The heart has contractile cells that produce powerful contractions to propel blood flow and a conducting system to control and coordinate the activity of the contractile cells. The conducting system is made up of nodal and conducting cells that initiate and distribute electrical impulses without contracting. It establishes the heart rate and ensures coordinated contraction of the atria and ventricles. The cardiac cycle involves systole where the heart contracts and diastole where it relaxes, moving blood from high to low pressure areas. Cardiac output, the amount of blood pumped per minute, is regulated by factors like blood volume, autonomic innervation, hormones, ion concentration and temperature.
The document discusses the cardiac cycle, cardiac blood flow, and the intrinsic conduction system of the heart. It explains that the sinoatrial node initiates impulses that travel through the atrioventricular node and bundle of His to stimulate ventricular contraction. It also reviews factors that influence stroke volume and cardiac output, such as preload, contractility, and the autonomic nervous system.
The circulatory system document provides an overview of the structure and function of the circulatory system. It notes that the circulatory system is over 60,000 miles long and pumps 2000 gallons of blood per day. It describes the pathways of blood flow from the heart to lungs to body and back. Key components discussed include the heart, arteries, veins, capillaries, and blood content. Diagrams show the direction of blood flow and internal structures of the heart.
The document summarizes cardiac physiology, including:
1) The circulatory system consists of the heart, blood vessels, and blood, with the heart serving as a pump that establishes blood pressure.
2) The heart has two main functions - generating blood pressure and routing blood flow between the pulmonary and systemic circulations to ensure one-way flow.
3) An electrocardiogram (ECG) provides a non-invasive record of the heart's electrical activity and can help identify conditions like arrhythmias.
The document discusses cardiac muscle and the physiology of the heart. It describes the structure of cardiac muscle including specialized excitatory and conductive fibers. It explains the cardiac muscle action potential and how it differs from other muscles. The cardiac cycle and its components are outlined including atrial and ventricular systole and diastole. The roles of preload and afterload on heart function are introduced.
The document summarizes the conduction system of the heart and the cardiac cycle. It discusses the following key points:
1. The heart's conduction system originates in specialized cardiac muscle cells called autorhythmic cells, which generate electrical impulses to initiate and coordinate heart contractions. The main structures of the conduction system are the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers.
2. The cardiac cycle involves coordinated contraction and relaxation of the atria and ventricles. It begins with depolarization of the sinoatrial node, followed by atrial contraction, ventricular depolarization through the conduction system, ventricular contraction, and finally relaxation of both chambers.
The document provides an overview of cardiovascular physiology:
- It defines cardiovascular physiology as the study of the circulatory system, including the heart and blood vessels.
- The objectives are to explain circulation and perfusion, describe the cardiac cycle, and discuss factors that impact the cardiac cycle.
- Key topics covered include the anatomy and electrophysiology of the heart, regulation of the cardiovascular system, cardiac pump dynamics, the cardiac cycle, and influences on the cycle like nerves, hormones, preload and afterload.
- Physiology of the heart and blood vessels is discussed in detail through diagrams and explanations of concepts like the cardiac conduction system, action potentials, the ECG,
1) The document discusses the rhythmicity and automaticity of the heart, which refers to the heart's ability to beat regularly and generate impulses without external stimuli.
2) It originates from within the heart itself (myogenic, not neurogenic) and several factors can influence the heart rate such as the autonomic nervous system, temperature, drugs, blood gases, and inorganic ions.
3) The sinoatrial node acts as the pacemaker for the heart and has membrane properties that allow it to spontaneously depolarize, initiating the heartbeat via an action potential involving sodium, calcium, and potassium ion fluxes.
The heart has contractile cells that produce powerful contractions to propel blood flow and a conducting system to control and coordinate the activity of the contractile cells. The conducting system is made up of nodal and conducting cells that initiate and distribute electrical impulses without contracting. It establishes the heart rate and ensures coordinated contraction of the atria and ventricles. The cardiac cycle involves systole where the heart contracts and diastole where it relaxes, moving blood from high to low pressure areas. Cardiac output, the amount of blood pumped per minute, is regulated by factors like blood volume, autonomic innervation, hormones, ion concentration and temperature.
The document discusses the cardiac cycle, cardiac blood flow, and the intrinsic conduction system of the heart. It explains that the sinoatrial node initiates impulses that travel through the atrioventricular node and bundle of His to stimulate ventricular contraction. It also reviews factors that influence stroke volume and cardiac output, such as preload, contractility, and the autonomic nervous system.
The circulatory system document provides an overview of the structure and function of the circulatory system. It notes that the circulatory system is over 60,000 miles long and pumps 2000 gallons of blood per day. It describes the pathways of blood flow from the heart to lungs to body and back. Key components discussed include the heart, arteries, veins, capillaries, and blood content. Diagrams show the direction of blood flow and internal structures of the heart.
The document summarizes cardiac physiology, including:
1) The circulatory system consists of the heart, blood vessels, and blood, with the heart serving as a pump that establishes blood pressure.
2) The heart has two main functions - generating blood pressure and routing blood flow between the pulmonary and systemic circulations to ensure one-way flow.
3) An electrocardiogram (ECG) provides a non-invasive record of the heart's electrical activity and can help identify conditions like arrhythmias.
The document discusses cardiac muscle and the physiology of the heart. It describes the structure of cardiac muscle including specialized excitatory and conductive fibers. It explains the cardiac muscle action potential and how it differs from other muscles. The cardiac cycle and its components are outlined including atrial and ventricular systole and diastole. The roles of preload and afterload on heart function are introduced.
The document summarizes the conduction system of the heart and the cardiac cycle. It discusses the following key points:
1. The heart's conduction system originates in specialized cardiac muscle cells called autorhythmic cells, which generate electrical impulses to initiate and coordinate heart contractions. The main structures of the conduction system are the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers.
2. The cardiac cycle involves coordinated contraction and relaxation of the atria and ventricles. It begins with depolarization of the sinoatrial node, followed by atrial contraction, ventricular depolarization through the conduction system, ventricular contraction, and finally relaxation of both chambers.
The document provides an overview of cardiovascular physiology:
- It defines cardiovascular physiology as the study of the circulatory system, including the heart and blood vessels.
- The objectives are to explain circulation and perfusion, describe the cardiac cycle, and discuss factors that impact the cardiac cycle.
- Key topics covered include the anatomy and electrophysiology of the heart, regulation of the cardiovascular system, cardiac pump dynamics, the cardiac cycle, and influences on the cycle like nerves, hormones, preload and afterload.
- Physiology of the heart and blood vessels is discussed in detail through diagrams and explanations of concepts like the cardiac conduction system, action potentials, the ECG,
1) The document discusses the rhythmicity and automaticity of the heart, which refers to the heart's ability to beat regularly and generate impulses without external stimuli.
2) It originates from within the heart itself (myogenic, not neurogenic) and several factors can influence the heart rate such as the autonomic nervous system, temperature, drugs, blood gases, and inorganic ions.
3) The sinoatrial node acts as the pacemaker for the heart and has membrane properties that allow it to spontaneously depolarize, initiating the heartbeat via an action potential involving sodium, calcium, and potassium ion fluxes.
The heart is a hollow muscular pump located in the chest cavity. It has four chambers - two upper atria and two lower ventricles. The heart is surrounded by the pericardium and has three layers - epicardium, myocardium, and endocardium. It receives deoxygenated blood from the body and pumps it to the lungs for oxygenation, then receives oxygenated blood from the lungs and pumps it out to the body. The heart has valves that ensure one-way blood flow and a specialized conduction system that generates electrical impulses to coordinate contractions.
1) The heart has four chambers and uses electrical signals to coordinate contractions that pump blood through two circuits.
2) The sinoatrial node initiates electrical impulses that spread through the heart, causing atria to contract before ventricles.
3) Cardiac output depends on heart rate, preload, afterload and contractility and is regulated by nervous and hormonal factors.
This document provides an overview of cardiovascular physiology. It begins with a brief history of the field and introduces the concept of the heart as a pump. It then discusses the anatomy of the heart including the chambers, valves, conduction system, and cardiac muscle structure. Next, it covers the autorhythmic pacemaker cells, cardiac action potentials, excitation-contraction coupling, and the cardiac cycle. It also discusses neural and hormonal control of the heart, coronary circulation, hemodynamic calculations, and cardiac reflexes.
Term paper on ECG and cardiac arrhythmiasRomena Begum
The document provides information about ECGs and cardiac arrhythmias. It discusses the history and development of ECGs, the anatomy and conduction system of the heart, common arrhythmias like sinus tachycardia and sinus bradycardia, and how to diagnose and manage various types of cardiac arrhythmias using ECGs. The document contains diagrams of ECG readings and the heart to illustrate different arrhythmias and the heart's structure and function.
The document describes the physiology of the heart, including its muscular wall, conductive system, cardiac action potential, and excitation-contraction coupling. It discusses how electrical signals are initiated in the heart and conducted between cells, causing contraction. Finally, it summarizes how different anesthetics can impact the heart's electrical and mechanical functions by altering ion channels and calcium handling.
Ppt cvs phsiology a small review for anaesthetistdrriyas03
The document discusses the cardiovascular system and heart function. It describes the heart as a pump that circulates blood through vessels to distribute essential substances and remove waste. The cardiovascular system transports 5 liters of blood per minute through a network of arteries, veins, and capillaries. Precise regulation of the cardiovascular system is achieved through neural, hormonal, and local control mechanisms.
Here are the answers to your questions:
1. A muscular fiber is also called a muscle cell. It contains myofibrils which are bundles of actin and myosin filaments. A sarcomere is the basic contractile unit along the myofibril, defined as the region between two Z-lines.
2. Muscle fiber shortening occurs via the sliding filament model. During muscle contraction, the heads of myosin cross-bridge with and pull on the actin filaments, drawing the Z-lines closer together and shortening the sarcomere. Many sarcomeres shortening leads to shortening of the entire muscle fiber.
3. The Starling's law states that the greater
The document discusses cardiac muscle and the physiology of the heart. It describes the structure of cardiac muscle including specialized excitatory and conductive fibers. It explains the cardiac muscle action potential and how it differs from other muscles. The cardiac cycle and its components are outlined including atrial and ventricular systole and diastole. The roles of preload and afterload on heart function are introduced.
The document summarizes key aspects of heart physiology:
1. The heart generates blood pressure, routes blood flow through two circuits (pulmonary and systemic), and ensures one-way blood flow through valves.
2. The left side of the heart is more muscular to pump blood throughout the body. Valves prevent backflow of blood.
3. Cardiac muscle contracts as a unit through a conduction system including the sinoatrial node, atrioventricular node, and Purkinje fibers.
4. An electrocardiogram records the heart's electrical activity and can indicate damage or abnormalities.
The document discusses the physiology of pacemaker and contractile cells in the heart. It begins by describing the characteristics of pacemaker cells, including their automaticity due to unstable membrane potentials. It then discusses how sympathetic and parasympathetic activity can alter the activity of pacemaker cells to increase or decrease heart rate. The document next describes the characteristics of contractile myocardial cells and their action potentials. It compares skeletal and cardiac action potentials. Finally, it discusses excitation-contraction coupling in contractile cells and the roles of calcium in both contraction and relaxation.
The document provides an overview of cardiovascular physiology, including:
1. It describes the basic components and regulation of the cardiovascular system, including the heart, vessels, and regulatory mechanisms.
2. It discusses the pulmonary and systemic circulations in terms of pressure, resistance, and flow.
3. It covers the structure and function of the heart as a pump, including cardiac cycle, regulation of contractility, and the Frank-Starling mechanism.
The cardiac cycle describes the sequence of events in one heartbeat. It begins with spontaneous generation of an action potential in the sinus node which then spreads to the atria and ventricles. Each cycle consists of a diastolic phase where the heart relaxes and fills with blood, followed by a systolic phase where the heart contracts and pumps blood out. Key events include atrial systole, isovolumetric contraction, ventricular ejection, reduced ejection, isovolumetric relaxation, and rapid ventricular filling. The cycle repeats with each heartbeat to circulate blood through the body.
The document summarizes key aspects of cardiac physiology, including:
- The functions of the heart in generating blood pressure, routing blood flow, ensuring one-way flow, and regulating blood supply.
- The cardiac cycle and its phases of isovolumic contraction, ejection, isovolumic relaxation, and diastole.
- Factors that affect cardiac output including venous return, heart rate, contractility, and peripheral resistance.
- Key reflexes that regulate cardiac function such as the baroreceptor, chemoreceptor, and Bezold-Jarisch reflexes.
This document summarizes cardiac muscle mechanics and the cardiac cycle. It describes how cardiac muscle operates on the ascending limb of the active tension curve, allowing force of contraction to increase with stretching. It then outlines the key components and phases of the cardiac cycle from both mechanical and electrical perspectives. This includes definitions of systole, diastole, and the isovolumic phases. Pressure and volume relationships throughout the cycle are depicted in diagrams. Factors influencing cardiac performance like preload, contractility, and afterload are also defined.
HEART RATE
REGULATION OF HEART RATE
VASOMOTOR CENTER – CARDIAC CENTER
MOTOR (EFFERENT) NERVE FIBERS TO HEART
FACTORS AFFECTING VASOMOTOR CENTER
for all medical & health care students
The cardiac cycle describes the sequence of events in one heartbeat. It begins with atrial systole which pushes additional blood into the ventricles. This is followed by ventricular systole where the ventricles contract to pump blood out. Isovolumic contraction occurs as ventricular pressure rises, closing the AV valves before ejection. Ejection then proceeds rapidly initially and more slowly later. Isovolumic relaxation happens as ventricular pressure falls, opening the AV valves before rapid ventricular filling from the atria. The cycle then repeats with atrial systole.
The cardiovascular system consists of the heart and blood vessels. The heart has four chambers and uses valves to ensure one-way blood flow. It pumps deoxygenated blood to the lungs and oxygenated blood throughout the body. Blood travels through arteries, capillaries, and veins in both pulmonary and systemic circuits. The heart's conduction system uses electrical signals to coordinate contractions. Factors like preload and afterload influence cardiac output. Blood pressure is regulated by baroreceptors, chemoreceptors, and the renin-angiotensin system.
The document discusses cardiac muscle and the cardiac cycle. It provides details on:
- Cardiac muscle histology and action potential, including ion channels involved
- The cardiac cycle and components such as atrial systole, ventricular ejection, and filling phases
- How the cardiac cycle is coordinated by the conduction system and regulated by the autonomic nervous system
- Key concepts like the Frank-Starling law of the heart and factors affecting cardiac performance
This document discusses the anatomy and physiology of the heart. It covers topics like cardiac muscle contraction, the sequence of heart excitation starting from the sinoatrial node, the relationship between heart electrical activity and the electrocardiogram, heart sounds, phases of the cardiac cycle, and regulation of heart rate by the autonomic nervous system. It also briefly discusses congenital heart defects, developmental aspects of the heart, and age-related changes affecting the heart.
This document discusses the physiology of the heart. It begins by describing the different types of cardiac muscle and how cardiac muscle cells are interconnected. It then covers the cardiac cycle, including diastole and systole. Action potentials in cardiac muscle are longer than in skeletal muscle due to slow calcium channels. Contraction is triggered by calcium release from the sarcoplasmic reticulum and extracellular fluids. The heart pumps in two stages - the atria prime the ventricles, then the ventricles eject blood. Various waves in pressures, ECG, and sounds are related to the different cardiac cycle events.
The heart functions to pump blood throughout the body via two circulatory systems - pulmonary and systemic. It generates blood pressure and ensures one-way blood flow. Cardiac output, the amount of blood pumped, is determined by heart rate and stroke volume. Intrinsic factors like the Frank-Starling mechanism and extrinsic neural and hormonal controls regulate cardiac output in response to the body's changing needs.
The cardiovascular system includes the heart and blood vessels. The heart weighs 200-400 grams and pumps around 7,751 litres of blood daily. It is located behind the sternum and is surrounded by membranes. Blood enters and exits the heart through major vessels while valves regulate flow between chambers. The heart muscle generates electrical impulses and contractions to circulate blood throughout the body. Cardiac output is regulated intrinsically through preload and afterload as well as extrinsically through the nervous and endocrine systems.
The heart is a hollow muscular pump located in the chest cavity. It has four chambers - two upper atria and two lower ventricles. The heart is surrounded by the pericardium and has three layers - epicardium, myocardium, and endocardium. It receives deoxygenated blood from the body and pumps it to the lungs for oxygenation, then receives oxygenated blood from the lungs and pumps it out to the body. The heart has valves that ensure one-way blood flow and a specialized conduction system that generates electrical impulses to coordinate contractions.
1) The heart has four chambers and uses electrical signals to coordinate contractions that pump blood through two circuits.
2) The sinoatrial node initiates electrical impulses that spread through the heart, causing atria to contract before ventricles.
3) Cardiac output depends on heart rate, preload, afterload and contractility and is regulated by nervous and hormonal factors.
This document provides an overview of cardiovascular physiology. It begins with a brief history of the field and introduces the concept of the heart as a pump. It then discusses the anatomy of the heart including the chambers, valves, conduction system, and cardiac muscle structure. Next, it covers the autorhythmic pacemaker cells, cardiac action potentials, excitation-contraction coupling, and the cardiac cycle. It also discusses neural and hormonal control of the heart, coronary circulation, hemodynamic calculations, and cardiac reflexes.
Term paper on ECG and cardiac arrhythmiasRomena Begum
The document provides information about ECGs and cardiac arrhythmias. It discusses the history and development of ECGs, the anatomy and conduction system of the heart, common arrhythmias like sinus tachycardia and sinus bradycardia, and how to diagnose and manage various types of cardiac arrhythmias using ECGs. The document contains diagrams of ECG readings and the heart to illustrate different arrhythmias and the heart's structure and function.
The document describes the physiology of the heart, including its muscular wall, conductive system, cardiac action potential, and excitation-contraction coupling. It discusses how electrical signals are initiated in the heart and conducted between cells, causing contraction. Finally, it summarizes how different anesthetics can impact the heart's electrical and mechanical functions by altering ion channels and calcium handling.
Ppt cvs phsiology a small review for anaesthetistdrriyas03
The document discusses the cardiovascular system and heart function. It describes the heart as a pump that circulates blood through vessels to distribute essential substances and remove waste. The cardiovascular system transports 5 liters of blood per minute through a network of arteries, veins, and capillaries. Precise regulation of the cardiovascular system is achieved through neural, hormonal, and local control mechanisms.
Here are the answers to your questions:
1. A muscular fiber is also called a muscle cell. It contains myofibrils which are bundles of actin and myosin filaments. A sarcomere is the basic contractile unit along the myofibril, defined as the region between two Z-lines.
2. Muscle fiber shortening occurs via the sliding filament model. During muscle contraction, the heads of myosin cross-bridge with and pull on the actin filaments, drawing the Z-lines closer together and shortening the sarcomere. Many sarcomeres shortening leads to shortening of the entire muscle fiber.
3. The Starling's law states that the greater
The document discusses cardiac muscle and the physiology of the heart. It describes the structure of cardiac muscle including specialized excitatory and conductive fibers. It explains the cardiac muscle action potential and how it differs from other muscles. The cardiac cycle and its components are outlined including atrial and ventricular systole and diastole. The roles of preload and afterload on heart function are introduced.
The document summarizes key aspects of heart physiology:
1. The heart generates blood pressure, routes blood flow through two circuits (pulmonary and systemic), and ensures one-way blood flow through valves.
2. The left side of the heart is more muscular to pump blood throughout the body. Valves prevent backflow of blood.
3. Cardiac muscle contracts as a unit through a conduction system including the sinoatrial node, atrioventricular node, and Purkinje fibers.
4. An electrocardiogram records the heart's electrical activity and can indicate damage or abnormalities.
The document discusses the physiology of pacemaker and contractile cells in the heart. It begins by describing the characteristics of pacemaker cells, including their automaticity due to unstable membrane potentials. It then discusses how sympathetic and parasympathetic activity can alter the activity of pacemaker cells to increase or decrease heart rate. The document next describes the characteristics of contractile myocardial cells and their action potentials. It compares skeletal and cardiac action potentials. Finally, it discusses excitation-contraction coupling in contractile cells and the roles of calcium in both contraction and relaxation.
The document provides an overview of cardiovascular physiology, including:
1. It describes the basic components and regulation of the cardiovascular system, including the heart, vessels, and regulatory mechanisms.
2. It discusses the pulmonary and systemic circulations in terms of pressure, resistance, and flow.
3. It covers the structure and function of the heart as a pump, including cardiac cycle, regulation of contractility, and the Frank-Starling mechanism.
The cardiac cycle describes the sequence of events in one heartbeat. It begins with spontaneous generation of an action potential in the sinus node which then spreads to the atria and ventricles. Each cycle consists of a diastolic phase where the heart relaxes and fills with blood, followed by a systolic phase where the heart contracts and pumps blood out. Key events include atrial systole, isovolumetric contraction, ventricular ejection, reduced ejection, isovolumetric relaxation, and rapid ventricular filling. The cycle repeats with each heartbeat to circulate blood through the body.
The document summarizes key aspects of cardiac physiology, including:
- The functions of the heart in generating blood pressure, routing blood flow, ensuring one-way flow, and regulating blood supply.
- The cardiac cycle and its phases of isovolumic contraction, ejection, isovolumic relaxation, and diastole.
- Factors that affect cardiac output including venous return, heart rate, contractility, and peripheral resistance.
- Key reflexes that regulate cardiac function such as the baroreceptor, chemoreceptor, and Bezold-Jarisch reflexes.
This document summarizes cardiac muscle mechanics and the cardiac cycle. It describes how cardiac muscle operates on the ascending limb of the active tension curve, allowing force of contraction to increase with stretching. It then outlines the key components and phases of the cardiac cycle from both mechanical and electrical perspectives. This includes definitions of systole, diastole, and the isovolumic phases. Pressure and volume relationships throughout the cycle are depicted in diagrams. Factors influencing cardiac performance like preload, contractility, and afterload are also defined.
HEART RATE
REGULATION OF HEART RATE
VASOMOTOR CENTER – CARDIAC CENTER
MOTOR (EFFERENT) NERVE FIBERS TO HEART
FACTORS AFFECTING VASOMOTOR CENTER
for all medical & health care students
The cardiac cycle describes the sequence of events in one heartbeat. It begins with atrial systole which pushes additional blood into the ventricles. This is followed by ventricular systole where the ventricles contract to pump blood out. Isovolumic contraction occurs as ventricular pressure rises, closing the AV valves before ejection. Ejection then proceeds rapidly initially and more slowly later. Isovolumic relaxation happens as ventricular pressure falls, opening the AV valves before rapid ventricular filling from the atria. The cycle then repeats with atrial systole.
The cardiovascular system consists of the heart and blood vessels. The heart has four chambers and uses valves to ensure one-way blood flow. It pumps deoxygenated blood to the lungs and oxygenated blood throughout the body. Blood travels through arteries, capillaries, and veins in both pulmonary and systemic circuits. The heart's conduction system uses electrical signals to coordinate contractions. Factors like preload and afterload influence cardiac output. Blood pressure is regulated by baroreceptors, chemoreceptors, and the renin-angiotensin system.
The document discusses cardiac muscle and the cardiac cycle. It provides details on:
- Cardiac muscle histology and action potential, including ion channels involved
- The cardiac cycle and components such as atrial systole, ventricular ejection, and filling phases
- How the cardiac cycle is coordinated by the conduction system and regulated by the autonomic nervous system
- Key concepts like the Frank-Starling law of the heart and factors affecting cardiac performance
This document discusses the anatomy and physiology of the heart. It covers topics like cardiac muscle contraction, the sequence of heart excitation starting from the sinoatrial node, the relationship between heart electrical activity and the electrocardiogram, heart sounds, phases of the cardiac cycle, and regulation of heart rate by the autonomic nervous system. It also briefly discusses congenital heart defects, developmental aspects of the heart, and age-related changes affecting the heart.
This document discusses the physiology of the heart. It begins by describing the different types of cardiac muscle and how cardiac muscle cells are interconnected. It then covers the cardiac cycle, including diastole and systole. Action potentials in cardiac muscle are longer than in skeletal muscle due to slow calcium channels. Contraction is triggered by calcium release from the sarcoplasmic reticulum and extracellular fluids. The heart pumps in two stages - the atria prime the ventricles, then the ventricles eject blood. Various waves in pressures, ECG, and sounds are related to the different cardiac cycle events.
The heart functions to pump blood throughout the body via two circulatory systems - pulmonary and systemic. It generates blood pressure and ensures one-way blood flow. Cardiac output, the amount of blood pumped, is determined by heart rate and stroke volume. Intrinsic factors like the Frank-Starling mechanism and extrinsic neural and hormonal controls regulate cardiac output in response to the body's changing needs.
The cardiovascular system includes the heart and blood vessels. The heart weighs 200-400 grams and pumps around 7,751 litres of blood daily. It is located behind the sternum and is surrounded by membranes. Blood enters and exits the heart through major vessels while valves regulate flow between chambers. The heart muscle generates electrical impulses and contractions to circulate blood throughout the body. Cardiac output is regulated intrinsically through preload and afterload as well as extrinsically through the nervous and endocrine systems.
The document summarizes key aspects of heart anatomy and physiology. It describes the location and layers of the heart walls. It details the four chambers of the heart and the valves that prevent backflow of blood. It explains the pulmonary and systemic blood circulation circuits. It also outlines the specialized conduction system that controls heart rhythm, including the sinoatrial node, atrioventricular node, and Purkinje fibers. In addition, it discusses how sympathetic and parasympathetic nerves regulate heart rate and conduction.
The heart is a muscular organ that pumps blood throughout the body via four chambers. It has a size comparable to a fist and beats 70 times per minute, pumping oxygenated blood from the left ventricle through the aorta and deoxygenated blood from the right ventricle through the pulmonary arteries. The cardiac cycle involves atrial systole where the atria contract and force blood into the ventricles, followed by ventricular systole where the ventricles contract and pump blood out of the heart through semilunar valves that prevent backflow. The heart's rhythm is controlled by the sinoatrial node which acts as the pacemaker, transmitting electrical signals that cause coordinated contractions.
Term paper on ecg and cardiac arrhythmiasROMENABEGUM
The document provides information on ECGs and cardiac arrhythmias. It begins with an introduction to ECGs and what they measure. It then discusses the history of ECGs, the anatomy and conduction system of the heart, common indications for ECGs, how ECGs are arranged and interpreted, and definitions of heart rate and rhythm. The majority of the document categorizes and describes different types of cardiac arrhythmias like sinus tachycardia, sinus bradycardia, premature atrial contractions, atrial flutter, atrial fibrillation, junctional rhythm, junctional tachycardia, premature junctional contractions, and supraventricular tachycardia. For each type it discusses causes
Cardiovascular System, Heart, Blood Vessel, ECG, Hypertension, Arrhythmia Audumbar Mali
Cardiovascular System,
Human Anatomy and Physiology-I,
The Blood Vessels,
The Heart,
The Electrocardiogram,
The Vascular Pathways,
As per PCI syllabus,
Atherosclerosis,
Coronary bypass operation,
Heart Transplants and Artificial Hearts
The document summarizes key aspects of heart physiology:
- The heart pumps blood through two circuits and uses valves to ensure one-way blood flow.
- Cardiac muscle cells contract as a unit due to intercalated disks and gap junctions.
- The heart's conduction system uses specialized pacemaker cells and Purkinje fibers to coordinate contractions.
- An electrocardiogram tracks the heart's electrical activity during a cardiac cycle of atrial and ventricular filling/contraction.
The document summarizes key aspects of cardiac physiology including the cardiac cycle, myocardial action potential, coronary circulation, and jugular venous pulse (JVP). It describes the electrical and mechanical events of the heart during one cardiac cycle as represented by an electrocardiogram (ECG) and pressures. It also discusses the anatomy and regulation of coronary blood flow to meet metabolic demand of the myocardium.
The cardiovascular system functions to transport blood and nutrients throughout the body while removing waste. It is composed of the heart, which pumps blood through a closed system of arteries, capillaries and veins. The heart has four chambers and uses electrical conduction pathways to generate rhythmic contractions. Blood flows through two circuits - systemic circulation which oxygenates tissues, and pulmonary circulation which oxygenates blood in the lungs. The cardiovascular system is regulated through neural and hormonal mechanisms to maintain blood pressure and meet the body's needs.
The document summarizes the cardiac conduction system and electrocardiogram (ECG). It describes how the conduction system initiates and propagates electrical signals throughout the heart to coordinate contractions. Specialized pacemaker cells in the sinoatrial node initiate signals that spread through atria and ventricles via pathways like the atrioventricular node and bundle of His. This electrical activity generates currents detectable by ECG, which can provide information on conduction abnormalities and heart health.
1. The document discusses the biomechanics of circulation, including anatomy and physiology of the fetal circulation and adult circulation. It describes the structure and function of the heart, blood vessels, and cardiac cycle.
2. Special structures in fetal circulation that allow oxygenated blood to bypass the lungs, such as the foramen ovale, ductus arteriosus, and ductus venosus, are explained.
3. After birth, these fetal structures close or become ligaments as the infant transitions to lung-based respiration and circulation.
The document discusses the biomechanics of circulation, including:
1. An overview of cardiac anatomy and electrophysiology, the cardiac cycle, and pressure.
2. Key properties of cardiac muscle cells and the intrinsic conduction system that generates heartbeats.
3. The roles of atrioventricular valves, semilunar valves, and coronary and nerve vessels in regulating blood flow through the heart.
The document summarizes the cardiac cycle, including the electrical and mechanical events of the heart. It describes the conduction system that controls heart rhythm, including the sinoatrial node as the pacemaker. The main phases of the cardiac cycle are described in detail: atrial systole, isovolumetric contraction, ejection, isovolumetric relaxation, and ventricular filling. Pressure values for the different chambers are also provided. The coordination of these electrical and mechanical events ensures effective pumping of blood throughout the cardiovascular system.
The document describes the conducting system of the heart which initiates and spreads electrical impulses, including the SA node, AV node, bundle of His, and Purkinje fibers. It then explains the cardiac cycle, including the roles of the atria and ventricles, heart sounds, and how blood pressure and ECG readings can monitor cardiac function.
The document summarizes key aspects of the cardiovascular system. It describes the anatomy of the heart, including the four chambers and major valves. It explains that deoxygenated blood enters the right side of the heart and is pumped to the lungs, while oxygenated blood enters the left side and is pumped out to the body. It also discusses regulation of blood flow and pressure through the heart cycle and autonomic nervous system.
The heart has four chambers that pump blood through two circuits. Deoxygenated blood enters the right atrium and is pumped to the right ventricle before exiting through the pulmonary artery to the lungs. Oxygenated blood returns to the left atrium and is pumped to the left ventricle to exit through the aorta to the body. The heart's rhythm is controlled by a natural pacemaker and conduction system which stimulates coordinated contractions of the cardiac muscles in two phases: atrial systole and ventricular systole. One full cardiac cycle of relaxation and contraction takes approximately 0.8 seconds.
The document describes the structure and function of the heart and cardiovascular system. It discusses:
1) The heart is made up of four chambers that pump blood through two circuits - the pulmonary circuit oxygenates blood in the lungs, and the systemic circuit delivers oxygenated blood to the body.
2) Valves between the chambers prevent backflow of blood, and the heart's conduction system coordinates contractions to efficiently pump blood.
3) Arteries, veins and capillaries work together to transport blood throughout the body and back to the heart in a continuous closed circuit.
The document summarizes the electrical conduction system of the heart and the cardiac cycle. It discusses how electrical impulses originate in the sinoatrial node and propagate through the conduction system to coordinate contractions. The cardiac cycle involves periodic atrial and ventricular contractions and relaxations that pump blood through the heart. Key stages include atrial systole, ventricular systole, and diastole. The electrocardiogram records these electrical events.
Oral Lefamulin vs Moxifloxacin for Early Clinical Response Among Adults With ...farah al souheil
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knowledge, attitude and practice of Lebanese adult population towards topical...farah al souheil
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the presentation starts with a quick overview of COVID-19 followed by Remdesivir focused clinical trials assessment and evaluation for the treatment of Corona virus
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patient presenting with bloody stools and systemic signs with no previous medical complaints was diagnosed with amoebiasis on top ulcerative colitis (sigmoid-proctitis)
pelvic inflammatory disease: case presentation & disease overview farah al souheil
pelvic inflammatory disease is a very common type of Sexually transmitted disease among young sexually active females. in this presentation we discuss a case suffering from PID and then we evaluate the plan of discharge based on disease and treatment overview
COPD exacerbation case presentation and disease overview farah al souheil
management of a simulated case scenario: patient presenting with COPD exacerbation: what's the best next step? summary of the guideline is then described
Endometrial cancer: Disease & Treatment Overview & Journal club farah al souheil
general overview of endometrial (uterine) cancer followed by treatment options followed by journal club about the possible effects of metformin on Ki-67 one of the approved prognostic factors for EC
This document provides an overview and management of pericarditis and myocarditis. It begins with a case presentation of a 21-year-old male student presenting with fever, chills, and muscle pain. It then defines pericarditis and myocarditis, discusses their diagnosis, clinical presentation, staging, complications, treatment, and prognosis. Diagnostic tests like electrocardiography, echocardiography, viral genomes, and cardiac magnetic resonance imaging are covered. Complications like dilated cardiomyopathy are also summarized.
Eczema is a chronic skin condition that causes red, itchy and irritated skin. It occurs when the skin's protective barrier is damaged, allowing moisture to evaporate quickly. Common triggers include soaps, fragrances, fabrics and stress. Treatment focuses on moisturizing, bathing in lukewarm water, and using hydrocortisone cream for flare-ups. Seeing a doctor is recommended if symptoms are severe or the skin becomes infected. While not contagious, eczema can be exacerbated by various environmental factors and allergens.
This document provides an outline for a presentation on pediatric obesity. It covers causes, consequences, and intervention approaches for pediatric obesity. The outline includes sections on introduction, definitions, epidemiology, classification criteria, etiology, pathophysiology, risk factors, complications, management approaches including non-pharmacological, pharmacological, and surgical options, prevention, promising future drugs, and conclusion. Evaluation and treatment approaches involve taking history, conducting a physical exam, ordering investigations, setting nutrition and lifestyle goals, considering pharmacologic options such as Orlistat and Phentermine, and potential surgical interventions.
infantile hemangioma, also known as birthmarks, is a disease of the pediatrics. most birthmarks fade away by the 12th year of life. however, others necessitate treatment and care.
anemia is a very common marker of underlying diseases. it's sometimes gone under diagnosed due to lack of knowledge. here's an overview of the different types and causes of anemia and the pharmacists approach in addressing such problem.
this ppt presentation handles the topic of acne vulgaris which has proven to be a wide epic disease necessitating pharmacologic and non pharmacologic care for best outcomes
this presentation is for children care providers whether in school or in any other facility where children are in close proximity making them more prone to infection.
This document summarizes the mechanisms of pathogenesis for microbes. It discusses the key steps microbes use to cause disease: entry through portals like mucous membranes or skin, adherence to host cells, penetration of host defenses, and damage through nutrient acquisition, direct invasion, or toxin production. Specific virulence factors like capsules, cell wall components, exoenzymes, and antigen variation are described. The differences between exotoxins and endotoxins in their modes of action and impacts on hosts are also highlighted.
Amino acids can be used for energy production through various pathways. They undergo deamination to remove amino groups, which are then used in the urea cycle or released as ammonia. There are three main methods of deamination: transamination, oxidative deamination, and non-oxidative dehydration. Errors in amino acid metabolism can cause disorders like phenylketonuria (PKU) or maple syrup urine disease. Amino acids can be classified as essential or non-essential depending on whether humans can synthesize them, and they serve important roles as building blocks of protein and as precursors for other molecules.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...Travis Hills MN
By harnessing the power of High Flux Vacuum Membrane Distillation, Travis Hills from MN envisions a future where clean and safe drinking water is accessible to all, regardless of geographical location or economic status.
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
(June 12, 2024) Webinar: Development of PET theranostics targeting the molecu...Scintica Instrumentation
Targeting Hsp90 and its pathogen Orthologs with Tethered Inhibitors as a Diagnostic and Therapeutic Strategy for cancer and infectious diseases with Dr. Timothy Haystead.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
3. Cardiac cells comparing to other cells
● Uninucleated
● Has intercalated disc which is a thickening of the sarcolemma conecting
cardiac fibers with one another and it's made up of :
– Desmosome : hold fibers together
– Gap junction : for conduction of muscle action potential b/w fibers
● Larger and more numerous mitochondria
● Same arrangement of actin and myosin as in skeletal muscle.
● Wider t-tubules but less abundant
● Smaller SR
… Farah El Soheil
4. The conduction system: autorythmic
fibers
● The source of rhythmical electric activity of the
heart is the auto-rhythmic fibers that repeatedly
generate AP necessary for contraction. They're
self excitable. They stimulate the heart
● Function :
– Pacemaker : excitation of heart by “AP”
– Conducting system : provide a path for cardiac
excitation so the heart contract in a coordinated
manner
… Farah El Soheil
5. The conducting system
● Excitation starts in SA node ( sinoatrial node) of the right atria that
repeatedly depolarize to threshold “ pacemaker pot “ so AP is triggered
and pass to both atria via the gap junctions so both atria contract
● AP in atrial fibers move to AV node (inter-atrial system) where
conduction slows which provides time fr blood emptying
● AP then pass from AV node to AV bundle “ bundle of HIS” where AP
conduct from atria to ventricle then to bundle branches : interventricular
septum the purkinji conduct AP to ventricles which contract as a result
NB: SA has the fastest rate of AP conduction so AP is reached before it's generated which set rhythm of heart “
pacemaker”
… Farah El Soheil
6. ● Note :
hormones ( epinephrine) And ANS set the
frequency and the force of heart beat not
rhythm which is regulated by pacemaker cells
… Farah El Soheil
7. Coronary circulation
● Coronary arteries branch from aorta ( blood
flows through the arteries during heart
relaxation due to high pressure in aorta that
propel blood from coronary artery to capillary
then to coronary veins.
– Left : supplies ventricles and left atrium ( LAD is a
branch of the left coronary artery
– Right: supplies right atrium.
8. Coronary circulation
● Coronary vein : major vein is the coronary sinus
( vascular sinus) that has no smooth muscle so
can't dilate or constrict.
PS: Valves open or close in response pressure and they prevent backflow.
9. Heart sounds
● S1 : lubb : closure of AV valve ( at the
beginning of ventricle systole)
● S2 : dupp : closure of SL valve ( at the
beginning of ventricle diastole)
● S3: ventricular filling
● S4:atrial systole.
10. Regulation of heart rate
● 1) ANS (autonomic) : by CV center of medulla that
receive nerve impulses from proprioreceptor”that monitor
position of body”, chemoreceptor “ that monitor
hormones and chemicals of the blood”, baroreceptor* “
that monitor the stretching of blood vessels caused by
pressure of blood flow”). Those direct either increase or
decrease in frequency of AP in sympathetic or
parasympathetic states respectively.
*present in aorta and carotid.
… Farah El Soheil
11. Sympathetic state
● Epinephrine hormone
– Speeds the rate of pacemaker potential in SA and AV nodes so
the heart rate (HR) increase
– Increase the calcium entry in contractile fibers so contraction
increase
● Effect: increase in HR leads to decrease in preload ( blood
present before contraction ) so the stroke volume (SV)
decrease (directly proportional to preload). However,
increased HR has a greater effect than decreased preload
so contraction increase.
… Farah El Soheil
13. ● 2) chemical :
– Hormones : epinephrine and NE ( by adrenal medulla) and
thyroid hormones increase contraction and HR.
– Cations:
● Difference in ions important for AP production
● Increase in Na+ block Ca2+ entry so contraction decrease.
● Increase in K+ decrease AP production
● Increase of Ca2+ in interstitial fluid leads to increase n HR and
contraction.
… Farah El Soheil
14. ● 3) other factors:
– Increase in temperature : increase SA impulse
which leads to increase in HR
– decrease in temperature leads to decrease in
metabolism which leads to increase in ability to
withstand decreased blood flow
… Farah El Soheil
15. Regulation of SV
● Preload :
– Caused by EDV ( ventricular filling during diastole)
that's increased by venous return or increase in
duration of ventricle diastole( I.e.: decreased HR)
– stretch of heart before it contracts
– Increase in HR leads to decreased duration
,decreased venous return and decreased EDV
eventually.
… Farah El Soheil
16. ● Contractility :
– Positive ionotropics increase Ca2+ entry during AP
ex: sympathetic and epinephrine and NE.
– Negative ionotropics as increase in K+ leads to
decrease in ca2+ inflow.
… Farah El Soheil
17. ● Afterload: the pressure to be overcame
– If : Pressure in ventricles > pressure in
artery(afterload) , the valve opens.
PS: HTN leads to narrowed arteries so afterload increase so SV decrease and blood
remains in ventricle
18. AP of contractile fibers
● Depolarization : due to opening of Na+
channels* ( due to depolarization to threshold
by neighboring fibers) and Na+ enters
* fast because they open directly in response to depolarization to threshold
19. ● Plateau:state of maintained depolarization due to
opening of slow Ca2+ channels in sarcolemma
and entry to cytosol. This inflow of Ca2+ causes
Ca2+ to exit from SR due to increase in CA2+ this
leads to contraction due to binding of Ca2+ to
troponin and the slide of actin across myosin and
the start of tension. Before plateau K+ in
sarcolemma opens so K+ leaves But the Ca2+
entry = K+ release so depolarization continues.
20. ● Repolarization : due to additional K+ channels
opening so K+ exits and the closure of Ca2+
channels in SR and sarcolemma
21. Refractory period
● It lasts longer than contraction so contraction
can't occur except after relaxation so no
tetanus occurs ( extended contraction) which is
good because pumping depends on alternating
contraction and relaxation so blood flows.
22. Energy used by cardiac cells
● Aerobic
● From oxidation of FA “mainly”, glucose, A.A.,
lactic acid “during exercise” ketone bodies and
creatinine phosphate.
23. Signs of infarction
● Creatinine kinase (CK) in blood where it should
be always inside muscles
● Enlarged Q wave
24. Electrocardiogram
● Sum of all AP generated by cardiac fibers per
beat
● Uses:
– Amplifies heart electrical signals
– Determine if conducting pathway is abnormal
● If heart is enlarged
– Enlarged P wave then the atrium is enlarged
– Enlarged R wave then the ventricles are enlarged
25. ● P wave: depolarization of the atria contractile fibers
( after p wave atria contracts)
● QRS wave : depolarization of cells of ventricles and
repolarization of atria( masked by QRS wave). After
this wave the ventricles contract.
● T wave: repolarization of the ventricles ( smaller and
wider than the QRS wave since repolarization is
slower than depolarization ) after repolarization atria
and venticles are relaxing.
26. Cardiac cycle
● In each side of the heart same volume of blood
is expelled but with different pressure ( it's
higher in left side)
● Each cycle takes 0.8 sec as a total when HR=
75 beat/ min
27. Cardiac cycle
● Atrial systole : and ventricular diastole (0.1 sec)
depolarization (dep.) in SA node followed by
dep. In atrial fibers then atrial systole
( contraction ) so blood is forced into ventricles
through opened AV valves (25ml) but there's
(105ml) already present so the end of
ventricular diastole ( relaxation) there's EDV=
130 ml as a total.
28. Cardiac cycle
● Ventricular systole : and atrial diastole (0.3 sec)
– Dep. In ventricle followed by ventricle systole so blood is
forced to AV valve which close ( prevent backflow ). SL and
AV valves are closed. Isovolumetric contraction state takes
place where :
● Fibers are contracting but not shortening “isometric cont.”
● Volume in ventricle is the same “ isovolumic”
– More contraction of ventricles so pressure increase. Once
p(ventricle)> p(artery) SL valve opens so SV= 70 ml of
blood is ejected
– At the end of contraction ESV=60 ml remaining in the
ventricles
29. Cardiac cycle
● Relaxation period : it's the variable period of the cycle
based on HR but mainly it's (0.4 sec)
● Ventricles and atria relax
● Repolarization of the ventricle (DIASTOLE) so
p( ventricle) decrease so blood flows from arteries back
to ventricles SL closes as a result and AV are already
closed. Hence there's a state of isovolumetric volume.
● More relaxation leads to p(ventricle)<p(atria) so AV
valve open and blood flows (45 ml) : ventricular filling so
ventricles are ¾ filled at end of relaxation.
30. AV valves
● Open : when ventricles are relaxed papillary
muscles are relaxed.
● Close: when ventricles contract so papillary
myscles contract
31. notes
● No valve between vein and heart but
contraction of atria close venous entry points.
● Fibrous skeleton of the heart :
– Prevent overstretching of valves
– Insulates atria from ventricles electrically.