Oxygen is essential for respiration because the body uses it to ‘burn’ food molecules. Animals take in oxygen when inhaling and give off carbon dioxide when exhaling. Oxygen occurs naturally in the air. It makes up almost 21% of the total gases in air, with most of the remaining gas in the air being nitrogen which is physiologically not active. Human beings inhaled air contains 21% oxygen, and the exhaled breath contains about 16%.
Oxygen plays several important roles in the human body. It is important in the transformation of food into energy. This process is known as cellular respiration. During this process, a substance in the body cells called the mitochondria uses oxygen to help break down glucose which is the end product of the food we into a usable fuel source. This provides the energy (calories) needed to live. This process is very vital and is basically the foundation of life as survival is impossible without oxygen.
Why is oxygen important in the body?
While oxygen is important in the body, there are some body parts where it is much more important.
- First is the brain. The brain only makes up 2% of the total body weight, but it is responsible for 20% of the body’s total oxygen consumption. This is because it needs a lot of energy to perform its many functions. The brain cells need around 0.1 calories per minute just to perform its basic functions like controlling breathing, the cardiovascular center, regulation of temperature, etc for human survival. It needs 1.5 calories per minute when a person is actively using the brain like in thinking hard. To create that energy, the brain needs a lot of oxygen. The brain cells start to die, which means severe brain damage if it is deprived of oxygen for as little as 3 minutes.
- The heart muscles: The cells in the heart also need oxygen to survive. This is very important because they need energy to work very hard to ensure the heart is always pumping blood to all the body organs, especially the brain.
- The immune system: cells in the immune system are fueled by oxygen to function properly. Breathing oxygen purified through something like an air sanitizer makes it easier for the immune system to use the oxygen, and low oxygen levels suppress parts of the immune system.
In summary, most body cells begin to die off after a particular period of time without oxygen. While there are varying figures for each cell, the Brain cells are known to start dying after 3 minutes of no oxygen (a state called hypoxia), the Kidneys and liver cells start dying off after about 15-20 min of hypoxia, for the Skeletal muscles, it is about 60-90 minutes, the smooth muscles of the blood vessels can tolerate about 24-72 hours of hypoxia, while the hair and nails can stay several days in a state of hypoxia.
How does the body get oxygen?
The oxygen in the air we breathe is delivered to the cells in the body through the function of the respiratory system. The respiratory system starts at the nose and mouth and continues through the airways and the lungs. The air we breathe enters the respiratory system through the nose and mouth and passes down the throat (pharynx) and through the voice box, or larynx. The pharynx is like a tube that delivers air from the mouth and nose to the trachea (windpipe), which acts as a passage leading to the lungs. The trachea is the largest airway and branches into two smaller airways: the left and right bronchi, which lead to the two lungs.
The bronchi themselves inside the lungs branch many times into smaller airways, ending in the narrowest airways (bronchioles). There are thousands of small air sacs (alveoli) are at the end of each bronchiole. Together, the millions of alveoli of the lungs form a surface of more than 100 square meters. Each alveolus is surrounded by tiny blood vessels called capillaries that are linked to the bigger blood vessels coming out of the heart.
The air we inhale gets to the lungs through the above passages, it then gets to the tiny air sacs in the lungs and the oxygen in the air diffuses from the lungs into the tiny blood vessels around the air sac. Once in the blood, the oxygen is bound to another molecule called hemoglobin in red blood cells, then taken through the bigger blood vessels to the heart. The heart then pumps it to the whole body to use for energy production.
How do we measure the oxygen level in the blood?
There are several ways to measure the oxygen level in the blood. These are:
- pulse oximetry
- blood gas test
- long term oxygen therapy (LTOT) assessment
- hypoxic challenge (fitness-to-fly) test
The most popular and easiest method is the use of the pulse oximeter. The Pulse oximetry measures how much oxygen the hemoglobin in the red blood cells is carrying. This is called the oxygen saturation and is a percentage (scored out of 100). It is a simple, painless test which uses a sensor or pulse oximeter placed on the fingertip or earlobe.
The oximeter display shows the percentage of oxygen in the blood. For someone who is healthy, the normal blood oxygen saturation level will be around 95–100%.
Is an oxygen level of 94 bad?
The oxygen level may be lower in some people with lung conditions, even when they are feeling well. Asa rule of thumb when interpreting the oxygen level:
Values 96 to 100% are regarded as normal and there is no need for concern.
A value of 95%, is considered acceptable
A value of 93 to 94% is borderline and not regarded as normal, there may be need to seek a doctor’s advice if the oxygen level remains at this level
Any oxygen level less than 93% is bad and should seek immediate evaluation by the doctor
So if your oxygen level is consistently 94% as measured by a pulse oximeter, you may need to see your doctor to make sure nothing is wrong with your lungs.