AP Biology Notes: Other Organ Systems

Five Things to Know about Other Organ Systems

1. Lungs are the primary structures for respiration in mammals. The circulatory system connects the lungs and the cells around an organism’s body. All mammalian lungs end in blind sacs called alveoli, which are surrounded by a dense net of capillaries into which oxygen diffuses and from which carbon dioxide is excreted.
2. Blood pressure is the force per area that blood exerts on the walls of blood vessels and is expressed as a systolic number over a diastolic number. Blood pressure drops as blood moves farther away from the heart because the distance from the pump has increased and because of the muscular construction of arteries versus veins.
3. Mechanical digestion is the physical breakdown of food, by chewing in the mouth and churning in the stomach. Chemical digestion starts in the mouth with the break-down of carbohydrates and continues through the stomach and small intestine. Nutrients, water, and minerals are absorbed into the body in the colon.
4. Excretion is the removal of metabolic wastes, and all metabolic processes lead to the production of mineral salts that must be excreted.
5. Kidneys regulate the concentration of water, ions, and other dissolved substances in the blood through the formation and excretion of urine.