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KEY CONCEPT The respiratory and circulatory systems bring oxygen and nutrients to the cells. 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 oxygenrich blood Oxygen-rich blood Oxygen-poor blood • The respiratory system is where gas exchange occurs. – picks up oxygen from inhaled air – expels carbon dioxide and water When you stand up after lying down, why do your heart rate and breathing rate increase? sinus nose mouth epiglottis trachea lungs 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 • 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. The circulatory system moves blood to all parts of the body. • The system includes the heart, arteries, veins, and capillaries. – – – – veins 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 • There are three major functions of the circulatory system. – transporting blood, gases, nutrients – collecting waste materials – maintaining body temperature 30.2 KEY CONCEPT The respiratory system exchanges oxygen and carbon dioxide. Your cells perform cellular respiration. They need: They give off: Gas exchange occurs in the alveoli of the lungs. • Oxygen and carbon dioxide are carried by the blood to and from the alveoli. – oxygen diffuses from alveoli into capillary – oxygen binds to hemoglobin in red blood cells – carbon dioxide diffuses from capillary into alveoli GAS EXCHANGES ALVEOLI capillary alveolus Co2 diffuses into alveolus. co2 o2 capillaries O2 diffuses into blood. Gas exchange occurs in the alveoli of the lungs. • Breathing is regulated by the brain stem. • This means you don’t have to think about it, Why is that important? midbrain pons medulla oblongata spinal chord Respiratory diseases interfere with gas exchange. • Lung diseases reduce airflow and oxygen absorption. – Emphysema destroys alveoli. – Asthma constricts airways. – Cystic fibrosis produces sticky mucus. • Smoking is the leading cause of lung diseases. KEY CONCEPT The heart is a muscular pump that moves the blood through two pathways. The tissues and structures of the heart make it an efficient pump. • Cardiac muscle tissue works continuously without tiring. NORMAL HUMAN HEART • The heart has four chambers: two atria, two ventricles. • Valves in each chamber prevent backflow of blood. • Muscles squeeze the chambers in a powerful pumping action. pulmonary valve aortic valve left atrium right atrium mitral valve left ventricle tricuspid right ventricle septum • The heartbeat consists of two contractions. – SA node, or pacemaker, stimulates atria to contract – AV node stimulates ventricles to contract SA node VA node • 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 • Blood flows through the heart in a specific pathway. 1 3 2 4 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 • 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. KEY CONCEPT Blood is a complex tissue that transports materials. Blood is composed mainly of cells, cell fragments, and plasma. • Whole blood is made up of different materials. – – – – plasma red blood cells white blood cells platelets plasma red blood cells, white blood cells, and platelets • Plasma is a key factor in maintaining homeostasis. – – – – molecules diffuse into and out of plasma contains proteins that stabilize blood volume contains clotting factors contains immune proteins Platelets and different types of blood cells have different functions. • The bone marrow manufactures most of the blood components. red blood cell platelet white blood cell • Red blood cells make up 40-45 % of all blood cells. – transport oxygen to cells and carry away carbon dioxide – have no nuclei and contain hemoglobin • White blood cells fight pathogens and destroy foreign matter. red blood cell platelet white blood cell • Protein markers define blood types and Rh factors. – ABO blood group the most common – Rh factor can be negative or positive – blood types must be compatible for transfusions • Platelets help form clots that control bleeding. platelets fibrin white blood cell red blood cell