Dilluting and concentrating function of the kidneys

Question 1

Urine as a product of the kidneys represent?

Answer 1

A complex solution containing multiple organic and inorganic solutes

Question 2

Solutes are drawn or secreted from…?

Answer 2

drawn from blood plasma or secreted in the tubules of the nephrons

Question 3

Which steps does urine production include?

Answer 3

1) Primary urine after glomerular filtration

2) secondary (definitive) urine after reabsorption and secretion in kidney tubules –> excretion

Question 4

Most important parameters of urine as a diluted substance is..?

Answer 4

Specific mass (density) (consistence, specific gravity)

Question 5

What does the diluting and concentrating functions of the kidney refer to?

Answer 5

Mechanisms allowing for changes of the specific mass of the urine according to dynamic need of organism.

Question 6

Instrument for measurement of specific mass is called?

Answer 6

Urometer (urinometer)

Question 7

Which other instrument can also be used to measure density of urine?

Answer 7

Refractometer

Question 8

How can we test the diluting function of the kidneys?

Answer 8

Measure pre- dilution.
Person drink 1,5 l of water
Re-measure specific mass after 15, 30, 45 and 60 min

Question 9

What is diuresis?

Answer 9

increased or excessive production of urine.

Question 10

How can drinking a large volume of liquid influence the urine?

Answer 10

By increased diuresis, increase of volume and decrease of specific mass

Question 11

What is polyuria?

Answer 11

production of abnormally large volumes of dilute urine.

Question 12

Which function inhibits the release of ADH?

Answer 12

Water reabsorbed from GIT –> increase in osmotic BP i

Question 13

Inhibition of ADH leads to…?

Answer 13

A higher excretion of hypotonic (little solutes) urine

Question 14

When does water excretion start after water intake and why?

Answer 14

After 15 minutes –> maximum after 40 min. delay due to time intervals necessary for water reabsorption, ADH inhibition and degradation of present ADH.

Question 15

Which temperature is the urometer usually calibrated against?

Answer 15

15 C

Question 16

How must the value be corrected if the measured temperature is different than 15 C?

Answer 16

For every 3 C up –> + 0,001 g/l
for every 3 C down –> - 0,001 g/l
to the specific mass value.

Question 17

Specific mass of urine depends on…?

Answer 17

• conc. of diluted substances
• ability of water reabsorption
• food/water inntake
• physical load
• temperature
• water release

Question 18

What can shift the specific mass value to higher levels?

Answer 18

Ascorbic acid (700 mg/l)

Question 19

What can shift specific mass to a lower value?

Answer 19

pH increase above 6,5

Question 20

What is the specific mass interval in farm animals?

Answer 20

1,010 - 1,045 g/l

Question 21

Urine colour depends on?

Answer 21

concentration of solutes, diet, treatment ( drugs)