Chapter 30 – Respiratory & Circulatory Systems UNIT 5: Human Biology Chapter 30 – Respiratory & Circulatory Systems

CH. 30.3 – The Heart and Circulation The Circulatory System The circulatory system transports nutrients, hormones, and gases; gets rid of wastes; and helps maintain a constant body temperature. The blood, heart, and blood vessels form the cardiovascular system. The lymph, lymph nodes, and lymph vessels form the lymphatic system. The cardiovascular and lymphatic systems make up the circulatory system.

CH. 30.3 – The Heart and Circulation Structures of the Heart The septum vertically divides the heart into two sides (left/right). The right side pumps deoxygenated blood to the lungs to be oxygenated; the pulmonary circuit. The left side pumps oxygenated blood to the rest of the body; the systemic circuit. Each side of the heart is divided into an upper and lower chamber. Each upper chamber is called an atrium. Each lower chamber is called a ventricle.

CH. 30.3 – The Heart and Circulation Structures of the Heart (contd.) Valves are flaps of tissue in the heart that open in only one direction. The atrioventricular valve (AV) on the right side is called the tricuspid valve. The mitral valve, or bicuspid valve, is on the left. As the ventricles pump, blood pressure closes the AV valves to prevent blood from flowing back into the atria.

CH. 30.3 – The Heart and Circulation aorta pulmonary artery superior vena cava aortic valve left atrium mitral valve left ventricle septum pulmonary valve right atrium tricuspid valve right ventricle inferior vena cava

CH. 30.3 – The Heart and Circulation Four Basic Steps of Circulation in the Heart The Right Atrium receives deoxygenated blood from the body via the superior and inferior vena cava and pumps it to the Right Ventricle, which pumps the deoxygenated blood to the lungs via the pulmonary artery. The Left Atrium receives oxygenated blood from the lungs via the pulmonary veins and pumps it to the left ventricle. The Left Ventricle pumps oxygenated blood to all parts of the body via the aorta.

CH. 30.3 – The Heart and Circulation

CH. 30.4 – Blood Vessels & Transport Blood vessels transport blood to all parts of the body. Arteries carry oxygenated blood away* from the heart to the rest of the body. Veins carry deoxygenated blood toward* the heart from the rest of the body. *Exceptions: pulmonary artery carries deoxygenated blood away from the heart to the lungs. Pulmonary veins carry oxygenated blood toward the heart from the lungs.

CH. 30.4 – Blood Vessels & Transport Blood vessels transport blood to all parts of the body. Capillaries are very thin and allow for the diffusion of nutrients, gases, and wastes into and out of the blood.

CH. 30.4 – Blood Vessels & Transport Circulation and Blood Pressure Blood Pressure is the force with which blood pushes against the wall of an artery. Healthy blood pressure for a young adult is around 120/70 mm Hg. The top, higher number is the systolic pressure and is the amount of pressure on the walls of an artery when the left ventricle contracts to pump blood through the body. The bottom, lower number is the diastolic pressure and is the pressure in the artery when the left ventricle closes.

CH. 30.4 – Blood Vessels & Transport Circulation and Blood Pressure (contd.) Blood pressure depends on how elastic and unblocked the arteries are and on the strength of the heart. The less elastic the arteries and the more blockages that reduce the flow, the harder the heart must pump; blood pressure rises. Blood pressure also rises with activity and stress, but should drop again with rest. People with permanently high blood pressure have a condition called hypertension, which could lead to heart attack or stroke.