Chapter 20 Cardiovascular System: The Heart AP2 Chap. 20: Cardio Syst-Heart 1 Cardiovascular System: The Heart I. Fxns of the heart II. Size, Shape, & Location of the heart III. Anatomy of the heart IV. Route of blood flow thru the heart V. Histology VI. Electrical Properties VII. Cardiac Cycle VIII. Mean Arterial BP IX. Regulation of the heart X. Heart & Homeostasis XI. FX of aging on the heart AP2 Chap. 20: Cardio Syst-Heart 2 Cardiovascular System • Heart is actually 2 pumps: 1st pump receives O2 poor blood from the body and pumps it to the lungs – Pulmonary Circulation 2nd pump receives O2 rich blood from the lungs and pumps it to the body – Systemic Circulation Fig. 20.1 pg 679 AP2 Chap. 20: Cardio Syst-Heart 3 I. Functions of the Heart AP2 Chap. 20: Cardio Syst-Heart 4 I. Fxns of the heart 1. Generating BP (blood pressure) Pg 680 Figure 20.2a – Contractions of the ♥ generate the BP, wh/ is responsible for blood mvment thru vessels 2. Routing Blood – ♥ is the interchange between pulmonary & systemic circulation, thus insuring better oxygenation of bld going to tissues 3. Insuring One-Way blood flow – Valves of the heart are 1-way thus insuring no backflow 4. Regulating Blood Supply – As metabolic needs of the tissues Δ the heart can Δ rate & force of contraction to aid the tissues AP2 Chap. 20: Cardio Syst-Heart 5 II. Size, shape, & location of the ♥ AP2 Chap. 20: Cardio Syst-Heart 6 • ~ size of a Front View closed fist, Pg 684 Figure 20.5 a shaped like a blunt cone • Lies obliquely within the ♥ mediastinum with its base directed the back and superior & apex coming forward inferiorly to the left. Posterior View II. Size, shape, & location of AP2 Chap. 20: Cardio Syst-Heart Pg 685 Figure 20.5 c 7 III. Anatomy of the ♥ A. Pericardium B. Heart Wall C. External Anatomy & Coronary Circulation D. Heart Chambers & Valves AP2 Chap. 20: Cardio Syst-Heart 8 III. Anatomy of the heart: Pericardium • A sac surrounding the heart made of 2 layers that can also be called the pericardial sac. • It can Δ in size to accommodate more fluid or Δ in heart size 1. Fibrous Pericardium Pg 681 Figure 20.3 – Aids in holding the heart in place 2. Serous Pericardium – Reduces friction as the heart beats and is made up of 3 regions: a) Parietal Pericardium • Lies just under & Lines #1 b) Pericardial Cavity • Lies between a) & c) filled with pericardial fluid • Helps reduce friction as heart moves in the pericardial sac c) Visceral Pericardium • Lines the exterior surface of the heart 9 III. Anatomy of the Heart: Heart Wall • Has 3 main layers: 1. Epicardium • Outermost layer that protects from Pg 682 Figure 20.4 friction 2. Myocardium • Middle layer responsible for contraction 3. Endocardium • Innermost layer & protects from friction created by flowing blood • Simple squamous epi over CT • Heart valves are modified Endocardium • Atria (top chambers) – Mainly smooth w/some raised areas called pectinate muscles that are separated by smooth parts by a ridge called cristae terminalis • Ventricles (bottom chambers) – Have large ridges called trabeculae carneae 10 III. Anatomy of the Heart: External Anatomy & Coronary Circulation Right Auricle Left Auricle There is also a posterior Interventricular Sulcus AP2 Chap. 20: Cardio Syst-Heart 11 III. Anatomy of the Heart: External Anatomy & Coronary Circulation These veins come from the These veins come from the body with O poor blood and 2 lungs with O Rich blood and empty into the right atrium 2 empty into the left atrium. + Coronary Sinus 12 III. Anatomy of the Heart: External Anatomy & Coronary Circulation These arteries exit the heart This major artery exits the heart carrying O2 poor blood to the carrying O2 rich blood to the lungs body. 13 III. Anatomy of the Heart: External Anatomy & Coronary Circulation Blood flow to the coronary blood vessels isn’t continuous. • Cardiac Muscle contracts blood vessels get compressed & blood doesn’t readily flow • Cardiac Muscle relaxes Blood vessels aren’t compressed & blood flow thru the coronary blood vessels resumes AP2 Chap. 20: Cardio Syst-Heart 14 III. Anatomy of the Heart: External Anatomy & Coronary Circulation Major Arteries (A) supplying heart tissue • Lie within the coronary sulcus & interventricular sulci. • Rt. & Lt. Coronary Arteries (CA) – Major A’s supplying blood to heart – Exit the aorta just as it leaves the heart and lie w/in the coronary sulcus – Right is smaller in diameter than left Branches of the Rt.CA Branches of the Lt.CA Pg 685 Figure 20.6a • Rt. Marginal A • Ant. Interventricular A • Supply bld to lat’l – Supplies most of wall of the rt the ant. heart ventricle • Left Marginal A • Post’r Interventricular – Supplies bld to the A. lat. lt. ventricle • Supplies bld to • Circumflex A the posterior & – supplies most of inferior region of the posterior the heart heart. 15 III. Anatomy of the Heart: External Anatomy & Coronary Circulation Major veins (V) draining the heart tissue • Great Cardiac V Pg 685 Figure 20.6a – Major vein draining the tissue on the left side of the heart • Small Cardiac Vein – Drains the right margin of the heart • Both empty into the Coronary Sinus – Empties into the right atrium AP2 Chap. 20: Cardio Syst-Heart 16 Interatrial Septum • piece of tissue that separates L from R atrium • Foremen Ovale/ Fossa Ovalis • Ovale, an opening between the atria in a embryo & fetus to bypass pulmonary circulation that seals and forms the Ovalis Pg 686 Figure 20.7 Right Atrium Left Atrium – Upper R chamber – Upper L chamber – 3 openings: – 4 uniform openings: 1. Superior Vena Cava Pulmonary Veins – Drains upper body 1. 2 from each lung 2. Inferior Vena Cava 2. Drains lungs after – Drians Lower Body getting O 3. Coronary Sinus 2 III. Anatomy of the heart: III. – Drains the Heart 17 Chambers & Valves Chambers & Valves Interventricular Septum • Thick muscular piece of tissue that separates L from R ventricle • Each ventricle has 1 large, superiorly placed outflow route near midline Pg 686 Figure 20.7 Right Ventricle Left Ventricle – Lower R chamber – Lower L chamber – Opens to the – Opens to the aorta pulmonary trunk III. Anatomy of the heart: III. 18 Chambers & Valves Chambers & Valves Semilunar Valves Pulmonary Valve Aortic Valve • Composed of 3 pocket like Between the R Between L ventricle semilunar cusps/flaps the ventricle and the and the Aorta free inner borders meet in Pulmonary Trunk the center of the arteries to block blood flow. III. Anatomy of the heart: Chambers & Valves 19 Atrioventricular Valves Tricuspid Valve Bicuspid Valve – Composed of cusps/ Between the R Between the flaps allow blood to atrium and R L atrium and flow from atrium to the ventricle L ventricle ventricles but because 3 cusps/flaps 2 cusps/flaps of design help to prevent back flow III. Anatomy of the heart: Chambers & Valves 20 Pg 687 Figure 20.9 • Blood pushing out of the ventricle causes enough pressure to push the semilunar valves open while at the same time causing the atrioventricular valves to seal with the help of the chordae tendineae and the papillary muscle. As the ventricle relaxes the semilunar valves get sucked back effectively sealing them while the atrioventricular valves open • Chordae Tendineae • Strong CT strings that connect to the cusps of AV-valves • Papillary Muscle • Cone-shaped muscular pillars, that contract when V contract & prevent flaps from protracting 21 IV. Route of blood flow thru the heart AP2 Chap. 20: Cardio Syst-Heart 22 Pg 688 Figure 20.10 AP2 Chap. 20: Cardio Syst-Heart 23 Cardiac Cycle • Arteries: • BLUE: – Carries blood away – Deoxygenated blood from the heart • RED • Veins: – Oxygenated blood – Carries blood toward the heart AP2 Chap. 20: Cardio Syst-Heart 24 Lung Tissue Body Tissue Right Left Atrium Atrium Right Left Ventricle Ventricle AP2 Chap. 20: Cardio Syst-Heart 25 Tricuspid Bicuspid Valve Valve Pulmonary Aortic Semilunar Semilunar Valve Valve AP2 Chap. 20: Cardio Syst-Heart 26 Aorta Pulmonary Arteries Coronary Arteries Aorta Inferior Vena Pulmonary Cava Veins Superior Vena Cava Pulmonary Trunk Coronary Sinus AP2 Chap. 20: Cardio Syst-Heart 27 Body Tissue Inferior Vena Cava Superior Vena Cava Coronary Sinus • Deoxygenated blood drains into the Right atrium via the: – The inferior vena cava drains the lower body tissue – The superior vena cava drains the upper body tissue 28 – The coronary sinus drains the heart tissue Right Atrium • The right atrium fills with deoxygenated blood AP2 Chap. 20: Cardio Syst-Heart 29 Right Atrium Tricuspid Valve • Deoxygenated blood goes from the right atrium thru the tricuspid valve into the right ventricle. 30 Right Ventricle • The right ventricle fills with deoxygenated blood 31 Pulmonary Semilunar Valve Pulmonary Trunk Right Ventricle • Deoxygenated blood is squeezed from the right ventricle thru the pulmonary semilunar valve into the pulmonary trunk. 32 Pulmonary Arteries Lung Tissue Pulmonary Trunk • The pulmonary trunk splits into the right and left pulmonary arteries carrying deoxygenated blood in to the right and left lungs respectively to pick up oxygen and drop off carbon dioxide. 33 Lung Tissue • In the lungs CO2 is exchanged for O2 AP2 Chap. 20: Cardio Syst-Heart 34 Lung Tissue Left Atrium Pulmonary Veins • The right and left pulmonary veins carry the newly oxygenated blood back to the left atrium from the right and left lungs respectively. 35 Left Atrium • The left atrium fills with freshly oxygenated blood. 36 Left Atrium Bicuspid Valve Left Ventricle • The oxygenated blood is pumped from the left atrium thru the bicuspid valve into the left ventricle. 37 Left Ventricle • The left ventricle fills with freshly oxygenated blood. 38 Aorta Aortic Semilunar Valve Left Ventricle • Oxygenated blood is squeezed from the left ventricle thru the aortic semilunar valve into the aorta.