Heart

THE HEART IS TWO PUMPS: LEFT AND RIGHT LEFT PUMP: From lungs to body RIGHT PUMP: From body to lungs 2

The Pulmonary and Systemic Circuits Figure

Heart Chambers Each pump has two types of chambers: ATRIUM and VENTRICLE Left Atrium Left Ventricle Right Atrium Right Ventricle 4

Blood Flow Deoxygenated blood from body enters the RA through the superior and inferior vena cava. It pours through the TRICUSPID (RIGHT AV) VALVE into the right ventricle. Right atrium contracts, pushes blood into the right ventricle  ventricle expands, then contracts with force. To prevent the blood from going back up into the atrium, need a valve. 5

Blood Flow Blood comes from the superior or inferior vena cava, into the right atrium, past the tricuspid valve, into the right ventricle. It then goes past the pulmonary semilunar valve, and into the pulmonary arteries. IVC Pulmonary arteries SVC RA RV Tricuspid valve Pulmonary Semilunar valve 6

VALVES Valves are like a swinging door that can only open one direction. But you can push against this door, since it’s only tissue. But if you tie a rope to the doorknob, it won’t be able to go the wrong way. The ropes are called CHORDAE TENDONAE, (“heart strings”) which are anchored to pieces of myocardium called PAPILLARY MUSCLES. The contraction of the papillary muscles pulls on the chordae tendonae to close the valves, preventing a PROLAPSED VALVE (turned inside out). 7

Figure 18.9a Valves 8

Function of the Atrioventricular Valves Figure 18.9b 9

Heart Valves – Valve Structure Figure 18.8a 10

Trabeculae carneae (spongy meat) Trabeculae carnae are masses of irregular spongy tissues which project from the inner surface of the right and left ventricles. The purpose of the trabeculae carneae is to prevent suction that would occur with a flat surface and thus impair the heart's ability to pump efficiently. The trabeculae carneae also serve a similar function to papillary muscles in that their contraction pulls on the chordae tendineae, preventing prolapsed mitral (bicuspid) and tricuspid valves. 11

Trabecula Carnae 12

What is an artery? An artery is a vessel that carries blood AWAY from the heart. It does not matter if it is oxygenated or deoxygenated blood. A vein is a vessel that carries blood TOWARD the heart. It does not matter if it is oxygenated or deoxygenated blood. 13

Blood Flow With the ventricular contraction, blood can go only one way: into the PULMONARY ARTERY (one of the few arteries with deoxy blood). When the ventricles relax, the PULMONARY SEMILUNAR VALVE closes to prevent blood from going from the pulmonary artery back into the right ventricle. IVC Pulmonary arteries Pulmonary veins SVC RA RV Tricuspid valve Pulmonary semilunar valve 14

Function of the Semilunar Valves Figure 18.10a, b 15

Blood Flow When the ventricles relax, the PULMONARY SEMILUNAR VALVE closes to prevent blood from going from the pulmonary artery back into the right ventricle. Do the semilunar valves have a chordae tendonae? No; the blood is not being forced back (with a contraction), it just falls back with gravity, so there’s not as much pressure. 16

Blood Flow Blood then goes into lungs, gets oxygenated, and returns on the left side through the PULMONARY VEINS (one of the few veins with oxy blood), into the LEFT ATRIUM. LA LV Pulmonary arteries Pulmonary veins Tricuspid valve Bicuspid (mitral) valve 17 Lungs

Blood Flow From the LEFT ATRIUM, it goes through the MITRAL VALVE (BICUSPID VALVE) into the LEFT VENTRICLE(there are also chordae tendonae here), which contracts. Therefore, the left ventricle is the chamber which is responsible for generating the largest pressure upon contraction. LA LV Pulmonary arteries Pulmonary veins Tricuspid valve Bicuspid (mitral) valve 18 Lungs

Mitral Valve The mitral valve gets its name from being the shape of a Bishop’s hat, called a mitre. 19

Blood Flow The blood then goes past the AORTIC SEMILUNAR VALVE, into the AORTA, and out to the body. 20 LA LV IVC Pulmonary arteries Aorta Pulmonary veins SVC RA RV Tricuspid valve Bicuspid valve Pulmonary semilunar valve The semilunar valves are located between the ventricles and the great arteries.

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VALVES: “Try before you Buy” TRICUSPID VALVE BICUSPID VALVE (MITRAL VALVE) PULMONARY SEMILUNAR VALVE AORTIC SEMILUNAR VALVE Structures associated with tricuspid and bicuspid valves –CHORDAE TENDONAE –PAPILLARY MUSCLES 22

Blood Flow Deoxy blood  sup/inf vena cava  R atrium  tricuspid valve  R ventricle  pulmonary semilunar valve  pulmonary artery  lungs  pulmonary veins  Left atrium  mitral (bicuspid) valve  Left ventricle  aortic semilunar valve  aorta  rest of body. 23 LA LV IVC Pulmonary arteries Aorta Pulmonary veins SVC RA RV Tricuspid valve Bicuspid valve Pulmonary semilunar valve Aortic semilunar valve

STRUCTURES TO KNOW ON THE SHEEP HEART A. myocardium B. endocardium C. visceral pericardium 1. apex 2. interventricular septum (IV septum) 3. left ventricle 4. right ventricle 5. right atrium 6. left atrium 7. chordae tendinae 8. papillary muscles 9. tricuspid valve 10. bicuspid (mitral) valve 11. trabeculae carni 12. aortic semilunar valve

Apex Myocardium (meaty areas of brown muscle Endocardium (inside all chambers where blood touches) Visceral pericardium (outer shiny surface of heart) What LAYER of tissue is this?

Apex What CHAMBER is this? Right ventricle What CHAMBER is this? Right atrium What CHAMBER is this? Left atrium What CHAMBER is this? Left ventricle

Apex Atrial septum Interventricular septum Mitral (bicuspid) valve Apex Tricuspid valve

Mitral (bicuspid) valve Cordae tendonae Papillary muscles Aortic semilunar valve Trabeculae carnae

Aorta Superior vena cava Pulmonary artery

STRUCTURES TO KNOW ON THE HUMAN HEART A. myocardium B. endocardium C. visceral pericardium D. pulmonary trunk E. pulmonary veins (there are four) F. pulmonary arteries G. right coronary artery H. left coronary artery I. Circumflex artery J. posterior interventricular artery K. anterior interventricular artery L. Right brachiocephalic M. Right subclavian N. Right common carotid O. Left common carotid P. Left subclavian

Visceral pericardium (outer shiny surface) Myocardium Endocardium

STRUCTURES TO KNOW ON THE HUMAN HEART 1. apex 2. Interventricular septum (IV septum) 3. left ventricle 4. right ventricle 5. right atrium 6. left atrium 7. atrial septum 8. chordae tendinae 9. papillary muscles 10. trabeculae carni 11. mitral valve (bicuspid valve) 12. tricuspid valve 13. aortic semilunar valve 14. pulmonary semilunar valve 15. aorta 16. superior vena cava 17. inferior vena cava

Pulmonary trunk Left coronary artery Right coronary artery Superior vena cavae Aorta Right Atrium Left Atrium L. Pulmonary artery Apex Right Auricle (ear shaped)

Posterior view of heart Superior vena cavae Inferior vena cavae Trachea Aorta Right Atrium Left Atrium Pulmonary veins Posterior interventricular artery Coronary sinus

Anterior interventricular artery Left Atrium Left Ventricle Interventricular septum Right Atrium Right Ventricle Atrial septum Right Auricle (ear shaped)

Pulmonary semilunar valve Papillary muscles Cordae tendonae Trabeculae carnae Mitral (bicuspid) valve Tricuspid valve Aortic semilunar valve (look deep under here)

Look up here to see aortic semilunar valve Pulmonary semilunar valve

R. Coronary artery Pulmonary veins L. Coronary artery Anterior interventricular artery Circumflex artery

Aorta Pulmonary trunk Left subclavian artery Left common carotid artery R. Brachiocephalic artery R. common carotid artery L. Pulmonary artery R. subclavian artery Superior vena cava

Trachea Esophagus Inferior vena cava

Fetal Circulation

FETAL CIRCULATION Umbilical vein carries oxygenated blood from the placenta; it is the VESSEL where blood is most highly oxygenated. Right atrium is the CHAMBER where blood is most highly oxygenated Foramen ovale is the hole between the fetal atria Ductus arteriosus is the connection between the pulmonary artery and the aorta

Fetal Circulation