C4 - Section 1. THE BUFFER SYSTEM Flashcards
in the human body are extremely efficient, and different systems work at different rates.
buffer systems
It takes only (?) for the chemical buffers in the blood to make adjustments to pH.
seconds
can adjust the blood pH upward in minutes by exhaling CO2 from the body.
respiratory tract
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.
renal system
The buffer systems functioning in blood plasma include
plasma proteins, phosphate, and bicarbonate and carbonic acid buffers.
help control acid-base balance by excreting hydrogen ions and generating bicarbonate that helps maintain blood plasma pH within a normal range.
kidneys
work predominantly inside cells.
Protein buffer systems
Nearly all (?) can function as buffers.
proteins
Proteins are made up of amino acids, which contain positively charged ? and negatively charged (?).
amino groups
carboxyl groups
The charged regions of these molecules can bind (?), and thus function as buffers.
hydrogen and hydroxyl ions
Buffering by proteins accounts for (?) of the buffering power of the blood and most of the buffering within cells.
two-thirds
is the principal protein inside of red blood cells and accounts for one-third of the mass of the cell.
Hemoglobin
During the conversion of CO2 into bicarbonate, hydrogen ions liberated in the reaction are buffered by (?), which is reduced by the dissociation of oxygen.
hemoglobin
This buffering helps maintain (?).
normal pH
The process is reversed in the (?) to re-form CO2, which then can diffuse into the air sacs to be exhaled into the atmosphere.
pulmonary capillaries
This process is discussed in detail in the chapter on the respiratory system.
The (?) is regulated in the blood by sodium, as are the phosphate ions.
bicarbonate
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.
NaCl
When carbonic acid comes into contact with a strong base, such as NaOH, (?) are formed.
bicarbonate and water
As with the (?), a weak acid or weak base captures the free ions, and a significant change in pH is prevented.
phosphate buffer
Bicarbonate ions and carbonic acid are present in the blood in a (?) ratio if the blood pH is within the normal range.
20:1
With 20 times more (?) than carbonic acid, this capture system is most efficient at buffering changes that would make the blood more acidic.
bicarbonate
This is useful because most of the body’s metabolic wastes, such as (?), are acids.
lactic acid and ketones
(?) in the blood are controlled by the expiration of CO2 through the lungs.
Carbonic acid levels
In red blood cells, (?) forces the dissociation of the acid, rendering the blood less acidic.
carbonic anhydrase
Because of this acid dissociation, (?) is exhaled.
CO2
The level of bicarbonate in the blood is controlled through the (?), where bicarbonate ions in the (?) are conserved and passed back into the blood.
renal system
renal filtrate
However, the (?) is the primary buffering system of the IF surrounding the cells in tissues throughout the body.
bicarbonate buffer
The (?) contributes to the balance of acids and bases in the body by regulating the blood levels of carbonic acid.
respiratory system
(?) in the blood readily reacts with water to form (?), and the levels of (?) in the blood are in equilibrium.
CO2; carbonic acid
CO2 and carbonic acid
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 (?).
CO2
blood pH
Increasing the (?) (which you might feel the “urge” to do after holding your breath) allows you to exhale more CO2.
rate and/or depth of respiration
The loss of (?) from the body reduces blood levels of (?) and thereby adjusts the pH upward, toward normal levels.
CO2
carbonic acid
As you might have surmised, this process also works in the (?).
opposite direction
Excessive deep and rapid breathing (as in hyperventilation) rids the blood of CO2 and reduces the level of carbonic acid, making the blood too (?).
alkaline
This brief (?) can be remedied by rebreathing air that has been exhaled into a paper bag.
alkalosis
Rebreathing exhaled air will rapidly bring (?) down toward normal.
blood pH
The chemical reactions that regulate the levels of CO2 and carbonic acid occur in the (?) when blood travels through the (?).
lungs
lung’s pulmonary capillaries
Minor adjustments in breathing are usually sufficient to adjust the pH of the blood by changing how much (?) is exhaled.
CO2
In fact, doubling the respiratory rate for less than 1 minute, removing “extra” CO2, would increase the blood pH by (?).
0.2
This situation is common if you are (?) over a period of time.
exercising strenuously
To keep up the necessary energy production, you would produce excess (?) (and lactic acid if exercising beyond your aerobic threshold).
CO2
In order to balance the increased acid production, the respiration rate goes up to remove the (?). This helps to keep you from developing (?).
CO2
acidosis
The body regulates the respiratory rate by the use of (?), which primarily use CO2 as a signal.
chemoreceptors
Peripheral blood sensors are found in the walls of the (?).
aorta and carotid arteries
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.
CO2
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.
medulla oblongata
(?), or abnormally elevated blood levels of CO2, occurs in any situation that impairs respiratory functions, including pneumonia and congestive heart failure.
Hypercapnia
Reduced breathing (?) due to drugs such as morphine, barbiturates, or ethanol (or even just holding one’s breath) can also result in hypercapnia.
hypoventilation
(?), 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.
Hypocapnia
