separates the plasma and interstitial fluid?
capillary wall
