BIOM1052 Integrated Anatomy & Physiology Lectures 1 and 2 2024 PDF

BIOM1052: Integrated Anatomy & Physiology Lectures 1 and 2 Dr Niwanthi Rajapakse Email: [email protected]  Recommended Reading Chapter 20: The Heart Martini 11th Edn. Fundamentals of Anatomy & Physiology Tips for the EOS exam Make sure you can answer questions provided at...

BIOM1052: Integrated Anatomy & Physiology Lectures 1 and 2 Dr Niwanthi Rajapakse Email: [email protected]  Recommended Reading Chapter 20: The Heart Martini 11th Edn. Fundamentals of Anatomy & Physiology Tips for the EOS exam Make sure you can answer questions provided at the end of each lecture; practice answering these questions as you go Revise these in your PASS classes with your tutors  Heart Anatomy & Physiology Lecture 1: Heart Structure and Function (Heart valves, blood flow through the heart) Lecture 2: Systole, diastole, EDV, ESV, Stroke volume, cardiac output Preload, Afterload (make sure you know this terminology extremely well), heart failure, pulmonary hypertension Lecture 3 : Cardiac muscle cells and cardiac conduction system Lecture 4: Cardiac action potential and electrocardiography (ECG) Lecture 5: Blood pressure All the content covered in my lectures is examinable except the content in the videos. Videos are provided for animations and information only.  Lecture 1 objectives At the end of Lecture 1 – To be familiar with the structure of the Heart – To understand the structure and function of heart valves - To understand how blood flows through the heart 5  Cardiovascular System: The heart ▪ Heart: Serves as a pump that establishes the pressure gradient needed for blood to flow to tissues Heart anatomy – General Introduction  Structure of the Heart Four chambers – two upper chambers (atria), two lower chambers (ventricles) Septum: The septum of the heart is the dividing wall between the right and left sides of the heart. The pericardium: is a double-walled sac containing the heart and the roots of the great vessels. The great vessels = the major arteries and veins that convey blood to and away from the heart: aorta, pulmonary artery, pulmonary veins, superior vena cava (more details later). Pericardium  The heart is surrounded by the pericardium The pericardium: maintains the hearts position prevents heart from overfilling outer fibrous pericardium inner serous pericardium parietal layer of serous pericardium visceral layer of serous pericardium The pericardial cavity is between the 2 serous layers (fluid) Martini, Nath & Bartholomew 2012  Structure of the Heart Superior vena cava (returns blood from Aorta the upper half of the Pulmonary trunk body – more details transporting later) deoxygenated blood to the lungs for oxygenation Right atrium Left atrium Inferior vena cava returns blood from Valve the lower half of the body Left Ventricle (more details later) Septum Right ventricle  Coronary arteries The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ of the body. The coronary arteries wrap around the entire heart. The Heart – Anatomical differences Between the right and left ventricles Left ventricular wall – Thicker as it has to pump blood to the entire body. The left ventricle has thicker walls than the right because it needs to pump blood to most of the body while the right ventricle pumps blood only to the lungs. comparative ventricle wall thickness Anterior view: Tortora & Nielsen 2012 Right ventricle Left ventricle pump for pumps for high low pressure pressure pulmonary circuit systemic circuit Rohen 2011  Heart structure Deoxygenated venous blood from the peripheral organs and tissues enters the right atrium through the superior and inferior vena cava Note there is no connection between any of the heart chambers other than via the heart valves. This blood then enters the right ventricle via the tricuspid valve Heart valves Tricuspid valve: right side of the heart. Another name right atrioventricular valve. Bicuspid valve: Left side of the heart. Another name mitral valve or left atrioventricular valve.  Structure of Heart Valves Bicuspid valve: Left side of the heart. Another name mitral valve or left atrioventricular valve. a bicuspid valve works better on the high pressure side because with only two sides to the valve, the muscles and ligaments are able to spring back from the high pressure on the left side of the heart.  Papillary muscles The papillary muscles are muscles located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae and contract to prevent inversion or prolapse of these valves during ventricular contraction.  The semilunar valves The semilunar valves (aortic and pulmonary valve): situated between the aorta and the left ventricle and between the pulmonary artery and the right ventricle. These valves permit blood to be forced into the arteries, but prevent backflow from the arteries into the ventricles  The semilunar valves Unlike the atrioventricular valves, though, they do not have chordae tendineae that attach to papillary muscles  Heart valves - video https://www.youtube.com/watch?v=VA84Fn3gvP0  THE HEART IS A PUMP: 2 CIRCUITS, 4 CHAMBERS RIGHT LEFT UNIDIRECTIONAL FLOW! The blood MUST flow through each circuit before returning to the heart. Rohen 2011 Left Heart = Systemic Circulation (high pressure) Right Heart = Pulmonary Circulation (low pressure) Heart function  In the systemic circulation blood flows in parallel through many different organs and tissues (i.e., it is ‘shared’ between these organs and tissues) In the pulmonary circulation all the blood flows only through the lungs. Venae cavae Right Pulmonary artery Right Vent atrium -ricle Other Digestive Systemic Pulmonary systemic Brain Kidneys Muscles Lungs organs tract circulation circulation Left Left ventricle atrium Pulmonary veins Aorta Sherwood, Human Physiology, 5th ed  DISTRIBUTION OF BLOOD FLOW in the SYSTEMIC CIRCULATION (at rest) Other 10% Brain Kidneys 13% 25% Skin 7% Liver + gut Heart 20% 5% Skeletal muscle 20% For the pulmonary circulation, 100% of the flow is through the lungs The Cardiovascular System Regions of high and low blood oxygen content Systemic Circulation ◼ High O2 in the arteries ◼ Low O2 in the veins Pulmonary Circulation ◼ Low O2 in the arteries ◼ High O2 in the veins Vander Figure 12-2 Where is Figure 12.44 ~16% in pulmonary circulation our blood? ~84% in systemic circulation Variable reservoir of blood Components of the Cardiovascular System Atria - receive blood returning to the heart from the HEART (Atria) veins (RA = deoxygenated, LA = oxygenated) Contraction fills ventricles Ventricles - their contraction generates the HEART (Ventricles) pressure to drive the flow of blood (RV = lungs, LV = systemic) Arteries - conduct blood to organs and tissues ARTERIES with little loss of pressure. Arterioles - smallest arteries branch into arterioles. ARTERIOLES Control resistance to flow, thus, the distribution of flow to different organs and tissues. CAPILLARIES Capillaries – main site where substances are exchanged between the blood and cell of the body. Venules - collect blood from the capillaries. VENULES VEINS Veins = return blood to the heart The Heart – The systemic and pulmonary circuits L Ventricle - pumps blood to systemic circulation R Ventricle – pumps blood to pulmonary circulation Arteries and veins in the heart Superior vena cava: return deoxygenated blood from the systemic circulation to the right atrium of the heart. It receives venous return from the upper half of the body Inferior vena cava: return deoxygenated blood from the systemic circulation to the right atrium of the heart. It receives venous return from the lower half of the body Pulmonary veins: Brings oxygenated blood from the lungs to the heart Pulmonary artery: Takes deoxygenated blood from the heart to the lungs Aorta: carries oxygenated blood to peripheral organs  Function of the Heart Deoxygenated venous blood from the peripheral organs and tissues enters the right atrium through the superior and inferior vena cava This blood then enters the right ventricle via the tricuspid valve  Function of the Heart From the right ventricle blood is pumped to the pulmonary artery via the pulmonary valve to blood vessels in the left and right lungs Lungs remove Co2 and add O2 to the blood Oxygenated blood enters the left atrium via the pulmonary vein Blood then enters the left ventricle through the mitral valve (biscuspid valve) Left ventricle ejects blood to the aorta via the aortic valve Aorta distributes blood into various organs in the body Blood Flow through the heart  Heart structure and function - video https://www.youtube.com/watch?v=qmpd82mpVO4 The heart – recap…. How many circuits does the cardiovascular system have? – Pulmonary & systemic Which system has the highest pressure? – Systemic How many chambers does the heart have? –? 34 The heart – recap…. How many circuits does the cardiovascular system have? – Pulmonary & systemic Which system has the highest pressure? – Systemic How many chambers does the heart have? – Two atria & two ventricles 35 The heart – recap…. Which chamber is the most muscular? –? How many valves does the heart have? –? –? Why are valves important? –? 36 The heart – recap…. Which chamber is the most muscular? – Left ventricle How many valves does the heart have? –? –? Why are valves important? –? 37 The heart – recap…. Which chamber is the most muscular? – Left ventricle How many valves does the heart have? – 2 x atrioventricular valves (tricuspid & bicuspid) – 2 x semilunar valves (pulmonary & aortic) Why are valves important? –? 38 The heart – recap…. Which chamber is the most muscular? – Left ventricle How many valves does the heart have? – 2 x atrioventricular valves (tricuspid & bicuspid) – 2 x semilunar valves (pulmonary & aortic) Why are valves important? – To prevent backflow of blood 39 REVISION Blood flow through the heart  Heart Anatomy & Physiology Lecture 1: Heart Structure and Function (Heart valves, blood flow through the heart) Lecture 2: Systole, diastole, EDV, ESV, Stroke volume, cardiac output Preload, Afterload (make sure you know this terminology extremely well), heart failure, pulmonary hypertension Lecture 3 : Cardiac muscle cells and cardiac conduction system Lecture 4: Cardiac action potential and electrocardiography (ECG) Lecture 5: Blood pressure  Lecture 2 objectives At the end of Lecture 2 you should be able to define the terms: systole, diastole, end diastolic volume, end systolic volume, stroke volume and cardiac output define the terms preload and afterload Understand how changes in venous return affect end diastolic volume, stroke volume and cardiac output Define heart failure (HF) and understand how chronic activation of the sympathetic nervous system contribute to this condition. Understand how pulmonary hypertension affects heart function 42 Diastole and systole phases of the heart Diastole and systole are two phases of the cardiac cycle. They occur as the heart beats, pumping blood through a system of blood vessels that carry blood to every part of the body. Systole = when heart contracts to pump blood out. Diastole = when the heart relaxes after contraction (filling). Can you tell which of the below diagrams depict diastole and systole phases of the heart?  End diastolic volume End diastolic volume (EDV): Volume of blood in the ventricle before contraction 45  End systolic volume (ESV) End systolic volume (ESV): Volume of blood in the ventricle after contraction 46 End diastolic volume and end systolic volume EDV = amount of blood in the ventricle immediately before ventricular contraction ESV = amount of blood in the ventricle immediately after ventricular contraction 47  Stroke volume End diastolic volume (EDV): Volume of blood in the ventricle during relaxation and prior to ventricular contraction End systolic volume (ESV): Volume of blood in the ventricle after contraction Stroke volume = EDV - ESV 48  Stroke volume (SV) Volume of blood pumped out of each ventricle during a single contraction (volume of blood pumped per heart beat). Stroke volume = End diastolic volume (EDV) – end systolic volume (ESV) ESV = amount of blood in EDV = amount of blood in the ventricle immediately the ventricle immediately after ventricular contraction before ventricular contraction 49  EDV Stroke volume ESV Sherwood: Fig 9.22 50  Cardiac output Volume of blood pumped by each ventricle per minute Indicates blood flow through peripheral tissues Cardiac output (CO) = Heart rate (beats/min) x stroke volume (ml/beat) How fast the heart Volume of blood pumped is beating out of ventricle during each contraction 51  Cardiac output Resting CO: 5 litres/min Exercising CO: 25 litres/min Example: Patient has heart rate of 70 beats/min and stroke volume of 100 ml CO = HR x SV = 7 litres/min 52 Cardiac Output (CO) at Rest Image from Sherwood Human Physiology Preload and afterload  Preload Preload = amount of stretch during diastole (diastole = when the heart is relaxing) More stretch of the cardiac muscle = greater force of the cardiac contraction Primary determinant of preload = left ventricular end diastolic volume (EDV) Greater the EDV, greater the cardiac contraction End diastolic volume (EDV): Volume of blood in the ventricle during relaxation and prior to ventricular contraction  Afterload Afterload = amount of resistance the heart must overcome when ejecting blood Main determinant of afterload is resistance in the blood vessels  Venous return Venous return = The volume of blood returning back to the heart each minute – Increased venous return increases EDV – Causes heart muscle to stretch (increased preload due to increased EDV) – As cardiac muscle stretches, the next contraction will be stronger Increased venous return stretches the ventricle and makes the next contraction stronger 58  Frank-Starling law of the heart (intrinsic property of cardiac tissue) The greater the end diastolic volume, the greater the force of contraction during systole (within limits!) Sherwood: Fig 9.22 Stretching the cardiac muscle cells produces a more optimum overlap between thick & thin filaments, leading to a stronger contraction 59 venous return, EDV and Stroke Volume Stroke volume: Volume of blood pumped out of the ventricle during a single contraction End diastolic volume (EDV): Volume of blood in the ventricle during relaxation prior to ventricular contraction Venous return: Amount of blood returning to heart 60  Sympathetic stimulation enhances the contractile strength of the heart Sherwood: Fig 9.23 Note: Parasympathetic nervous system does not extensively innervate the ventricles and has minimal effect on stroke volume 61 The nervous system and the heart Veins and Venous Return Image from Sherwood Human Physiology Factors that influence Cardiac Output (CO) ▪ Volume of blood ejected by each ventricle each minute ▪ CO= HR X SV Image from Sherwood Human Physiology  Factors involved in determining cardiac output Venous Sympathetic Parasympathetic return Contractility activity activity EDV (preload) ESV Stroke volume (SV) Heart rate (HR) Cardiac output (CO = SV  HR) © 2016 Pearson Education, Ltd.  Factors involved in determining cardiac output Severe dehydration reduces plasma volume reducing venous return which in turn reduces end diastolic volume and hence stroke volume. A reduction in stroke volume leads to a reduction in cardiac output. Note, the kidneys act to restore plasma volume back to the control point (more about this in the renal module) Opposite will occur if the initial stimulus is overhydration  Heart failure Heart failure is defined as failure of the heart muscle to eject blood either due to a stiff heart (trouble filling in diastole) and/or a weak heart muscle (trouble pumping blood during systole).  Sympathetic nerve activity in heart failure Sympathetic nerve activity increases in heart failure to increase muscle contraction and to preserve cardiac output. In the short term, this can improve cardiac function to an extent. In the long run, chronic overactivation of the sympathetic nervous system injures the cardiac muscle, further reducing cardiac function contributing to heart failure.  Pulmonary hypertension Pulmonary hypertension affects blood vessels in the lung Hypertension = high blood pressure Pulmonary hypertension = high blood pressure within the pulmonary circulation Pulmonary hypertension can reduce blood flow in the pulmonary circulation which reduces gas exchange efficiency in the lung.  Lecture 1 and 2 - Revision 1. What is stroke volume 2. Discuss how an increase in venous return increases cardiac output. Use a flow diagram COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you by or on behalf of the University of Queensland pursuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. 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