18 pH of blood
pH of blood
An important part of being healthy is for the blood to maintain a normal
degree of acidity or alkalinity. The acidity or alkalinity of any solution,
including blood, is indicated on the pH scale. The pH scale ranges from 0
(strongly acidic) to 14 (strongly basic or alkaline). A pH of 7.0, in the
middle of this scale, is neutral. Blood is normally slightly basic, with a
normal pH range of about 7.35 to 7.45. Usually, the body maintains the pH of
blood close to 7.40.
A doctor evaluates a person's acid-base balance by measuring the pH and
levels of carbon dioxide (an acid) and bicarbonate (a base) in the blood.
Blood acidity increases when the
Level of acidic compounds in the body rises (through increased intake or
production, or decreased elimination)
Level of basic (alkaline) compounds in the body falls (through decreased
intake or production, or increased elimination)
Blood alkalinity increases when the level of acid in the body decreases
or when the level of base increases.
Control of Acid-Base Balance
The body's balance between acidity and alkalinity is referred to as
acid-base balance.
The blood's acid-base balance is precisely controlled because even a
minor deviation from the normal range can severely affect many organs. The body
uses different mechanisms to control the blood's acid-base balance. These
mechanisms involve the
Lungs
Kidneys
Buffer systems
Role of the lungs
One mechanism the body uses to control blood pH involves the release of
carbon dioxide from the lungs. Carbon dioxide, which is mildly acidic, is a
waste product of the processing (metabolism) of oxygen and nutrients (which all
cells need) and, as such, is constantly produced by cells. It then passes from
the cells into the blood. The blood carries carbon dioxide to the lungs, where
it is exhaled. As carbon dioxide accumulates in the blood, the pH of the blood
decreases (acidity increases).
The brain regulates the amount of carbon dioxide that is exhaled by
controlling the speed and depth of breathing (ventilation). The amount of
carbon dioxide exhaled, and consequently the pH of the blood, increases as
breathing becomes faster and deeper. By adjusting the speed and depth of
breathing, the brain and lungs are able to regulate the blood pH minute by
minute.
Role of the kidneys
The kidneys are able to affect blood pH by excreting excess acids or
bases. The kidneys have some ability to alter the amount of acid or base that
is excreted, but because the kidneys make these adjustments more slowly than
the lungs do, this compensation generally takes several days.
Buffer systems
Yet another mechanism for controlling blood pH involves the use of
chemical buffer systems, which guard against sudden shifts in acidity and
alkalinity. The pH buffer systems are combinations of the body's own naturally
occurring weak acids and weak bases. These weak acids and bases exist in pairs
that are in balance under normal pH conditions. The pH buffer systems work
chemically to minimize changes in the pH of a solution by adjusting the
proportion of acid and base.
The most important pH buffer system in the blood involves carbonic acid
(a weak acid formed from the carbon dioxide dissolved in blood) and bicarbonate
ions (the corresponding weak base).
Types of Acid-Base Disorders
There are two abnormalities of acid-base balance:
Acidosis: The blood has too much acid (or too little base), resulting in
a decrease in blood pH.
Alkalosis: The blood has too much base (or too little acid), resulting
in an increase in blood pH.
Acidosis and alkalosis are not diseases but rather are the result of a
wide variety of disorders. The presence of acidosis or alkalosis provides an
important clue to doctors that a serious problem exists.
Types of acidosis and alkalosis
Acidosis and alkalosis are categorized depending on their primary cause
as
Metabolic
Respiratory
Metabolic acidosis and metabolic alkalosis are caused by an imbalance in
the production of acids or bases and their excretion by the kidneys.
Respiratory acidosis and respiratory alkalosis are caused by changes in
carbon dioxide exhalation due to lung or breathing disorders.
People can have more than one acid-base disorder.
Compensation for acid-base disorders
Each acid-base disturbance provokes automatic compensatory mechanisms
that push the blood pH back toward normal. In general, the respiratory system
compensates for metabolic disturbances while metabolic mechanisms compensate
for respiratory disturbances.
At first, the compensatory mechanisms may restore the pH close to
normal. Thus, if the blood pH has changed significantly, it means that the
body's ability to compensate is failing. In such cases, doctors urgently search
for and treat the underlying cause of the acid-base disturbance.
What makes blood pH change or become abnormal?
Health problems that make your body too acidic or too alkaline are
usually linked to the pH of blood. Changes in your normal blood pH might be a
sign of certain health conditions and medical emergencies. These include:
asthma
diabetes
heart disease
kidney disease
lung disease
gout
infection
shock
hemorrhage (bleeding)
drug overdose
poisoning
2. https://www.healthline.com/health/ph-of-blood#changes-in-blood-p-h
Published on 9 May 2024