1. The human body is made up of a head, neck, torso, two arms and two legs. The average height of an adult human is about 5 to 6 feet tall. The human body is made to stand erect, walk on two feet, use the arms to carry and lift, and has opposable thumbs (able to grasp).
2. The adult body is made up of: 100 trillion cells, 206 bones,
600 muscles, and 22 internal organs.
3. There are many systems in the human body:
Circulatory System (heart, blood, vessels)
Respiratory System (nose, trachea, lungs)
Immune System (many types of protein, cells, organs, tissues)
Skeletal System (bones)
Excretory System (lungs, large intestine, kidneys)
Urinary System (bladder, kidneys)
Muscular System (muscles)
Endocrine System (glands)
Digestive System (mouth, esophogus, stomach, intestines)
Nervous System (brain, spinal cord, nerves)
Reproductive System (male and female reproductive organs)
4. Every square inch of the human body has about 19 million skin cells.
5. Every hour about 1 billion cells in the human body must be replaced.
6. The average human head has about 100,000 hairs.
7. The circulatory system of arteries, veins, and capillaries is about 60,000 miles long.
8. The heart beats more than 2.5 billion times in an average lifetime.
9. There are about 9,000 taste buds on the surface of the tongue, in the throat, and on the roof of the mouth.
10. The strongest muscle in the body is the tongue.
11. The human heart creates enough pressure when it pumps out to the body to squirt blood 30 feet.
12. You blink over 10,000,000 times a year.
13. The human brain weighs about 3 pounds.
14. It takes about 20 seconds for a red blood cell to circle the whole body.
15. Only 10% of the population are left handed.
16. One fourth of the bones in your body are in your feet.
17. Children tend to grow faster in the spring.
18. The most sensitive finger on the human hand is the index finger.
19. More men are color-blind than women.
20. More people have brown eyes than any other color.
The skeletal system plays an important role in our bodies. It supports and protects internals such as lungs, heart, brain, kidneys, etc, but it performs some other functions too. For example, it also fixes the muscles; stores the bone marrow2, which is the source of blood formation; provides calcium for the whole body, etc.
Bones make up the “structural frame” for the human skeleton. If we had no bones, we would not be able to move, our internals would have poor protection, and they would lack blood and calcium. As you can guess, we have many bones, but do you know their exact number.
There can be two different answers to the question about how many bones are in the body, depending on whether we mean babies or adult humans.
- A newborn baby’s skeleton consists of approximately 300 – 350 bones
- An adult human body consists of 206 bones
Now, if somebody asks you, “How many bones are in a human body?” you can give the correct answer:
The number of bones changes because in the process of growing some of them fuse together during first years of life. The most illustrative example of this phenomenon is the human skull. In fact, formation of bones never ends. They are constantly renewed throughout life. Several types of cells take part in this remodeling:
- Osteocytes maintain bones
- Osteoclasts destroy bones
- Osteoblasts form new bones
Scientists divide all the bones into four groups: short bones, long bones, irregular bones, and flat bones. They are also distributed in two different systems: the axial skeleton and the appendicular skeleton. The stapes3 is the shortest bone (about one tenth of an inch), and the femur4 is the longest one.
The table below will give you useful information about the names of different bones and their numbers.
|Names of bones
||Number of Bones
|The Axial Skeleton
|Vertebral column (cervical, thoracic, lumbar, sacrum, and coccyx)
|Bones of the thorax (sternum and ribs)
|The Appendicular Skeleton
|Shoulder girdles (clavicles and scapulae)
|Upper limbs: arms (humerus), forearms (clavicles and scapulae), and hands (carpus, digits, and metacarpus)
|Lower limbs: (femur, patella, tibia, fibula, tarsus, digits, and metatarsus)
||Total: 206 bones
All the bones support and maintain our body making the adult human skeleton. You should also remember that some people have extra ribs or lumbar vertebra, though not everyone has sutural bones.
Some Facts about Human Skeletons
Here are some interesting facts about human skeletons:
- The femur, which is the longest bone in the body, equals about one fourth of the man’s height.
- Necks of giraffes and humans consist of the same quantity of bones.
- Hands and feet have most of the skeleton bones.
- The skeletal system means the system of different bones, cartilages and joints of the body. All these structures make up the skeleton.
- The bone marrow is a pliant tissue which can be found inside of bones. It is very important for human bodies because it produced blood cells and lymphocytes. It also prevents the backflow of the lymph. The bone marrow composes about four percent of the human body mass.
- The stapes (also called stirrup because of its shape) is the smallest bone in the human body. It is situated in the middle ear. The stapes transmits vibrations to the inner ear.
- The femur is the longest bone in the human body. It is articulated at the knee and the hip.
There are 78 organs in the human body. Below are just some of them.
An organ is a structure that contains at least two different types of tissue functioning together for a common purpose. Some organs in the human body include:
• adrenal glands
• gall bladder
• larynx (voice box)
• large intestine
• lymph nodes
• parathyroid glands
• pituitary gland
• salivary glands
• skin (the largest)
• skeletal muscles
• small intestine
• spinal cord
• thymus gland
Tissues and Organs
Related cells joined together are collectively referred to as a tissue. The cells in a tissue are not identical, but they work together to accomplish specific functions. A sample of tissue removed for examination under a microscope (biopsy) contains many types of cells, even though a doctor may be interested in only one specific type.
Connective tissue is the tough, often fibrous tissue that binds the body’s structures together and provides support. It is present in almost every organ, forming a large part of skin, tendons, and muscles. The characteristics of connective tissue and the types of cells it contains vary, depending on where it is found in the body.
The body’s functions are conducted by organs. Each organ is a recognizable structure—for example, the heart, lungs, liver, eyes, and stomach—that performs specific functions. An organ is made of several types of tissue and therefore several types of cells. For example, the heart contains muscle tissue that contracts to pump blood, fibrous tissue that makes up the heart valves, and special cells that maintain the rate and rhythm of heartbeats. The eye contains muscle cells that open and close the pupil, clear cells that make up the lens and cornea, cells that produce the fluid within the eye, cells that sense light, and nerve cells that conduct impulses to the brain. Even an organ as apparently simple as the gallbladder contains different types of cells, such as those that form a lining resistant to the irritative effects of bile, muscle cells that contract to expel bile, and cells that form the fibrous outer wall holding the sac together