NSCI5720 CVS 1 Intro and Anatomy 2023 (4).pptx
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Cardiovascular System 1 – Heart NSCI5720 Vertebrate Anatomy & Physiology Objectives By the end of this section you will be able to Name, locate and describe the structures of the heart, and how they enable the heart to function --> atria and ventricles, valves, heart wall structure Name and describe...
Cardiovascular System 1 – Heart NSCI5720 Vertebrate Anatomy & Physiology Objectives By the end of this section you will be able to Name, locate and describe the structures of the heart, and how they enable the heart to function --> atria and ventricles, valves, heart wall structure Name and describe the two pumps of the heart --> Pulmonic (right side, lungs) & Systemic (left side, body) Explain how blood flows through the heart in the systemic & pulmonary circulations Describe whether blood is oxygenated or deoxygenated as it passes through the different sides of the heart and the systemic & pulmonic circulations Explain the blood supply to the heart muscle. Name and be able to locate the blood vessels that supply blood to the heart. Lecture Structu re Intro to the cardiovascular system (CVS) Anatomy of the heart Anatomy of the heart wall (layers of the heart wall) How the heart functions to pump blood around the body New Terms Septum – partition separating two chambers Coronary – from corona (wreath/crown), arteries surrounding and supplying the heart muscle Auscultate – examining a patient by listening to sounds eg. listening to the heart and lungs Pulmonary/pulmonic – relating to the lungs Systemic – circulation to the body Parietal – relating to the wall of the body/organ Visceral – relating to the viscera (organs) Intro to the CVS Made up of the heart and vessels (veins and arteries) Heart has two sides – each a pump One side pumps to the body – takes O2 and nutrients to the tissues (cells) One side pumps to the lungs – takes deoxygenated, CO2 rich blood to the lungs Great vessels – big arteries and veins leaving the heart Arteries – always away from the heart Veins – always toward the heart Oxygenated blood – erythrocytes (RBC) with O2 attached to them Deoxygenated blood – erythrocytes (RBC) without O2 attached to them What is the function of the cardiovascular system? The heart pumps oxygenated blood (water, electrolytes, nutrients, waste products, red blood cells and white blood cells) to the tissues via the arteries. It then returns the deoxygenated blood (with carbon dioxide and other waste products) from the tissues to the lungs via the veins to be reoxygenated and sent to the tissues again Cells lecture for our cells to produce energy they need oxygen (O2). Carbon dioxide (CO2 ) is produced as a waste product Anaesthesia (and disease) affects the function of our CVS Heart Anatomy Position in the Body Found in the cranioventral thorax Approximately between the 3rd and 6th/7th ribs, to the left side (behind elbow) Surrounded by lungs and ribs Apex beat Where you can palpate (feel) the heart beat This is the best place to put your stethoscope to auscultate (hear) the heartbeat the loudest 5th intercostal space Normal heart rates Cats – 160 - 200 Dogs – 70 – 140 Note: these will change if the patient is anaesthetised Directional Terms Base – widest part of the heart, through atria Apex – tip of the heart, left ventricle Cranial – toward the head (cranium) of the animal Caudal – toward the tail (cauda) of the animal Whenever we look at pictures of the heart, it is a mirror image of the heart – the left side of the heart will be on the right and the right side of the heart will be on the left. Heart Chambers There are four heart chambers – 2x atria (upper) and 2x ventricles (lower) Valves separate the atria from the ventricles Muscular walls coordinated contractions of cardiac muscle pumps blood Atria Two smaller chambers at the base (top) of the heart – left and right atria Atrium – singular Atria - pleural Receive blood from body/lungs when relaxed Pump blood into the ventricles when contracted Right atrium – blood from body Left atrium – blood from the lungs Ventricles Two large chambers at the apex (bottom) of the heart – left and right ventricles Left and right sides are divided by an interventricular septum Receive blood from the atria when relaxed Pump blood out of the heart (to body/lungs) when contracted Left ventricle aorta to the body Right ventricle pulmonary artery to the Cardiac Valves Function - prevent backflow of blood during ventricular contraction and relaxation ensure one-way flow of blood through the heart Made up of “leaflets” or “cusps” Two shapes/locations of valves: Atrioventricular valves Where do you think these are found? Between atria and ventricles Semi-lunar valves In the arteries leaving the heart pulmonary artery and aorta Cardiac Valves Atrioventricular (AV) valves Between the atria and ventricles Prevent backflow of blood from the ventricle into the atrium when the ventricle contracts Right AV valve = commonly called tricuspid – 3 cusps Left AV valve = commonly called mitral – 2 cusps Semi-lunar (“half moon”) valves In the arteries leaving the heart (pulmonic artery and aorta) Prevent backflow of blood from the arteries into the ventricle when the ventricle relaxes Aortic valve – in the aorta Pulmonic valve – in the pulmonary Vid eo Chordae Tendinae Cord-like tendons (connective tissue) that maintain the position of the valve leaflets (preventing them from opening backwards into the atrium) during ventricular contraction In AV valves only (not semi-lunar valves) Attach to the papillary muscles Papillary muscles can contract and relax a small amount to help support the chordae tendinae Papilla - nipple Blood Vessels Arteries always carry blood AWAY from the heart, usually carry oxygenated blood (red blood cells have oxygen molecules attached) Veins always carry blood TOWARD the heart, usually contain deoxygenated blood (red blood cells do not have oxygen molecules attached) But, there are a few exceptions – pulmonary arteries and Great Vessels Aorta – large artery that carries blood from the heart (left ventricle) to the body Cranial and caudal vena cavae – large veins that carry blood from the body to the heart (right atrium) Pulmonary arteries – large arteries that carry deoxygenated blood from the heart (right ventricle) to the lungs Pulmonary veins – large veins that carry oxygenated blood from the veins to the heart Pulmonary arteries and veins are the exception to the oxygenation rule Coronary Circulation Corona – wreath, crown The heart pumps blood with oxygen and nutrients to the tissues, but how does the heart muscle itself receive oxygen and nutrients? The coronary arteries originate the base of the aorta supplies oxygenated blood to the heart muscle Coronary veins – drain deoxygenated blood from the heart muscle back into the right atrium The coronary vessels are on the exterior of the heart and lie in lines of fat eg. in the interventricular grooves (grooves in fat between the ventricles) Ngā pātai? Any questions? Structure of the Heart Wall Layers of the Heart Pericardium – two outer connective tissue layers Myocardium – the heart muscle, middle layer Endocardium – inner-most epithelial lining Pericardi um Peri- = around, Cardium = heart Connective tissue sac around the heart 1.Fibrous pericardium (outer) Tough, fibrous, non-elastic, connective tissue Protects the heart 2.Serous pericardium (inner) Consists of two layers that have a space between them (pericardial space) Serous – resembling serum (fluid component of blood) this layer produces serous fluid Provides lubrication for when the heart contracts 3.Pericardial space Potential space between the two layers of serous pericardium. Contains serous fluid. Myocardium Myo- = muscle, Cardium = heart Middle, muscular layer of the heart – cardiac muscle Thickest layer Fuction – muscle contraction Endocardium Endo- = within, Cardium = heart Thin lining – endothelial cells (type of epithelial cell) Continuous with endothelium lining of blood vessels Function – smooth surface for blood flow Effusion Normal Normal Effusion For interest only – pericardial effusion (not tested) Pericardiocentesis – aspiration (sucking) of fluid out of the pericardial space Ngā pātai? Any questions? Blood flow through the heart (Physiology) Function of the Heart The heart acts as a pump to supply blood to the body allows blood to carry nutrients and oxygen etc to the tissues, and removes carbon dioxide and waste products. So how does it do this.... The Heart as a Pump – Two Pumps Systemic – Left side Body – the “system” High pressure in the vessels – has to pump blood a long way Left ventricle – thick-walled ventricle Pulmonic/pulmonary – Right side Lungs Pulmonic is used interchangeably with pulmonary Lower pressure in the vessels – lungs are close to the heart, blood doesn’t have to go as far or through as many organs Right ventricle – thin-walled ventricle Systemic Circulation Systemic circulation takes oxygenated blood from the lungs and sends it to the body for the tissues to use for cellular respiration, and then returns the depleted blood to the heart again Left atrium: Receives oxygenated blood from the lungs (relaxed) Sends it to the left ventricle (contraction) through the mitral (left AV) valve Left ventricle: Receives oxygenated blood from the left atrium (relaxed) Sends oxygenated blood to the body via the aorta Pulmonary/pulmonic circulation Pulmonary circulation takes deoxygenated blood from the body and sends it to the lungs – as the blood passes through the lungs it releases CO2 and picks up more O2 Right atrium receives deoxygenated blood from the body and sends it to the right ventricle Right ventricle – sends Ngā pātai? Any questions?
