Urine Concentration And Dilution

Question 1

The kidneys help with regulation of water ____ and ____.

Answer 1

Loss

Conservation

Question 2

What happens when there is a Large EXCESS of water in the body?

Answer 2

• The Kidneys can EXCRETE as much as 20LITERS/DAY

- With a [ ] as low as 50mOsm/L

Question 3

With excess water in the system, can the kidneys continue to reabsorb SOLUTES?

Answer 3

Yes

Question 4

What things stay relatively constant after the ingestion of 1 L of water?

Answer 4

1. Plasma OSMOLARITY

2. Urinary Solute EXCRETION

Question 5

Ascending Thick Limb of Henle during Excretion of Dilute urine.

Answer 5

• Na+, K+, Cl- reabsorbed
• IMPERMEABLE to water
• Tubular fluid becomes MORE dilute as it flows up

Question 6

Osm of DILUTE urine at the EARLY distal Tubule segment?

Answer 6

100 mOsm/L

Question 7

Late Distal convoluted tubule during excretion of DILUTE Urine?

Answer 7

• More Reabsorption of NaCl

- IMPERMEABLE to water
In absence of ADH

Question 8

Osm of urine in the LATE distal convoluted tubule?

Answer 8

50 mOsm/L

Question 9

Dilute Urine forms when _____ levels are Low.

Answer 9

ADH

Question 10

Most reabsorption of water takes place where?

Answer 10

Descending limb

Question 11

The normal [ ] at the loop of Henle is ______ mOsm but can reach a [ ] of _______ mOsm.

Answer 11

600

1200-1400

Question 12

Kidneys can produce a urine [ ] of ______ mOsm/L

Answer 12

1200-1400

Question 13

Req for forming a concentrated urine?

Answer 13

1. Presence of ADH
2. High Osm of renal MEDULLARY interstitial tubule
   - establishes a gradient for Water REABSORPTION

Question 14

A normal human must excrete how much solute each day?

Answer 14

600mOsm

Question 15

What is the average Obligatory urine volume?

Answer 15

About 0.5L/day

Question 16

Fxn of the Proximal Tubule?

Answer 16

• Reabsorbs 65% of filtered ELECTROLYTES

- Highly permeable to WATER

Question 17

Osm of the Prox Tubule?

Answer 17

300mOSm/L

Question 18

Fxn of the descending limb

Answer 18

• Highly permeable to WATER

- LESS permeable to NaCl and Urea

Question 19

Fxn of the THIN ascending limb?

Answer 19

• Impermeable to WATER
• Reabsorbed NaCL
• Urea diffuses INTO the ascending limb

Question 20

Fxn of the Thick ascending limb

Answer 20

• Impermeable to water

- Large amounts of Ions are TRANSPORTED from the Tubule into the medullary interstitium
Ions move OUTWARD

Question 21

Tubular fluid [ ] in the Thick Ascending limb

Answer 21

100 mOsm/L

Question 22

The [ ] in the ascending Limb is Reduced because of what?

Answer 22

The ACTIVE Ion Pumps

Question 23

[ ] in the descending limb reaches equilibrium because of _____.

Answer 23

Osmosis

Question 24

What type of fluid moves through the ascending limb?

Answer 24

Hyperosmotic

Question 25

Where is Urea impermeable?

Answer 25

1. THICK ascending Limb

2. Distal CORTICAL Tubule

Question 26

Increase of ADH in the MEDULLARY collecting duct leads to what?

Answer 26

• More Water reabsorption

Higher [ ] of Urea

Question 27

Higher [ ] of urine of in the Medullary duct leads to what?

Answer 27

Diffusion of UREA into the interstitial space

Question 28

What percentage of the Recirculating Urea is EXCRETED?

Answer 28

20%

Question 29

Purpose of the Vasa Recta?

Answer 29

Prevents the Medullary HYPER-osmolarity from being DISSIPATED

• Does NOT create it

Question 30

BOTH Water and Solutes are reabsorbed where?

Answer 30

PROXIMAL Tubule

Question 31

Absorption of water in the distal segments depend on what?

Answer 31

The Presence of ADH

Question 32

ADH Is formed by what kind of Neurons?

Where?

Answer 32

• Magnocellular

- Supraoptic Nuclei & Paraventricular Nuclei

Question 33

A subtle increase in sodium intake leads to what?

Answer 33

• A block of ADH secretions

- A block in Thirst systems

Question 34

Aldosterone has very little effect on what?

Answer 34

[Na+] in the Plasma