<< Chapter < Page Chapter >> Page >
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.

The ph scale

This table gives examples of solutions from PH of zero to 14. Examples of solutions with a PH of zero include battery acid and strong hydrofluoric acid. An example of a solution with a pH of one is the hydrochloric acid secreted by the stomach lining. Examples of solutions with a PH of two include lemon juice and vinegar. Examples of solutions with a PH of three include grapefruit juice, orange juice and soda. Examples of solutions with a PH of four include tomato juice and acid rain. Examples of solutions with a PH of five include soft drinking water and black coffee. Examples of solutions with a PH of  six include urine and saliva. An example of a solution with a PH of seven is pure water. An example of a solution with a PH of eight is sea water. An example of a solution with a PH of nine is baking soda. Examples of solutions with a PH of ten  include saline lake water and milk of magnesia. An example of a solution with a PH of eleven is an ammonia solution. An example of a solution with a PH of twelve is soapy water. Examples of solutions with a PH of  thirteen include bleach and oven cleaner. An example of a solution with a PH of fourteen is liquid drain cleaner.
This chart shows where many common substances fall on the pH scale.

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 ( Na 2 H 2 PO 4 ), which is a weak acid, and sodium monohydrogen phosphate ( Na 2 HPO 4 2- ), which is a weak base. When Na 2 HPO 4 2- comes into contact with a strong acid, such as HCl, the base picks up a second hydrogen ion to form the weak acid Na 2 H 2 PO 4 and sodium chloride, NaCl. When Na 2 HPO 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.

Questions & Answers

what is meant by control center?
Freeman Reply
what is anatomy
Ajibola Reply
is the study of the structure of the body and their relationship to each refers to the shapes iyo sizes
Khadar
what is a blastomere?
Toluba Reply
In biology, a blastomere is a type of cell produced by cleavage (cell division) of the zygote after fertilization and is an essential part of blastula formation.
Adnan
what is cell
Shivaani
Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. ... Cells have many parts, each with a different
Adnan
function
Adnan
cell is a membrane bound unit that contains the fundamentals molecules of life
Sushma
A1
Adnan
excellent
Adnan
movement,reproduction, excretion, respiration ,growth ,nutrition, response to external stimuli.
Sushma
good
Adnan
sister excellent
Adnan
questions pushy ja sukty hy kya
Maryam
jwab forun milta hy ya ak do din k bad
Maryam
Maryam Riaz sister what you say
Adnan
i want to say that k kush questions k answer mil sukty hy mjhy
Maryam
inshallah
Adnan
zaror mere behen
Adnan
question kari
Adnan
hn mil mil sakte h na esly
Ziya
Which muscle of the gluteal region originates from lumber spine? a. Gluteus medius b. Psoas major c. Iliacus d. Gluteus maximus
Maryam
sweet sister's
Adnan
question tu kari Inshallah Allah behtar kariga
Adnan
to mcqs kia to hy
Maryam
answer ni mila abhi
Maryam
wait sister
Adnan
what is the functional unit of kidneys
Khadar
nephron is the functional unit of kidney
Maryam
Maryam Riaz sister option. d. gluteus maximus
Adnan
thanks
Maryam
sorry Maryam Riaz sister
Adnan
option b. psoas major
Adnan
right answer this one
Adnan
nephron is the functional unit of kidney
Ihsan
I discussed with to my teachers
Adnan
d
Ihsan
d. is right option bro
Adnan
yes
Ihsan
what is cell
Shilpa
cell is the smallest unit of life
Maryam
ok
Shilpa
Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. ... Cells have many parts, each with a different
Adnan
function
Adnan
Maryam Riaz sister I m clear option d. also right thank you ihan bro
Adnan
type structure function origin insertion action of muscles
DAMINI Reply
oxygn amount in our body
Tg Reply
A normal level of oxygen is usually 95% or higher. Some people with chronic lung disease or sleep apnea can have normal levels around 90%. The “SpO2” reading on a pulse oximeter shows the percentage of oxygen in someone's blood
Adnan
What is the difference between cytoplasmic and endoplasmic
Ajibola Reply
The cytoplasm is 90℅ water and 10℅ of organic and inorganic compounds. The cytoplasm contains mitochondria. ... Lysosomes of Cytoplasm contains 50 different enzymes that digest proteins, lipids, and nucleic acids. The endoplasmic reticulum produces process and transport proteins, lipids for all the
Adnan
tarsal are cube shaped broad and long whiles metatarsal they are longer than they are wide
Priscilla Reply
articular cartilage serve as shock absorber and also reduces friction
Priscilla
articular cartilage serve as shock absorber and also reduces friction
Priscilla
when a bone joint with another bone
Priscilla
to know how you body function to know the relationship between the body parts to know specific functions of a certain body parts
romeo Reply
To know our body function we shd know chemical secretion of our glands, we can map all the function of our body and also relation ship between the body parts.
KUSUMA
that z it kusuma
kanaku
can you get fungi infection by seating on a public toilet?
Calls Reply
explain how blood acts as a connective tissue in the body
Rymz Reply
how does blood act as a connective tissue in the body
Rymz
what is anatomy
Victoriah Reply
fat deficiency in the body
Agbor Reply
Explain how body exercise regulates blood pressure
dranimva Reply
thank you
Thelma
what is cillia and flangella
Kalah Reply
what are the proceduers of condactive system ?
Salua Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Anatomy & Physiology' conversation and receive update notifications?

Ask