Our Bodies Are Amazing!

Unless you were a Biology major in college, the likelihood of you knowing a lot about the internal workings of the body is pretty slim.

I recently found some information on our body's major systems that's very interesting.  It also illustrates just how amazing we all are!

The Skeletal System

- The longest bone is the 'femur', in the thigh. It makes up almost one quarter of the body's height.
- The smallest bone is the 'stirrup', deep in the ear. It is slightly larger than a grain of rice.
- The ears and end of the nose do not have bones. Their inner supports are cartilage or 'gristle', which is lighter and more flexible than bone. This is why the nose and ears can be bent.
- After death, cartilage decomposes faster than bone. This is why skulls have no nose or ears.

The Muscular System

- The longest muscle in the body is the sartorius, from the outside of the hip, down and across to the inside of the knee. It rotates the thigh outwards and bends the knee.
- The smallest muscle in the body is the stapedius, deep in the ear. It is only 5mm long and thinner than cotton thread. It is involved in hearing.
- The largest muscle in the body is the gluteus maximus, in the buttock. It pulls the leg backwards powerfully for walking, running and climbing steps.

The Circulatory System

- In a 70 year lifetime, the average human heart beats more than 2.5 billion times.
- About two million red blood cells are produced in the human body every second.
- Within a few droplets of whole blood, there are about 1 billion red blood cells.
- Blood takes about 20 seconds to circulate throughout the entire vascular system.
- Red blood cells may live for about 120 days circulating throughout the body, feeding trillions of other body cells.
- On average an adult human system of blood vessels is more than 60,000 miles long – that’s long enough to circle Earth twice.

The Nervous System

- The brain looks like a giant, wrinkled walnut.
- The brain and spinal cord are surrounded and protected by cerebrospinal fluid.

The Immune System

- The skin secretes antibacterial substances. These substances explain why you don't wake up in the morning with a layer of mold growing on your skin - most bacteria and spores that land on the skin die quickly.
- Tears and mucus contain an enzyme (lysozyme) that breaks down the cell wall of many bacteria.
- Lymph nodes contain filtering tissue and a large number of lymph cells. When fighting certain bacterial infections, the lymph nodes swell with bacteria and the cells fighting the bacteria, to the point where you can actually feel them. Swollen lymph nodes may therefore be a good indication that you have an infection of some sort.

The Digestive System

- Adults eat about 500 kg of food per year.
- 1.5 litres of saliva are produced each day.
- The esophagus is approximately 25 cm long.
- Muscles contract in waves to move the food down the esophagus. This means that food would get to a person's stomach, even if they were standing on their head.
- We get two sets of teeth; 20 'baby teeth' are replaced around age six with 32 'adult teeth'.
- The average adult has at least 7.5 meters of intestines in their body

The Respiratory System

- The right lung is slightly larger than the left.
- Hairs in the nose help to clean the air we breathe as well as warming it.
- The highest recorded "sneeze speed" is 165 km per hour.
- The surface area of the lungs is approximately the same size as a tennis court.
- The capillaries in the lungs would extend 1,600 km if placed end to end.
- We lose half a litre of water a day through breathing. This is the water vapor we see when we breathe onto glass.
- On average a person at rest usually breathes between 12 and 15 times a minute.
The breathing rate is faster in children and women than in men.

Pretty amazing stuff right? -CB