Digestion, Respiration, and Circulation. By: (Your name)

Introduction Body contains multiple organ systems. Focus on three systems Digestive system Respiratory system Circulatory system The body has multiple organ systems that work together for a common goal. Here I will focus on three that carry out three essential everyday tasks. I will describe the purpose of each system along with the pathway that material travels through it.

Digestion Purpose - break down ingested materials into their most basic units Pathway - oral cavity, esophagus, stomach, small intestine, large intestine. Purpose To break down ingested materials into their most basic units This provides energy This provides materials to repair cells Pathway Oral cavity, esophagus, stomach, small intestine, large intestine. The liver, pancreas, and gallbladder are all also involved although the food is never directly passed through these organs.

Organs Involved Primary Organs Stomach Small Intestine Large Intestine Secondary Organs Pancreas Liver Gallbladder Primary Organs – food passes and is actively digested here. Secondary organs – secrete chemicals that pass through ducts into one of the primary organs to aid in digestion. Stomach – churns food and regulates the amount of food that enters the small intestine at one time. Small Intestine – site of most digestion. Large Intestine – no digestion occurs here, but it works to reabsorb water.

Molecular Digestion Carbohydrates Proteins Fats Carbohydrate digestion begins in the mouth with the enzyme amylase and continues in the small intestine with pancreatic amylase. Protein digestion begins in the stomach with the enzyme pepsin and also conitinues in the small intestine with various chemicals. Fat digestion begins in the small intestine with the enzyme lipase.

Respiration Purpose - provide the lungs with oxygen to replenish deoxygenated tissues and to remove carbon dioxide from the body. Pathway - Mouth/nose, trachea, lungs Purpose Trade oxygen for carbon dioxide. Provide the body with the oxygen needed for life Eliminate toxic carbon dioxide from the body. Pathway - Mouth/nose, trachea, lungs (bronchi, bronchioles, alveoli) This is for inhalation Air travels the opposite way in exhalation Lungs, trachea, moth/nose.

Circulation Purpose - to supply the body with oxygenated blood. Pathway Two separate pathways Pulmonary circuit Systemic circuit Purpose To supply the body with oxygenated blood. To take carbon dioxide to the lungs to be eliminated To transport hormones to the appropriate target organs To carry energy to cells. Pathway Two separate pathways Pulmonary circuit (heart – lungs – heart) Systemic circuit (heart – body – heart)

Circulatory Accessories Heart Arteries Veins Capillaries Heart is the primary organ of the circulatory system Arteries carry oxygenated blood away from the heart Veins return deoxygenated blood to the heart Capillaries are the sites where the blood is mixed with the interstitial fluid allowing things to flow either into or out of the blood Picture The red represents the oxygenated blood in the arteries The blue represents the deoxygenated blood in the veins

Interrelationships Respiratory and Circulatory Digestive and Circulatory Respiratory and Digestive The respiratory system exchanges oxygen with carbon dioxide in the alveoli of the lungs, but the circulatory system is the actual transportation mechanism that carries these two compounds throughout the body. There are distinct organs where digestions begins, but the circulatory system is used to transport hormones so that digestion can begin. After the molecules are broken down they are absorbed into the circulatory system and transported to where they are needed. The portal of entry for both the respiratory system and the digestive system is the oral cavity.

References How Digestion Works. Retrieved January 17, 2009, from Children Memorial Hospital Web site: http://www.childrensmemorial.org/depts/gastroenterology/how_digest_works.aspx Retrieved January 17, 2009, Web site: http://www.brianmac.co.uk/respiratory.gif Retrieved January 17, 2009, Web site: http://www.telemediamagazine.com/images/circulation_Img01.jpg The Human Heart. Retrieved January 17, 2009, from The Franklin Institute Web site: http://www.fi.edu/learn/heart/vessels/vessels.html