MEDU1110 Systemic Anatomy Cardiovascular System PDF

MEDU1110 Systemic Anatomy Cardiovascular System Heart & Circulation 9 Sep 2024 Josephine Lau Office: 610K, BMSB Tel: 3943 4224 [email protected] MEDU1110 CVS p.1 Contents: ❑ Overview of the cardiovascular...

MEDU1110 Systemic Anatomy Cardiovascular System Heart & Circulation 9 Sep 2024 Josephine Lau Office: 610K, BMSB Tel: 3943 4224 [email protected] MEDU1110 CVS p.1 Contents: ❑ Overview of the cardiovascular system ❑ Heart o Location, chambers, valves & their respective auscultation positions o Its great blood vessels ❑ Pulmonary and systemic circulations ❑ Blood vessels o Types and abnormalities o Aorta and its principal branches o Coronary circulation o Tributaries of venae cavae o Superficial vs deep veins o Circulatory routes and their respective significance MEDU1110 CVS p.2 Do you know?! Question Go to … Why the heart has its own blood supply, and what 1. p.19 happens when it's blocked? Why improper closure of a heart valve can lead to 2. P.10 & 11 certain heart conditions? How can the internal lining of coronary arteries 3. p.20 influence the risk of developing heart attack? Why venous valves are crucial in preventing varicose 4. p.24 & 25 veins? MEDU1110 CVS p.3 Overview of the Cardiovascular System Components: Capillary beds of lungs where gaseous exchange occurs ❑ Heart Lungs ❑ Blood vessels ❑ Blood Vein Artery Heart Capillary beds of all body tissues O2-rich, CO2-poor blood where gaseous exchange occurs O2-poor, CO2-rich blood MEDU1110 CVS p.4  Midsternal line Heart – Size & Location 2nd rib ❑ Approx. size of fist Sternum Location: Diaphragm Apex o Bet’n 2nd rib & 5th intercostal space 6th rib o On superior surface of diaphragm o 2/3 left of midsternal line o Anterior to vertebral column o Posterior to sternum o Apex of heart points toward left → In mediastinum (thoracic cavity bet’n the lungs) Sternum Diaphragm MEDU1110 CVS p.5 Vertebral column  Heart Chambers (Frontal) ❑ Atria are the receiving chambers of the heart ❑ @ atrium has a protruding auricle * on the anterior surface (next page) Left atrium Right atrium Left ventricle (w/ thicker cardiac muscle wall) Right ventricle (w/ thinner cardiac muscle wall) ❑ Ventricles are the discharging chambers of Interventricular the heart Anterior view septum MEDU1110 CVS p.6  Great Vessels of the Heart (Anterior) Blood enters right atrium from: Blood enters left atrium from: 1. Superior vena cava 6. Pulmonary veins 2. Inferior vena cava   3. Coronary sinus       * *  *, Auricle of the atrium Right ventricle pumps blood into: 4. Pulmonary trunk (transports blood to the lungs) Left ventricle pumps → branches to 5. Pulmonary arteries  blood into: 7. Aorta (supplies blood to body tissue except the lungs) MEDU1110 CVS p.7 Great Vessels of the Heart (Posterior) 7. Aorta   1. Superior vena cava 5. Pulmonary arteries     6. Pulmonary veins    2. Inferior vena cava 3. Coronary sinus MEDU1110 CVS p.8  ❑ Ensure unidirectional blood flow through the heart Heart Valves ❑ Open & close in response to pressure changes Atrioventricular (AV) valves: 1. Tricuspid valve (right AV valve) Aorta 2. Bicuspid valve (left AV / mitral valve) → Prevent backflow into the atria when ventricles contract changes 3. Chordae tendineae anchor cusps to 4. Papillary muscle             Semilunar valves: 5. Aortic valve 6. Pulmonary valve → Prevent backflow into the ventricles when ventricles relax MEDU1110 CVS p.9 Atrioventricular Valve - Function > > MEDU1110 CVS p.10 Semilunar Valve - Function MEDU1110 CVS p.11  Heart Sound ❑ “Lub-dup” – sound of valves closing o 1st sound “lub” – the AV valves closing o 2nd sound “dup” – the semilunar valves closing “Lub” “Dup” MEDU1110 CVS p.12  Auscultation Positions for Heart Valves Aortic valve (2ndintercostal space, right of sternum) Pulmonary valve (2nd intercostal space, left of sternum) Tricuspid valve Bicuspid valve (5thintercostal space, (5th intercostal space, left of sternum) mid clavicle, left of sternum) MEDU1110 CVS p.13 Pathway of Blood Through the Heart & Lungs MEDU1110 CVS p.14  Vascular Pattern of the Body Pulmonary circuit ❑ Consists of blood vessels that carry blood from the heart to the lungs & back to the heart Systemic circuit ❑ Consists of blood vessels that lead from the heart to all body parts (except the lungs) & back to the heart Includes o Aorta & its branches o The system of veins that return blood to the right atrium MEDU1110 CVS p.15  Blood vessels Flow of blood in systemic circuit From heart To heart Capillaries: - Site of nutrient & gas exchange Arteries : - Microscopic blood vessels - Transport blood away from heart composed of only 1 layer of Veins: - Large arteries act as pressure cells - Return blood to heart reservoirs → Thin walls allow simple - Act as blood reservoirs - Smaller arteries regulate flow of diffusion of materials blood to different body organs MEDU1110 CVS p.16 Aorta & its Principal Branches Key: → supplies blood to that region/organ(s) MEDU1110 CVS p.17 Aneurysm ❑ Abnormal local dilations of arteries ❑ Results from congenital or acquired weakness of arterial wall ❑ Can grow large and rupture eventually, causing dangerous bleeding / death ❑ Occurs in the aorta, arteries in the brain, heart and other parts of the body. Cerebral (berry) aneurysm AAA If an aneurysm in the brain bursts, Reconstructed computed it causes hemorrhagic stroke tomographic angiogram AAA = abdominal aortic aneurysm Credit: Sparks et al., 2002 MEDU1110 CVS p.18 Coronary Circulation: Functional blood supply to heart muscle Coronary Arteries Myocardial infarction (MI) myocardial tissue dying off due to lack of oxygenated blood MEDU1110 CVS p.19  Coronary Artery Disease ❑ Occurs when the buildup of plaque within the arteries obstructs the blood flow & reduces the flexibility of vessels ❑ Condition developed → atherosclerosis ❑ Restricted blood flow → ischemia ❑ If untreated, coronary artery disease can lead to MI In this coronary angiogram (X-ray), the dye makes visible two occluded coronary arteries. Such blockages can lead to decreased blood flow and insufficient oxygen delivered to the cardiac tissues. If untreated, this can lead to cardiac muscle death (myocardial infarction). (OpenStax: Anatomy & Physiology 2e) Atherosclerotic plaques - Composed of cholesterol, fat, fiber, white blood cells … - Quite often form in the branching points or where the vessels curve MEDU1110 CVS p.20  Coronary Circulation: Cardiac Veins Coronary sinus N.B. Coronary arteries & cardiac veins run next to each other MEDU1110 CVS p.21  Internal jugular v. Tributaries of Venae Cavae  Almost all blood from brain External jugular v.  Scalp & part of face Brachiocephalic v. Superior vena cava  Head & upper limbs  All regions superior to diaphragm Azygos v. Inferior vena cava Hemiazygos v.  All body regions inferior to diaphragm Suprarenal v.  Suprarenal glands Renal v. Gonadal v. Common iliac v. External iliac v.  Lower limbs Internal iliac v.  Pelvic organs Key:  drains blood from that region/organ(s) MEDU1110 CVS p.22  Superficial & Deep Veins Deep veins: ❑ Veins that accompany deep arteries ❑ Deep veins of limbs usually occur as double or triple form of accompanying veins (L. venae comitantes) o Expansion of artery during heart contraction stretches & flattens veins, assisting venous return to heart (Arteriovenous pump) Superficial veins: ❑ Veins that run independent from Deep veins Superficial veins named arteries in subcutaneous tissue under skin MEDU1110 CVS p.23  Venous Valves Blood flow direction Cusp of venous valve Blood flow direction ❑ Present in the limbs & other Musculovenous locations where the flow of blood pump is opposed by the pull of gravity →Prevent backflow of blood MEDU1110 CVS p.24  Varicose Veins ❑ Abnormal irregular dilations in superficial veins ❑ Develop when the valves of veins become weak o Great saphenous vein is more prone to develop o Hemorrhoids are varicose veins in the rectum Anus (hemorrhoids) Scrotum (varicocele) Credit: National Heart Lung & Blood Institute MEDU1110 CVS p.25  Anastomosis - Point where 2 blood vessels merge (c) Arteriovenous anastomoses (AV shunts) Permit blood to pass directly from arterial to venous side without passing through capillaries (a) Simplest pathway o e.g. In skin (1 capillary bed) (d) Venous anastomoses Provide alternate drainage of organs (b) Portal system (2 capillary beds) o Most common, in the form of venous plexuses (c) Arteriovenous (e) Arterial anastomoses anastomosis (AV shunt) ❑ Provide potential detours for blood flow (collateral routes) in case the usual pathway is obstructed o e.g. Coronary circulation, Circle of Willis Terminal (end) arteries (arteries that do not anastomose w/ adjacent MEDU1110 CVS p.26 arteries) e.g. Renal artery  Hepatic Portal Circulation ❑ Serves function unique to the digestive system ❑ Detours venous blood from GI tract to liver on its way to the heart → Liver stores or modifies nutrients MEDU1110 CVS p.27  Hepatic Portal Circulation Inferior vena cava Hepatic v. Liver Splenic v.  Spleen Hepatic portal v. Inferior mesenteric v.  Distal region of large intestine Superior mesenteric v.  All small intestine & Small intestine 1st half of large intestine Rectum Large intestine Key:  drains blood from that region/organ(s) MEDU1110 CVS p.28  Hepatic Portal Circulation ( ) ❑ Subdivision of systemic circulation MEDU1110 CVS p.29 Cerebral Arterial Circle (Circle of Willis) Anterior Anterior communicating a.* *Internal carotid a. Anterior cerebral a.* (a very short segment only) Posterior communicating a.* Middle cerebral a. Posterior cerebral a.* Basilar a. Vertebral a. * Components of cerebral arterial circle Posterior Inferior view of base of brain MEDU1110 CVS p.30  Dural Venous Sinuses of the Brain ❑ Not typical veins ❑ Channels supported by walls of dura mater Inferior sagittal sinus Superior sagittal sinus Straight sinus Transverse sinus (right) Sigmoid sinus Dura mater: the outermost protective covering around the brain and the spinal cord Oblique lateral view MEDU1110 CVS p.31 Reference: Core textbook: ❑ Human Anatomy (2018) Martini FH, Tallitsch RB & Nath JL. 9th Edition. Pearson Images sources: ❑ https://www.aafp.org/pubs/afp/issues/2002/0415/p1565.pdf ❑ https://openstax.org/books/anatomy-and-physiology-2e/pages/19-1-heart-anatomy MEDU1110 CVS p.32