Anatomy of CVS PDF

Anatomy of CVS CVS Heart Blood Blood Vessels (Pump) (Transport medium) (Passageway) 1. Arteries 2. A...

Anatomy of CVS CVS Heart Blood Blood Vessels (Pump) (Transport medium) (Passageway) 1. Arteries 2. Arterioles 3. Capillaries 4. Venules 5. Veins  Basic structure of arteries Wall of an artery is made up of three layers 1. Tunica intima (innermost layer) 2. Tunica media 3. Tunica adventitia (outermost layer) 1. Tunica intima (innermost layer) It consists of,  An endothelial lining  A thin layer of glycoprotein which lines the external aspect of endothelium and is called the basal lamina.  A delicate layer of sub endothelial connective tissue.  A membrane formed by elastic fibres called the internal elastic lamina. 2. Tunica media (middle) It consists of,  Elastic tissue or smooth muscle.  Some connective tissue is usually present.  On the outside the media is limited by a membrane formed by elastic fibres, this is the external elastic lamina. 3. Tunica adventitia (outermost layer) It consists of,  Connective tissue in which collagen fibres are prominent.  This layer prevents undue stretching or distension of the artery.  Classifications of arteries (Tissue that predominates in the tunica media) 1. Elastic Arteries 2. Muscular Arteries The arteries have abundant elastic These arteries control the amount of fibres in their walls. blood flowing through them according E.g. to the activity of the part. They have the 1. Aorta ability to alter the size of its lumen by 2. Large arteries supplying the head contraction or relaxation of smooth and neck (Carotid arteries) muscle in its wall. 3. Large arteries supplying the limbs E.g. (Subclavian, axillary, iliac) 1. Brachial , Radial , Popliteal artery  Types of blood capillaries, 1. Continuous capillaries (skin, muscle, lung, CNS) 2. Fenestrated capillaries (exocrine glands, renal glomeruli, intestinal mucosa) 3. Sinusoidal capillaries (liver, spleen, bone marrow) Artery Vein 1. Carry blood away from the heart 1. Carry blood to the heart 2. High pressure (compare to) 2. Low pressure 3. Thick wall 3. Thin wall 4. Narrow lumen 4. Wide lumen 5. No valves 5. Valves present  Heart  Position  Lies in the middle mediastinum (the space between the lungs).  Lies obliquely, a little more to the left than right.  Presents a base above and an apex below.  The apex is about 9 cm to the left of the midline at the level of the 5th intercostal space.  The base extends to the level of the 2nd rib.  A horizontal plane passing through the sternal angle and intervertebral disc between vertebrae TIV and TV separates the mediastinum into superior and inferior parts.  Cardiac orientation  The general shape and orientation of the heart are that of a pyramid that has fallen over and is resting on one of its sides.  The sides of the pyramid consist of, 1. A diaphragmatic (inferior) surface – on which the pyramid rests 2. An anterior (sternocostal) surface – oriented anteriorly 3. A right pulmonary surface 4. A left pulmonary surface  External sulci 1. Coronary sulcus – separates atria from the ventricles 2. Anterior and posterior interventricular sulci – separate two ventricles  Heart wall All layers, Three layers of tissue, 1. Fibrous Pericardium 2. Parietal Pericardium of Serous Pericardium 1. Pericardium (Pericardial Cavity) 2. Myocardium 3. Visceral Pericardium of Serous Pericardium 3. Endocardium 4. Myocardium 5. Endocardium 1. Pericardium  A fibroserous sac surrounding the heart and the roots of the great vessels. Consists of two components. 1. Fibrous pericardium  The fibrous pericardium is continuous with the tunica adventitia of the great blood vessels above and is adherent to the diaphragm below.  Its inelastic, fibrous nature prevents over distension of the heart. 1. Parietal layer 2. Serous pericardium 2. Visceral layer (epicardium)  The outer layer, parietal pericardium, lines the fibrous pericardium.  The inner layer, visceral pericardium, which is continuous with the parietal pericardium, is adherent to the heart muscle.  A similar arrangement of a double membrane forming a closed space is seen also with the pleura, the membrane enclosing the lungs.  The serous membrane consists of flattened epithelial cells.  It secretes serous fluid, called pericardial fluid, into the space between the visceral and parietal layers, which allows smooth movement between them when the heart beats.  The space between the parietal and visceral pericardium is only a potential space.  In health the two layers lie closely together, with only the thin film of pericardial fluid between them. 2. Myocardium  Thickest layer of the heart  Thickest in left ventricle because must pump hard to overcome high pressure of systemic circulation  Right atrium the thinnest because of low resistance to back flow  Consist of cardiac muscle cells 3. Endocardium  Innermost layer Composed of: 1. Simple squamous epithelium (endothelium) – Connective Tissue 2. Subendocardium: in contact with cardiac muscle and contains small vessels, nerves, and Purkinje Fibers.  Internal of Heart Chambers 1. Interatrial septum – wall that separates atria. 2. Pectinate muscles – internal ridges of myocardium in right atrium and both auricles. (absorber) 3. Interventricular septum – wall that separates ventricles. 4. Trabeculae carneae – internal ridges in both ventricles. (absorber)  Heart Valves 1. Right AV valve (tricuspid valve) 2. Left AV valve (bicuspid valve) 3. Semilunar valves- found in the arteries leaving the heart to prevent blood from flowing back into the ventricles.  Chordae tendineae, fibrous cords anchor the cusps to the ventricle walls via papillary muscles.  Superior & Inferior Vena Cava Left Right Atrium Atrium Pulmonary Circulation Pulmonary Right Veins Ventricle Pulmonary Lungs Artery Pulmonary Veins Right Left Atrium Atrium Systemic Superior & Circulation Inferior Left Vena Cava Ventricle Body Aorta  Coronary Circulation  Coronary arteries supply blood to the heart muscle.  Like all other tissues in the body, the heart muscle needs oxygen-rich blood to function, and oxygen-depleted blood must be carried away.  They were called “Coronary” arteries (Corona = Crown), because they encircle the base of the ventricles somewhat like a crown.  The heart is supplied by the, 1. Right coronary artery 2. Left coronary artery  Both arteries arise from the aortic sinuses.  Aortic sinuses  An aortic sinus is one of the anatomic dilations of the ascending aorta, which occurs just above the aortic valve.  These widening are between the wall of the aorta and each of the three cusps of the aortic valve.  There are generally three aortic sinuses, 1. Right aortic sinus 2. Left aortic sinus 3. Posterior aortic sinus  The left aortic sinus gives rise to the left coronary artery.  The right aortic sinus gives rise to the right coronary artery.  Usually, no vessels arise from the posterior aortic sinus, which is therefore known as the non-coronary sinus.  Each aortic sinus can also be referred to as the sinus of Valsalva, the sinus of Morgagni, the sinus of Mehta, the sinus of Otto, or Petit's sinus.  Cardiac vein  The coronary sinus receives 4 major tributaries, 1. Great cardiac vein 2. Middle cardiac vein 3. Small cardiac vein 4. Posterior cardiac vein  Coronary lymphatic  The lymphatic vessels of the heart follow the coronary arteries and drain mainly into, 1. Brachiocephalic nodes – anterior to the brachiocephalic veins 2. Tracheobronchial nodes – at the inferior end of the trachea  Pathological and congenital conditions of CVS 1. Valve diseases – due to,  Incompetence (insufficiency), which results from poorly functioning valves  Stenosis, a narrowing of the orifice, caused by the valve’s inability to open fully. Ex - 1. Mitral valve disease 2. Aortic valve disease 3. Valve diseases in right side (affecting the tricuspid or pulmonary valve) is most likely caused by infection. 2. Congenital heart defects Most common abnormalities that occur during development are those produced by a defect in the atrial and ventricular septa. 1. Atrial Septal Defect (ASD) 2. Ventricular Septal Defect (VSD) - This leads to right ventricular hypertrophy and pulmonary arterial hypertension. 3. Patent or Persistent Ductus Arteriosus (PDA) - A blood vessel in the developing fetus connecting the trunk of the pulmonary artery to the proximal descending aorta - produces pulmonary hypertension.