Membrane Transport Flashcards
Oxygen can ____ into the cell along a concentration gradient, because oxygen is _____ and there is ___ energy in the oxygen gradient that fuels net movement of oxygen into the cell
Diffuse
Nonpolar
Potential
_____ is mostly hydrophobic, but has a hydroxyl group that allows it to orient in the bilayer in a specific way. _____ changes the fluidity and stability of the membrane.
Cholesterol
The ____ the cholesterol content is, the more brittle the membrane is
Higher
Outside of the cell there is ___ concentrations of oxygen and glucose. Inside of the cell there is ___ concentration of oxygen and glucose
High
Low
Both oxygen and glucose move into the cell ____ their concentration gradient. Because oxygen and glucose are used within the cell, the gradient is maintained.
Down
Oxygen is moving across the membrane by ___ ____, as the concentration gradient increases, diffusion flux _____.
Simple diffusion
Increases
Glucose moves across the membrane by ___ ___. transport of glucose into the cell reaches a transport ____ when all the transporters are bound to glucose. The process cannot happen any faster.
Facilitated diffusion
Maximum
Substances that are ___ and ____ can move across the membrane by simple diffusion
Small
Non-polar
Substances that are ____ or ____ require proteins to get across the membrane by facilitated diffusion. The gradient still provides the energy for transport, but this process _____ when all of the transporters are in use
Charged
Larger
Saturates
A _____ is a protein, that forms a poor through which a small polar molecule/ion can move through
Channel
A _____ binds the solute on one side of the membrane, changes shape, and then release is the solute on the other side of the membrane
Transporter
Sodium and potassium transporters use ____ and active transport to move molecules against their gradient
ATP
There are two kinds of active transport ____ active transport, and ____ active transport
Primary
Secondary
Primary active transport directly uses the energy in ____ to move substances against a concentration gradient. They are also called _____. They are both transporters and ____.
ATP
Pumps
Enzymes
With ____ ____ transport, the proteins that moves the substance is the same protein that hydrolyzes the ATP.
Example: ____
Primary active
Sodium/potassium ATPase
Secondary active transport ____ uses ATP by using the sodium that the primary active transporter generated.
Indirectly
___ ____ transporters move molecules against a concentration gradient by using the pen, pencil energy in a sodium gradient. It is still active transport, because the movement of the substance would not occur if ____ had not hydrolyzed elsewhere in the cell.
Example:
Secondary active
ATP
Sodium/glucose transporter
How is glucose being transported on the capillary side of the cell in the small intestine and proximal tubule of the kidney?
Facilitated diffusion
The cell uses primary active transport to generate a sodium gradient and secondary active transport to generate a glucose gradient, so that glucose can enter and travel in the blood.
A ____ ___ secretes HCl into the stomach lumen. They exhibit _____ Na/K ATPases, moving ions against their concentrated gradient, using ATP.
Parietal cell
Basolateral
Inhibition of the H+/K+ ATPase in parietal cells would cause ____ acid secretion and a ____ luminal pH.
Less
Higher
HCO3-/Cl- exchanger is located on the ___ side of the parietal cell. HCO3- leaving the cell permits ___ to enter the cell along an electrochemical gradient
Basolateral
Cl-
Small intestine:
The cells in the villi have transporters that promote absorption of ___, ___, ___.
The cells in the ____ contain transporters that promote the secretion of chlorine ions, sodium ions, and water are secreted as a result
Water, nutrients, and ions
Crypts
In the small intestine typically more ____ is absorbed than secreted
Water
The Na/K ATPase on the basolateral side of the cells in the villi use the chemical energy in ATP to create an ___ sodium gradient. On the luminal side, sodium is moving ____ its concentration gradient
Inward
With
Water moves across enterocytes in the small intestine through water channels called ____.
Aquaporins (AQN)
As sodium and other molecules are transported across the cell layer, the concentration of particles in the lumen decreases as a concentration of particles in the interstitium increases. As this occurs, the opposite occurs with ____ concentration. Water in the lumen is ____ then in the interstitium period water crosses the cells layers through aqua Porins, or between the cells through the tight junction via _____
Water
Higher
Osmosis
When ____ is present, the kidneys, save water, because aquaPourin 2 is inserted in the luminal membrane
ADH
When ADH is _____, the kidneys, permit water to stay in the urine, because the aquaporin 2 is internalized
Absent
____ is the most abundant cation in the extracellular fluid. If the kidneys save too much water, plasma sodium concentration ____ below normal, causing hyponatremia
Na+
decreases
Muscle contraction depends on ____ released from the sarcoplasmic reticulum
Calcium
During contraction of muscles, the electrical signal from the muscle action potential is converted into it a chemical stimulus that opens a ___ channel.
Calcium
Calcium ions bind to ____ within fibers to allow the whole muscle to contract and shorten
Myofilaments
In order for the muscle to ___, calcium must be removed
Relax
_______ generates an inward gradient for sodium
Na/K ATPase
The ___ active Ca2+ ATPase in the plasma membrane removes Ca from the cell
Primary
The ____ active Na/Ca2+ exchanger uses a sodium gradient to move calcium out the intracellular space
Secondary
