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The ph scale

This figure shows a vertical arrow with the top half showing the basic scale and the bottom half showing the acidic scale. Different chemicals and their pH are also shown.


The pH of human blood normally ranges from 7.35 to 7.45, although it is typically identified as pH 7.4. At this slightly basic pH, blood can reduce the acidity resulting from the carbon dioxide (CO 2 ) constantly being released into the bloodstream by the trillions of cells in the body. Homeostatic mechanisms (along with exhaling CO 2 while breathing) normally keep the pH of blood within this narrow range. This is critical, because fluctuations—either too acidic or too alkaline—can lead to life-threatening disorders.

All cells of the body depend on homeostatic regulation of acid–base balance at a pH of approximately 7.4. The body therefore has several mechanisms for this regulation, involving breathing, the excretion of chemicals in urine, and the internal release of chemicals collectively called buffers into body fluids. A buffer    is a solution of a weak acid and its conjugate base. A buffer can neutralize small amounts of acids or bases in body fluids. For example, if there is even a slight decrease below 7.35 in the pH of a bodily fluid, the buffer in the fluid—in this case, acting as a weak base—will bind the excess hydrogen ions. In contrast, if pH rises above 7.45, the buffer will act as a weak acid and contribute hydrogen ions.

Homeostatic imbalances

Acids and bases

Excessive acidity of the blood and other body fluids is known as acidosis. Common causes of acidosis are situations and disorders that reduce the effectiveness of breathing, especially the person’s ability to exhale fully, which causes a buildup of CO 2 (and H + ) in the bloodstream. Acidosis can also be caused by metabolic problems that reduce the level or function of buffers that act as bases, or that promote the production of acids. For instance, with severe diarrhea, too much bicarbonate can be lost from the body, allowing acids to build up in body fluids. In people with poorly managed diabetes (ineffective regulation of blood sugar), acids called ketones are produced as a form of body fuel. These can build up in the blood, causing a serious condition called diabetic ketoacidosis. Kidney failure, liver failure, heart failure, cancer, and other disorders also can prompt metabolic acidosis.

In contrast, alkalosis is a condition in which the blood and other body fluids are too alkaline (basic). As with acidosis, respiratory disorders are a major cause; however, in respiratory alkalosis, carbon dioxide levels fall too low. Lung disease, aspirin overdose, shock, and ordinary anxiety can cause respiratory alkalosis, which reduces the normal concentration of H + .

Metabolic alkalosis often results from prolonged, severe vomiting, which causes a loss of hydrogen and chloride ions (as components of HCl). Medications also can prompt alkalosis. These include diuretics that cause the body to lose potassium ions, as well as antacids when taken in excessive amounts, for instance by someone with persistent heartburn or an ulcer.

Chapter review

Inorganic compounds essential to human functioning include water, salts, acids, and bases. These compounds are inorganic; that is, they do not contain both hydrogen and carbon. Water is a lubricant and cushion, a heat sink, a component of liquid mixtures, a byproduct of dehydration synthesis reactions, and a reactant in hydrolysis reactions. Salts are compounds that, when dissolved in water, dissociate into ions other than H + or OH . In contrast, acids release H + in solution, making it more acidic. Bases accept H + , thereby making the solution more alkaline (caustic).

The pH of any solution is its relative concentration of H + . A solution with pH 7 is neutral. Solutions with pH below 7 are acids, and solutions with pH above 7 are bases. A change in a single digit on the pH scale (e.g., from 7 to 8) represents a ten-fold increase or decrease in the concentration of H + . In a healthy adult, the pH of blood ranges from 7.35 to 7.45. Homeostatic control mechanisms important for keeping blood in a healthy pH range include chemicals called buffers, weak acids and weak bases released when the pH of blood or other body fluids fluctuates in either direction outside of this normal range.

Questions & Answers

what is systematic anatomy?
nsofor Reply
it is the anatomy or study of a certain body system for example the digestive system. or respiratory system.
It is a group of structure that work together to perform a unique function..
describe the division of anatomy and physiology
Vissa Reply
the what and the how
anatomy is the structure. physiology is the function.
what is homeostasis?
the balance if everything in your body
is the tendency of the body to maintain the internal environment
It is the ability of systems and living organisms to adjust its internal environment
how does a saggital plane look like and a frontal plane
susan Reply
saggital plane divides left and right.. frontal plane divides front and back.. I'm trying to upload a picture but idk how.
tnx sis
what is a neurones?
Angella Reply
how many systems are there in human
It is a cell that specialized to conduct nerve impulse
What is ovulation
Joy Reply
Ovulation is release of mature ovum from ovary
what is physiology
Firdaus Reply
The study of how e body systems or structures function and interrelate with each other
what is the composition of the ground substance?
Nana Reply
large carbohydrates and proteins which is known as acid mucopolysacchrides
you guy welcome
Hi guys am new here
how does the negative feedback helps in maintaining body temperature at its normal range
I need good sites that I can test myself on chapters 1,3,4,5. I have an exam tomorrow
please can you kindly share your questions here after the exams please
What causes the banding pattern seen in the muscle fibril under the electron microscope
what organelles controls protein synthesis?
Katie Reply
hmm...the ribosomes?
are ribisomes made in the rRNA?
nop they are produced by cells of Nucleolus
Is there anything about nerve and muscle physiology?
AMEL Reply
how many types of epithelial tissues do we have
Benedicta Reply
Epithelial tissues are grouped in two ways.. ●Based on the number of layers.(Simple and stratified ) ●Based of their shapes(Squamous,Cuboidal and columnar) Also we can have a combination of the two,say,simple Squamous
awww thanks dearie😊😊😊💖
describe the function and structure of blood
Belindah Reply
It has four main components: plasma, red blood cells, white blood cells, and platelets. Blood has many different functions, including: transporting oxygen and nutrients to the lungs and tissues.
well answered arlena.. #thumbs up#
have u some prepared MCQs on CNS and Special senses physiology?
Anyone got the human heart labelled diagram
you can download from Google... I don't think it's possible to share docs or files here
ok thanks
you're welcome..
Thank you
what's an easy way of knowing the different structures of tissues what they do and where their found
are you know function of the blood?
to carry nutrients to parts of the body
well Lola the easiest way is to attributes the tissues based on their funcs(especially those with similar funcs)..you can create your own mnemonics that will help you rmba em..and the a random reading.. it helps you retain em better
and try random reading*
ok thanks
funtction of WBCs
bone tissue
Blood is a fluid connective tissue made up of blood cells suspended in plasma, which is the fluid part of blood. The cell include erthrocytes, leukocytes and thrombocytes. Blood is responsible for transportation of substances around e body eg hormones oxygen and substances
Blood is responsible for defence... As it acts as a defense mechanism against microbes through action of leukocytes which destroy any foreign substances
identy the vein and arteries of coronary circulation
abdifatah Reply
to be a nurse a doctor or just to understand the body
Drew Reply
what is the basic part of life
cell remains the basic unit of life...
A cell is the basic part of life
The coronary arteries branches off of what
Ada Reply
rephrase your question
Discuss Active Myosin contraction theory
Xavier Reply

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