Anatomy

BONES

The human skeleton is an engineering marvel with numerous functions: Not only does it give the body its needed support and a protective framework for vital internal organs, bit it also serves as a storehouse for calcium and other essential minerals and is critical in making new blood cells.

Facts About Bones

• There are over 300 bones in a human infant.
• Because bones fuse in childhood, there are 206 bones in a human adult.
• Bones are metabolically active, meaning they are constantly breaking down and rebuilding.
• Bones become stronger under stress, and weaker when they are not stressed.
• They contain large amounts of calcium.
• The inside of the bone is light and made of a spongy like substance.
• The outside of the bone is very hard.
• Bones protect organs, store minerals (such as calcium, iron, magnesium), produce blood cells, and of course allow for movement in conjunction with muscles.
• They are held together by strong fibrous tissue called ligaments.
• For more information on bone facts.

Human teeth are crucial when it comes to chewing food. Teeth are made of bone and begin to appear in humans around 6 months of age. Babies are born with no teeth and when they first start to appear they tear through the gums and the process can be quite painful.

The integumentary system is comprised of skin, hair, nails, and sweat glands. The integumentary system is responsible for maintain body temperature, is the first line of defense from pathogens, offers protection of the underlying tissue, holds sensory neurons responsible for sensory reception, controls the excretion of perspiration (part of temperature control), controls the pores (part of temperature control), and is vital for the production of vitamin D.

The kidneys are bean-shaped organs located at the back of the lower abdomen. Their main function is to filter blood to remove waste products created by normal bodily functions. They are also responsible for maintain adequate water levels either by eliminating water or by reabsosbing it after it is filtered. Water which is eliminated is sent to the urinary bladder and stored as urine until time of secretion.

Muscle is a tissue that has the ability to contract. It is comprised fibers that slide beside each. These fibers are connected by bridges. When these bridges move the fibers move making the muscle shorter. As the muscle shortens it contracts which creates movement. Muscles do not lengthen unless they are pulled by an opposing muscle or by an external force.

Interesting Facts About Voluntary Muscles

• The human body has over 600 voluntary/skeletal muscles. This means muscles which we can control, as opposed to muscles of the heart and intestines which we can not voluntarily control.
• Muscles are made of microscopic filaments which contract and slide over each other causing the the muscles to shorten and therefore contract.
• No matter how much you exercise you can not increase the number of muscle cells you have. By getting bigger, via strength training, you are simply increasing the size of each muscle cell. The quantity of muscle cells remain the same.
• Muscles can only contract, they do not lengthen unless an opposing muscles contracts and causes lengthening of the first muscle.
• Muscles are metabolically active and are responsible for a large amount of our caloric requirements.

About 75 to 80 percent of an adult's body consists of slightly salty water; the rest is made up of chemical compounds, many of them unique to human beings. These various compounds are arranged to form hundreds of different kinds of cells, the body's smallest, most basic units.

While most of us taking hearing for granted it is quite a complex process where sound is detected and transformed into nerve impulses that travel to the brain, where they are processed and acted upon. The primary purpose of sound is for communication. However, it is also needed to avoid danger. For example, hearing an approaching car will warn us to move out of the way.

The eye is a round object and is filled with fluid. At the back of the eye is the optic nerve which is responsible for sending the signals to the brain.

Smell is one of our 5 senses. It works by sensing chemicals in the air. All smells are combination of different molecules. Different molecules, and different combinations, result in different smells.

Gustation, which most of us know as taste, is a sense that uses chemoreception. In order for taste to take place something has to be touching the tongue. We can have 4 primary tastes; sweet, salty, bitter, and sour. Some experts believe we can also taste fatty acids which would explain our like for fatty foods. Umami is the 6th taste that is not well classified and is still controversial. It is the taste of salts of glutamic asic, e.g. MSG (monosodium glutamate). By using these tastes we can create an unlimited variety of combinations of tastes.

Sense of touch is a bit different than the other 4 senses. Unlike the other senses, which are located at specific body parts, touch is a sense that is all over your body. Almost any part of the skin is able to sense touch. And although most of us take the sense of touch for granted, without it we would be in big trouble.

The heart is a 4-chambered fist-sized organ located in the centre of the chest just behind the breastbone (sternum). It is responsible for pumping the blood throughout the body. At rest, the heart will beat about 60-80 times per minute. During extreme exertion the heart can beat up to 200 beats per minute. At rest, each time the heart contracts it pumps about 70 ml of blood (in an adult). See below for more info on cardiac output.