Learn about Digestion in this educational video from dizzo95.
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Learn about Digestion In total, there are 11 systems of defense in the human body. Tonsils and adenoids are composed of lymphoid tissue located at the entrance to the throat. They act as barriers to bacteria and viruses. Lacrimal glands above the outer corner of each eye secrete tears which wash dust and dirt from the eyes. They also contain chemicals that kill bacteria. The salivary glands found in the cheek and under the tongue secrete saliva that contains substances which help to resist infection. Lymph nodes are small glands which produce white blood cells. Some of these cells produce antibodies and others ingest bacteria. The lymphatic system carries tissue fluid or lymph around the body. Lymph contains white cells and carries bacteria to the lymph nodes where they’re trapped and destroyed. The liver produces some of the factors which make blood clot and does helps initiate wound repair. The stomach produces hydrochloric acid which sterilizes ingested food and kills bacteria. The spleen composed of lymphoid tissue produces white blood cells and removes unwanted debris from the blood. The small intestine is usually sterile for bacteria have previously been killed by gastric acid band broken down by digestive enzymes. The large intestine contains harmless bacteria which affectively exclude harmful bacteria from colonizing. And the skin is the body’s main protection against disease. Invasion of organisms through the skin only occurs when it is damaged.

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