C4 - Section 1. THE BUFFER SYSTEM

Question 1

in the human body are extremely efficient, and different systems work at different rates.

Answer 1

buffer systems

Question 2

It takes only (?) for the chemical buffers in the blood to make adjustments to pH.

Answer 2

seconds

Question 3

can adjust the blood pH upward in minutes by exhaling CO2 from the body.

Answer 3

respiratory tract

Question 4

can also adjust blood pH through the excretion of hydrogen ions (H+) and the conservation of bicarbonate, but this process takes hours to days to have an effect.

Answer 4

renal system

Question 5

The buffer systems functioning in blood plasma include

Answer 5

plasma proteins, phosphate, and bicarbonate and carbonic acid buffers.

Question 6

help control acid-base balance by excreting hydrogen ions and generating bicarbonate that helps maintain blood plasma pH within a normal range.

Answer 6

kidneys

Question 7

work predominantly inside cells.

Answer 7

Protein buffer systems

Question 8

Nearly all (?) can function as buffers.

Answer 8

proteins

Question 9

Proteins are made up of amino acids, which contain positively charged ? and negatively charged (?).

Answer 9

amino groups

carboxyl groups

Question 10

The charged regions of these molecules can bind (?), and thus function as buffers.

Answer 10

hydrogen and hydroxyl ions

Question 11

Buffering by proteins accounts for (?) of the buffering power of the blood and most of the buffering within cells.

Answer 11

two-thirds

Question 12

is the principal protein inside of red blood cells and accounts for one-third of the mass of the cell.

Answer 12

Hemoglobin

Question 13

During the conversion of CO2 into bicarbonate, hydrogen ions liberated in the reaction are buffered by (?), which is reduced by the dissociation of oxygen.

Answer 13

hemoglobin

Question 14

This buffering helps maintain (?).

Answer 14

normal pH

Question 15

The process is reversed in the (?) to re-form CO2, which then can diffuse into the air sacs to be exhaled into the atmosphere.

Answer 15

pulmonary capillaries

Question 16

This process is discussed in detail in the chapter on the respiratory system.

Question 17

The (?) is regulated in the blood by sodium, as are the phosphate ions.

Answer 17

bicarbonate

Question 18

When sodium bicarbonate (NaHCO3), comes into contact with a strong acid, such as HCl, carbonic acid (H2CO3), which is a weak acid, and (?) are formed.

Answer 18

NaCl

Question 19

When carbonic acid comes into contact with a strong base, such as NaOH, (?) are formed.

Answer 19

bicarbonate and water

Question 20

As with the (?), a weak acid or weak base captures the free ions, and a significant change in pH is prevented.

Answer 20

phosphate buffer

Question 21

Bicarbonate ions and carbonic acid are present in the blood in a (?) ratio if the blood pH is within the normal range.

Answer 21

20:1

Question 22

With 20 times more (?) than carbonic acid, this capture system is most efficient at buffering changes that would make the blood more acidic.

Answer 22

bicarbonate

Question 23

This is useful because most of the body’s metabolic wastes, such as (?), are acids.

Answer 23

lactic acid and ketones

Question 24

(?) in the blood are controlled by the expiration of CO2 through the lungs.

Answer 24

Carbonic acid levels

Question 25

In red blood cells, (?) forces the dissociation of the acid, rendering the blood less acidic.

Answer 25

carbonic anhydrase

Question 26

Because of this acid dissociation, (?) is exhaled.

Answer 26

CO2

Question 27

The level of bicarbonate in the blood is controlled through the (?), where bicarbonate ions in the (?) are conserved and passed back into the blood.

Answer 27

renal system

renal filtrate

Question 28

However, the (?) is the primary buffering system of the IF surrounding the cells in tissues throughout the body.

Answer 28

bicarbonate buffer

Question 29

The (?) contributes to the balance of acids and bases in the body by regulating the blood levels of carbonic acid.

Answer 29

respiratory system

Question 30

(?) in the blood readily reacts with water to form (?), and the levels of (?) in the blood are in equilibrium.

Answer 30

CO2; carbonic acid

CO2 and carbonic acid

Question 31

When the (?) level in the blood rises (as it does when you hold your breath), the excess (?) reacts with water to form additional carbonic acid, lowering (?).

Answer 31

CO2

blood pH

Question 32

Increasing the (?) (which you might feel the “urge” to do after holding your breath) allows you to exhale more CO2.

Answer 32

rate and/or depth of respiration

Question 33

The loss of (?) from the body reduces blood levels of (?) and thereby adjusts the pH upward, toward normal levels.

Answer 33

CO2

carbonic acid

Question 34

As you might have surmised, this process also works in the (?).

Answer 34

opposite direction

Question 35

Excessive deep and rapid breathing (as in hyperventilation) rids the blood of CO2 and reduces the level of carbonic acid, making the blood too (?).

Answer 35

alkaline

Question 36

This brief (?) can be remedied by rebreathing air that has been exhaled into a paper bag.

Answer 36

alkalosis

Question 37

Rebreathing exhaled air will rapidly bring (?) down toward normal.

Answer 37

blood pH

Question 38

The chemical reactions that regulate the levels of CO2 and carbonic acid occur in the (?) when blood travels through the (?).

Answer 38

lungs

lung’s pulmonary capillaries

Question 39

Minor adjustments in breathing are usually sufficient to adjust the pH of the blood by changing how much (?) is exhaled.

Answer 39

CO2

Question 40

In fact, doubling the respiratory rate for less than 1 minute, removing “extra” CO2, would increase the blood pH by (?).

Answer 40

0.2

Question 41

This situation is common if you are (?) over a period of time.

Answer 41

exercising strenuously

Question 42

To keep up the necessary energy production, you would produce excess (?) (and lactic acid if exercising beyond your aerobic threshold).

Answer 42

CO2

Question 43

In order to balance the increased acid production, the respiration rate goes up to remove the (?). This helps to keep you from developing (?).

Answer 43

CO2

acidosis

Question 44

The body regulates the respiratory rate by the use of (?), which primarily use CO2 as a signal.

Answer 44

chemoreceptors

Question 45

Peripheral blood sensors are found in the walls of the (?).

Answer 45

aorta and carotid arteries

Question 46

These sensors signal the brain to provide immediate adjustments to the respiratory rate if (?) levels rise or fall. Yet other sensors are found in the brain itself.

Answer 46

CO2

Question 47

Changes in the pH of CSF affect the respiratory center in the (?), which can directly modulate breathing rate to bring the pH back into the normal range.

Answer 47

medulla oblongata

Question 48

(?), or abnormally elevated blood levels of CO2, occurs in any situation that impairs respiratory functions, including pneumonia and congestive heart failure.

Answer 48

Hypercapnia

Question 49

Reduced breathing (?) due to drugs such as morphine, barbiturates, or ethanol (or even just holding one’s breath) can also result in hypercapnia.

Answer 49

hypoventilation

Question 50

(?), or abnormally low blood levels of CO2, occurs with any cause of hyperventilation that drives off the CO2, such as salicylate toxicity, elevated room temperatures, fever, or hysteria.

Answer 50

Hypocapnia