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Cardiorespiratory Anatomy Ethan Thom 2362076t@student.gla.ac.ukHeart • Heart is located in the mediastinum • 4 chambers • Right atrium • Right ventricle • Left atrium • Left ventricleCardiac V alves • 2 Atrioventricular valves • Right AV: Tricuspid (right atrium/right ventricle) • Left AV: Mitral/Bicuspid (left atrium from left ventricle) • Semilunar valves • Pulmonary (right ventricle into pulmonary artery) • Aortic (left ventricle into aorta) • Chordae tendinea tether AV valves to ventricular papillary pull on these, causing AV valve opening during atrial systoleCoronary Artery Origin Supplies Circumflex Left Left atrium, Left vasculature ventricle Anterior Left Both ventricles • Blood supply/venous drainage of heart interventricular (LAD) • ascending aortacoronary artery branch off Posterior Right Both ventricles • Left divides into circumflex and anterior interventricular (usually) interventricular (left anterior descending) • Right divides into atrial branch (SA nodal Marginal branch Right Right ventricle branch), right marginal, posterior of right interventricular • Anastomoses allows for alternative routes Atrial branch of Right Right atrium if a vessel becomes blocked right • NB: normal anatomical variationsCoronary dominance • Origin of posterior interventricular artery determines coronary dominance. • Arises from right coronary (67%) = Right dominance • Arises from circumflex (left coronary) (15%) = Left dominance • Arises from both right and left coronaries = codominanceVenous drainage • Great cardiac vein (LA + LV) • Middle cardiac vein (LV + RV) • Small cardiac vein (RA + RV) • Most deoxygenated blood from the heart drains into coronary sinus on posterior surface on heartLayers of the heart • Epicardium • Mesothelium (visceral layer of the serous pericardium) – produce pericardial fluid for lubrication of movement of heart • Thick connective tissue layer • Myocardium • Cardiomyocytes with connective tissue and abundant capillary vascular supply • Endocardium • Thin connective tissue layer – contains purkinje fibres • Endothelium (simple squamous)Cardiac conduction system • Initiates and coordinates myocardial contraction • specialized cardiomyocytes arranged into: • Sinoatrial (SA) node • Atrioventricular (AV) node • Atrioventricular bundle • Left and right bundles • Subendocardial conduction cells (Purkinje fibres)• SA node is a collection of pacemaker cells in the RA– these generate spontaneous electrical impulses • Wave of depolarization spreads via gap junctions across both –tria atrial depolarization (atrial systole) • SA node firing rate influenced by ANS • Impulses converge at AV node at RA/septum. Delay of ~120ms to allow atria to empty • Excitation passes down AV bundle (continuation of the AV node)Conduction system cont. • septum and divided into Left and Right bundle branches • ventricles by Purkinje fibres inh subendocardial surface – these have extensive gap junctions to allow for efficient impulse transmission • Coordinated ventricular contractionECG • Summation of all the action potentials • P wave – Atrial depolarization • PR interval - Delay at AV node (gives ventricles time to fill) • QRS complex – ventricular depolarization (+ atrial repolarization) • ST segment– plateau phase • T wave – ventricular repolarizationRegulation of cardiac output • Autonomic nervous system • Sympathetic (adrenaline/noradrenal↑ HR via adrenoceptors) • Parasympathetic (vagus nerve) • Frank-Starling law • Stroke volume increases in response to volume of blood in ventricles • More blood flows into ventricles, stretches cardiac muscle fibres, causes ↑ force of contraction • RAAS • ANPUpper Respiratory • Air enters through nasal cavity – mucosa is goblet cells (secrete mucous)umnar with • Passes into the pharynx • Nasopharynx (contains pharyngeal tonsil/adenoid) • Oropharynx (contains palatine tonsils) • Laryngopharynx – from superior margin of epiglottis to top of oesophagus at C6 levelLower resp • Larynx protects airways and seals off lower resp tract + voice production & vocalization • Below this is bronchial tree – trachea begins at C6 and branches off at T4 at the carina • 10-12 C shaped hyaline cartilaginous rings with trachealis muscle posteriorly • Right primary bronchus more vertical, shorter and thicker diameter than L – foreign bodies more common in right • Pseudostratified ciliated columnar with goblet cellsLower resp • Beyond primary bronchi, splits into 2 (left) and 3 (right) secondary bronchi • Then into 8 (left) and 10 (right) tertiary bronchi and further into bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts • Lungs divided into bronchopulmonary segments – areas of lung supplied by a tertial bronchus and its pulmonary artery branchAlveoli • Thin-walled air sacs made of 2 main cell types: • Type 1 pneumocyte– simple squamous epithelium for gas exchange • Type 2 pneumocyte– cuboidal cells that bulge into alveolar space and produce surfactant (this reduces surface tension and prevents alveoli collapsing on expiration). Also function as progenitor cells for new Type 1 and Type 2 pneumocytes following lung injury • Alveolar macrophages – these trigger inflammation and neutrophil migration in response to infectious particles • Blood-air barrier is made of 3 components: 1. Type 1 pneumocytes 2. Capillary endothelial cells 3. Fused basement membrane between theseHilum • Pulmonary artery (superior) • 2 Pulmonary veins (inferior) • Main bronchus (posterior) • Bronchial vessels • Nerves • LymphaticsUseful stuff to know beyond anatomy • Cardio • Cardiac cycle • Control of blood pressure– RAAS • Hypertension • Cardiovascular drugs • Resp • COPD vs Asthma • Functional testing: FVC, FEV1 etc • ABG interpretation • PneumothoraxMCQ 1 • What type of cartilage are the tracheal rings made of? • A: Elastic • B: Hyaline • C: Fibrous• Answer B • Hyaline cartilage makes up the rings of the trachea as well as articular surfaces of synovial joints. Hyaline cartilage matrix is made up of type II collagen fibres. It is avascularMCQ 2 • The origin of which vessel determines coronary dominance? • A: Circumflex • B: Left anterior descending • C: Right marginal branch • D: Posterior interventricular • E: Branch to sinoatrial node• Answer: D – Posterior interventricular • This can arise from the left, right or both coronary arteries and this determines coronary dominance MCQ 3 • Identify the abnormality • A: Heart failure with cardiomegaly and pulmonary oedema • B: Left ventricular hypertrophy • C: Unilateral pneumonia • D: Acute pulmonary embolism • E: Tension pneumothorax• Answer: E – Tension pneumothorax • Air in the thorax between lung and chest wall + mediastinal shiftMCQ 4 • In first degree heart block, there is a prolongation of the delay in cardiac impulse transmission at the AV node. How may this present clinically on an ECG: • A: Absent P waves • B: Prolonged PR interval • C: QT prolongation • D: T wave inversion • E: ST depression• Answer: B – Prolonged PR interval • The PR interval represents the delay of the electrical impulse at the AV node. In 1 degree AV block, this delay is increased therefore the length of the PR interval is prolonged.MCQ 5 • Which of these drugs does not work through inhibition of the renin- angiotensin-aldosterone system? • A – Furosemide • B – Valsartan • C – Ramipril• Answer: A – Furosemide is a loop diuretic, it works on the NKCC2 channel in the loop of henle in the kidney. Valsartan is an angiotensin II receptor blocker (ARB) and ramipril is an ACE inhibitor• 2362076t@student.gla.ac.uk