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14 Cards in this Set
- Front
- Back
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Transport at proximal tubule? And what is being reabsorbed at this location?
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Co-transport of Amino Acid and Glucose.
Glucose, or aa, with Na with NO ATP leaving lumen into epithelial cell. Then Glu and aa both enter blood from cell. H2O is also reabsorbed here. Note, these molecules are absorbed by active transport! |
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Co-transport systems tend to depend on which ion to transport solutes across membrane?
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Na.
This can take place with a second active transport, then followed by a facilitated diffusion to transport the solute out into blood. |
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What happens to water and Na as the filtrate moves through the loop and to CD?
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They get continually reabsorbed. H2O flows out by osmosis because the interstitial fluid is very hypertonic. This occurs because Na is actively transported out of the tubular fluid.
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What 3 processes are used by the kidneys to regulate blood composition?
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Filtration
Reabsorption Secretion (i.e. NH3 gets secreted from plasma into lumen and excreted inside urine) |
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What is the function of ADH? and where is its site of action?
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To reduce osmolarity, i.e. if Na conc. is high, then ADH is release from posterior pituitary.
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Why is HCL secreted in the stomach?
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To denature protein.
Kill bacteria Open protein structures for access by enzymes. |
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How is H+ produced inside stomach?
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By the reaction btw:
H2O and CO2. |
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Outline the process of HCL production inside stomach:
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CO2 and H2O combine to eventually produce HCO3 and H+.
Bicarb transports outward into blood by facilitated diffusion (WITHOUT ATP) while bringing in Chloride ion from the blood. Chloride then simply diffuses into lumen from cell. As bicarb is doing its thing, H+ gets ACTIVELY transported into lumen of stomach with its K+ counterpart. |
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The strength of the contraction of the heart is ultimately controlled by?
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Intracellular [Ca] of the myocardial cells which is controlled by the Ca transporters.
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What is the mechanism of digitalis?
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Digitalis binds to Na/K ATPase pump and decreases its function. This causes an increase in Na since Na normally gets transported out. This increase level of Na affects the gradient for Ca/Na to work push Ca out of cells as there is less tendency for Na to be transported in.
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What is tonicity?
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Tonicity of a cell membrane refers ONLY to the impermeable solute. Just keep in mind that the movement will be that of water, and it will move from area of high water content to low, or low conc. to high conc. in order to reduce and equilibriate the concentration.
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What is osmolarity?
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Osmolarity refers to ALL of the solutes regardless of its membrane permeability.
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If BOTH the solute and water can cross the membrane equally, then would you have swelling or shrinkage?
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No. Diffusion will take place until both concentrations AND vol. will be the same.
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If there is an impermeant solute, and water is the only thing that can move across, what will be the consequence on the final concentration and vol in both the compartments?
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The movement of water will stop when the concentrations of both solute and water on both sides are EQUAL, but the vol. WILL NOT BE EQUAL due to shrinkage or swelling.
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