Urine Concentration And Dilution Flashcards
The kidneys help with regulation of water ____ and ____.
Loss
Conservation
What happens when there is a Large EXCESS of water in the body?
- The Kidneys can EXCRETE as much as 20LITERS/DAY
- With a [ ] as low as 50mOsm/L
With excess water in the system, can the kidneys continue to reabsorb SOLUTES?
Yes
What things stay relatively constant after the ingestion of 1 L of water?
- Plasma OSMOLARITY
2. Urinary Solute EXCRETION
Ascending Thick Limb of Henle during Excretion of Dilute urine.
- Na+, K+, Cl- reabsorbed
- IMPERMEABLE to water
- Tubular fluid becomes MORE dilute as it flows up
Osm of DILUTE urine at the EARLY distal Tubule segment?
100 mOsm/L
Late Distal convoluted tubule during excretion of DILUTE Urine?
- More Reabsorption of NaCl
- IMPERMEABLE to water
In absence of ADH
Osm of urine in the LATE distal convoluted tubule?
50 mOsm/L
Dilute Urine forms when _____ levels are Low.
ADH
Most reabsorption of water takes place where?
Descending limb
The normal [ ] at the loop of Henle is ______ mOsm but can reach a [ ] of _______ mOsm.
600
1200-1400
Kidneys can produce a urine [ ] of ______ mOsm/L
1200-1400
Req for forming a concentrated urine?
- Presence of ADH
- High Osm of renal MEDULLARY interstitial tubule
- establishes a gradient for Water REABSORPTION
A normal human must excrete how much solute each day?
600mOsm
What is the average Obligatory urine volume?
About 0.5L/day
Fxn of the Proximal Tubule?
- Reabsorbs 65% of filtered ELECTROLYTES
- Highly permeable to WATER
Osm of the Prox Tubule?
300mOSm/L
Fxn of the descending limb
- Highly permeable to WATER
- LESS permeable to NaCl and Urea
Fxn of the THIN ascending limb?
- Impermeable to WATER
- Reabsorbed NaCL
- Urea diffuses INTO the ascending limb
Fxn of the Thick ascending limb
- Impermeable to water
- Large amounts of Ions are TRANSPORTED from the Tubule into the medullary interstitium
Ions move OUTWARD
Tubular fluid [ ] in the Thick Ascending limb
100 mOsm/L
The [ ] in the ascending Limb is Reduced because of what?
The ACTIVE Ion Pumps
[ ] in the descending limb reaches equilibrium because of _____.
Osmosis
What type of fluid moves through the ascending limb?
Hyperosmotic
Where is Urea impermeable?
- THICK ascending Limb
2. Distal CORTICAL Tubule
Increase of ADH in the MEDULLARY collecting duct leads to what?
- More Water reabsorption
Higher [ ] of Urea
Higher [ ] of urine of in the Medullary duct leads to what?
Diffusion of UREA into the interstitial space
What percentage of the Recirculating Urea is EXCRETED?
20%
Purpose of the Vasa Recta?
Prevents the Medullary HYPER-osmolarity from being DISSIPATED
- Does NOT create it
BOTH Water and Solutes are reabsorbed where?
PROXIMAL Tubule
Absorption of water in the distal segments depend on what?
The Presence of ADH
ADH Is formed by what kind of Neurons?
Where?
- Magnocellular
- Supraoptic Nuclei & Paraventricular Nuclei
A subtle increase in sodium intake leads to what?
- A block of ADH secretions
- A block in Thirst systems
Aldosterone has very little effect on what?
[Na+] in the Plasma
