LECTURE 5. Anatomy of the heart

Transcription

1 LECTURE 5. Anatomy of the heart

2 Main components of the CVS: Heart Blood circulatory system arterial compartment haemomicrocirculatory (=microvascular) compartment venous compartment Lymphatic circulatory system lymphomicrocirculatory compartment lymphatic vessels, trunks and ducts

3 Four Functions of the Cardiovascular system. Pump Material through body Transport blood Deliver O2 and nutrients and remove wastes Return lymph to circulation FOUR FUNCTIONS

4 Cardiovascular System Arteries Arterioles Capillaries

5 Cardiovascular System Veins differ from arteries because they carry blood toward heart, have valves, and have thinner walls; they are more numerous and have larger capacity

6 Blood Vessel Function Vessel Function Examples Artery Vein Capillary Transports blood AWAY from the heart Transports blood TOWARDS the heart Material exchange between blood and body Aorta Pulmonary artery Vena cava Pulmonary vein Capillary beds found throughout body

7 Systemic and Pulmonary Circulation Pulmonary circulation The flow of blood from the heart through the lungs back to the heart Picks up oxygen and releases carbon dioxide in the lungs Systemic circulation The flow of blood from the heart through the body back to the heart Delivers oxygen and picks up carbon dioxide in the body s tissues Cardiac circulation: blood flow within the heart

8 The heart beat is strong enough to squirt blood 30 feet The human heart beats ~35 million times per year Your heart beats 100,000 times and pumps ~2000 gallons of blood every day The heart pumps ~1,000,000 barrels of blood in a lifetime Most heart attacks occur between 8-9 a.m.

9 The blue whale has the largest heart it weights ~ one ton The hummingbird has a heart that beats 1000 times per minute Your entire volume of blood goes through your entire body once every minute Humans have ~60,000 miles of blood vessels in their bodies (more than twice the circumference of the earth!) Pig and baboon hearts have been transplanted into humans

10 Functions of the Heart 1. Generating blood pressure Required for blood flow through the blood vessels 2. Routing blood Two pumps, moving blood through the pulmonary and systemic circulations 3. Regulating blood supply Adjusts blood flow by changing the rate and force of heart contractions as needed

11 ONTOGENESIS Heart develops from the mesoderm on 3rd week embryogenesis a pair of tubes (sacks) at the level of the pharynx to either side of the primary gut between endoderm and splanchnopleura. 2 weeks

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13 ONTOGENESIS 2.5 weeks 3 weeks The tubular heart with a two-layer wall. In the future, the inner layer of the tube formed endocardium, and from the outside - the myocardium and epicardium. Primordium the heart is located in the neck.

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15 Development of the heart

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18 Folding and rotation of the heart tube Straight heart tube C- shaped tube S - shaped tube

19 Development of the heart

20 Natural embryonic heart after the torsion

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23 Development of the heart On the 4th week of embryogenesis from upper rear of the inner surface of the total atrial growing primary interatrial septum toward the atrioventricular opening and separetes the common atrium into right and left.

24 This separation is not complete, because stored in the partition wide primary atrial opening. Right from the primary partition of the upper posterior wall of the atrium is growing secondary interatrial septum, which merges with the primary, completely separating the two atria. Cranial part of the secondary partitions breaks, forming a secondary atrial hole (foramen ovale).

25 At the beginning of the 8th week of embryogenesis on low back wall of the ventricles the fold is formed - the future interventricular septum, which grows upward and forward

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27 Skeletopy of the Heart Oblique Position Apex: in the 5 th intercostal space 1cm from the left mammilary line toward the midline; Superior border passes on a level with the superior margin of the 3 rd costal cartilages; Right border passes 2-3cm to the right of the right sternal border between the 3 rd and 5 th ribs; Inferior border stretches transversely from the cartilage of the 5 th right rib to the heart apex; Left border passes from the cartilage of the 3 rd rib to the heart apex.

28 The heart surfaces: The anterior (sternocostal) surface comprises the: right atrium, atrioventricular groove, right ventricle, a small strip of left ventricle and the auricle of the left atrium. The inferior (diaphragmatic) surface comprises the: right atrium, atrioventricular groove and both ventricles separated by the interventricular groove. The posterior surface (base) comprises the left atrium receiving the four pulmonary veins. The Heart

29 Heart Wall The heart wall has three layers Epicardium Visceral layer of the serous pericardium (visceral pericardium) Provides protection against the friction of rubbing organs Myocardium Cardiac muscle layer forming the bulk of the heart Responsible for contraction Endocardium Endothelial layer over crisscrossing, interlacing layer of connective tissue Inner endocardium reduces the friction resulting from the passage of blood through the heart Ventricles have ridges called trabeculae carneae The inner surfaces of the atria are mainly smooth Auricles have raised areas called musculi pectinati

30 Myocardium

31 Papillary Muscles Flaps of muscles connected to various valves on one end by chordae tendinae and to ventricular walls on the other Stabilize valves

32 Fibrous Skeleton of the Heart Consists of a plate of fibrous connective tissue Forms fibrous rings around the AV and SL valves for support Provides a point of attachment for heart muscle Electrically insulates the atria from the ventricles

33 Fibrous skeleton (rings, trigons) and myocardium Connective tissue heart frame: 1 - fibrous base mouth LA; 2 - fibrous base of the aorta; 3 - right atrial arch of fibrous ring; 4 - back arch of right fibrous ring; 5 - posterior arch of the left fibrous ring; 6 - a forward arch of left fibrous ring; 7 - left fibrotic triangle; 8 - right fibrous triangle; 9 - the front part of the right fibrous triangle; 10 posterior part of right fibrous triangle

34 The Heart Pericardium includes the parietal and visceral layers with potential cavity

35 The Heart Chambers Atria Features small, thin-walled chambers Functions receiving chambers for blood returning to the heart from the circulation push the blood into the adjacent ventricles.

36 The Heart Chambers Atria Receive blood from Right side Superior and Inferior Vena Cava Coronary Sinus (draining the myocardium) Left side Pulmonary Veins

37 Receives deoxygenated blood from the inferior vena cava below and from the superior vena cava above. Receives the coronary sinus in its lower part. The upper end of the atrium projects to the left of the superior vena cava as the right auricle. The Right Atrium

38 Receives oxygenated blood from four pulmonary veins which drain posteriorly. The cavity is smooth walled except for the atrial appendage. On the septal surface a depression marks the fossa ovalis. The Left Atrium

39 Ventricles Features The Heart Chambers make up most of the mass of the heart the walls of the left ventricle are thicker than those of the right

40 Ventricles Functions The Heart Chambers discharging chambers of the heart propel blood to Pulmonary Trunk (right ventricle), Aorta (left ventricle)

41 The Right Ventricle Receives blood from the right atrium through the tricuspid valve. The edges of the valve cusps are attached to chordae tendineae which are, in turn, attached below to papillary muscles.

42 The Right Ventricle The wall of the right ventricle is thicker than that of the atria but not as thick as that of the left ventricle. The wall contains a mass of muscular bundles known as trabeculae carneae. The infundibulum is the smooth walled outflow tract of the right ventricle.

43 The Right Ventricle The pulmonary valve is situated at the top of the infundibulum. It is composed of three semilunar cusps. Blood flows through the valve and into the pulmonary arteries via the pulmonary trunk to be oxygenated in the lungs.

44 The vestibule is a smooth walled part of the left ventricle which is located below the aortic valve. The Left Ventricle

45 Heart valves ensure unidirectional blood flow through the heart Composed of an endocardium with a connective tissue core. Two major types Atrioventricular valves Semilunar valves The Heart Valves

46 The Heart Valves Atrioventricular valves Right AV (Tricuspid) separates the right atrium from the right ventricle. Prevents backflow into atrium. Left AV (Bicuspid) separates the left atrium from the left ventricle. Prevents backflow into atrium. Semilunar valves Pulmonary valve separates the right ventricle from the pulmonary arteries. Prevents backflow after ventricular contraction. Aortic valve separates the left ventricle from the aorta. Prevents backflow after ventricular contraction.

47 Atrioventricular (AV) Valves Atrioventricular (AV) valves lie between the atria and the ventricles R-AV valve = tricuspid valve L-AV valve = bicuspid or mitral valve AV valves prevent backflow of blood into the atria when ventricles contract Chordae tendineae anchor AV valves to papillary muscles of ventricle wall Prevent prolapse of valve back into atrium

48 Atrioventricular Valve

49 Semilunar Heart Valves Semilunar valves prevent backflow of blood into the ventricles Have no chordae tendinae attachments Aortic semilunar valve lies between the left ventricle and the aorta Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk Heart sounds ( lub-dup ) due to valves closing Lub - closing of atrioventricular valves Dub - closing of semilunar valves

50 VALVULAR APPARATUS OF THE HEART Right AV (tricuspid) valve Chordai tendineae Papillary muscle Pulmonary semilunar valve Aortic semilunar valve Left AV (bicuspid) valve

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52 Cardiac Cycle Overview of Systole and Diastole During systole AV valves close Pressure increases in the ventricles Semilunar valves are forced to open Blood flows into the aorta and pulmonary trunk At the beginning of diastole Pressure in the ventricles decreases Semilunar valves close to prevent backflow of blood from the aorta and pulmonary trunk into the ventricles When the pressure in the ventricles is lower than in the atria, the AV valves open and blood flows from the atria into the ventricles During atrial systole, the atria contract and complete the filling of the ventricles

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55 FINISH!