The Digestive System

-An adult esophagus ranges from 10 to 14 inches in length, and 1 inch in diameter.

We make 1 to 3 pints of saliva a day.

-Muscles contract in waves to move the food down the oesophagus. This means that food would get to a person's stomach, even if they were standing on their head.

-It takes your mouth, esophagus, stomach, small intestine, large intestine, gallbladder, pancreas and liver just to digest a glass of milk.

- An adults stomach can hold approximately 1.5 liters of material.

-The average male will eat about 50 tons of food during his lifetime in order to sustain a weight of 150 pounds.

-Within the colon, a typical person harbors more than 400 distinct species of bacteria

The liver is the largest organ in the body and performs more than 500 functions.

The Nervous System

- There are more nerve cells in the human brain than there are stars in the Milky Way.

- If we lined up all the neurons in our body it would be around 600 miles long.

- There are 100 billion neurons in your brain alone.

- A newborn baby's brain grows almost 3 times during the course of its first year.

- The left side of human brain controls the right side of the body and the right side of the brain controls the left side of the body.

- A New born baby loses about half of their nerve cells before they are born.

- As we get older, the brain loses almost one gram per year.

- There are about 13, 500,00 neurons in the human spinal cord.

- The total surface area of the human brain is about 25, 000 square cm.

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.

Muscular System

- There are about 60 muscles in the face. Smiling is easier than frowning. It takes 20 muscles to smile and over 40 to frown.

- 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 biggest muscle in the body is the gluteus maximus, in the buttock. It pulls the leg backwards powerfully for walking, running and climbing steps.

The Skeletal System

- The largest bone is the pelvis, or hip bone. In fact it is made of six bones joined firmly together.

- The longest bone is the 'femur', in the thigh. It makes up almost one quarter of the body's total height.

- The smallest bone is the 'stirrup', deep in the ear. It is hardly larger than a grain of rice.

- The ears and end of the nose do not have bones inside them. 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 rots faster than bone. This is why the skulls of skeletons have no nose or ears.