Cardiovascular System 2024 MSPC112_AHS102 PDF

Introduction to organ systems- circulatory system By B. Hottor (BSc; MB ChB; PhD) Learning objectives-1 By the end of the session student will be able to: List components of the circulatory system Describe the circulation of blood through the heart...

Introduction to organ systems- circulatory system By B. Hottor (BSc; MB ChB; PhD) Learning objectives-1 By the end of the session student will be able to: List components of the circulatory system Describe the circulation of blood through the heart describe the pulmonary circulation and systemic circulations their and its characteristics 7/6/2024 Footer Text 2 Learning objectives 2 By the end of the session the student will be able to: Discuss the types of blood vessel Describe the lymphatic system Describe some clinical problems of the circulatory system 7/6/2024 Footer Text 3 Introduction to the circulatory system Circulatory system transport fluid around the body It consists of: Cardiovascular system (CVS) Lymphatic system Propel and conduct fluids around the body 7/6/2024 Footer Text 4 Cardiovascular system The heart and the blood vessels forms the CVS The CVS transports blood around the body Distributes oxygen, nutrient, hormones and waste to and from tissues  The heart It is hollow fibromuscular organ that acts as a suction and a pump in the CVS It is conical/pyramidal in shape Weighs 300 g in the male and 250 g in the female Lies in the thoracic cavity between the lungs Central in location with 2/3 to the left of the midline The heart has 4 chambers- two atria and two ventricles Circulation of blood through the heart Vascular circuits The heart is made up 2 muscular pumps arranged in series. It divides the circulation into 2 components Pulmonary- Deoxygenated blood from RV to lung and back to left atrium Systemic - LV to RA 7/6/2024 Footer Text 8 7/6/2024 Footer Text 9  Blood vessels There are three kinds of blood vessels Artery Capillary Vein 7/6/2024 Footer Text 10  Arteries They carry blood at relatively higher pressure away from the heart Different types distinguished based on overall size, structure and function Usually carry blood rich in nutrient and Oxygen Pulsate and hence palpable Smallest arteries are called arterioles 7/6/2024 Footer Text 11 Names arteries of the body Aorta to arteriolar level Parts of aorta Ascending Arch Descending Ascending Coronary arteries Arch Brachiocephalic a. Left common carotid a. Left subclavian a. Descending Thoracic branches Abdominal branches Terminal branches Common iliac aa. Median sacral a. 7/6/2024 12 Communication between arteries Anastomosis is a union between multiple branches of arteries: Collateral circulation End-to-end anastomosis occurs when arteries communicate directly Convergent arteries - converge and merge – vertebral arteries forming basilar artery Transverse anastomosis – short arterial vessel links two large arteries transversely eg. between two anterior cerebral arteries True terminal arteries (end arteries) in the retinal and functional terminal arteries in the brain, kidney, spleen, liver and intestines heart. 7/6/2024 Footer Text 13  Convegence Collateral anastomosis anastomosis Capillaries Are simple endothelial tubes Allows exchange of material between the blood and extra cellular space They are arranged in capillary beds between arterioles and venules Starling forces causes fluid to leave the capillary end and re-enter at the venular end. Arteriolovenular (arteriovenous) anastomoses 7/6/2024 Footer Text 15 Portal venous circulation Venous system between two capillary beds. veins Return blood to the heart Usually deoxygenated blood except the pulmonary veins Have thinner wall They do not pulsate or squirt or spurt Contain nutrients and hormones Used for drug administration generally 7/6/2024 Footer Text 17 Types of veins Venules- smallest veins, drains capillary bed and they form venous plexus Medium veins drains venous plexuses; accompany medium arteries, and in the limbs have valves e.g. cephalic and basilic veins Large veins have large bundles of longitudinal smooth muscles and thick tunica adventitia. e.g. superior vena cava 7/6/2024 Footer Text 18 Characteristics of veins Outnumber arteries Variable pattern than arteries Larger diameter but thinner wall than accompanying arteries Can be compressed by external pressure or by valsava manoeuvre Capacitance vessels, they hold about 80 % of total blood compared with 20 % in arteries 7/6/2024 Footer Text 19  Relationship between veins and arteries Venae commitantes important as counter current heat exchanger e.g. testicular veins Vascular sheath Arteriovenous pumps Musculovenous pumps 7/6/2024 Footer Text 20 VASCULAR PATTERNS: SHUNTS AND ANASTOMOSES Vascular shunts – communications exist between arteries and veins in many regions Microcirculation or capillary circulations can be bypassed by wider ‘thoroughfare’ channels formed by metarterioles (A-V anastomosis) Blood is delivered to capillary bed or venule according to local demand or conditions Simple A-V anastomoses are widespread 7/6/2024 21 FACTORS AIDING BLOOD FLOW Left ventricular contraction Right ventricular relaxation Changes in intrathoracic pressure Muscular contraction (muscular pump) in calf muscles Arterial pulsation - venae commitantes Unidirectional valves 7/6/2024 22 Clinical application Arteriosclerosis- thickening and loss of elasticity of the arterial wall Atherosclerosis- build up of fat in the arterial wall Atheromas Thrombus and embolus Ischaemia- reduced blood flow to tissue Infarction – local death of an area of tissue e.g. myocardial infarction, stroke, gangrene Varicose veins 7/6/2024 Footer Text 23 7/6/2024 Footer Text 24  Also called lymphoid system Widely distributed but less visible Essential for survival Lymphatic Important clinically for the spread of system cancer Starling hypothesis 3 L of ECF is left unabsorbed by the venous system daily 7/6/2024 Footer Text 25 7/6/2024 Footer Text 26  Lymphatic plexus Lymphatic vessels (lymphatic)- found everywhere there is capillary except bone marrow, teeth CNS Components of Lymph- Similar in composition to blood Lymphatic Lymphocytes- circulating cells of system immune system Lymph nodes Lymphoid organs – parts of the body that produce lymphocytes (thymus, spleen, tonsils, red marrow) 7/6/2024 Footer Text 27 Lymphatic system Superficial lymphatics run independently or accompany superficial veins Deep lymphatics accompany arteries Almost all lymphatics reach the right lymphatic duct or the thoracic duct 7/6/2024 28 Major lymphatic vessels Right lymphatic duct Drains right half of head and neck, thorax and contents, superficial tissues of abdomen and trunk, right upper limb Empties into right brachiocephalic vein Thoracic duct Drains remaining part of body into left brachiocephalic vein Commences in abdomen as confluence of lymph trunks or cisterna chyli 7/6/2024 Footer Text 29 Lymphatic system Lymph nodes Small, oval or bean-shaped bodies Lie in the course of lymphatics Usually at the junction of many lymphatic vessels Contains immune cells that remove harmful materials from lymph 7/6/2024 30 Naming of lymph nodes Named according to topographical position With respect to deep fascia – superficial or deep. Superficial lymph nodes closely applied to prominent superficial veins and deep ones, to arteries Relations to vasculature – majority of nodes and node groups are clustered around prominent blood vessels e.g. coeliac Relation to viscera - e.g. liver (hepatic) Region of body – these are most accessible to clinical examination e.g axillary and inguinal nodes 7/6/2024 Footer Text 31  Spread of cancer Lymphangitis Clinical correlate Lymphadenitis lymphedema Footer Text 7/6/2024 32