TRANSPORT MECHANISMS Flashcards
______
- random molecular movement of substances molecule by molecule, either through intermolecular spaces in the membrane or in combination with a carrier protein
Diffusion
______
- utilizes energy of the normal kinetic motion of matter
Diffusion
______
- movement of ions or other substances across the membrane in combination with a carrier protein
Active transport
______
- the carrier protein causes the substance to move against an energy gradient (low-concentration to a high concentration state)
Active Transport
______
- requires an additional source of energy besides kinetic energy.
Active transport
Types of Diffusion:
Simple Diffusion
Facilitated Diffusion
______ diffusion
- kinetic movement of molecules or ions occurs through a membrane opening or through intermolecular spaces without interaction with carrier proteins in the membrane
Simple
Simple diffusion
- rate of diffusion is determined by:
• amount of substance available
• velocity of kinetic motion
• number & sizes of openings in the membrane through which the molecules or ions can move
______ diffusion can occur
• through the interstices of the lipid bilayer if the diffusing substance is lipid soluble
Simple
______ diffusion can occur
• through watery channels that penetrate all the way through some of the large transport proteins
Simple
______ diffusion
• requires interaction of a carrier protein that aids passage of molecules or ions through the membrane by binding chemically with them and shuttling them through the membrane
Facilitated
______ diffusion
• “carrier mediated diffusion”
Facilitated
______ diffusion
• a substance transported in this manner diffuses through the membrane with the help of a specific carrier protein
Facilitated
______ diffusion
• the carrier facilitates diffusion of the substance to the other side
Facilitated
______ of Substances Through Membranes
• a cell membrane moves molecules or ions uphill against a concentration gradient (or uphill against an electrical or pressure gradient)
Active Transport
______ of Substances Through Membranes
• sodium, potassium, calcium, iron, hydrogen, chloride, iodide, and urate ions, several different sugars, and most of the amino acids.
Active Transport
Active Transport
types according to the source of the energy used to facilitate the transport:
Primary active transport
Secondary active transport
______ active transport
• energy is derived directly from the breakdown of adenosine triphosphate (ATP) or some other high-energy phosphate compound
Primary
______ active transport
• energy is derived secondarily from energy that has been stored in the form of ionic concentration differences of secondary molecular or ionic substances between the two sides of a cell membrane, created originally by primary active transport
Secondary
______
• transport depends on carrier proteins that penetrate through the cell membrane
Active Transport
______
• the carrier protein functions differently from the carrier in facilitated diffusion because it is capable of imparting energy to the transported substance to move it against the electrochemical gradient
Active Transport
Primary active transport
______ Pump
• transports Na ions out of Cells and K ions into cells
Sodium-Potassium
Primary active transport
______ pump
• pumps sodium ions outward through the cell membrane of all cells and pumps potassium ions from the outside to the inside
Na+-K+
Primary active transport
______ Pump
• responsible for maintaining the sodium and potassium concentration differences across the cell membrane and establishing a negative electrical voltage inside the cells.
Sodium-Potassium
Primary active transport
______ pump
• Calcium ions are maintained mainly by two primary active transport calcium pumps
Calcium
Primary active transport
______ Pump in the cell membrane
• pumps calcium to the outside of the cell
Calcium
Primary active transport
______ pump
• the other pumps calcium ions into one or more of the intracellular vesicular organelles of the cell, such as the sarcoplasmic reticulum of muscle cells and the mitochondria in all cells
Calcium
Primary active transport
______ pump
• the carrier protein penetrates the membrane and functions as an enzyme ______ which has a specific binding site for calcium
Calcium, ATPase
______ Active Transport of Hydrogen Ions
- ______ glands of the stomach
- Deep-lying ______ cells
• most potent primary active mechanism for transporting hydrogen ions in the body
• basis for secreting ______ in stomach digestive secretions.
Primary, Gastric, parietal, hydrochloric acid
______ Active Transport of Hydrogen Ions
• Late distal tubules and cortical collecting ducts of the ______
• special ______ cells transport hydrogen ions by primary active transport
Primary, kidneys, intercalated
______ active transport
______
• when sodium ions are transported out of cells by primary active transport, a large concentration gradient of ______ across the cell membrane usually develops
• this gradient represents a ______ of energy, because the excess sodium outside the cell membrane is always attempting to diffuse to the interior
• this diffusion energy of sodium can pull other substances along with the sodium through the cell membrane.
Secondary, Co-Transport, sodium ions, storehouse
______ active transport
______ of Glucose along with Sodium lons •transport carrier protein has two binding sites on its exterior side, one for ______ and one for ______
• the concentration of sodium lons is ______ on the outside and ______ on the inside, which provides energy for the transport
• a conformational change in the transport protein to allow sodium movement to the interior will not occur until a glucose molecule also attaches.
Secondary, Co-Transport, sodium, glucose, high, low
______ active transport
______ of Amino Acids along with Sodium Ions
• occurs in the same manner as for glucose, except that it uses a different set of transport proteins
• the substance to be transported is on the ______ of the cell and is transported to the ______
Secondary, Co-Transport, inside, outside
______ active transport
______
• occurs through all or almost all cell membranes, with sodium ions moving to the interior and calcium ions to the exterior, both are bound to the same transport protein in a counter transport mode.
Secondary, Sodium-calcium counter-transport
______ active transport
______
• In the proximal tubules of the kidneys sodium lons move from the lumen of the tubule to the interior of the tubular cell and hydrogen ions are counter-transported into the tubule lumen.
Secondary, Sodium-hydrogen counter-transport
______ active transport
______
• counter-transport is not nearly as powerful as the primary active transport of hydrogen ions that occurs in the more distal renal tubules, but it can transport extremely large numbers of hydrogen ions, thus making it a key to hydrogen ion control in the body fluids
Secondary, Sodium-hydrogen counter transport
