Lab 4: Renal Function

Question 1

What is the major function of the urinary system?

Answer 1

Keeps chemicals and water in balance by removing urea (waste) from the blood

Question 2

What is urea produced from?

Answer 2

Foods containing protein, such as meat, poultry, and certain vegetables

Question 3

Where is urea carried?

Answer 3

In the bloodstream to the kidneys

Question 4

How many kidneys does a mammal contain? Where are they found?

Answer 4

• Two kidneys

- Located below the ribs towards the middle of the back

Question 5

Which hormone is produced by the kidneys? What is its function?

Answer 5

• Erythropoietin

- Aids in the formation of RBCs

Question 6

What are the filtering units of the kidneys?

Answer 6

Nephrons

Question 7

What does each nephron consist of?

Answer 7

• Glomerulus: ball formed of small blood capillaries

- Renal tubule: small tube

Question 8

What forms the urine?

Answer 8

• Urea
• Water
• Other waste substances

Question 9

What does urine pass through?

Answer 9

Nephrons, and down the renal tubules of the kidney

Question 10

What is the function of ureters? How many do we have?

Answer 10

• Two ureters

- Carry urine from the kidneys to the bladder

Question 11

Which muscles continually tighten and relax to force urine downward?

Answer 11

Muscles in the ureter

Question 12

How often are small amounts of urine emptied into the bladder from the ureters?

Answer 12

About every 10 to 15 seconds

Question 13

Where is the bladder located?

Answer 13

Located in the lower abdomen

Question 14

How is the bladder held in place?

Answer 14

By ligaments that are attached to other organs and the pelvic bones

Question 15

What function does the bladder exert during relaxation and during contraction?

Answer 15

• Relax and expand to store urine

- Contract and flatten to empty urine through the urethra

Question 16

How much urine can the typical adult healthy bladder store?

Answer 16

Up to 2 cups for 2 to 5 hours

Question 17

What are the functions of the two sphincter muscles?

Answer 17

• Circular muscles that help keep urine from leaking

- Close tightly like a rubber band around the opening of the bladder

Question 18

What is the function of the nerves in the bladder?

Answer 18

Alert a person when it is time to urinate, or empty the bladder

Question 19

What is the function of the urethra?

Answer 19

The tube that allows the urine to pass outside of the body

Question 20

How does normal urination occur through nervous signalling?

Answer 20

• The brain signals the bladder muscles to tighten, which squeezes urine out of the bladder
• The brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra

Question 21

What is the volume and composition of urine adjusted by? Why?

Answer 21

• Neural and hormonal mechanisms

- To maintain constancy of volume and electrolyte concentrations in the body fluids

Question 22

What is usually accompanied by sodium reabsorption in the renal tubules? Why?

Answer 22

• Chloride

- To maintain electrostatic neutrality

Question 23

How can the amount of sodium excreted be approximately determined?

Answer 23

By the estimation of chloride concentration

Question 24

The number of drops of silver nitrate is equal to what in this experiment?

Answer 24

The number of grams of sodium chloride per liter of solution

Question 25

How is specific gravity (or density) determined?

Answer 25

With a urinometer

Question 26

What is the specific gravity of pure water?

Answer 26

1.000

Question 27

What is the definition of specific gravity?

Answer 27

The ratio of the density (compactness) of a substance (urine) to that of distilled water at a specific temperature

Question 28

What does a higher specific gravity infer?

Answer 28

A higher composition of dissolved solids (urea, sodium chloride, etc.)

Question 29

How may a rough approximation of the total dissolved substances in urine may be obtained?

Answer 29

By multiplying the final two figures of the specific gravity reading by 2.66 (Long’s coefficient)

Question 30

What is the normal specific gravity of a 24-hour specimen of urine?

Answer 30

1.020 (range: 1.016 to 1.025)

Question 31

What does a specific gravity of 1.001 indicate?

Answer 31

Following ingestion of a large amount of fluids

Question 32

What does a specific gravity of 1.040 indicate?

Answer 32

Heavy perspiration

Question 33

What are the major components of urine?

Answer 33

• 95% water
• 2% urea
• 0.18% sulphate
• 0.12% phosphate
• 0.1% creatine and sodium
• 0.6% potassium and chloride

Question 34

What type of instrument is a urinometer?

Answer 34

Hydrometer

Question 35

What does each line of a urinometer represent?

Answer 35

0.001

Question 36

What is specific gravity a function of?

Answer 36

• Number
• Density
• And weight of the solute particles present

Question 37

Specific gravity is used as a measure of the power of what?

Answer 37

Concentration power of the kidney

Question 38

What is the indicator in the chloride concentration procedure?

Answer 38

K2CrO4 (potassium chromate)

Question 39

What is the function of silver nitrate (AgNO3)?

Answer 39

• Reacts with the chloride in urine to precipitate AgCl (silver chloride)
• Any excess AgNO3 reacts with potassium chromate to form a reddish precipitate of silver chromate (Ag2CrO4), which indicates the endpoint

Question 40

Is specific gravity a physical or chemical characteristic?

Answer 40

Physical characteristic of urine measured through a chemical test

Question 41

When would a urine sample be recommended if a lab technician is looking for a very small amount of protein?

Answer 41

• In the morning

- A concentrated morning urine specimen is superior to a diluted specimen

Question 42

What is the normal range of sodium in a random urine sample?

Answer 42

25 to 100 mEq

Question 43

How do you determined the number of mg from the mEq of sodium?

Answer 43

mg = mEq x 35.4

Question 44

What is the normal urine sodium value over a day?

Answer 44

40 to 220 mEq/L per day