SYSTEMS

Circulatory System: The Circle of Blood

On average, your body has about 5 liters of blood continually traveling through it by way of the circulatory system. The heart, the lungs, and the blood vessels work together to form the circle part of the circulatory system. The pumping of the heart forces the blood on its journey.

The body's circulatory system really has three distinct parts:pulmonary circulation, coronary circulation, and systemic circulation. Or, the lungs (pulmonary), the heart (coronary), and the rest of the system (systemic). Each part must be working independently in order for them to all work together.

Respiratory System: Oxygen Delivery System

The primary function of the respiratory system is to supply the blood with oxygen in order for the blood to deliver oxygen to all parts of the body. The respiratory system does this through breathing. When we breathe, we inhale oxygen and exhale carbon dioxide. This exchange of gases is the respiratory system's means of getting oxygen to the blood.

Respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm. Oxygen enters the respiratory system through the mouth and the nose. The oxygen then passes through the larynx (where speech sounds are produced) and the trachea which is a tube that enters the chest cavity. In the chest cavity, the trachea splits into two smaller tubes called the bronchi. Each bronchus then divides again forming the bronchial tubes. The bronchial tubes lead directly into the lungs where they divide into many smaller tubes which connect to tiny sacs called alveoli. The average adult's lungs contain about 600 million of these spongy, air-filled sacs that are surrounded by capillaries. The inhaled oxygen passes into the alveoli and then diffuses through the capillaries into the arterial blood. Meanwhile, the waste-rich blood from the veins releases its carbon dioxide into the alveoli. The carbon dioxide follows the same path out of the lungs when you exhale.

The diaphragm's job is to help pump the carbon dioxide out of the lungs and pull the oxygen into the lungs. The diaphragm is a sheet of muscles that lies across the bottom of the chest cavity. As the diaphragm contracts and relaxes, breathing takes place. When the diaphragm contracts, oxygen is pulled into the lungs. When the diaphragm relaxes, carbon dioxide is pumped out of the lungs.

Integumentary System: Cutting Dead Cells

The body's integumentary system supports the excretory system in the removal of waste. Skin, hair, fingernails and toenails make up the system by which surface level wastes are removed.

The skin protects the body and also provides for the removal of dead cells and sweat, which contains waste products. Hair, fingernails and toenails are actually accumulations of dead epidermal cells. As more cells die and need to be removed, the hair and nails grow.

Excretory System: Poison Protection

If you knew there was poison hidden in your house, you would surely do everything possible to find and remove that poison. If you didn't, you and your family would slowly die. How would you find it? How would you remove it? You would probably figure out a system of searching and removing. That would be an excretory system.

Your body does the same thing every day. Hidden throughout your body are dangerous poisons that must be removed in order for it to survive. The process of excretion involves finding and removing waste materials produced by the body.

The primary organs of excretion are the lungs, kidneys, and skin. Waste gases are carried by blood traveling through the veins to the lungs where respiration takes place. Dead cells and sweat are removed from the body through the skin which is part of theintegumentary system.

Liquid waste is removed from the body through the kidneys. Located beside the spine in your back within your ribcage, the kidneys are small (about 10 centimeters long) reddish-brown organs that are shaped like beans.

During circulation, blood passes through the kidneys in order to deposit used and unwanted water, minerals, and a nitrogen-rich molecule called urea. The kidneys filter the wastes from the blood, forming a liquid called urine. The kidneys funnel the urine into the bladder along two separate tubes called ureters. The bladder stores the urine until muscular contractions force the urine out of the body through the urethra. Each day, your kidneys produce about 1.5 liters of urine. All of it needs to be removed from your system. This occurs through urination.

If your kidneys are diseased and not working properly, the buildup of waste in your system will eventually lead to death. Some kidney diseases can be treated with medication. Severe kidney diseases require more intense treatment. One treatment is called dialysis. The patient's blood is pumped through a dialysis machine which filters the waste from the blood and returns the clean blood. A dialysis patient has to spend nearly sixty hours each week attached to the machine.

The most radical treatment for kidney disease is a kidney transplant. Healthy people can live comfortably with only one kidney. Therefore, their other kidney can be donated to a person with kidney disease. The donor and patient must have very similar genetic structures in order for the patient to accept the new kidney without complications. The patient also receives anti-rejection drugs. During a kidney transplant operation, the healthy kidney is placed in the abdomen of the patient and attached to the blood vessels and bladder. The patient's original kidneys are not removed.

The digestive system

The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. There are also two solid digestive organs, the liver and the pancreas, which produce juices that reach the intestine through small tubes. In addition, parts of other organ systems (for instance, nerves and blood) play a major role in the digestive system.

The Muscular system

The muscular system makes up nearly half the weight of the human body, this is why when we train we sometimes put on weight instead of losing it. We put on muscle weight.
The muscles provide the forces that enable the body to move. Muscles stretch across joints to link one bone with another and work in groups to respond to nerve impulses.

The skeletal system

Our skeleton is tough and flexible. It supports weight and protects our internal organs. Bone tissue stores minerals, such as calcium, and it is constantly renewed, which is how our bones are able to heal.
Bones are cleverly designed to allow movement at the joints and provide great stability. The bones provide alight but strong framework for the bodies soft tissues.
The number of bones in the human body actually varies from person to person but the average number is 206.