<< 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

tell the easyst way to learn anatomy
Khaliif Reply
hello im new here, im a nursing student
SHUGA Reply
ooh
shiv
welcome
shiv
wlcm
Rahil
dub
Ndowmi
maleria
Ndowmi
Anopheles
shiv
welcome shuga
Om
please am new here. Am a nurse awaiting to be posted .
Ntiamoah
hi I'm new here too
faleke
Feleke Sharon Welcome
FAKE
FAKE DrLUPO thank you
faleke
hello guys
Chuks
hello guys 🤗
Sneha
hello
Chuks
whose in Nigeria
Chuks
🙋🙋
faleke
what is inner breeding
Vijay Reply
you don't have any answer
Vijay
please don't waste my time
Vijay
wait
shiv
inbreeding is mating or breeding with organism that are genetically related
shiv
s
Pankaj
who this SRY
Pankaj
inner breeding is breeding among the same species of organisms
Anna
*inbreeding
Anna
yes same speciesor same genetic organism
shiv
description of the menstruation cycle
Namyalo Reply
explain the menstruation cycle
Namyalo
explain the menstrual cycle
Ugo
menstrual cycle is came due to FSH and LH
shiv
fsh
Ndowmi
Description of menestraul cycle
Amos Reply
what is the anatomy
FAKE Reply
Anatomy is study of structure of organs.
Sneha
thanks
FAKE
The scientific study of the structure of human or animal bodies.
FAKE
I was confused as to which one would be right and I asked
FAKE
My answer and you answer both are right.
Sneha
i want to improve my study i like this app i interest physiology and anatomy
Su Reply
I also like this app am really interested in learning anatomy and physiology.
Johny
I have this book with my anatomy class it's awesome! also if look at crashcourse anatomy on you tube!
AMY
what the name
isaiah
umesh. rede
Rede
what is heart and long type answer
Lalita Reply
its a organ in the body
ay
describe about hear chambers.. valves.. arteries.. veins.. circulation.. inferior/superior venacava, aorta., tricuspid valve, mitral valve. pulmonary artery/vein, how oxigenation occur,systolic presure diastolic pressure.. stroke volume,cardiac output, ets.. heart located in which place, describe it
Sanjith
if you describe what I cited up, thogh you can write a long type answer about heart
Sanjith
autonomic functions took over
Vanarith Reply
What did they take over?
Eric
what is the average volume of blood in men and why does it varrie from women?
Esther Reply
what is the average volume of blood in men
Esther
5to6liter
Sarita
5to6liter dt
Sarita
umesh. rede
Rede
what is the definition of anatomy
Noriah Reply
Search google
killer
^of
chieng
The study of the structure or internal workings of something. "Machiavelli's anatomy 
Eric
post. communi. artey... this may be true 70% hope correct
vikash Reply
what is the strongest muscle in the human body?
Robiam Reply
masseter muscles
Om
yes masseter..... jaw muscle is the strongest muscle..
Sarita
Kidneys have direct effect on which
The function the loop
function of the loop?
Eric
the function of the loop of henle is to increase surface area for reasorbtion.
Conan
what is an atom and it's functions
Jany
An atom is the basic building block of matter.
Eric
which is the largest digestive gland in our body
Shubu
stomach
Barbara
What is the smallest bone in the body of the human being?
Kelvin
pisiform
Chulit
how many found in the head
obakunmi
4
ayesha
I think stapes is the smallest bone in human body
Sanjith
22
Sanjith
yes stapes is the smallest bone of our body
Sarita
the smallest bone is stapes in the ear
Isaac
smallest bone in human body is stapes or stirrup present in the middle ear ..
Om
stapes yes
Robiam
blood work and purification and it leads to cardiac systen
vikash
explain function of kidney
Noel Reply
filtration
Naqash
Secretagogue hormones
Sa
Organising water
Sa
hi
Jany
they help in the reproduction of sperms
Jany
Their main job is to cleanse the blood of toxins and transform the waste into urine. The kidney have several functions though. I think it is important to know them, but not in depth. But to truly understand the kindney's over all importance.
Eric
I meant to say the kidneys have.
Eric
how kidney help in reprdution of sperms?
Amir
the basic and functinal unit of kidney is Nephron
Sanjith

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