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30.1 Respiratory and Circulatory Functions KEY CONCEPT The respiratory and circulatory systems bring oxygen and nutrients to the cells. 30.1 Respiratory and Circulatory Functions The respiratory and circulatory systems work together to maintain homeostasis. • The circulatory system transports blood and other materials. – brings supplies to cells – carries away wastes – separates oxygen-poor and oxygen-rich blood Oxygen-rich blood Oxygen-poor blood 30.1 Respiratory and Circulatory Functions • The respiratory system is where gas exchange occurs. – picks up oxygen from inhaled air – expels carbon dioxide and water sinus nose mouth epiglottis trachea lungs 30.1 Respiratory and Circulatory Functions The respiratory system moves gases into and out of the blood. • The lungs contain the bronchi, bronchioles, and alveoli. • Millions of alveoli give the lungs a huge surface area. • The alveoli absorb oxygen from the air you inhale. alveoli bronchiole 30.1 Respiratory and Circulatory Functions • Breathing involves the diaphragm and muscles of the rib cage. • Air flows from areas of high pressure to low pressure. Air inhaled. Air exhaled. Muscles and rib cage relax. Muscles contract and rib cage expands. Diaphragm flattens and moves downward. Diaphragm relaxes and rises. 30.1 Respiratory and Circulatory Functions The circulatory system moves blood to all parts of the body. • The system includes the heart, arteries, veins, and capillaries. – heart pumps blood throughout body – arteries move blood away from heart – veins move blood back to heart – capillaries get blood to and from cells arteries veins 30.1 Respiratory and Circulatory Functions • There are three major functions of the circulatory system. – transporting blood, gases, nutrients – collecting waste materials – maintaining body temperature 30.3 The Heart and Circulation KEY CONCEPT The heart is a muscular pump that moves the blood through two pathways. 30.3 The Heart and Circulation The tissues and structures of the heart make it an efficient pump. • Cardiac muscle tissue works continuously without tiring. NORMAL HUMAN HEART 30.3 The Heart and Circulation • The heart has four chambers: two atria, two ventricles. • Valves in each chamber prevent backflow of blood. pulmonary valve aortic valve left atrium right atrium mitral valve left ventricle tricuspid right ventricle septum • Muscles squeeze the chambers in a powerful pumping action. 30.3 The Heart and Circulation • The heartbeat consists of two contractions. – SA node, or pacemaker, stimulates atria to contract – AV node stimulates ventricles to contract SA node VA node 30.3 The Heart and Circulation • Blood flows through the heart in a specific pathway. 1 3 2 4 30.3 The Heart and Circulation • Blood flows through the heart in a specific pathway. – oxygen-poor blood enters right atrium, then right ventricle – right ventricle pumps blood to lungs – oxygen-rich blood from lungs enters left atrium, then left ventricle – left ventricle pumps blood to body 30.3 The Heart and Circulation The heart pumps blood through two main pathways. • Pulmonary circulation occurs between the heart and the lungs. – oxygen-poor blood enters lungs – excess carbon dioxide and water expelled – blood picks up oxygen – oxygen-rich blood returns to heart 30.3 The Heart and Circulation • Systemic circulation occurs between the heart and the rest of the body. – oxygen-rich blood goes to organs, extremities – oxygen-poor blood returns to heart • The two pathways help maintain a stable body temperature. 30.6 Lymphatic System KEY CONCEPT The lymphatic system provides another type of circulation in the body. 30.6 Lymphatic System Lymph is collected from tissues and returned to the circulatory system. • The lymphatic system collects fluid that leaks out of the capillaries. heart – Lymph vessels have valves to prevent backflow. – Lymph nodes filter the lymph lymph nodes and destroy foreign matter. – Lymph vessels return cleaned lymph vessels fluid to the circulatory system. • If lymph vessels or nodes are damaged, lymph collects in an area. 30.6 Lymphatic System The lymphatic system is a major part of the immune system. • Structures in the lymphatic system help fight disease. – tonsils filter bacteria and viruses – thymus develops white blood cells – spleen filters lymph, contains immune cells tonsils thymus spleen • Lymphocytes help destroy pathogens, parasites, and foreign matter.