The Urinary System and Balance Part 1 Flashcards
True or False: The concept of balance is to maintain homeostasis, what goes in must come out eventually.
True. Input+production=utilization+output
What factors affect plasma composition?
- Kidneys regulate water and solute content, which determines volume
- acid-base balance
- Exchange between different compartments of the body.
What are the different sources of body water input and output?
Input-Ingestion
Output-Feces, Sweating/Hemorrhage/Respiration, Urine
What does it mean when there is balance in the water/solute balance?
That the input matches the output. Homeostasis.
What does positive balance mean?
There is more going in than going out.
What does negative balance mean?
There is more going out than in.
Cells in the DCT and collecting ducts regulate balance. What are the cells and what do they affect?
Principal cells-water and electrolytes
Intercalated cells-acid-base balance
True or False: Solute concentrations have no affect on water balance and movement.
False.
In regards to water reabsorption in the PCT, is it considered active transport or passive transport?
Passive
In regards to water reabsorption in the DCT and Collecting Ducts, is it considered active or passive transport?
Passive, but it requires aquaporons to get the water through the tight junctions.
Normovolemia is…..
normal blood volume
Hypervolemia is….
high blood volume due to positive water balance
Hypovolemia is….
low blood volume due to negative water balance
True or False: Water moves from an area of high solute concentration to low solute concentration.
True.
When fluid is moving down the descending limb of the Loop of Henle, which way is it moving in the vasa recta?
Up
When fluid is moving up the descending limb of the Loop of Henle, which way is it moving in the vasa recta?
Down
What is the reason for concurrent flow in the Loop of Henle and vasa recta?
It facilitates reabsorption.
Explain the control of water balance and osmolarity by antidiuretic hormone.
ADH stimulates the insertion of auqaporin-2 into the apical membrane of the DCT and CD, letting water be reabsorbed through osmosis. When osmolarity is up, the membrane is more permeable to water.
The descending limb of the loop of Henle is permeable to what?
Water only, solutes can’t be transported.
The ascending limb of the loop of Henle is permeable to what?
Solutes only, they need to be actively transported.
Fluid in the descending limb of the loop of Henle’s osmolarity ______ as it descends
increases
Fluids in the ascending limb of the loop of Henle’s osmolarity ________ as it ascends
decreases
Fluid in the PCT is at _______ mOsm
300 mOsm
Fluid in the DCT is at ________ mOsm
100 mOsm
Cortical ISF is at _______ mOsm.
300 mOSm
Why is the countercurrent multiplier important?
it facilitates reabsorption in DCT and CD
Where are Urea transporters located?
PCT, CD, and descending vasa recta (located on the ascending limb of the loop of Henle)
What is important about Urea?
It is approximately 40% of the osmolarity of the gradient.
What does the anatomical arrangement of the vasa recta prevent?
the diffusion of water and solutes from dissipating the medullary osmotic gradient.
What does water permeability depend on and where are the transporters located?
Water permeability depends on water channels called aquaporins. Aquaporin-3 is present in the basolateral membrane ALWAYS. Aquaporin -2 is present in apical membrane only when ADH is present in blood.
What is the range of osmolarity of urine?
100-1400 mOsm
Where does most water reabsorption occur in the renal tubules?
Proximal Convoluted Tubule
Where does the regulation of water reabsorption in the renal tubules occur?
Distal Convoluted Tubules and Collecting Ducts
Can pure water be excreted as urine?
No, there will always be solutes and wastes filtered from the kidneys
How does the movement of water and solutes in the loop of Henle establish an osmotic gradient in the renal medulla?
It is a countercurrent multiplier, meaning that on the descending limb, the osmolarity of the filtrate increases due to water moving into the ISF and on the ascending limb, the osmolarity of the filtrate decreases because of solute transportation into the ISF. This movement creates the Medullary Osmotic Gradient.
Name two stimuli for ADH release from the posterior pituitary.
- blood volume
2. blood pressure
What effect does ADH have on principal cells?
ADH increases their permeability to water by making aquaporin-2 present on the apical side.
