# 26.4 Acid-base balance

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By the end of this section, you will be able to:
• Identify the most powerful buffer system in the body
• Explain the way in which the respiratory system affects blood pH

Proper physiological functioning depends on a very tight balance between the concentrations of acids and bases in the blood. Acid-balance balance is measured using the pH scale, as shown in [link] . A variety of buffering systems permits blood and other bodily fluids to maintain a narrow pH range, even in the face of perturbations. A buffer is a chemical system that prevents a radical change in fluid pH by dampening the change in hydrogen ion concentrations in the case of excess acid or base. Most commonly, the substance that absorbs the ions is either a weak acid, which takes up hydroxyl ions, or a weak base, which takes up hydrogen ions.

## Buffer systems in the body

The buffer systems in the human body are extremely efficient, and different systems work at different rates. It takes only seconds for the chemical buffers in the blood to make adjustments to pH. The respiratory tract can adjust the blood pH upward in minutes by exhaling CO 2 from the body. The renal system 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.

The buffer systems functioning in blood plasma include plasma proteins, phosphate, and bicarbonate and carbonic acid buffers. The kidneys help control acid-base balance by excreting hydrogen ions and generating bicarbonate that helps maintain blood plasma pH within a normal range. Protein buffer systems work predominantly inside cells.

## Protein buffers in blood plasma and cells

Nearly all proteins can function as buffers. Proteins are made up of amino acids, which contain positively charged amino groups and negatively charged carboxyl groups. The charged regions of these molecules can bind hydrogen and hydroxyl ions, and thus function as buffers. Buffering by proteins accounts for two-thirds of the buffering power of the blood and most of the buffering within cells.

## Hemoglobin as a buffer

Hemoglobin is the principal protein inside of red blood cells and accounts for one-third of the mass of the cell. During the conversion of CO 2 into bicarbonate, hydrogen ions liberated in the reaction are buffered by hemoglobin, which is reduced by the dissociation of oxygen. This buffering helps maintain normal pH. The process is reversed in the pulmonary capillaries to re-form CO 2 , which then can diffuse into the air sacs to be exhaled into the atmosphere. This process is discussed in detail in the chapter on the respiratory system.

## Phosphate buffer

Phosphates are found in the blood in two forms: sodium dihydrogen phosphate ( ${\text{Na}}_{2}{\text{H}}_{2}{\text{PO}}_{4}{}^{-}$ ), which is a weak acid, and sodium monohydrogen phosphate ( ${\text{Na}}_{\text{2}}{\text{HPO}}_{\text{4}}^{\text{2-}}$ ), which is a weak base. When ${\text{Na}}_{\text{2}}{\text{HPO}}_{\text{4}}^{\text{2-}}$ comes into contact with a strong acid, such as HCl, the base picks up a second hydrogen ion to form the weak acid ${\text{Na}}_{2}{\text{H}}_{\text{2}}{\text{PO}}_{\text{4}}{}^{-}$ and sodium chloride, NaCl. When ${\text{Na}}_{2}{\text{HPO}}_{\text{4}}^{2}{}^{-}$ (the weak acid) comes into contact with a strong base, such as sodium hydroxide (NaOH), the weak acid reverts back to the weak base and produces water. Acids and bases are still present, but they hold onto the ions.

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Sentamu
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Sentamu
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Shubham
any one elaborate fr me foramens of the skull and features which they transmit
Sentamu
icant undrestand plz
try to read I hop you will understand
state and explain 20 radiology uses
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Mike
study up on the basics of the periodic chart, learn bones and muscles attachments, and learn muscles. Those take the longest to memorize. After that it should be a little easier.
Toni
what are the two types of body cells
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Claire
malnutrition refers to faulty nutrition resulting from malabsorption,poor diet or overeating. Sometimes too these food do not contain all the six food nutrients in their right proportion.
Yakubu
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Claire
welcome
Yakubu
Will u be malnourished?
Baigwa
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Budumari
gabriel
Nothing! Radiology it means the study or using of radiation in medical science it can be 1.diagnose or treatment diagnosed radiology! x- ray. ultrasound. ct-scan. mammogram. MRI. 2. treatmen- radiation oncology, like Cobalt 60. and nuclear medicine
Larry
what is X-ray?
Nissar
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KUNDAN
How the nervous system develops
From the cells at the back of an embryo
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breifly explain anatomy of thorax
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Konneh
how many bon of human being
Nura
206
John
how to study for the skeletal system
ryaisha
and anatomy
ryaisha
I really need sources immediately
ryaisha
I printed out all the different bones. Put them in the see through protective sheaths and got dry erase markers. I could right on them and erase to help me learn to spell the names of markings and bones.
Toni
Or go to a book store, Barnes and Noble(doesn't have to be this) and they have coloring books for anatomy. \$16. Really helpful.
Toni
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ryaisha
*what are
ryaisha
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Roopa
I prefer diagrams, pictures that lay out each step with the information in each step. For Example: how action potential creates muscles to move. A pictured diagram gives me a better understanding of how each piece plays a role in each step of the process.
Toni
Also for basics, such as memorizing vocab. Flash cards are great. Don't become discouraged if you don't get them all right the first times through. The more you go through them, your brain will remember pieces of information from each and help you to pull out the information 😉
Toni
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ryaisha
what is the functions of the lips in human
could I say sensation?
Sovilace
kissing
Obrian
for protection
Omar
Lips assist in speech and eating
Cindy
Too many easy questions. Which bones are the axial and appendicular? What are the abbreviations for TEE, TTE, AED, A-Mode, B-Mode, and LTH? What is the difference between hypothalamus and thalamus? Where is the parathyroid located? How many True Ribs do we have?
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Inam
what is anatomy
anatomy is scientific study of body structures and how they relate to each other
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Are there other functions of the nucleolus apart from synthesis of RNA and formation of ribosomes
plays a role in cell response to stress
airiz
what is angle of auscultation
Anatomy which is the study of the human body structure has a couple of reasons it is been studied It helps to discover genetic disease cytology And histology which is the study of tissues Physiology is the study of function of the human cells It helps to know how the different body part works Its helps to know how part of the brain works And lastly It gives the essential to understand more about anatomy
describe the external features of a spinal cord
Spinal nerves emerge in pairs, one from each side of the spinal cord along its length. The cervical nerves form a plexus (a complex interwoven network of nerves—nerves converge and branch). The cervical enlargement is a widening in the upper part of the spinal cord (C 4–T 1). Nerves that extend in
Inam
Hormones regulate certain target cell responses. These can include which of the following?
describe the external features of spinal cord
okoche