Cardiovascular System I 27.9-02.10.2023 PDF

Cardiovascular system pt.1 27 Sept & 2 Oct 2023 Professor Dr Panagiotis Karanis Professor and Director of Anatomy Institute Coordinator Unit of Anatomy and Morphology UNic Medical School  In today’s session we will… Identify the four chambers of the heart an...

Cardiovascular system pt.1 27 Sept & 2 Oct 2023 Professor Dr Panagiotis Karanis Professor and Director of Anatomy Institute Coordinator Unit of Anatomy and Morphology UNic Medical School  In today’s session we will… Identify the four chambers of the heart and the surfaces of the heart (anterior, posterior, base, etc.). Describe the normal flow of blood though the heart Identify the branches of the arch of the aorta (brachiocephalic artery, left common carotid artery, left subclavian artery) and the structures they supply Identify the branches of the descending thoracic aorta (paired posterior intercostal, bronchial, oesophageal, mediastinal arteries) and the structures they supply. Describe the common variations of the branches of the arch of the aorta and their clinical significance. Identify the azygos, hemiazygos and accessory hemiazygos veins and describe the communications of the azygos system with the caval system of veins & its purpose. Go through the different types of blood vessels and their main characteristics. CARDIOVASCULAR SYSTEM The circulatory system transports fluids throughout the body; it consists of the cardiovascular and lymphatic systems. The heart and blood vessels make up the blood transportation network, the cardiovascular system. Like an irrigation system, the body’s blood vessels form an extensive network of “irrigation channels” to deliver needed fluid — in this case the homeostatically maintained blood — to all the body’s cells. In fact, this delivery system is probably the most phenomenal irrigation network imaginable. The irrigation network of blood vessels are of no value without a pump. The heart is the dual, self-regulating pump that generates the pressure to drive the blood through this impressive irrigation network. It pumps the blood through two cycles — a pulmonary cycle to pick up oxygen from the lungs and a systemic cycle to deliver the oxygen to all the cells of the body. Vascular Circuits Powered by the heart, a muscular pump with four chambers (two atria & two ventricles) Two main subdivisions in the circulatory system Pulmonary circulation  De-oxygenated blood leaves the right side of heart to be re-oxygenated in the lungs It is then returned to the left side of the heart to enter the… Systemic circulation  The right and left heart depicted as two pumps in series. The pulmonary and Provides the body with oxygenated blood systemic circulations are actually serial Then returns the de-oxygenated blood to the components of one continuous loop.  A bit more detail… The heart is a double, suction self-adjusting and pressure pump. The parts of the pump work in unison to propel blood to all parts of the body. The right heart receives poorly venous blood from the body through the SVC and IVC and pumps it through the pulmonary trunk and arteries to the lungs for Oxygenation. Soon after conception, and up until death, the heart pumps blood. It averages ca. 70 beats per minute, or about 3 billion contractions in an average lifetime. The left heart receives arterial blood from Two the muscular pumps lungs through (right and the pulmonary veinsleft andheart) serving the pulmonary and systemic pumps it into the aorta for distributioncirculations to There are three types of blood vessels: arteries, veins, and capillaries Arteries are blood vessels responsible for carrying oxygen- rich blood away from the heart to the body. Veins generally return low-oxygen blood from the capillary beds to the heart, which gives the veins a dark blue appearance. Capillaries are simple endothelial tubes connecting the arterial and venous sides of the circulation that allow the exchange of materials with the interstitial or extracellular In even more detail… Veins from body  vena cavas  RA  RV  pulmonary arteries  lungs  pulmonary veins  LA  LV  aorta  back to body From body via SVC, IVC & coronary sinus to RA Then to RV through the tricuspid valve To lungs through the pulmonary valve that leads to the pulmonary arteries Q: Normally arteries contain oxygenated blood and veins de-oxygenated blood Can you think of some exceptions?  Pulmonary Circulation Deoxygenated blood passes from the right ventricle to the pulmonary trunk which divides into left and right pulmonary arteries that enter the lungs. Return of oxygenated blood to the heart is by way of the four pulmonary veins that enter the left atrium. Bronchial arteries The systemic circulation consists of many parallel circuits serving the various organs and regions of the body. This circular pattern of flow to and from the heart constitutes the vascular (blood vessel) component of the cardiovascular (circulatory) system. This irrigation network is so impressive, that if all the blood vessels of the body were placed end-to-end they would extend 25,000 miles (96,500 km), which is approximately two times the equatorial circumference of the earth. The walls of most blood vessels have three concentric layers of tissue, called tunics (L. tunicae, coats). With less A liquid red plastic was injected into the muscle, veins are thinner walled than their companion coronary arteries through the aorta under high arteries and have wide lumens (L. luminae) that usually pressure appear flattened in tissue sections. Head – Neck - Arteries; Anterior view Four colour-technic applied to show the four regions Q: Other structures with lumen? Examples of body structures that have a lumen include the large intestine, small intestine, veins, and arteries.  ATLAS OF HUMAN ANATOMY / MARK NIELSEN SHAWN MILLER, p. The263 heart From its origin in the embryo as a simple pumping tube, the heart develops into a strong fibromuscular organ. During its development the original tubular pump is folded and subdivided into a four chambered organ that has a pyramidal or conical form. It is approximately the size of a closed fist and weights ca. 300 grams in males and a little less than this in females. For its small size, comprising only one half of one percent of the total body mass, it is an important and functionally amazing organ. The wall of the heart consists of three structural layers that each play significant roles in its function as an efficient pump. While the tissue make up of this wall is similar at any location in the heart, the thickness can vary considerably. Internally a septum and series of valves divide the heart into four chambers through which the Anterior view blood moves in a unidirectional flow. The Posterior view chambers differ in structure and function, which Cardiovascular System Q: What two systemic veins return blood to the right atrium of the heart? A: Superior and inferior venae cavae.  The heart - Heart’s position in thorax The mediastinum The mediastinum is defined as ‘the space which is sandwiched between the two pleural sacs’. For descriptive purposes the mediastinum is divided by a line drawn horizontally from the sternal angle to the lower border of T4 (angle of Louis) into the superior and inferior mediastinum. The inferior mediastinum is further subdivided into the anterior in front of the pericardium, a middle mediastinum containing the pericardium itself with the heart and great vessels, and the The heart - Heart’s position What is the in thorax mediastinum ? Subdivisions and levels of mediastinum. The subdivisions of the mediastinum are demonstrated as if the person were in the supine position. The heart - Heart’s position in thorax  Heart’s position in thorax In the middle mediastinum – behind sternum and pointing left Lying on the diaphragm It weights 250-350 g (about 1 pound) Slightly larger than one’s clenched fist 9 The heart is a hollow muscular pump, which lies in the middle mediastinum. On its surface, it has several distinctive features which are of anatomical and clinical importance. Orientation and Surfaces The heart has been described by many texts as “a pyramid which has fallen over”. The apex of this pyramid pointing in an anterior-inferior direction. In its typical anatomical orientation, the heart has 5 surfaces, formed by different internal divisions of the heart: Anterior (or sternocostal) – Right ventricle. Posterior (or base) – Left atrium. Inferior (or diaphragmatic) – Left and right ventricles. Right pulmonary – Right atrium. Left pulmonary – Left ventricle. Borders Separating the surfaces of the heart are its borders. There are four main borders of the heart: Right border – Right atrium Inferior border – Left ventricle and right ventricle Left border – Left ventricle (and some of the left atrium) Superior border – Right and left atrium and the great vessels Sulci of the Heart The heart is a hollow structure. On the interior, it is divided into four chambers. These divisions create grooves on the surface of the heart – these are known as sulci. The coronary sulcus (or atrioventricular groove) runs transversely around the heart – it represents the wall dividing the atria from the ventricles. The sulcus contains important vasculature such as the right coronary artery. The anterior and posterior interventricular sulci can be found running vertically on their respective sides of the heart. They represent the wall separating the ventricles.  The apex of the heart is formed by the inferolateral part of the left ventricle. lies posterior to the left 5th intercostal space in adults is where the sounds of mitral valve closure are maximal (apex beat). The heart appears trapezoidal The four borders of the heart: The four surfaces of the heart: 1. right border, (RA between the SVC and the 1. anterior (sternocostal) surface, (mainly by IVC). the RV). 2. inferior border, (RV and slightly by the LV). 2. diaphragmatic (inferior) surface, (mainly 3. left border, (LV and slightly by the left auricle). by the LV and 4. superior border, (RA, LA and auricles in an partly by the RV; related to the central tendon of anterior The base of the heart posterior aspect (opposite the apex). is formed mainly by the LA, with a lesser contribution by the RA. faces posteriorly toward the bodies of vertebrae T6–T9 extends superiorly to the bifurcation of the pulmonary trunk and inferiorly to the coronary sulcus. receives the pulmonary veins on the right and left sides of its left atrial portion and the SVC + IVC. Postero - inferior views  See you tomorrow 🤗 Have a nice day ahead Coverings of the heart: Pericardium The middle mediastinum includes pericardium the pericardium, heart, and roots of its great vessels —ascending aorta, Three layered: pulmonary trunk, and SVC—passing to and from the heart. Fibrous pericardium Serous pericardium of layers (x2) Parietal layer of serous pericardium Visceral layer of serous pericardium = epicardium: on heart and is part of its wall (Between the layers is the pericardial The pericardium is a fibro-serous membrane that covers the heart and the cavity) beginning of its great vessels. The pericardium is a closed sac composed of two layers (fibrous and serous pericardium). Pericardium and heart. A. The heart occupies the middle mediastinum and is enclosed by pericardium, composed of two parts. The tough, outer fibrous pericardium stabilizes the heart and helps prevent it from overdilating. Between the fibrous pericardium and the heart is a “collapsed” sac, the serous pericardium. The embryonic heart invaginates the wall of the serous sac (B) and soon practically obliterates the pericardial cavity (C), leaving only a potential space between the layers of serous pericardium. C and D. The pericardiacophrenic ligament is the continuity of the fibrous pericardium with the central tendon of the The wall of each heart chamber consists of three layers, from superficial to deep: diaphragm. 1. Endocardium; 2. Myocardium; 3. Epicardium Layers of pericardium and heart wall Pericardium Q? Pericardium ATLAS OF HUMAN ANATOMY / MARK NIELSEN SHAWN MILLER, p. 264  Pericardial Sinuses The pericardial sinuses are not the same as ‘anatomical sinuses’ (such as the paranasal sinuses). They are passageways formed the unique way in which the pericardium folds around the great vessels. The oblique pericardial sinus is a blind ending passageway located on the posterior surface of the heart. The transverse pericardial sinus is found superiorly on the heart. It can be used in coronary artery bypass grafting. Clinical Relevance: Transverse Pericardial Sinus The location of the transverse pericardial sinus is: Posterior to the ascending aorta and pulmonary trunk. Anterior to the superior vena cava. Superior to the left atrium. In this position, the transverse pericardial sinus separates the arterial vessels (aorta, pulmonary trunk) and the venous vessels (superior vena cava, pulmonary veins) of the heart. This can be used to identify and subsequently ligate (to tie  Chambers of the heart divided by septae: Two atria-divided by interatrial septum Right atrium Left atrium Two ventricles- divided by interventricular septum Circulation of blood through the heart. The right heart (blue side) is the pump for the pulmonary circuit; the left heart (red side) is the pump for the systemic circuit. Relative thickness of muscular walls LV thicker than RV because it forces blood out against more resistance; The systemic circulation is much higher pressure circulation than the pulmonary Atria are thin because ventricular filling requires little atrial effort  Valves of the heart Aortic Pulmonary Mitral The only one Tricuspid with 2 cusps Describe the route the blood takes starting from the right atrium  Pulmona ry Opening and closure of the Aorti c heart valves Mitr Tricusp al id  Pulmona ry Opening and Aorti closure of the c heart valves Mitr Tricusp al id  Muscle cells are long, slender cells that have special arrangements of the proteins actin and myosin within the cytoplasm. The architectural design of these proteins forms the muscle cell “machinery” that allows the cell to specialize at contracting (shortening). The names of the different types of muscle tissues arise from the arrangement of the contractile proteins within their cells. In some tissues the protein arrangement gives the cell a striated, or Smooth (non-striated) muscle tissue striped, appearance (striated muscle), while in other Longitudinal section of muscular wall tissues the striped appearance is not evident (non- of intestine 1 Nucleus; 2 Sarcoplasm; 6 Intercalated disc striated or smooth muscle). Cardiac striated muscle tissue Skeletal striated muscle tissue Section of ventricle of heart Section of vastus lateralis muscle  Histology of the heart Heart muscle (myocardium) has striations like skeletal muscle but looks more "stringy".  Skeletal muscle cells are very large and run in parallel bundles.  Cardiac muscle cells are smaller, butted together at their ends and irregularly shaped, with many blood vessels between them.  The result is a network rather than parallel series of fibres.  The nuclei of the myocardial cell are quite clearly visible in the middle. Cardiac Skeletal muscle muscle  1 Aorta Great vessels and 2 Brachiocephalic artery 3 Right common carotid nerves of the thorax: artery 4 Right subclavian artery The aortic arch 5 Right internal thoracic artery 6 Left common carotid artery 7 Left subclavian artery The superior mediastinum arch of aorta: brachiocephalic trunk left common carotid artery left subclavian artery left and right brachiocephalic veins (L) subclavian vein (L) vein (L) internal jugular vein (R) vein (R) subclavian vein (R) internal jugular vein (L) and (R) brachiocephalic veins join to form the superior vena cava Aortic arch – anatomical variations Rare – failure in normal embryonic development Most common types : Double aortic arch Right sided aortic arch Img : 13 Coeliac trunk; 14 Common hepatic artery; 15 Left gastric artery; 16 Splenic artery; 17 Superior mesenteric artery; 18 Right renal artery; 19 Left renal artery; The thoracic aorta  Azygos (=unpaired) vein is the main tributary, the hemi- e azygos system of veins, on each site of the Azygos azygos vein usually arise from ‚roots‘ arising from the posterior aspect of the IVC and or renal vein, resp., which rtebral column, drains the back and thoraco- merge with the ascending lumbar vein dominal walls and mediastinal viscera. Accessor between the SVC and IVC and drains blood from the y The azygos vein forms a collateral pathway azygos posterior walls of the thorax and abdomen Thoraci c duct Hemiazygo s Notice the anastomoses between the inferior vena cava – azygos – superior vena cava  The left side of the mediastinum, ‘the red side’, is dominated by arterial structures Look at the main nerves and their relations (phrenic, vagus – recurrent laryngeal, syphathetic trunk)  Abdominal Aorta (common iliac arteries) Jmg : Kenhub, PIinterest Vessel s Largest, conducting arteries – lead directly from heart, subject to high pressures External and internal External and internal jugular, brachial & femoral carotids, brachial & femoral veins arteries  Capillari Only endothelium/ Variably permeable es ~8 µm Characterized by somewh circular fenestrae or at pores that penetrate the permea endothelium - permit ble exchange of larger molecules. Intestinal mucosa, Choroid Most body plexus, endocrine glands, Thank you!Literature Images and videos used in this presentation come from various Atlas’ and internet sites including : Netter’s Anatomy Wikipedia.org Atlas of Human Anatomy/ Mark Nielsen Shawn Miller teachMe Anatomy Moore/Dalley/Agur/Clinically-Oriented-Anatomy 8th edition) and are the property of their respective owners.