<< 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

Functions of the thoracic cage
Fereh Reply
protect all the organs and tissues from any impact or injury
Javier
why sickle cell carrier people don't get malaria
Boakye Reply
What is the amniotic fluid
bollywood Reply
structure of heart and it's function (10 mark )
Priyanka Reply
What is the best book on physiology?
cesar Reply
describe varicocele
malulu
what do you mean by peritoneum
Siba Reply
It is thick covering surrounding the abdomen
Awais
r8
how to become good in Anatomy and physiology
malulu
hi
Milkah
hlo
Wani
What are is the last solution to abdomen pain in pregnant women
Umoru
no it is in kidney
Tantray
Kk
Umoru
structure of heart and it's function
Priyanka
Serous membrane lining the cavity of the abdomen
bollywood
it is four lobs structure and it is triangular in shaped. it 's function pumping the blood
ABDULLAH
explain root of lungs
ABDULLAH
Glomerular pressure -capsule pressure -colloid osmosis pressure
malulu Reply
how to describe mechanism of micturition
malulu
spleen is important?
AKASH Reply
helpful in destruction of rbc
It is imp in storing blood and destruction of microbes and harmful particles
Awais
ty sir
AKASH
K
Umoru
what are the sources of glucose in the body
malulu
describe mechanism of micturition
malulu
Pancreatic hormones with function
mami Reply
Insulin, which helps to regulate our blood sugar levels.
Bb
glucagon which is antagonistic to insulin increase the blood glucose level,. Somatostatin help to regulate the levels of both insulin and glucagon
Ashish
thnks for helping
nimco
thanks
Narendra
what is a lymph node.?
AKASH
lymph nodes are small kidney shaped organs of the lymphatic system.
Trishauna
there are several hundred lymph nodes found mostly throughout the thorax and abdomen of the body with the highest concentrations in the auxiliary (armpit) and inguinal groin regions.
Trishauna
what is life
Yar Reply
life is the existence of an individual human being animal or plant
Furmose
how I join this
Ahmed
meaning
Furmose
to day I am new person and I can't participate questions so to morow I shall participate question sopleas excuse me
Ahmed
I had a debate earlier about nutrition and it didn't get a clear answer on that,can one tell me what the definition of nutrition.?
kelvin
the nutrition is nourish person is feeling an nutrition
Ahmed
I think nutrition is the process of taking food and using it for growth, metabolism and repair.
Methila
life is full of happy and sorrow
Sanamacha
life is achievement
Nandini
life is the nothing but god gave us 1 body. and we all service k in this body. The things which we do for the Survivation for this body I felt that this is called as the life
AKASH
Yes God gave us life but not god who gave us the life. Hope u understood what i meant by God n not god who gave life..... ?
laku
What's the question?
Sherman Reply
once you lose pigmentation can you ever get it back
Shannon Reply
s
Nandini
females are lesser prone to acne
Ritika Reply
why please expain
Janvi
described the skin
Yayra Reply
skin is outer covery of human body and it is largest organ of human body. it do three fauntion protection regulation and sensation of human body that is men fauntion of human skin it has seven part.
ABDULLAH
how thick is the epidermis?
Sovilace
the integumentary system is the largest system of the body 16% of body weight and 1.5 to 2m² in area
Trishauna
function of the endocrine system
Hamo Reply
produces hormones that plays specific functions
has endocrine gland calld as ductless gland so as produces hormones

Get the best Anatomy & Physiology course in your pocket!





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