Interesting Facts About the Human Body

1. If all the arteries, veins and capillaries in your body could be stretched out together to their full length, they would reach a distance from Minnesota to California to New York and back to Minnesota again-a total of 12,000 miles.

2. The heart pumps 8,000 gallons of blood through this circulatory system every day.

3. Muscle fibers can hold loads of up to 1,000 times their own weight if a real emergency occurs.

4. In an average day, your lungs move enough air to and fro to blow up over 1,000 balloons.

5. Each square inch of skin contains:

 78 nerves  650 sweat glands  19 or 20 blood vessels  78 sensory mechanisms  1300 nerve ending for for heat recording pain  13 sensory mechanisms  160-165 pressure points for cold for the sense of touch  95-100 sebaceous  65 hairs and muscles glands  19, 500 cells

6. If you could spread all you lung tissues out flat, it would cover half a tennis court.

7. Stomachs can stretch to twice their normal size when full. An adult stomach is about eight inches long from top to bottom and four inches across. MUSCULAR AND SKELETAL SYSTEM

Your musculoskeletal system is the partnership forming the framework and movement mechanism of your body.

The skeletal system is made up of over 200 strong bony rods, blocks and plates cushioned by cartilage and linked by joints. The different bones of the skeletal system have several functions. Some shield and protect vital organs. Some are muscle-operated levers providing body movement. Most bones have semi-soft centers containing bone marrow, which manufactures or makes blood and stores reserve supplies of elements needed by the body.

Bones must be held together to form the skeleton. Places where bones connect are called joints. Most joints are movable, such as the shoulder, elbow, and knee. Some joints aren’t movable, such as those holding the sections of skull together. Many bones are held together by strong bands of flexible tissue called ligaments. Strong cords of tissue called tendons anchor MUSCULAR AND SKELETAL SYSTEM page 2 muscles to bones. These tendons pull the bones to make them move around your joints.

The muscular system holds and moves the skeleton and gives the body its shape. You have over 600 muscles working together in different combinations. In fact, over 100 muscles are at work in your face and neck alone. It takes more muscles working to frown then to smile. Want to exercise your face muscles? Eat, laugh, smile, cry, and look around.

There are three basic kinds of muscles: 1. Skeletal muscle. These muscles are joined to bones and make them move. Each muscle consists of fibers (little strips) which are bound together into bundles by connective tissues. These fiber bundles are organized by tasks they perform. Skeletal muscles are called voluntary muscles because our brains toll them what to do; however, sometimes they also work automatically in reflex actions, as when you jerk your hand away from something hot.

2. Smooth muscles. These muscles line the organs of your body and make up the walls of your blood vessels. They are also called involuntary muscles because you can’t control them. They are not under direct control of the brain but contract at a rate influenced by hormones and the autonomic nervous system.

3. Cardiac, or heart muscles. Your heart muscle is striped like a skeletal muscle but contracts automatically like smooth muscle. It’s so strong that it beats continually from about 6 months before you’re born to the day you die. That’s 2 1/2 to 3 billion times!

Muscles work by contacting and relaxing. When one muscle relaxes another one contracts. How Many Bones?

 Skull and upper jaw 21 bones  3 tiny bones in each ear  Lower jaw (mandible)  Front neck bone (hyoid)  Backbone or spine (26 separate bones or vertebrae)  Ribs (12 pairs - same number for men and women)  Breastbone  Each upper limb has 32 bones: 2 in shoulder, 3 in arm, 8 in wrist, 19 in hand and fingers.  Each lower limb has 31 bones: 1 in hip (one side of pelvis), 4 in leg, 7 in ankle, 19 in foot and toes.

Total = 206 bones NERVOUS SYSTEM

The nervous system is like a vast telephone system with billions of interconnected cells called neurons serving as its wires. Without it, all body systems would be immobilized. The job of the nervous system is to receive messages from inside and outside the body and react by sending signals to the appropriate muscles and glands and then receiving messages back from these muscles and glands back to the brain.

The nervous system centers on the brain spinal cord but has three main parts: 1. The central nervous system is the brain cranial nerves from the brain and spinal cord. It’s the command center of the body. 2. The peripheral nervous system included the sensory and motor nerves leading to and from the spinal cord. The peripheral nervous system has two overlapping parts: the somatic nerves and the autonomic nerves. There are 31 pairs of somatic motor and sensory nerves branching from the spinal cord, supplying limbs and trunk. There are also 12 pairs of cranial nerves arising from the brain to supply ears, eyes, nose, tongue and other facial and skin muscles and various internal organs. 3. The autonomic nervous system is the part of the peripheral nervous system that normally functions automatically, or outside our conscious, willed control. It controls the smooth muscle of internal organs (like the heart, stomach, blood vessels, and bladder) and some glandular secretions (as adrenal glands and sweat glands). CIRCULATORY SYSTEM

Your heart is the muscle that is the center of the circulatory system. Its function is to circulate blood throughout the body.

Blood is the life-stream of the body. This fluid must flow to all parts of the body to nourish the cells with food substances and oxygen. It also carries away waste products such as carbon dioxide and dead cells.

The heart pumps the oxygen-rich blood into arteries that lead to your arms, legs, and organs of your body. The arteries split into tiny blood vessels called capillaries. Capillaries supply oxygen to the muscles for movement and also carry the wastes that muscles make when they burn food for energy. Capillaries lead from muscles and organs into bigger blood vessels called veins. The job of the veins is to collect blood from all over the body and return it to the heart. The heart then pumps the oxygen- depleted blood back to the lungs for a new supply of oxygenated blood. Your blood makes 1,000 complete trips around your body each day and each trip takes less than one minute! RESPIRATORY SYSTEM

---Deals with the breathing of the body

The purpose of this system is to bring oxygen into the bloodstream and to get rid of carbon dioxide and other gases.

Organs of the respiratory system include:  the lungs  diaphragm  the muscles and ribs of the chest cavity (these muscles expand and decrease the size of the chest cavity as you breathe and breathe out)

Only about ¼ of the air you take into the lungs is exchanged in any one breath. About 15 to 20 times a minute (that’s 21,600 times a day) you breathe air in through your nose or mouth. RESPIRATORY SYSTEM page 2 WHAT HAPPENS? 1. Air comes into the nasal cavity and is warmed and filtered in the nasal cavity.

2. Air passes past the epiglottis (which closes when food is swallowed to keep it from entering the passage), through the larynx (voice box), and down a long tube called the trachea (windpipe).

3. It is then divided into two bronchial tubes which enter the lungs. Each tube passes into each lung. In each lung, the tubes divide into smaller and smaller passageways until the end in over

6 million tiny air sacs called alveoli. These alveoli are branched out like grapes on a vine to make a huge spongy area with tiny blood vessels running through it. These air sacks are like a swap shop for gases in you body. The oxygen and the carbon dioxide pass through their walls, and the oxygen is carried off by the red blood cells. The carbon dioxide is exhaled

in the next breath. DIGESTIVE SYSTEM

The food you eat contains nutrients from fat, carbohydrates, and proteins, but these nutrients have to be digested (broken down) into smaller building blocks so the cells can absorb them into your bloodstream.

The 32foot (from the mouth to the rectum) digestive track does the breaking down of these foods in the following steps: 1. Food is taken into the mouth, mixed with the saliva, and chewed by the teeth. 2. The tongue then pushes the partially ground up food to the back of the mouth. 3. Food is then swallowed through the esophagus to the stomach. The epiglottis is the flap that shuts to stop food from entering the nasal cavity or the windpipe. This swallowing movement takes about 4 to 6 seconds. DIGESTIVE SYSTEM page 2 4. Then the food passes to the stomach where it remains for 1 to 6 hours. In the stomach, the food mixes with digestive enzymes (stomach acid-hydrochloric acid) to continue to digest the food. This acid is strong enough to burn skin, but does not attack the stomach’s walls because of its protective mucous coating. The average meal stays in the stomach churning for 3-5 hours where the sugar, salt, water, and alcohol are absorbed directly into the bloodstream. The remainder of the partly digested food is then travels to the small intestine.

5. The small intestine is a 22 foot long track where most of your food’s digestion takes place. It takes food 2 to 9 hours to pass through the small intestine. The intestine uses pancreatic juices (from the pancreas) and bile (from the liver) to complete the breakdown of the food. The broken down nutrients in the food are then absorbed into the bloodstream through little finger-like projections in the lining of the small intestines called the villi and microvilli.

6. Not all of the food eaten is digested and absorbed. The large intestine (also known as the colon) takes the remainder of the unused food (now called waste) and turns it into feces and stored until it is time to go to the bathroom and is exited through the rectum. The large intestine is a 5 foot track that ends the digestive system.

The appendix is an organ in the body that has little known value to the body and can even be hurtful to the body if it gets inflamed. Serious complications occur if the appendix ruptures in the body. This organ can be removed from the body without any bad effects. URINARY SYSTEM

The urinary system eliminates wastes the body cannot use. The kidneys are the major urinary organs. The human body has two kidneys each about the size of an adult’s fist. These kidneys filter about 50 galleons of blood daily, taking from it vital substances needed by the body. These substance then rejoin the filtered blood, and the remaining waste materials are passed out of the kidneys into the ureter tube and then into the bladder. The bladder serves as a storage place for the urine so that, although the kidneys constantly produce urine, it can be eliminated at intervals.

Urine is about 96% water and 4% chemicals, minerals, and dissolved salts. If the urinary system were to stop functioning, this material would poison the body’s blood stream, and death would eventually occur.