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Circulatory System The heart pumps about 3,600 gallons of blood each day 720 Circulatory – Every organism must exchange materials with its environment. • The purpose of the circulatory system is to facilitate this exchange. – All but the simplest animals have circulatory systems with three main components: • • • A central pump A vascular system The circulating fluid Blue Blood & Red Blood Which one is his left arm? Which one is his Which is the right side and which is the left? • Video Open and closed circulatory system The Role of the Cardiovascular System in Homeostasis – The cardiovascular system performs several homeostatic functions: • • • • • Controlling chemical balance Controlling the composition of the blood Regulating body temperature Distributing hormones Defending against foreign invaders The Heart • The human heart is located near the center of your chest. • The heart is enclosed in a protective sac of tissue called the pericardium. • The heart has two sides and four chambers. – The two sides are divided by a septum (wall). – Prevents mixing of oxygen-poor blood and oxygen rich blood. • The upper chamber which receives blood is the atrium. • The lower chamber that pumps blood out of the heart is the ventricle Pericardium Atrium and Ventricle Pulmonary valve Left atrium Aortic valve Right atrium Mitral valve Left ventricle Tricuspid valve Septum Right ventricle Myocardium • The muscle of the heart • Strong and thick • Composed of spontaneously contracting cardiac muscle fibers Myocardium (heart muscle) shown in red Epicardium (Outer surface of myocardium) Endocardium (Inner surface of myocardium) • Can conduct electricity like nerves • It’s blood supply comes from the coronary arteries The Human Cardiovascular System – In the human cardiovascular system, • • • The central pump is the heart. The vascular system is the blood vessels. The circulating fluid is the blood. – In humans and other vertebrates, the three components of the cardiovascular system are organized into a double circulation system. • There are two distinct circuits of blood flow. • The pulmonary circuit. • The systemic circuit. • The pulmonary circuit carries blood between the heart and the lungs. • The systemic circuit carries blood between the heart and the rest of the body. Structures of the Heart • Valves Valves seen from above Pulmonary valve – Prevents backflow of blood – Keep blood moving in one direction Pulmonary veins Tricuspid valve Right atrium Chordea tendinea – Between the chambers – At junctions of artery and chamber Mitral valve Aortic valve Left atrium Pulmonary valve Superior Vena Cava Large vein that brings oxygen-poor blood from the upper part of the body to the right atrium Pulmonary Veins Bring oxygen-rich blood from each of the lungs to the left atrium Pulmonary Valve Prevents blood from flowing back into the right ventricle after it has entered the pulmonary artery Tricuspid Valve Prevents blood from flowing back into the right atrium after it has entered the right ventricle Inferior Vena Cava Vein that brings oxygen-poor blood from the lower part of the body to the right atrium Aorta Brings oxygen-rich blood from the left ventricle to the rest of the body Pulmonary Arteries Bring oxygen-poor blood to the lungs Aortic Valve Prevents blood from flowing back into the left ventricle after it has entered the aorta Mitral Valve Prevents blood from flowing back into the left atrium after it has entered the left ventricle Heartbeat – The pacemaker, or SA (sinoatrial) node, sets the tempo of the heartbeat. – The pacemaker is composed of specialized muscle tissue in the wall of the right atrium. Blood Vessels If the heart is the body’s “pump,” then the “plumbing” is the system of arteries, veins, and capillaries. • Arteries carry blood AWAY from the heart. – Aorta large blood vessel carries through the body back to the heart. • Veins carry blood toward the heart. • Capillaries allow for exchange between the bloodstream and tissue cells. Aorta • Video clip • Blood still moves through the veins against the force of gravity. • As skeletal muscles contract, they help squeeze the blood along. Blood Pressure The force that blood exerts against the walls of your blood vessels is called blood pressure. • Blood pressure is the main force driving the blood from the heart to the capillary beds. • A pulse is the rhythmic stretching of the arteries caused by the pressure of blood forced into the arteries during systole. • Blood pressure decreases when the heart relaxes • Systolic (arteries and ventricles contract) and diastolic (arties and ventricles relax) – 120/80 is a normal adult Disorders of the circulatory system • Atherosclerosis- fatty deposits (plaque) build up on the walls of the arteries. – Leads to high blood pressure (hypertension) – Can cause blood clots – Can cause heart attack – Can cause a stroke Cardiovascular disease accounts for 40% of all deaths in the United States. The leading cause of death in the United States is heart attack. Blood & The Lymphatic System Components of blood • Plasma- 90% water 10% dissolved gases, salts, nutrients, enzymes, hormones, waste products and proteins. – Allows blood to clot • Red blood cells (erthrocytes)-Transport oxygen – Contains protein hemoglobin • Contains iron which gives it the red-ish color • Made in red bone marrow • Circulate for about 120 days destroyed in liver and spleen Components of blood • White blood cells- (Leukocytes) Attack foreign substances or organisms. (Army) – Also made in red bone marrow – Phagocytes “eating cells” are a type of white blood cells that engulf and digest foreign cells • Platelets- (thrombocytes) are bits of cytoplasm pinched off from larger cells in the bone marrow – Fibrinogen is a membrane-wrapped protein found in plasma. Break in Capillary Wall Clumping of Platelets Clot Forms Blood vessels injured. Platelets clump at the site and release thromboplastin. Thromboplastin converts prothrombin into thrombin.. Thrombin converts fibrinogen into fibrin, which causes a clot. The clot prevents further loss of blood.. Lymphatic system • The lymphatic system has two main functions: • Return tissue fluid to the circulatory system • Fight infection • The fluid is known as lymph. • The organs of the lymphatic system are lymph nodes, packed with white blood cells that fight infection. – The lymphatic system Figure 24.7 Respiratory System • What is Respiration? • At the cellular level- The release of energy from the breakdown of molecules in food in the presence of oxygen. Blood carries oxygen and carbon dioxide between the lungs and trillions of cells throughout the body. Video Clip Figure 23.UN1 Human Respiratory System • Purpose- To bring about the exchange of oxygen and carbon dioxide. • With each breath air enters the body fills the lungs, where gas exchange takes place. • The respiratory system consists of the nose, pharynx, larynx, trachea, bronchi, and lungs. Figure 23.17 • Air moves through the nose to a tube at the back of the mouth called the pharynx (throat). • Pharynx serves as a passageway for both air and food. • From the pharynx air moves into the trachea (windpipe). • A piece of cartilage called the epiglottis covers the entrance to the trachea when you swallow Video Clip The Larynx • The larynx contains two highly elastic folds of tissue known as the vocal cords. • From the larynx, air passes through the trachea into two large passageways in the chest cavity called bronchi. • Each bronchus leads into one of the lungs. • Inside the lung the large bronchus subdivide into even smaller bronchi, which lead to even smaller passageways called bronchioles. Video Clip Lungs must be kept clean • In order to keep the lung healthy, the air must be warmed, moistened and filtered. • Large dust particles get trapped by little hairs lining the entrance to the nasal cavity. • A mucus moistens the air and traps inhaled particles of dust and smoke. • Cilia sweep the trapped particles and mucus away from the lungs towards the pharynx. Bronchioles • The bronchioles continue to subdivide until they reach a series of dead ends, these are millions of tiny air sacs called alveoli. Figure 23.18 Alveoli • There are about 350 million aveoli in a healthy lung, providing an enormous surface area for gas exchange. • Alveoli carry out the process of gas exchange in the lungs. • Grouped in clusters like grapes Video Clip The Air that you Inhale & Exhale Inhale: • 21% oxygen • 0.04% carbon dioxide Exhale: • Less than 15% oxygen • 4% Carbon dioxide How is breathing Controlled? • Medulla Oblongata • Cells in its breathing center monitor the amount of carbon dioxide in the blood. • As the Carbon dioxide levels rise, nerve impulses from the breathing center cause the diaphragm to contract, bringing air into the lungs. • The higher the carbon dioxide levels the stronger the impulse. – The breathing control centers increase or decrease breathing rate in response to CO2 levels in the blood. Taking a Breath – Breathing is the alternating process of inhalation and exhalation. Tobacco and The Respiratory System • Smoking tobacco damages and eventually destroys the lungs. • Tobacco contains 3 harmful substances: – Nicotine: stimulant – Carbon monoxide: poisonous gas that blocks the transportation of oxygen by hemoglobin in the blood. – Tar: is a cancer causing substance. Video clip Statistics • Only 30% of male smokers live to the age of 80. • 55% of nonsmokers live to 80 • 160,000 people in the US are diagnosed with lung cancer each year. • Smoking causes: – Bronchitis (acute, chronic) – Emphysema – Lung cancer