Big+Idea+8


 * Big Idea 8: Circulatory and Respiratory Systems**

__Summaries__ //Circulatory System:// The circulatory system is an organ system which allows movement of nutrients, gasses, and wastes to and from cells throughout the body in order to maintain homeostasis. There are two main parts: the cardiovascular system, which distributes blood throughout the body, and the lymphatic system, which distributes a fluid called //lymph//.

//Respiratory System:// The respiratory system allows the exchange of gas. In the lungs, between aveoli and capillaries, oxygen and carbon dioxide are diffused, allowing a steady flow of oxygen to the body. The respiratory system is a key part in providing the circulatory system with oxygen.

Key Parts:

__Heart__ The heart is the center of the circulatory system. It's responsibility is to pump blood around the body, allowing a constant flow of oxygen to all parts of the body. The heart also pumps blood to the lungs, where the lungs allow diffusion of oxygen. The heart is composed of cardiac muscle. The heart is divided into two halves,

__Circulatory System__ The circulatory is composed of the cardiovascular system, which includes blood vessels and the heart, and the lymphatic system. The cardiovascular system has two main "loops": the pulmonary loop, which is between the heart and lungs, and the systemic loop, which is in between the heart and the rest of the body.

__Pulmonary Circulation__ The pulmonary loop is between the heart and the lungs. This allows the blood flow to constantly have a supply of oxygen. It also serves to allow diffusion of carbon dioxide out of the body and other wastes that are expelled from the body as gases. The heart pumps oxygen depleted blood to the lungs, where, in the alveoli, oxygen diffuses into the red blood cells and carbon dioxide diffuses out. The newly oxygenated blood then returns to the heart to be pumped around the rest of the body.