Introduction to Cardiovascular System PDF

Dr Julie Townsend Senior Lecturer, [email protected] Introduction to body systems: Cardiovascular system Animal Health and the Veterinary Profession, VETS10022 Intended Learning Outcomes: Outline the components and key functions of the cardiovascular system Describe the structure of the diffe...

Dr Julie Townsend Senior Lecturer, [email protected] Introduction to body systems: Cardiovascular system Animal Health and the Veterinary Profession, VETS10022 Intended Learning Outcomes: Outline the components and key functions of the cardiovascular system Describe the structure of the different types of blood vessels Describe the structure of the pericardium Identify the key features of the structure of the heart Summarise the histology of the cardiovascular system Describe the structure of the different components of the lymphatic system and outline its importance Signposting: I introduced the concept of serous membranes (including pericardium) in my Skeleton, body cavities & serous membranes lecture in week 1 More detailed anatomy and physiology content to come! – Heart and circulation lectures and relevant practicals (weeks 9-11) You will use this information in the following CBLs: – Coughing cavalier week 9 – Lethargic cockapoo week 10 – The cat with ATE consolidation case week 12 Functions of the CVS: Transports cells and solutes around the body (includes gases, nutrients, waste products, hormones and immune system molecules) Transmits force Regulates blood pressure and supply Transports heat Composition of the CVS: Blood – plasma and cells (erythrocytes, leukocytes, platelets) Vessels: – Arteries/arterioles, veins/venules, capillaries – arteries carry blood - usually oxygenated - away from the heart – veins carry blood - usually deoxygenated - to heart Heart Structure of Blood Vessels: capillary large artery (elastic/ conducting) small artery (muscular/ distributing) venule arteriole vein Diagram: Dr A Roberts Photomicrograph of artery and vein Note that: The artery has a thicker wall, with the tunica media being the predominant layer The predominant layer in the wall of the vein is the tunica adventitia Fig 21.5 Seeley Veins contain valves to prevent backflow of blood. These consist of folds in the tunica intima which form 2 flaps Capillary Networks: Allow nutrients and waste products to enter/leave blood Capillaries can be fenestrated Amount of blood entering beds controlled by calibre of arterioles and venules, and by precapillary sphincters Fig 21.3 Seeley Portal systems: primary capillary bed Interconnecting vein(s) (eg hepatic portal vein in hepatic portal system) In a portal system, blood flows through two different capillary beds which are secondary capillary bed found in different locations (even different organs) before returning to heart Systemic circulation Anastomosis: Fig 7-33,Dyce Connection between 2 blood vessels that can provide an alternative route of blood flow Arterio-arterial anastomoses – Common in joints & gastrointestinal tract – Coronary arteries in heart – Circle of Willis in brain Veno-venous anastomoses – Abundant throughout body capillary bed arteriole venule Arterio-venous anastomoses – Important in skin for body temperature regulation precapillary sphincter arterio-venous anastomosis Circulation Patterns: Single circulation (most fish): low pressure in gills and tissues Double circulation (mammals): Allows higher blood pressure in tissues than in lungs 2 pumps in series have to pump exactly the same volume of blood over time Diagram: Dr A Roberts 12 Schematic diagram showing T. S. through thoracic cavity at level of heart Thoracic 12 cavity: Mediastinum Thoracic cavity contains – 2 pleural cavities – Mediastinum Heart contained in a sac (pericardium) within the mediastinum Lung Parietal pleura Visceral (pulmonary) pleura Pleural cavity Heart Parietal pericardium (purple) Visceral pericardium Fibrous pericardium (green) Pericardial cavity 13 Pericardium – a visual aid! 13 Visceral pericardium (aka epicardium) Heart Parietal pericardium Fibrous pericardium Pericardial cavity Ligament (Phrenopericardiac or sternopericardiac) 14 Pericardium: to summarise Within mediastinum, heart covered with pericardium Closed serous membrane sac, containing fluid Tough fibrous outer layer Ligamentous attachment to diaphragm (cat/dog; phrenopericardiac) OR sternum (large animals; sternopericardiac) Heart: structure and some terminology Heart wall has 3 layers aorta Pulmonary artery – Epicardium – Myocardium – Endocardium left atrium 2 pumps 4 chambers – right atrium and ventricle – left atrium and ventricle – Note auricles present on atria Systole: contraction of atria or ventricles right atrium left ventricle right ventricle Diastole: relaxation of atria or ventricles epicardium myocardium endocardium Beware - human heart! Canine heart (pericardium removed) – left lateral view NB: heart would sit at a more oblique angle in situ! Summary of the Histology of the Cardiovascular System Blood vessels – – – – Tunica intima: endothelial lining Tunica media: smooth muscle, innervated by sympathetic nervous system Tunica adventitia: connective/supporting tissue Capillaries: single layer endothelium, can be fenestrated Heart – Endocardium: endothelial lining – Myocardium: cardiac muscle. Unique feature present - intercalated discs – Epicardium = visceral layer of pericardium: serous membrane/mesothelium Lymphatic system – Lymphatic vessels: endothelial lining – Lymph nodes: highly organised structures containing lymphoid cells, immunological accessory cells and supporting cells Functions of the Lymphatic System: Drainage of tissue fluid Absorption and transport of fat Defense Components of the Lymphatic System: Lymph Lymphatic capillaries Lymphatic Capillaries: Fig 22.2a, Seeley et al, Anatomy & Physiology, McGraw Hill Lymphatic Capillaries: Fig 22.2b, Seeley et al, Anatomy & Physiology, McGraw Hill Components of the Lymphatic System: Lymph Lymphatic capillaries Lymphatic vessels – Thoracic duct (continuation of cisterna chyli) – Right lymphatic duct Lymph nodes Lymph Nodes: Lymphoma: 12 yo golden retriever with swollen left submandibular lymph node "Lymphoma in golden" by Joel Mills Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons https://commons.wikimedia.org/wiki/File:L ymphoma_in_golden.JPG#/media/File:Ly mphoma_in_golden.JPG Lymph Node Structure Capsule Trabecula Medullary cord Subcapsular sinus Diffuse lymphatic tissue Cortex Medulla Medullary sinus Cortical sinus Lymphatic nodule Germinal centre Efferent lymph vessel Vein Artery Afferent lymph vessels Fig 22.6a, Seeley et al, Anatomy & Physiology, McGraw Hill Components of the Lymphatic System: Lymph Lymphatic capillaries Lymphatic vessels – Thoracic duct (continuation of cisterna chyli) – Right lymphatic duct Lymph nodes Lymphoid organs (form lymphoreticular system) – Primary (bone marrow, thymus) – Secondary (spleen, tonsils, lymph nodes) Components of the Lymphatic System: Lymph Lymphatic capillaries Lymphatic vessels – Thoracic duct (continuation of cisterna chyli) – Right lymphatic duct Lymph nodes Lymphoid organs (form lymphoreticular system) – Primary (bone marrow, thymus) – Secondary (spleen, tonsils, lymph nodes) Lymphocytes Intended Learning Outcomes: Outline the components and key functions of the cardiovascular system Describe the structure of the different types of blood vessels Describe the structure of the pericardium Identify the key features of the structure of the heart Summarise the histology of the cardiovascular system Describe the structure of the different components of the lymphatic system and outline its importance