The document summarizes the anatomy and physiology of the human heart. It describes the heart's location in the thoracic cavity. It then details the three layers of the heart - pericardium, myocardium, and endocardium. It explains the interior structures of the heart including the atria, ventricles, and valves. The conducting system and cardiac cycle are then summarized. Finally, it briefly discusses cardiac output, factors affecting stroke volume and heart rate, and the baroreceptor reflex.
Muscular System: The Cardiac Muscle (Heart)hm alumia
Cardiac muscle is only found in the heart. It contracts involuntarily and has abundant mitochondria to power its contractions. Cardiac muscle cells are connected through intercalated discs that allow electrical signals to spread through the heart.
The heart has four chambers - two upper atria that receive blood and two lower ventricles that pump blood out. The right side receives deoxygenated blood and pumps it to the lungs, while the left side receives oxygenated blood and pumps it into the body. Valves ensure blood flows only in one direction through the heart's chambers and vessels.
The cardiac conduction system is a network of specialized cardiac muscle cells that initiate and transmit the electrical impulses responsible for the coordinated contractions of each cardiac cycle. These special cells are able to generate an action potential on their own (self-excitation) and pass it on to other nearby cells (conduction), including cardiomyocytes.
The presentation that will unable to create a clear cut concept regarding the Vessels the vascular system of the human body. It will let you know about the arteries, veins, capillaries how the exchange of nutrients and other substance takes place..and many more things related to the vessels of the body.
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.
The conduction system of the heart generates and conducts electrical impulses to coordinate the rhythmic contraction of the heart muscles. It consists of the sinoatrial node, internodal pathways, atrioventricular node, bundle of His, and Purkinje fibers. The sinoatrial node acts as the natural pacemaker by initiating electrical impulses. These impulses then travel through the internodal pathways to the atrioventricular node, where they are delayed to allow the atria to contract before the ventricles. The impulse then travels down the bundle of His which splits into right and left bundle branches to coordinate simultaneous contraction of the ventricles.
Descripition of heart and purkinje fibres Ali Muntazir
The document describes the structure and function of the heart and Purkinje fibers. It discusses the layers of the heart wall, the four chambers, and valves. It explains that Purkinje fibers are specialized cardiac muscle cells that rapidly conduct electrical impulses from the ventricles to contract the myocardium and eject blood from the heart. The document provides details on the histological appearance of Purkinje fibers and their role in ventricular conduction when pacemaker function is compromised.
A presentation on structural and functional properties of heartMahade Hashan
The document discusses the anatomy and function of the heart. It describes that William Harvey discovered the heart in the 17th century. The heart is located in the chest cavity and pumps blood through two circuits - the pulmonary and systemic circulations. The heart has four chambers and valves that ensure one-way blood flow. Common heart conditions include coronary heart disease, cardiomyopathy, and arrhythmias. Lifestyle changes, medications, procedures, and surgery are used to treat various heart diseases.
Muscular System: The Cardiac Muscle (Heart)hm alumia
Cardiac muscle is only found in the heart. It contracts involuntarily and has abundant mitochondria to power its contractions. Cardiac muscle cells are connected through intercalated discs that allow electrical signals to spread through the heart.
The heart has four chambers - two upper atria that receive blood and two lower ventricles that pump blood out. The right side receives deoxygenated blood and pumps it to the lungs, while the left side receives oxygenated blood and pumps it into the body. Valves ensure blood flows only in one direction through the heart's chambers and vessels.
The cardiac conduction system is a network of specialized cardiac muscle cells that initiate and transmit the electrical impulses responsible for the coordinated contractions of each cardiac cycle. These special cells are able to generate an action potential on their own (self-excitation) and pass it on to other nearby cells (conduction), including cardiomyocytes.
The presentation that will unable to create a clear cut concept regarding the Vessels the vascular system of the human body. It will let you know about the arteries, veins, capillaries how the exchange of nutrients and other substance takes place..and many more things related to the vessels of the body.
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.
The conduction system of the heart generates and conducts electrical impulses to coordinate the rhythmic contraction of the heart muscles. It consists of the sinoatrial node, internodal pathways, atrioventricular node, bundle of His, and Purkinje fibers. The sinoatrial node acts as the natural pacemaker by initiating electrical impulses. These impulses then travel through the internodal pathways to the atrioventricular node, where they are delayed to allow the atria to contract before the ventricles. The impulse then travels down the bundle of His which splits into right and left bundle branches to coordinate simultaneous contraction of the ventricles.
Descripition of heart and purkinje fibres Ali Muntazir
The document describes the structure and function of the heart and Purkinje fibers. It discusses the layers of the heart wall, the four chambers, and valves. It explains that Purkinje fibers are specialized cardiac muscle cells that rapidly conduct electrical impulses from the ventricles to contract the myocardium and eject blood from the heart. The document provides details on the histological appearance of Purkinje fibers and their role in ventricular conduction when pacemaker function is compromised.
A presentation on structural and functional properties of heartMahade Hashan
The document discusses the anatomy and function of the heart. It describes that William Harvey discovered the heart in the 17th century. The heart is located in the chest cavity and pumps blood through two circuits - the pulmonary and systemic circulations. The heart has four chambers and valves that ensure one-way blood flow. Common heart conditions include coronary heart disease, cardiomyopathy, and arrhythmias. Lifestyle changes, medications, procedures, and surgery are used to treat various heart diseases.
Origin and spread of cardiac impulse, pacemaker, conducting system of heart, ...Rajesh Goit
The document discusses the cardiac impulse and conduction system of the heart. It notes that the heartbeat originates from the sinus node, which acts as the natural pacemaker at a rate of 70-80 beats per minute. The impulse then spreads through the atrioventricular node and Purkinje fibers to contract the atria and ventricles in sequence. The conduction rates vary in different cardiac tissues. The sinus node controls the heartbeat under normal conditions, but abnormal pacemakers can develop elsewhere in rare cases. The conduction system ensures coordinated contraction of the heart chambers to effectively pump blood.
Sa nodal action potential, conducting system of heart and spread of cardiac i...Maryam Fida
SA NODE, AV NODE and Purkinje System are specialized cells of the heart having unstable phase IV.
SA Node has no role of Voltage gated sodium channels(although they are present in SA Node) and
so the depolarization in it occurs through voltage gated slow calcium channels
The membrane of SA Node is Inherently leaky to Sodium and Calcium Ions.
It is the Pre Potential Slope or spontaneous slow depolarization which accounts for the Pace maker activity of SA node i.e. Automaticity
It is caused by the inherent leakiness of SA Nodal membrane to Sodium and Calcium leading to influx of Na+ , causing a slow rise in the RMP in the positive direction.
Thus, the “resting” potential gradually rises between each two heartbeats.
When the potential reaches a threshold voltage of about -40 millivolts, the Sodium-Calcium channels become “activated,” thus causing the action potential.
It is the upstroke of action potential
When the membrane potential reaches the thresh hold level i.e. -40 mV, voltage gated slow calcium channels open up leading to influx of calcium causing depolarization
Voltage gated sodium channels has no role in SA nodal depolarization because at the level of -55 mV, the fast sodium channels mainly have already become “inactivated,” which means that they have become blocked.
The cause of this is that any time the membrane potential remains less negative than about -55 mV for more than a few milliseconds, the inactivation gates on the inside of the cell membrane that close the fast sodium channels become closed and remain so. Therefore, only the slow sodium-calcium channels can open (i.e., can become “activated”) and thereby cause the action potential.
The document summarizes the anatomy and electrophysiology of the human atrioventricular (AV) node. It describes the AV node's location near the triangle of Koch. Immunohistochemistry reveals the AV node is divided into the lower nodal bundle and compact node based on differences in connexin 43 expression. The dual pathway electrophysiology of the AV node involves faster conduction through the connexin 43-negative compact node and slower conduction through the connexin 43-positive lower nodal bundle and extensions. Understanding the molecular compartmentalization of the AV node provides insight into its roles in cardiac conduction and as a potential arrhythmia substrate.
The cardiac conduction system generates and coordinates the contraction of the heart muscle. It is made up of specialized cardiac muscle cells located in the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers. The sinoatrial node initiates each heartbeat by spontaneously generating an electrical impulse. This impulse then travels through the internodal pathways and atria to the atrioventricular node, which slows conduction before passing the impulse to the ventricles via the bundle of His and Purkinje fibers, causing synchronized ventricular contraction and pumping of blood. Defects or damage to the conduction system can lead to cardiac arrhythmias.
The document provides an overview of the human circulatory system, including:
- The heart pumps blood through vessels in a double circulatory system, with the pulmonary and systemic circuits.
- The heart has four chambers, with the right atrium and ventricle pumping to the lungs and the left pumping to the body. It is located in the mediastinum.
- Blood flows through one-way valves between the atria and ventricles, and into the pulmonary trunk and aorta.
- The cardiac conduction system coordinates heart chamber contractions for efficient blood flow.
The document discusses the cardiovascular system and the heart. It describes the heart as a muscular pump located in the chest cavity that circulates blood through two circuits - the pulmonary and systemic circuits. The heart has four chambers, valves to ensure one-way blood flow, and a conduction system to coordinate contractions. It discusses the cardiac cycle, heart sounds, cardiac output, and factors that influence pumping like preload and afterload. An electrocardiogram is described as a tool to monitor the heart's electrical activity.
Cardiac innervation seminar by Dr Manish Ruhela, SMS Medical College,jaipurmanishdmcardio
The document discusses the innervation of the heart. It notes that the heart receives nerve supply from the cardiac plexus, formed by sympathetic and parasympathetic fibers. The sympathetic fibers originate from the spinal cord and travel through the sympathetic trunk. They have long postganglionic fibers. The parasympathetic fibers originate from the brainstem and travel through the vagus nerve. They have short postganglionic fibers and more localized effects. Baroreceptors in the carotid sinus and aortic arch detect blood pressure changes and trigger the baroreceptor reflex to maintain blood pressure homeostasis.
The cardiac skeleton is composed of dense connective tissue that forms a fibrous framework. It consists of four rings surrounding the heart valves, two fibrous trigones, membranous parts of the septa, and a ligament in the conus arteriosus. The skeleton provides attachment points for heart valves and muscle fibers, separates the atria and ventricles, and electrically isolates the atria from the ventricles except where the AV bundle passes through.
This document summarizes the structure and function of the heart and its specialized tissues. It discusses how the heart is a muscular pump composed of cardiac muscle tissue. It describes how cardiac muscle forms syncytium connected by intercalated discs that allow electrical signals to spread between cells. It explains that the heart is myogenic, with pacemaker cells in the sinoatrial node that spontaneously depolarize, initiating an electrical impulse that spreads through pathways to contract the atria and ventricles in a coordinated manner. It outlines the roles of the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers in conducting the electrical signal throughout the heart.
The document provides an overview of the cardiovascular system including its main components and functions. It describes the heart anatomy, blood circulation, types of blood vessels, cardiac cycle, electrophysiology, role of calcium in muscle contraction, hemodynamics, and nervous system regulation. The cardiovascular system functions to pump blood throughout the body to deliver oxygen and nutrients and remove waste through a dual circulatory pathway consisting of the pulmonary and systemic circuits.
The conduction system of the heart is initiated by the sinoatrial node, which acts as the dominant pacemaker. It is located in the junction of the right atrium and superior vena cava and is innervated by the parasympathetic and sympathetic nervous systems. Conduction then proceeds through the atrioventricular node, which slows conduction to allow for ventricular filling, and the bundle of His divides into left and right bundle branches to stimulate the ventricles.
The fibrous skeleton of the heart:
1. Lies between the atria and ventricles.
2. Is composed of dense connective tissue that forms fibrous rings around the four heart valves.
3. Acts as an electrical insulator to prevent direct spread of electrical impulses from the atria to the ventricles, ensuring impulses pass through the bundle of His for coordinated ventricular contraction.
The cardiac conduction system sends signals through specialized cardiac muscle cells to coordinate the rhythmic contraction of the heart. It includes the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers. The sinoatrial node acts as the pacemaker by spontaneously generating electrical impulses that spread through the internodal pathways and cause the atria to contract. The impulse then travels to and through the atrioventricular node and bundle of His before reaching the Purkinje fibers, which trigger fast, coordinated ventricular contraction.
The cardiac electrical system controls the heart rate through specialized conduction cells. The sinoatrial node initiates electrical impulses that spread through the atria and cause contraction. Impulses then travel to the atrioventricular node where they are delayed before entering the bundle of His and spreading to the left and right bundle branches and Purkinje fibers, causing simultaneous ventricular contraction and pumping of blood out of the heart. This coordinated conduction system allows for efficient blood flow throughout the cardiac cycle.
The conduction system of the heart consists of specialized cardiac muscle fibers that generate and conduct electrical impulses through the heart to coordinate the cardiac cycle. The key components are the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers. The sinoatrial node initiates the heartbeat and stimulates the atria to contract. The impulse then travels to the atrioventricular node and through the bundle of His to stimulate simultaneous contraction of the ventricles. The autonomic nervous system also regulates heart rate in response to physiological demands on the body.
The heart's electrical system, also called the cardiac conduction system, includes three main parts: the sinoatrial (SA) node, the atrioventricular (AV) node, and the His-Purkinje system. The SA node generates electrical signals that travel through the heart and cause the chambers to contract and pump blood through the body in a coordinated, rhythmic manner called sinus rhythm. Electrical signals pass from the atria to the ventricles through the AV node, which causes a delay allowing the atria to contract and empty before the ventricles. The signals then travel through the His-Purkinje system to cause synchronized ventricular contraction and pumping of blood out of the heart.
The document describes the structure and function of the human heart. It discusses the heart's location in the thorax, its layers, chambers, valves, blood supply and nerve innervation. It explains the cardiac cycle in detail, describing the different phases of ventricular systole and diastole. It also discusses the generation of the four heart sounds and their timing in the cardiac cycle.
Cardiac muscle tissue forms the thick myocardium of the heart wall. It contains cardiac muscle cells that are joined together by intercalated discs to form branching networks called cardiac fibers. The contractions of cardiac muscle cells are stimulated by electrical signals that cause calcium ions to enter the cells, triggering contraction via the sliding filament mechanism. This allows for the synchronized contraction of the entire heart to pump blood throughout the circulatory system.
The cardiac conduction system is made up of four main structures that stimulate contraction of the heart muscle in a coordinated way. The sinoatrial node acts as the pacemaker and initiates electrical impulses throughout the heart. The atrioventricular node receives impulses from the atria and slows conduction to allow for proper atrial contraction before ventricular contraction. Impulses then travel through the atrioventricular bundle and Purkinje fibers to coordinate simultaneous contraction of the ventricles. An electrocardiogram is used to measure the electrical activity of the heart and detect any abnormalities.
The cardiovascular system consists of the heart and blood vessels. The heart pumps blood through a network of arteries, capillaries and veins. The heart has four chambers and is composed of three layers. It is located in the chest cavity slightly left of center. The heart's natural pacemaker, the sinoatrial node, initiates electrical impulses that cause coordinated contractions. Blood pressure, cardiac output and peripheral resistance determine blood flow. Diseases can disrupt blood flow and oxygen delivery, like atherosclerosis, heart failure and ischemic heart disease including angina and myocardial infarction.
The circulatory system consists of the heart, blood vessels, and blood. The heart pumps blood through two circuits - pulmonary circulation to the lungs and systemic circulation to the entire body. It has four chambers and four valves that ensure one-way blood flow. The cardiac cycle involves repeated heart contraction and relaxation to pump blood. Key components like arteries, veins, and capillaries form blood vessels that deliver oxygen and nutrients throughout the body.
Origin and spread of cardiac impulse, pacemaker, conducting system of heart, ...Rajesh Goit
The document discusses the cardiac impulse and conduction system of the heart. It notes that the heartbeat originates from the sinus node, which acts as the natural pacemaker at a rate of 70-80 beats per minute. The impulse then spreads through the atrioventricular node and Purkinje fibers to contract the atria and ventricles in sequence. The conduction rates vary in different cardiac tissues. The sinus node controls the heartbeat under normal conditions, but abnormal pacemakers can develop elsewhere in rare cases. The conduction system ensures coordinated contraction of the heart chambers to effectively pump blood.
Sa nodal action potential, conducting system of heart and spread of cardiac i...Maryam Fida
SA NODE, AV NODE and Purkinje System are specialized cells of the heart having unstable phase IV.
SA Node has no role of Voltage gated sodium channels(although they are present in SA Node) and
so the depolarization in it occurs through voltage gated slow calcium channels
The membrane of SA Node is Inherently leaky to Sodium and Calcium Ions.
It is the Pre Potential Slope or spontaneous slow depolarization which accounts for the Pace maker activity of SA node i.e. Automaticity
It is caused by the inherent leakiness of SA Nodal membrane to Sodium and Calcium leading to influx of Na+ , causing a slow rise in the RMP in the positive direction.
Thus, the “resting” potential gradually rises between each two heartbeats.
When the potential reaches a threshold voltage of about -40 millivolts, the Sodium-Calcium channels become “activated,” thus causing the action potential.
It is the upstroke of action potential
When the membrane potential reaches the thresh hold level i.e. -40 mV, voltage gated slow calcium channels open up leading to influx of calcium causing depolarization
Voltage gated sodium channels has no role in SA nodal depolarization because at the level of -55 mV, the fast sodium channels mainly have already become “inactivated,” which means that they have become blocked.
The cause of this is that any time the membrane potential remains less negative than about -55 mV for more than a few milliseconds, the inactivation gates on the inside of the cell membrane that close the fast sodium channels become closed and remain so. Therefore, only the slow sodium-calcium channels can open (i.e., can become “activated”) and thereby cause the action potential.
The document summarizes the anatomy and electrophysiology of the human atrioventricular (AV) node. It describes the AV node's location near the triangle of Koch. Immunohistochemistry reveals the AV node is divided into the lower nodal bundle and compact node based on differences in connexin 43 expression. The dual pathway electrophysiology of the AV node involves faster conduction through the connexin 43-negative compact node and slower conduction through the connexin 43-positive lower nodal bundle and extensions. Understanding the molecular compartmentalization of the AV node provides insight into its roles in cardiac conduction and as a potential arrhythmia substrate.
The cardiac conduction system generates and coordinates the contraction of the heart muscle. It is made up of specialized cardiac muscle cells located in the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers. The sinoatrial node initiates each heartbeat by spontaneously generating an electrical impulse. This impulse then travels through the internodal pathways and atria to the atrioventricular node, which slows conduction before passing the impulse to the ventricles via the bundle of His and Purkinje fibers, causing synchronized ventricular contraction and pumping of blood. Defects or damage to the conduction system can lead to cardiac arrhythmias.
The document provides an overview of the human circulatory system, including:
- The heart pumps blood through vessels in a double circulatory system, with the pulmonary and systemic circuits.
- The heart has four chambers, with the right atrium and ventricle pumping to the lungs and the left pumping to the body. It is located in the mediastinum.
- Blood flows through one-way valves between the atria and ventricles, and into the pulmonary trunk and aorta.
- The cardiac conduction system coordinates heart chamber contractions for efficient blood flow.
The document discusses the cardiovascular system and the heart. It describes the heart as a muscular pump located in the chest cavity that circulates blood through two circuits - the pulmonary and systemic circuits. The heart has four chambers, valves to ensure one-way blood flow, and a conduction system to coordinate contractions. It discusses the cardiac cycle, heart sounds, cardiac output, and factors that influence pumping like preload and afterload. An electrocardiogram is described as a tool to monitor the heart's electrical activity.
Cardiac innervation seminar by Dr Manish Ruhela, SMS Medical College,jaipurmanishdmcardio
The document discusses the innervation of the heart. It notes that the heart receives nerve supply from the cardiac plexus, formed by sympathetic and parasympathetic fibers. The sympathetic fibers originate from the spinal cord and travel through the sympathetic trunk. They have long postganglionic fibers. The parasympathetic fibers originate from the brainstem and travel through the vagus nerve. They have short postganglionic fibers and more localized effects. Baroreceptors in the carotid sinus and aortic arch detect blood pressure changes and trigger the baroreceptor reflex to maintain blood pressure homeostasis.
The cardiac skeleton is composed of dense connective tissue that forms a fibrous framework. It consists of four rings surrounding the heart valves, two fibrous trigones, membranous parts of the septa, and a ligament in the conus arteriosus. The skeleton provides attachment points for heart valves and muscle fibers, separates the atria and ventricles, and electrically isolates the atria from the ventricles except where the AV bundle passes through.
This document summarizes the structure and function of the heart and its specialized tissues. It discusses how the heart is a muscular pump composed of cardiac muscle tissue. It describes how cardiac muscle forms syncytium connected by intercalated discs that allow electrical signals to spread between cells. It explains that the heart is myogenic, with pacemaker cells in the sinoatrial node that spontaneously depolarize, initiating an electrical impulse that spreads through pathways to contract the atria and ventricles in a coordinated manner. It outlines the roles of the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers in conducting the electrical signal throughout the heart.
The document provides an overview of the cardiovascular system including its main components and functions. It describes the heart anatomy, blood circulation, types of blood vessels, cardiac cycle, electrophysiology, role of calcium in muscle contraction, hemodynamics, and nervous system regulation. The cardiovascular system functions to pump blood throughout the body to deliver oxygen and nutrients and remove waste through a dual circulatory pathway consisting of the pulmonary and systemic circuits.
The conduction system of the heart is initiated by the sinoatrial node, which acts as the dominant pacemaker. It is located in the junction of the right atrium and superior vena cava and is innervated by the parasympathetic and sympathetic nervous systems. Conduction then proceeds through the atrioventricular node, which slows conduction to allow for ventricular filling, and the bundle of His divides into left and right bundle branches to stimulate the ventricles.
The fibrous skeleton of the heart:
1. Lies between the atria and ventricles.
2. Is composed of dense connective tissue that forms fibrous rings around the four heart valves.
3. Acts as an electrical insulator to prevent direct spread of electrical impulses from the atria to the ventricles, ensuring impulses pass through the bundle of His for coordinated ventricular contraction.
The cardiac conduction system sends signals through specialized cardiac muscle cells to coordinate the rhythmic contraction of the heart. It includes the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers. The sinoatrial node acts as the pacemaker by spontaneously generating electrical impulses that spread through the internodal pathways and cause the atria to contract. The impulse then travels to and through the atrioventricular node and bundle of His before reaching the Purkinje fibers, which trigger fast, coordinated ventricular contraction.
The cardiac electrical system controls the heart rate through specialized conduction cells. The sinoatrial node initiates electrical impulses that spread through the atria and cause contraction. Impulses then travel to the atrioventricular node where they are delayed before entering the bundle of His and spreading to the left and right bundle branches and Purkinje fibers, causing simultaneous ventricular contraction and pumping of blood out of the heart. This coordinated conduction system allows for efficient blood flow throughout the cardiac cycle.
The conduction system of the heart consists of specialized cardiac muscle fibers that generate and conduct electrical impulses through the heart to coordinate the cardiac cycle. The key components are the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers. The sinoatrial node initiates the heartbeat and stimulates the atria to contract. The impulse then travels to the atrioventricular node and through the bundle of His to stimulate simultaneous contraction of the ventricles. The autonomic nervous system also regulates heart rate in response to physiological demands on the body.
The heart's electrical system, also called the cardiac conduction system, includes three main parts: the sinoatrial (SA) node, the atrioventricular (AV) node, and the His-Purkinje system. The SA node generates electrical signals that travel through the heart and cause the chambers to contract and pump blood through the body in a coordinated, rhythmic manner called sinus rhythm. Electrical signals pass from the atria to the ventricles through the AV node, which causes a delay allowing the atria to contract and empty before the ventricles. The signals then travel through the His-Purkinje system to cause synchronized ventricular contraction and pumping of blood out of the heart.
The document describes the structure and function of the human heart. It discusses the heart's location in the thorax, its layers, chambers, valves, blood supply and nerve innervation. It explains the cardiac cycle in detail, describing the different phases of ventricular systole and diastole. It also discusses the generation of the four heart sounds and their timing in the cardiac cycle.
Cardiac muscle tissue forms the thick myocardium of the heart wall. It contains cardiac muscle cells that are joined together by intercalated discs to form branching networks called cardiac fibers. The contractions of cardiac muscle cells are stimulated by electrical signals that cause calcium ions to enter the cells, triggering contraction via the sliding filament mechanism. This allows for the synchronized contraction of the entire heart to pump blood throughout the circulatory system.
The cardiac conduction system is made up of four main structures that stimulate contraction of the heart muscle in a coordinated way. The sinoatrial node acts as the pacemaker and initiates electrical impulses throughout the heart. The atrioventricular node receives impulses from the atria and slows conduction to allow for proper atrial contraction before ventricular contraction. Impulses then travel through the atrioventricular bundle and Purkinje fibers to coordinate simultaneous contraction of the ventricles. An electrocardiogram is used to measure the electrical activity of the heart and detect any abnormalities.
The cardiovascular system consists of the heart and blood vessels. The heart pumps blood through a network of arteries, capillaries and veins. The heart has four chambers and is composed of three layers. It is located in the chest cavity slightly left of center. The heart's natural pacemaker, the sinoatrial node, initiates electrical impulses that cause coordinated contractions. Blood pressure, cardiac output and peripheral resistance determine blood flow. Diseases can disrupt blood flow and oxygen delivery, like atherosclerosis, heart failure and ischemic heart disease including angina and myocardial infarction.
The circulatory system consists of the heart, blood vessels, and blood. The heart pumps blood through two circuits - pulmonary circulation to the lungs and systemic circulation to the entire body. It has four chambers and four valves that ensure one-way blood flow. The cardiac cycle involves repeated heart contraction and relaxation to pump blood. Key components like arteries, veins, and capillaries form blood vessels that deliver oxygen and nutrients throughout the body.
The cardiovascular system circulates blood throughout the body via the heart and blood vessels. The heart is a hollow, muscular organ located in the chest that pumps blood through two circuits: systemic circulation and pulmonary circulation. Systemic circulation pumps oxygenated blood from the heart to the body and returns deoxygenated blood to the heart. Pulmonary circulation pumps deoxygenated blood from the heart to the lungs to be oxygenated and returns oxygenated blood to the heart. The cardiovascular system is regulated by short term mechanisms like the autonomic nervous system and long term mechanisms like the renin-angiotensin-aldosterone system to maintain normal blood pressure.
This system has three main components: the heart, the blood vessel and the blood itself. The heart is the system's pump and the blood vessels are like the delivery routes. Blood can be thought of as a fluid which contains the oxygen and nutrients the body needs and carries the wastes which need to be removed.
✓Heart
✓Anatomy of heart
✓Blood circulation
✓Blood Vessels
✓Structure and function of artery, vein and capillaries
✓Elements of conduction system of heart and heart beat
✓Its regulation by nervous system
✓Cardiac output
✓Cardiac cycle
✓Regulation of bood pressure
✓Pulse
✓Electrocardiogram
✓Disorder of heart
A powerpoint designed for the South African Life Sciences syllabus for grade 11. Includes information about blood and it's transportation, the human heart, the lymph system etc. Hope it helps :)
1) Mammals require transport systems like the circulatory system to efficiently deliver oxygen and nutrients to cells throughout the body since diffusion is only effective over short distances. The circulatory system can be open, closed, or a double circulatory system.
2) In a closed circulatory system, blood remains within blood vessels and nutrients/gases are exchanged through vessel walls. A double circulatory system has two circuits - pulmonary and systemic - allowing blood to pass through the heart twice.
3) Diseases can occur if cholesterol builds up in artery walls, restricting blood flow and oxygen delivery. This can cause heart attacks, strokes, aneurysms, and high blood pressure. Proper diet, exercise, and managing
Structure & Function of Heart and its parts. Heart walls, pericardium, heart valves, septa, nodal tissues, coronary circulation, blood vessels of heart, AV bundle, bundle of his, purkinje fibers, myogenic nature of heart, action potential generation.
The circulatory system is divided into the heart and blood vessels. The heart pumps blood into the pulmonary and systemic circulations. The right side pumps blood to the lungs and the left side pumps oxygenated blood to the rest of the body. The heart has four chambers, valves to ensure one-way blood flow, and a conducting system to coordinate contractions. Arteries carry blood away from the heart while veins return blood to the heart.
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 the key anatomical features and locations of the heart and its chambers. It describes that the heart is located in the mediastinum, between the lungs. It has four chambers - two upper atria that receive blood and two lower ventricles that pump blood out. Blood flows through the heart in one direction, from the systemic circulation into the right atrium, then into the right ventricle to be pumped to the lungs, then back into the left atrium from the lungs and finally into the left ventricle to be pumped back out through the aorta to the systemic circulation. The document also briefly describes the layers of the heart wall and important structures like the valves.
The document discusses the structure and function of the circulatory system. It describes the heart as a hollow muscular organ that pumps blood through arteries, capillaries, and veins. The heart has four chambers and a conduction system that generates electrical signals to coordinate contractions. Blood vessels branch throughout the body to deliver oxygen, nutrients and remove waste. Arteries carry blood away from the heart, veins carry blood back to the heart, and capillaries facilitate exchange of materials between blood and tissues.
The heart is a hollow muscular organ located in the thoracic cavity between the lungs. It is composed of three layers: the outer pericardium, middle myocardium layer of muscle, and inner endocardium lining. The heart is further divided into four chambers - right and left atria on top which receive blood and right and left ventricles on bottom which pump blood out. It has a specialized conduction system including the sinoatrial node which initiates impulses and pacemaking, atrioventricular node which conducts impulses to ventricles, and Purkinje fibers which transmit the impulse through the ventricles to contract in a coordinated way. The heart is supplied by coronary arteries and drained
This document provides an overview of the cardiovascular system, including:
- The heart's structure, chambers, valves, and conduction system.
- Blood flow through the heart and the events of the cardiac cycle.
- Types of blood vessels and circulation (pulmonary, systemic, coronary, hepatic portal).
- Functions of the cardiovascular system like oxygen transport and nutrient delivery.
- Key terms like stroke volume and cardiac output.
The cardiovascular system allows blood to circulate oxygen and nutrients throughout the body. It consists of the heart and blood vessels.
The heart has four chambers and uses valves to ensure one-way blood flow. It is surrounded by layers including the pericardium. The heart's natural pacemaker, the sinoatrial node, initiates electrical signals that cause coordinated contractions of the atria and ventricles. Blood is pumped from the heart through arteries to the lungs and body.
Cardiac muscle cells contract in response to changes in electrical potential across their membranes. This allows for coordinated pumping of blood throughout the cardiovascular system.
The document discusses the structure and function of the human heart. It describes how the heart is made up of four chambers - two atria and two ventricles separated by valves. The cardiac cycle involves coordinated contractions of the atria and ventricles along with opening and closing of valves to ensure one-way blood flow. The heart rate is controlled by a natural pacemaker and nerves from the brain that can increase or decrease the rate.
The document summarizes the cardiovascular system, including the circulatory and lymphatic systems. It describes the heart, blood vessels, blood flow through pulmonary and systemic circulation. It also discusses common diseases like atherosclerosis, heart attack, angina, and their diagnosis and treatment. The circulatory system functions to transport blood throughout the body, while the lymphatic system transports lymph and maintains fluid balance.
This document provides an overview of the cardiovascular system and human heart. It begins with definitions and functions of the cardiovascular system. It then describes the internal and external structure of the heart, including the four chambers, valves, blood vessels, and conducting system. Key concepts covered include the cardiac cycle, blood pressure, electrocardiogram, coronary and systemic circulation. Common heart conditions such as coronary artery disease, heart attack, arrhythmias and valve disease are also summarized.
The document describes the anatomy and function of the heart and surrounding structures. It begins by introducing the pericardium, which has two layers that surround and protect the heart. The three layers of the heart wall are then described, with the myocardium being the thick middle layer responsible for pumping blood. The four chambers and valves of the heart are also outlined, explaining how blood flows from the right atrium to ventricle to lungs then left atrium to ventricle and out to the body in two separate circulation loops. Objectives of understanding heart structures and functions are also provided.
The male reproductive system consists of both internal and external organs that work together to produce sperm and facilitate fertilization. The internal organs include the testes, epididymis, vas deferens, seminal vesicles and prostate gland. The external organs are the scrotum and penis. During puberty, the testes begin to produce testosterone which leads to development of secondary sex characteristics and the ability to reproduce.
The endocrine system consists of glands that secrete hormones directly into the bloodstream to regulate bodily functions. The major glands include the pituitary, thyroid, parathyroid, adrenal, pancreas, ovaries, testes, and pineal glands. Hormones act as chemical messengers to influence cellular activity and maintain homeostasis. The pituitary gland regulates other endocrine glands by producing hormones that stimulate or inhibit their secretions. The hypothalamus controls the pituitary gland and regulates hormone production and release through feedback mechanisms.
The document discusses the digestive system. It describes the organs involved in digestion, including the mouth, tongue, teeth, esophagus, stomach, pancreas and intestines. It explains the processes of ingestion, secretion, digestion, absorption and defecation. Key points include that food is broken down mechanically and chemically by enzymes in the digestive tract, and absorbed nutrients pass into the bloodstream while waste is excreted.
The document discusses the anatomy and physiology of the olfactory system and sense of smell. It describes the key parts of the olfactory apparatus including the olfactory epithelium, olfactory receptors, supporting cells, basal cells, and olfactory glands. It explains how odorant molecules bind to receptors and trigger nerve impulses. The document also discusses the gustatory system and sense of taste, including the anatomy and function of taste buds. Finally, it provides an overview of the anatomy of the eye and visual system.
The document discusses the anatomy and functions of the nervous system and brain. It describes the central nervous system as consisting of the brain and spinal cord. The brain is protected by three membranes (meninges) and contains four ventricles that produce cerebrospinal fluid. The cerebrum is the largest part of the brain and is divided into four lobes with different functional areas. Other parts include the brain stem and cerebellum. The document provides detailed information on the structure and roles of the various parts of the nervous system.
Nervous tissue consists of neurons, also called nerve cells. Each neuron has a cell body containing the nucleus, and branched projections called dendrites that receive signals and a long axon that transmits signals. Axons are bundled together to form nerves. Large axons contain a fatty myelin sheath for insulation and faster signal transmission. At the end of an axon are synaptic terminals containing neurotransmitter-filled vesicles that transmit signals chemically to other neurons or effector cells. Neurons have the properties of irritability, responding to stimuli, and conductivity, transmitting signals along their length.
Muscular tissue is composed of muscle fibers that contract in response to electrical signals. There are three types of muscle tissue - skeletal, cardiac, and smooth muscle. Skeletal muscle is striated, voluntary, and attached to bones. It contracts through a sliding filament mechanism where actin and myosin interact powered by ATP hydrolysis. At the neuromuscular junction, a nerve impulse triggers the release of acetylcholine which binds receptors and generates a muscle action potential, causing contraction.
The urinary system regulates blood composition and excretes waste through the kidneys, ureters, bladder and urethra. The kidneys filter blood to form urine and regulate electrolyte and fluid levels. Urine passes from the kidneys through the ureters to the bladder, where it is temporarily stored until urination. During urination, urine exits the body through the urethra under control of sphincter muscles. The urinary system helps maintain homeostasis by regulating water balance and removing toxins and wastes from the bloodstream.
The respiratory system provides the route for oxygen to enter the body and carbon dioxide to exit. It includes the nose, pharynx, larynx, trachea, bronchi, bronchioles and lungs. The nose warms, moistens and filters inhaled air. The pharynx continues this process and is involved in swallowing and speech. The larynx contains the vocal cords and protects the lungs. The trachea divides into bronchi which branch into smaller bronchioles throughout the lungs, ending in alveoli where gas exchange occurs.
The document describes the major blood vessels and circulation pathways in the human body. It discusses the systemic circulation, where oxygenated blood leaves the heart through the aorta and returns to the heart through veins. It also describes the pulmonary circulation between the heart and lungs for gas exchange, as well as the portal circulation between the digestive organs and liver. Key blood vessels discussed include the aorta, vena cava, pulmonary and coronary arteries/veins, and the portal vein.
The document summarizes the key components and functions of the lymphatic system. It describes the lymph, lymphatic vessels, lymph nodes, spleen, and thymus. The lymphatic system is responsible for immunity and drains interstitial fluid via a network of lymph capillaries, vessels, nodes, and ducts. Lymph nodes filter foreign substances and allow immune cell proliferation. The spleen and thymus also play important roles in immune functions.
1. Blood is composed of plasma, red blood cells, white blood cells, and platelets suspended in plasma. Plasma is 91-92% water and contains proteins, electrolytes, nutrients, gases, enzymes, hormones, and waste products.
2. Red blood cells transport oxygen and carbon dioxide, are biconcave discs without nuclei, and develop through erythropoiesis over 7 days from stem cells. White blood cells include granulocytes and agranulocytes and protect against pathogens. Platelets help form blood clots to stop bleeding.
3. Blood has functions of transportation, regulation, and protection. It transports respiratory gases, nutrients, enzymes, and waste. Blood also
The document summarizes the main types of joints in the body - fibrous joints, cartilaginous joints, and synovial joints. It then describes the key characteristics and examples of different classes of synovial joints, including ball-and-socket, hinge, gliding, pivot, condyloid, and saddle joints. Finally, it provides details on specific synovial joints - the shoulder, elbow, wrist, hip, knee, and ankle joints, outlining their structural features, movements, and associated muscles.
Bone is a strong, durable connective tissue composed of water, organic constituents like osteoid and bone cells, and inorganic constituents like calcium phosphate. There are different types of bones including long bones that have a shaft and two extremities like the femur, short irregular bones like those in the wrist, flat bones like the ribs, and sesamoid bones like the patella. Long bones have a diaphysis shaft and two epiphyses extremities separated by epiphyseal cartilage that ossifies when growth is complete. Bone tissue is remodeled throughout life by osteoblasts that build bone and osteoclasts that destroy bone under the periosteum membrane. Microscopically, bone is made up
The document summarizes the axial and appendicular skeleton. The axial skeleton consists of the skull, vertebral column, ribs, and sternum. It describes the features of these bones in detail. The appendicular skeleton consists of the shoulder girdle (clavicle, scapula) and upper limbs as well as the pelvic girdle (innominate bones, sacrum) and lower limbs. It provides an overview of the bones of the upper and lower limbs.
This document discusses the different types of tissues in the body. It begins by defining tissues as groups of cells with similar structures and functions, and classifies them into four main categories: epithelial, connective, muscle and nervous tissue. It then focuses on epithelial tissues, describing simple and stratified epithelia. It also describes the different types of simple epithelia including squamous, cuboidal and columnar epithelium. The document then discusses connective tissues in depth, describing their components, fibers, cells and classifications. It covers loose connective tissues like areolar and adipose tissue, as well as dense connective tissues like fibrous and elastic tissue.
The document discusses the structure and components of cells. It describes that cells range in diameter from 2 to 120 microns and can take on different shapes depending on their function. The main parts of cells are the plasma membrane, cytoplasm, organelles, and nucleus. The plasma membrane forms the boundary of the cell and regulates what enters and exits. The cytoplasm contains cytosol and organelles. Organelles such as the endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, and peroxisomes perform specialized functions. The nucleus houses genetic material and controls cell activities.
This document defines key terms and concepts in anatomy and physiology. It explains that anatomy is the study of body structures and their relationships, while physiology is the study of how the body functions. It then describes the levels of body organization from chemical to organism. The document outlines the major body cavities, including the dorsal cavity containing the cranial and vertebral cavities, and the ventral cavity containing the thoracic and abdominopelvic cavities. It provides details on the regions of the abdomen and pelvis.
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1. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
HEART
• The heart is a cone-shaped, hollow
muscular organ. It is about 10 cm
long and is about the size of the
owner's fist. It weighs about 225 g
in women and about 310 g in men
• The heart lies in the thoracic cavity
in the mediastinum between the
lungs.
• It lies obliquely, a little more to
the left than the right, and presents
a base above, and an apex below.
• The apex is about 9 cm to the left of
the midline at the level of the 5th
intercostal space. The base extends
to the level of the 2nd rib.
2. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Structure
• The heart is composed of three layers of tissue:
pericardium, myocardium and endocardium
• Pericardium: is made up of two sacs. The outer sac
consists of fibrous tissue and the inner of a continuous
double layer of serous membrane. Its inelastic, fibrous
nature prevents overdistension of the heart.
• The outer layer of the serous membrane, the parietal
pericardium. The inner layer, the visceral pericardium, or
epicardium, is adherent to the heart muscle. The serous
membrane consists of flattened epithelial cells. It
secretes serous fluid into the space between the
visceral and parietal layers which allows smooth
movement between them when the heart beats. The
space between the parietal and visceral pericardium is
only a potential space.
5. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Myocardium:
The myocardium is composed of specialised
cardiac muscle found only in the heart .. Each
fibre (cell) has a nucleus and one or more
branches. The ends of the cells and their
branches are in very close contact with the
ends and branches of adjacent cells.
7. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
• Microscopically these 'joints', or intercalated discs,
can be seen as thicker, darker lines than the
ordinary cross-stripes. This arrangement gives
cardiac muscle the appearance of being a sheet
of muscle rather than a very large number of
individual cells. Because of the end-to-end
continuity of the fibres, each one does not need
to have a separate nerve supply. When an
impulse is initiated it spreads from cell to cell
via the branches and intercalated discs over the
whole 'sheet’ of muscle, causing contraction.
8. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
The 'sheet' arrangement of the
myocardium enables the atria and
ventricles to contract in a coordinated and
efficient manner. The myocardium is
thickest at the apex and thins out towards
the base . It is thickest in the left ventricle.
Endocardium:
This forms the lining of the myocardium
and the heart valves. It is a thin, smooth,
glistening membrane which permits
smooth flow of blood inside the heart. It
consists of flattened epithelial cells,
continuous with the endothelium that lines
the blood vessels.
9. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Interior of the heart
• The heart is divided into a right and left side by
the septum, a partition consisting of myocardium
covered by endocardium.
• Each side is divided by an atrioventricular valve into
an upper chamber, the atrium, and a lower chamber,
the ventricle.
• The atrioventricular valves are formed by double
folds of endocardium strengthened by a little
fibrous tissue. The right atrioventricular valve
(tricuspid valve) has three flaps or cusps and the left
atrioventricular valve (mitral valve) has two cusps.
11. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
• During ventricular systole (contraction) the pressure
in the ventricles rises above that in the atria and
the valves snap shut preventing backward flow
of blood. The valves are prevented from opening
upwards into the atria by threads called chordae
tendineae, which extend from the inferior surface of
the cusps to little projections of myocardium
covered with endothelium, called papillary
muscles
• Pulmonary valve is present between right
atrium & pulmonary artery; Arotic valve is
between left ventricle & arota
13. Conducting system of heart
• The heart has inbuilt system of cardiac
muscle contraction. Small groups of
specialized neuromuscular cells are
present in myocardium. These cells
conduct impulses, causing co-ordinated
and synchronized contraction of the heart
muscle.
Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
14. • Sinoatrial Node (SA node):
• This small mass of specialised cells is in the wall
of the right atrium near the opening of the
superior vena cava. This node initiates impulses
and spread through both atrial walls, that causes
contraction of atria.
• Atrioventricular node (AV node):
• This small mass of neuromuscular tissue. It is
situated in the wall of the atrial septum near the
atrioventricular valves. AV node conducts
impulses that arrive via atria. If there is problem
with SA node, then AV node generates
impulses.
Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
15. • Atrioventricular bundle, bundle
branches, and Purkinje fibers:
• This is a mass of specialized fibres that originate
from the AV node. The AV bundle at the upper
end of the ventricular septum, it divides into
right and left bundle branches. Within the
ventricular myocardium the branches break up
into fine fibres, called the Purkinje fibres.
• The AV bundle, bundle branches and Purkinje
fibers convey electrical impulses from AV node
to the apex of ventricles. It causes forceful
ventricular contraction.
Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
16. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
The cardiac cycle
• The function of the heart is to maintain a
constant circulation of blood throughout
the body. The heart acts as a pump and its
action consists of a series of events known
as the cardiac cycle
• During each heartbeat, or cardiac cycle,
the heart contracts and then relaxes. The
period of contraction is called systole and
that of relaxation, diastole.
17. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Stages of the cardiac cycle
• The normal number of cardiac cycles per
minute ranges from 60 to 80. Taking 75 as
an example each cycle lasts about 0.8 of a
second and consists of:
• atrial systole — contraction of the
atria(0.1s)
• ventricular systole — contraction of the
ventricles(0.3s)
• complete cardiac diastole — relaxation of
the atria and ventricles(0.4s)
18. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
•The superior vena cava and the inferior vena
cava transport deoxygenated blood into the
right atrium at the same time as the four
pulmonary veins convey oxygenated blood into
the left atrium.
•The atrioventricular valves are open and
blood flows through to the ventricles. The SA
node triggers a wave of contraction that
spreads over the myocardium of both atria,
emptying the atria and completing ventricular
filling (atrial systole 0.1 s).
19. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
•When the wave of contraction reaches
the AV node it is stimulated to emit an
impulse which quickly spreads to the
ventricular muscle via the AV bundle,
the bundle branches and Purkinje fibres.
This results in a wave of contraction
which sweeps upwards from the apex
of the heart and across the walls of both
ventricles pumping the blood into the
pulmonary artery and the aorta
(ventricular systole 0.3 s).
20. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
•The high pressure generated during
ventricular contraction is greater than that
in the aorta and forces the atrioventricular
valves to close, preventing backflow of
blood into the atria.
• After contraction of the ventricles there
is complete cardiac diastole, a period of 0.4
seconds, when atria and ventricles are
relaxed. During this time the myocardium
recovers until it is able to contract again, and
the atria refill in preparation for the next cycle.
22. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Heart sounds (Auscultation):
•Two sounds, separated by a short pause, can
be clearly distinguished. They are described in
words as 'lub dup'.
•The first sound, 'lub', is fairly loud and is due to
the closure of the atrioventricular valves. This
corresponds with ventricular systole.
•The second sound, 'dup', is softer and is due to
the closure of the aortic and pulmonary
valves. This corresponds with atrial systole.
23. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Electrical changes in the heart:
• The electrical activity
within the heart can be
detected by attaching
electrodes to the surface of
the body. The pattern of
electrical activity may be
displayed on an
oscilloscope screen or
traced on paper. The
apparatus used is an
electrocardiograph and the
tracing is an
electrocardiogram (ECG).
• The normal ECG tracing
shows five waves which,
by convention, have been
named P, Q, R, S and T.
24. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
•The P wave arises when the impulse
from the SA node sweeps over the
atria.
•The QRS complex represents the very
rapid spread of the impulse from the
AV node through the AV bundle and
the Purkinje fibres and the electrical
activity of the ventricular muscle.
•The T wave represents the relaxation
of the ventricular muscle.
25. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
•The ECG described originates from the
SA node and is known as sinus rhythm.
The rate of sinus rhythm is 60 to 100 beats
per minute.
•By examining the pattern of waves and
the time interval between cycles and
parts of cycles, information about the
state of the myocardium and the cardiac
conduction system is obtained.
26. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Cardiac output
Cardiac output = Stroke volume x Heart rate
• stroke volume: The amount of blood expelled
by each contraction of the ventricles.
• Cardiac output is expressed in liters per
minute (l/min)
• In a healthy adult at rest, the stroke volume
is approximately 70 ml and if the heart rate is
72 per minute, the cardiac output is 5
l/minute.
• This can be greatly increased to meet the
demands of exercise by 5 – 7 times.
28. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Factors affecting Stroke volume
• Ventricular end-diastolic volume:
The volume of blood in the ventricles
immediately before they contract, i.e. the
(VEDV), sometimes called preload. This
depends on the amount of blood returning to
the heart through the superior and inferior
venae cavae (the venous return). Increased
VEDV leads to stronger myocardial
contraction, and more blood is expelled.
29. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
•Venous return:
• the major determinant of cardiac output
• The force of contraction of the left ventricle
ejecting blood into the aorta is not sufficient
to return the blood through the veins and
back to the heart. Other factors are involved.
The position of the body: Gravity assists the
venous return from the head and neck when
standing or sitting and offers less resistance
to venous return from the lower parts of the
body when an individual is lying flat.
30. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Muscular contraction: Back flow of blood in
veins of the limbs, especially when standing,
is prevented by valves. The contraction of
skeletal muscles surrounding the deep veins
puts pressure on them, pushing blood
towards the heart. In the lower limbs, this is
called the skeletal muscle pump. When the
pressure in deep veins is lowered during muscle
relaxation, blood flows into them from
superficial veins through communicating veins.
31. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
The respiratory pump: During inspiration the
expansion of the chest creates a negative pressure
within the thorax, assisting flow of blood towards
the heart. In addition, when the diaphragm descends
during inspiration, the increased intra-abdominal
pressure pushes blood towards the heart.
•Strength of myocardial contraction:
factors that increase myocardial contraction include:
• increased stimulation of the sympathetic nerves
innervating the heart
• hormones, e.g. adrenaline, noradrenaline,
thyroxine
•Blood volume: This is normally kept constant by
the kidneys and if deficient the stroke volume,
cardiac output and venous return decrease.
32. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Factors affecting heart rate
• Autonomic nervous system: The rate at which
the heart beats is a balance of sympathetic and
parasympathetic activity and this is the most
important factor in determining heart rate.
• Circulating chemicals: The hormones adrenaline
and noradrenaline, secreted by the adrenal
medulla, have the same effect as sympathetic
stimulation, i.e. they increase the heart rate. Other
hormones including thyroxine increase heart rate
by their metabolic effect. Some drugs, dissolved
gases and electrolytes in the blood may either
increase or decrease the heart rate.
33. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Position: When the person is upright, the heart rate is
usually faster than when lying down.
Exercise: Active muscles need more blood than
resting muscles and this is achieved by an increased
heart rate and selective vasodilatation.
Emotional states: During excitement, fear or anxiety
the heart rate is increased. Other effects mediated by
the sympathetic nervous system may be present.
Gender: The heart rate is faster in women than men.
Age: In babies and small children the heart rate is
more rapid than in older children and adults
Temperature: The heart rate rises and falls with body
temperature
34. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Baroreceptor reflex:
• Baroreceptors are nerve endings sensitive to
pressure changes (stretch) within the vessel,
situated in the arch of the aorta and in the
carotid sinuses.
• A rise in blood pressure in these arteries
stimulates the baroreceptors, increasing their
input to the CVC. The CVC responds by
increasing parasympathetic nerve activity to
the heart; this slows the heart down. At the
same time, sympathetic stimulation to the
blood vessels is inhibited, causing
vasodilatation. The net result is a fall in
systemic blood pressure.
35. Prof.Sunil Chavan
Prin.K.M.Kundnani Pharmacy
Polytechnic
Conversely, if pressure within the aortic arch
and carotid sinuses falls, the rate of
baroreceptor discharge also falls. The CVC
responds by increasing sympathetic drive to
the heart to speed it up. Sympathetic activity
in blood vessels is also increased, leading to
vasoconstriction. Both these measures
counteract the falling blood pressure.