C4 - Section 2.Renal Regulation of Acid-Base balance

Question 1

The (?) of the body’s acid-base balance addresses the metabolic component of the buffering system.

Answer 1

renal regulation

Question 2

Whereas the (?) (together with breathing centers in the brain) controls the blood levels of carbonic acid by controlling the exhalation of CO2, the (?) controls the blood levels of bicarbonate.

Answer 2

respiratory system

renal system

Question 3

A decrease of blood bicarbonate can result from the inhibition of (?) by certain diuretics or from excessive bicarbonate loss due to diarrhea.

Answer 3

carbonic anhydrase

Question 4

Blood bicarbonate levels are also typically lower in people who have (?), in which aldosterone levels are reduced, and in people who have renal damage, such as (?).

Answer 4

Addison’s disease (chronic adrenal insufficiency)

chronic nephritis

Question 5

Finally, low bicarbonate blood levels can result from elevated levels of (?) (common in unmanaged diabetes mellitus), which bind bicarbonate in the filtrate and prevent its conservation.

Answer 5

ketones

Question 6

(?), found in the filtrate, are essential to the bicarbonate buffer system, yet the cells of the tubule are not permeable to bicarbonate ions.

Answer 6

Bicarbonate ions, HCO3−

Question 7

The steps involved in supplying bicarbonate ions to the system are seen in previous diagram and are summarized below:

 Step 1: (?) are reabsorbed from the filtrate in exchange for H+ by an antiport mechanism in the apical membranes of cells lining the renal tubule.
 Step 2: The cells produce (?) that can be shunted to peritubular capillaries.
 Step 3: When CO2 is available, the reaction is driven to the formation of carbonic acid, which dissociates to form a (?).
 Step 4: The bicarbonate ion passes into the peritubular capillaries and returns to the blood. The (?) is secreted into the filtrate, where it can become part of new water molecules and be reabsorbed as such, or removed in the urine.

Answer 7

Sodium ions

bicarbonate ions

bicarbonate ion and a hydrogen ion

hydrogen ion

Question 8

It is also possible that salts in the filtrate, such as (?), will capture hydrogen ions.

Answer 8

sulfates, phosphates, or ammonia

Question 9

If this occurs, the hydrogen ions will not be available to combine with (?) and produce (?)

Answer 9

bicarbonate ions

CO2

Question 10

In such cases, bicarbonate ions are not conserved from the filtrate to the blood, which will also contribute to a (?).

Answer 10

pH imbalance and acidosis

Question 11

The hydrogen ions also compete with (?) to exchange with sodium in the renal tubules.

Answer 11

potassium

Question 12

If more potassium is present than normal, potassium, rather than the (?), will be exchanged, and increased potassium enters the filtrate.

Answer 12

hydrogen ions

Question 13

When this occurs, fewer (?) in the filtrate participate in the conversion of bicarbonate into CO2 and less bicarbonate is conserved.

Answer 13

hydrogen ions

Question 14

If there is less potassium, more hydrogen ions enter the filtrate to be exchanged with sodium and more (?) is conserved.

Answer 14

bicarbonate

Question 15

(?) are important in neutralizing positive ion charges in the body.

Answer 15

Chloride ions

Question 16

If chloride is lost, the body uses (?) in place of the lost chloride ions.

Answer 16

bicarbonate ions

Question 17

Thus, lost chloride results in an (?) by the renal system.

Answer 17

increased reabsorption of bicarbonate