Archive for the ‘viruses and bacteria’ Tag

Admirable Clarity


How many cells are there in our body? This simple question deserves a simple answer. Some types of cells are easy to spot, while others–such as tangled neurons–weave themselves up into obscurity. Even if you could count ten cells each second, it would take you tens of thousands of years to finish counting. Plus, there would be certain logistical problems you would encounter along the way to counting all the cells in your body; for example, chopping your own body up into tiny patches for microscopic viewing.

If scientists can’t count all the cells in a human body, how can they estimate it? The mean weight of a cell is 1 nanogram. For an adult man weighing 70 kilograms, simple arithmetic would lead us to conclude that man has 70 trillion cells. Cells are the building blocks of the human body, but what is the total number of cells in a human body remains still a riddle. It is estimated that the body of an average person contains around 30 to 40 trillion cells, but scientists do not yet know the exact number and it also depends on whether or not one include the bacteria that are present in and on our bodies. The majority of the cells in our bodies are red blood cells. They make up over 80 percent of our body in number and comprise only around 4 percent of total body mass. This is because red blood cells only measure on average 8 micrometers in diameter, which is 10 times small in diameter than an average human hair.

The average size of a fat cell is 100 micrometers. The fat cells make up nearly 19 percent of our body mass. They contribute only under 0.2 percent to the total cell number. Calculating the actual cell number of the five most common cell types in an average adult male, which account for 97 percent of the cells in the body, the estimation is about 30 trillion cells, of which red blood cells make up 84 percent.

The human cells are not the only cells in our bodies. There are 10 times as many bacteria in our bodies than human cells and scientists estimate this number to be around 38 trillion. Although, large in number, bacteria are much smaller than human cells, and they actually make up only 200 grams of our total body mass. We are as much bacteria as we are human, bringing the total number up to around 70 trillion. The bacteria present in our body counts more in number than human cell, except these measure 200 gm only and that is really amazing.

This is not a final number, but it is a very good start. While it is true that people may vary in size and thus vary in their number of cells; adult humans do not vary by orders of magnitude except in the movies.

Each of our cells has over a hundred thousand machines within it, including DNA, which is a molecular machine that is not alive. DNA is composed of molecules that are not alive which are composed of atoms that are also not alive. In actual fact, our body is a type of cybernetic organism made of both organic and biomechatronic body parts.


Stress and Immunity

Stressed Woman

Stressed Woman

In times of peak stress our bodies react by producing fight or flight responses. This primal reaction has been a part of human instinct since the first people were faced with a hungry saber tooth tiger back in the Ice Age. Fight or flight responses prepare our systems for defense by releasing the hormones cortisol and adrenaline. Our heart rate speeds up and our digestive system and immune system slow down. Large amounts of oxygen and blood are sent to our muscles so we can easily spring into action.

As most modern day humans participate in fairly normal lives free from the need to defend ourselves from life threatening situations, one would think that the fight or flight instinct is becoming extinct. The opposite is actually true. Humans are experiencing fight or flight in response to other stressors in our lives, like work, relationships, and financial triggers. Because these stresses tend to hang around rather than present themselves and quickly disappear, the relaxation response that is supposed to follow a fight or flight instinct doesn’t always occur. 

Our bodies remain in high gear and the stress hormones remain in our systems far longer than intended. Stress can negatively affect our immune system because during periods of stress it is perpetually in low gear and instead of adapting, it just begins to waste away. 

People that experience chronic stress are more susceptible to headaches, colds, flu and other minor illnesses.  Additionally, because the immune system loses its ability to fight viruses and bacteria, risks of contracting autoimmune disorders, cancer and other diseases increases substantially. 

Activities like yoga, tai chi, and meditation can be useful tools for relieving stress levels and reducing the amount of cortisol present in our bodies. For periods of chronic stress: exercise, counseling, and even the strength of positive relationships can help to reduce feelings of anxiety and tension. 

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