Anatomy lessons will work from the inside out. Beginning with skeletal system, then muscles, circulatory/respiratory system, digestion finishing with lymphatic and nervous systems the lessons will be taught as a simplified overview to present the "whole picture" view rather than details so that lessons on healthy lifestyle choices can be the emphasis of the unit.
The skeletal system is our inner support system. It is made up of 206 different bones which are connected to each other and to other tissues by: ligaments, cartilage, tendons, and muscles. Bones, and the way they are shaped and fit together, make us able to sit up straight, stand up straight, walk, run, play sports, and dance. Bones also serve to protect many of our soft tissues and body organs.(Glencoe McGraw-Hill 2011)
Bones are made up of both living tissues called cells and minerals like calcium. Bones have three major layers that have different functions. The
is the thin, hard, outer coating that contains the nerves and blood vessels that bring nutrients to the bones. Just inside the periosteum is the thick, hard, smooth part called
. And, on the inside there are many layers of a spongy looking, but strong, material called
. Many bones also have an innermost cavity called bone marrow where blood cells are made. The bone marrow is like a thick liquid and it is protected by the cancellous bone around it.(Dowshen August 2009).
Image #1(Pbroks13 November 12, 2008)
Bones come in different sizes and have different functions. The spinal column is at the center of the skeletal system. It holds the body upright and allows the whole body to bend and twist in many directions. Also, the spinal column protects the spinal cord while the brain is protected by the skull bones. The ribs protect the heart, lungs, and digestive organs. The largest and longest bones are in the arms and legs, and along with the bones in the hands, feet, and hips, they support and move those extremities. Ear bones, the smallest bones in the body, help transmit sound from the outer ear to the inner ear. ("Learn Bones Anatomy" May 19, 2012).
There are three different kinds of muscles and over six hundred total muscles in the human body. Although the three different kinds of muscle are made from the same kind of elastic body tissue, they are shaped and controlled differently.
are the muscles that move the bones of the skeletal system. They are called "striated" because they consist of their "striped" appearance when observed under the microscope. These muscles are moved voluntarily when a person decides to lift, move, talk, or just show off by flexing a muscle. Not all muscles work this way. Some muscles work automatically or involuntarily such as the muscles in the digestive system and the heart. There are two kinds of these involuntary muscles: heart, or
which are found in the stomach and other internal organs.(Dowshen August 2009).
Muscles are made principally of amino acid fibers called proteins. These fibers break down as muscles are used. Eating enough protein allows muscles to be rebuilt.(Vonda August 31,2011)
The circulatory system goes around and round, like a circle. The heart is the center of this system. The muscles of the heart work by relaxing to let blood in and contracting, to send blood through the
. Nutrients that have been ingested by the body and processed through the digestive system make their way to the blood. When the heart beats, the nutrients in the blood are sent to all parts of the body. Blood travels through arteries to capillaries and finally to veins before returning to the heart. The circulatory system works like a system of highways and roads leading to all the body cells. Used blood that has already deposited nutrients to cells goes back to the heart through the veins to be sent to the lungs to be replenished with oxygen. When the circulatory system is working well, it takes less than a minute for blood to be pumped to all of the cells in the body. The harder a body works, the more rapidly and forcefully the heart contracts. Feeling the heart beat or feeling a pulse can help a person know how hard the heart is working. There are many places near the surface of the body where a pulse can be felt. A pulse is created by the rhythm of the heart beating and the pressure of the blood moving through the blood vessels.(Dowshen August 2009).
Image #2 (Castellon November 29, 2010)
Every cell of the body needs oxygen at every moment. Oxygen is in the air we breathe and the lungs bring this oxygen into the body. Air is carried to the lungs by the nose, mouth and
. Lungs look a little bit like an upside down tree split into two big branches. The trachea is the trunk of the tree and those two large branches are called
. Smaller branches coming off the bronchi are called
. At the end of the bronchioles are
, small sacs that fill with air when the body breathes. Capillaries cover the outside of each alveoli sac. It is through these capillaries, the smallest blood vessels, that oxygen from the air enters the circulatory system. Healthy lungs are the color pink because of all the oxygen in the blood in the capillaries around the alveoli.(Castellon November 29, 2010).
Image#3 (Becker March 20, 2012)
The digestive system is a long tube inside the body that runs from the mouth to the anus. It contains several twisting and turning organs, each doing a certain job to turn ingested food into smaller substances that can be carried by the bloodstream to the body's cells. In addition to the mouth and anus the main parts of the digestive tract are the esophagus, stomach, small intestine, large intestine and the rectum.(Becker March 20, 2012).
Digestion begins in the mouth. The jaw, teeth, saliva, and tongue work together to break food into small pieces and send it down the throat. Saliva has numerous functions. It contains a special chemical called
that changes starches into sugars before the chewed food enters the esophagus.(Becker March 20, 2012).
Muscles in the throat help push the food into the esophagus. There, the smooth muscles of the esophagus automatically push the food down to the stomach in a wave-like action is called
. This action is strong enough to push the food to the stomach even if the person is upside down.(Carone 2011).
Peristalsis continues during digestion in the stomach. There is a combination of several chemicals including gastric acid and enzymes that are secreted from the stomach lining to further work on breaking down the food.(Becker March 20, 2012).
By the time the food gets to the small intestines it is ready to be absorbed into the bloodstream. In the small intestines peristalsis works in a back and forth movement allowing food to be absorbed as it moves at a slower rate. After the nutrients are absorbed from the digested food it moves to the large intestines where water is absorbed and waste is sent to the rectum to be removed from the body.(Carone 2011).
Many of cells of the body depend on chemicals, called
to stimulate or inhibit their activity. These hormones are made by small organs in the body called endocrine glands. The glands release these hormones into the blood that brings them to the cells. Glands are responsible for keeping the body alert, telling the body to grow, and controlling reproduction, bringing energy from sugar to cells, and fighting off illnesses. When the body is stressed from poor eating habits, inadequate sleep, or psychological problems these glands may become overworked and start producing too much or too little of the hormones. This can lead to problems in the immune system, causing a variety of physical ailments and diseases.(Dowshen August 2009).
Living on the earth, human bodies are constantly exposed to things that can cause sickness, injuries and disease. Luckily, the body is equipped with a system to protect and heal itself. This is called the immune system. Many different parts of the body contribute to this system. In the digestive system there are many strong chemicals and helpful bacteria that fight off harmful microorganisms. Many structures in the body such as small hairs in the nose and lungs filter out harmful substances that can cause illness. In the blood, white blood cells, called leukocytes, capture and destroy invading microorganisms. When the immune system is in good working order and a person has healthy habits, the body will usually function quite well.(Dowshen August 2009).