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Organ Systems organ a group of tissues organized to perform specific functions organ system a group of organs organized to perform specific functions Primary Systems the three systems necessary to keep all cells alive involved in bringing needs to a cell and removing wastes from a cell the key needs are oxygen and nutrients the key wastes are carbon dioxide and urea 1. Respiratory System a. getting air into and out of the body a series of tubes bring the air inside the body trachea bronchus (2) bronchiole (thousands) once inside the lungs it moves to tiny air sacs alveoli gases inhaled air exhaled air nitrogen 78 % 78 % oxygen 21 % 16 % argon 1% 1% CO2 0.035 % 5% the only two gases that change are O2 and CO2 b. Diffusion of gases the air in the alveoli has more O2 than the blood as a result O2 moves into the blood O2 the air in the alveoli has less CO2 than the blood as a result CO2 moves into the alveoli CO2 O2 When the blood gets to the cells the blood has more O2 than the cell as a result O2 moves into the cell the blood has less CO2 than the cell as a result CO2 moves into the blood Additional systems of gas exchange a frog has lungs but Canadian frogs spend the winter buried in mud they can also exchange gases through their thin skin but as there is less surface area of thin skin than in the lungs this only works when the frog is inactive a turtle has shell and has thicker skin yet in Canadian winters they are buried in the mud with frogs so how do they do gas exchange? they gas exchange via their cloaca roughly equivalent to your rectum like a lung it has thin wall & a large surface area but only supplies enough O2 for inactive turtles 2. Digestive System key function is to convert food into nutrients a. foods can be assigned to three macronutrients carbohydrates starch, sugar from foods such as cereals, potatoes, fruit lipids vegetable oils and fats from foods such as nuts, seeds & meat proteins muscle, food for young and seeds from foods such as meat, milk, eggs, nuts, & seeds nutrients are: carbohydrates glucose Lipids glycerol & fatty acids + fatty acid proteins amino acids 3 amino acids a protein b. Physical breakdown muscular action breaking down food into smaller pieces of food mostly occurs in the mouth the chewed food called a bolus is now swallowed and muscular action called peristalsis moves the food down the esophagus to the stomach esophagus bolus stomach bile from the liver (via the gall bladder) enters and breaks large drops of fat into small droplets c. Chemical breakdown enzyme action breaking down food into nutrients 1. it starts in the mouth amylase in saliva breaks down starch 2. in the stomach pepsin breakdown proteins acid and pepsin 3. the duodenum, part of small intestine is the major site of digestion protein to amino acids continues starch to glucose continues lipids to fatty acids starts 29 different enzymes from the pancreas enter here d. Absorption of nutrients the small intestine absorbs the amino acids and glucose directly into the blood the fatty acids are absorbed into the lymph and then go into the blood e. Eliminating wastes all of the undigested food + dead bacteria leave through the anus as feces 3. Circulatory System a. Fluid this consists of plasma and cells cells were discussed in the tissues section plasma is mostly water with some proteins plus dissolved nutrients and minerals b. Vessels muscular tubes that move the blood cells, plasma and dissolved substances throughout the body arteries move blood away from the heart under high pressure they have thick, muscular walls and usually carry oxygen-rich blood so are shown as red in diagrams veins move blood towards the heart under low pressure they have thin, muscular walls and usually carry oxygen-poor blood so are shown as blue in diagrams capillaries connect arteries and veins these are tiny vessels with walls one cell thick they are the site of the diffusion of gases, nutrients, and wastes in or out of a cell thick small opening thin large opening single cell c. Pump the heart is actually two separate pumps one pumps oxygen-poor blood to the lungs one pumps oxygen-rich blood to the body the right atrium receives the oxygen-poor blood from the body the right ventricle pumps the oxygen-poor blood to the lungs right atrium right ventricle the left atrium receives the oxygen-rich blood from the lungs the left ventricle pumps the oxygen-rich blood to the body left atrium left ventricle less active animals such as frogs have two atria but only have one ventricle the oxygen-poor and oxygen-rich blood might mix on their way to the lungs & body