Lesson 7 - 12.2 Anatomy of the Heart PDF

Chapter 12: The Circulatory System 12.2 Structure and Function of the Heart  The Circulatory System The three primary components of the circulatory system are: 1. Blood 2. Blood Vessels 3. Heart  3. Heart: Anatomy The heart is a hollow organ bet...

Chapter 12: The Circulatory System 12.2 Structure and Function of the Heart  The Circulatory System The three primary components of the circulatory system are: 1. Blood 2. Blood Vessels 3. Heart  3. Heart: Anatomy The heart is a hollow organ between your lungs that is made almost entirely of muscle The structure of the heart allows for the pumping of both oxygenated and deoxygenated blood to your entire body As your heart contracts, blood is pumped out When your heart relaxes, blood enters the heart Atria receive blood and send it to the ventricle Ventricle walls more muscular → need to pump blood over longer distances Needs lots of oxygen (works continuously) → has its own supply of blood vessels (coronary blood vessels) 3. Heart: Anatomy  3. Heart: Anatomy - Chambers The human heart has four chambers: 1. Right atrium 2. Right ventricle 3. Left atrium 4. Left ventricle  How a Heart Pumps Blood: A Summary Remember that the process Checklist of concepts to of blood travelling to and LOOK and HEAR for: from the heart is a cycle. There is no clear beginning ❑ Right Side, Left Side and ending to this process ❑ Right atrium ❑ Right ventricle https://www.youtube.com/ ❑ Left atrium watch?v=JA0Wb3gc4mE ❑ Left ventricle  3. Heart: Anatomy - Chambers Atria Ventricles (singular, atrium) Receive blood returning to Pump blood out of the the heart heart to the rest of the Pumps blood a short body distance, into the Pumps blood a long ventricles distance, to the rest of the Walls are thin body Walls are thick 3. Heart: Anatomy - Chambers  3. Heart: Anatomy - Valves Valves control the flow of blood in one direction and prevent it from flowing backward into the atria The valves that are located between the atria and ventricles are known as atrioventricular valves – Tricuspid valve (right) – Mitral valve (left)  3. Heart: Anatomy - Valves Semilunar valves The pulmonary valve controls the flow of blood between the right ventricle and the pulmonary artery – Pulmonary comes from the Latin word “lung” The aortic valve controls the flow of blood between the left ventricle and the aorta – Aortic comes from the Greek work “lift”  How a Heart Pumps Blood: A Summary Checklist of concepts to https://www.youtube.com/wat LOOK for: ch?v=JA0Wb3gc4mE ❑ Atrioventricular valve ❑ Pulmonary valve ❑ Aortic valve  3. Heart: Anatomy – Vena Cava A large vein carrying deoxygenated blood into the heart There are two in humans: 1. The inferior vena cava (carrying blood from the lower body) 2. The superior vena cava (carrying blood from the head, arms, and upper body).  How a Heart Pumps Blood: A Summary Checklist of concepts to https://www.youtube.com/watc LOOK and HEAR for: h?v=JA0Wb3gc4mE ❑ Inferior Vena Cava ❑ Superior Vena Cava  How the Heart Pumps Blood: A Story 1. The normal heart has two sides: a right side and a left side 2. There are four chambers: the right atrium, right ventricle, left atrium and left ventricle 3. The atria receive blood, and the thick ventricles pump the blood into the rest of the body  How the Heart Pumps Blood: A Story 4. Deoxygenated blood from the body from either the superior vena cava or the inferior vena cava will enter into the right atrium 5. Blood flows from the right atrioventricular valve into the right ventricle 6. The right ventricle will squeeze blood through the pulmonary valve into the pulmonary artery  How the Heart Pumps Blood: A Story 7. The pulmonary artery splits into two vessels: the right pulmonary artery or the left pulmonary artery. 8. Each vessel goes to the lungs so that blood can be oxygenated 9. The oxygenated blood returns through the pulmonary veins into the left atrium  How the Heart Pumps Blood: A Story 10. The oxygenated blood travels through the left atrioventricular valve into the left ventricle 11. The left ventricle pumps blood up through the aortic valve where it leaves the heart through aorta 12. Blood from the aorta then travels to muscles, organs and skin in the human body 13. The entire process of pumping and filling the heart, known as the cardiac cycle, takes approximately 0.8 seconds  3. Heart: Sounds With each heartbeat, the valves open allowing blood to flow through The values close to prevent blood to flow back When the valves close, they cause a familiar sound of “lub dub”: – The “lub” sound is the atrioventricular valves closing – The “dub” sound is when the pulmonary and aortic valves closing  3. Heart: Sound Listen to a heart beat: https://www.youtube.com/watch?v=gJpT_wHZeF8  3. Heart: Anatomy The myocardium is the muscular wall of the heart The interventricular septum is the wall separating the two ventricles The pericardium (not shown) is a protective sac that lubricates the surface of the heart to prevent friction Septum separates heart into two parallel pumps  3. Heart: Two Circuits of Blood Flow Although the heart is one organ, the heart functions as two pumps 1. To the lungs - Pulmonary Circuit 2. To the rest of the body - Systemic Circuit 3. Heart: Two Circuits of Blood Flow Pulmonary Circuit Systemic Circuit Deoxygenated blood Oxygenated blood from travels from the right side the lungs travel through of the heart through the the left atrium and then pulmonary arteries, and to into the left ventricle the lungs  But Wait! Common misconception is that ALL arteries carry oxygenated blood (red) and veins carry deoxygenated blood (blue) Pulmonary artery carries deoxygenated blood, pulmonary vein carries oxygenated blood Correct definition: arteries carry blood AWAY from the heart, veins carry blood TOWARD the heart The Cardiac Cycle - Your Heartbeat Diastole Systole Ventricles relaxed, Ventricles gets filled with contract, ejects blood the blood Fun Fact The heartbeat sound you hear is caused by… The closing of the heart valves! First sound (lubb) → atrioventricular valve closes as the ventricles begin to contract Second sound (DUBB) → ventricles relax and semilunar valves shut  Heart Rhythm Regulation Stimulus for heart muscle contraction is within the muscle itself ○ Myogenic muscle (no external source aka nerves needed) 1 Heart beats even when nervous system is damaged Heartbeat initiated in the sinoatrial (SA) node 2 ○ Acts as a pacemaker Signals then reach atrioventricular (AV) node ○ Purkinje fibres (special conducting fibres) run down septum and through the muscle cells of the ventricle 3 Heart Rhythm Regulation Heart rate can be adjusted by sympathetic and parasympathetic nervous systems ○ Sympathetic - fight or flight ○ Parasympathetic - rest and digest Factors: emotional stress, physical stress (weight), physical activity, drugs, medical conditions  Observing the Heartbeat Electrocardiograph: a device that detects the electrical activity of the heart through electrodes placed on the body’s surface Records an electrocardiogram Both referred to as ECG  Analyzing the Heartbeat Start with SA node Stimulus spreads → atria contracts (P) Signal travels to AV node ○ Brief delay ○ QRS complex → stimulus moves via Purkinje fibres to the tip of the ventricles Contraction starts at tip and moves up Slight delay → ventricles recover ○ T = recovery period Additional Resources  Homework Label Practice Worksheet https://docs.google.com/document/d/1dGuRyWx5fxDLGfoU6bS V-vLQrGOOcDFUwk1SOsUnRA0/edit?usp=sharing Ch12 p. 488 #2, 9, 10, 11, 12, 13