Transcript Cardiovascular System - North Seattle College
Cardiovascular System
Heart
Introduction of Cardiovascular Sytem 1.
2.
3.
Consists of; Blood Heart Blood Vessels
Location of Heart Heart lies between the lungs in the mediastinum.
Location of Heart Two-thirds of its mass is to the left of the midline
Location of Heart Precordium – The area of the chest anterior to the heart
Location of Heart Lies between the vertebral column and the sternum
Structure and Function of Heart 1.
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Pericardium Layers of the Heart Wall
Pericardium The heart is enclosed and held in place by the pericardium
Pericardium 1.
2.
Consists of; Fibrous pericardium (outer) Serous pericardium (inner)
Pericardium Fibrous pericardium – anchors the heart in the mediastinum
Pericardium 1.
2.
Serous pericardium composed of; Parietal layer Visceral layer
Pericardium Pericardial cavity – a space between the parietal and visceral layers filled with pericardial fluid
Layer of the Heart 1.
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Epicardium Myocardium Endocardium
Epicardium Consists of the visceral layer of pericardium and connective tissue (adipose)
Myocardium Composed of cardiac muscle
Myocardium The cells are branched, involuntary, and have one nucleus
Myocardium The cells are connected by intercalated discs, which have gap junctions that allow ions to flow in between cells during depolarization
Endocardium Lines the chambers and covers the connective tissue in the heart valves
Endocardium It consists of endothelium
Chambers of the Heart 1.
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Right Atrium Right Ventricle Left Atrium Left Ventricle
Chambers of the Heart On the surface of the heart are
auricles and sulci
Chambers of the Heart Auricles – small pouches on the anterior surface of each atrium
Chambers of the Heart Sulci – Are grooves that contain coronary arteries and fat and separate the chambers
Right Atrium 1.
2.
3.
The right atrium receives systemic venous blood from; Superior Vena Cava Inferior Vena Cava Coronary sinus
Right Atrium The atrium receives blood low in O2 and high in CO2
Right Atrium Interatrial septum - separates the right and left atria
Right Atrium Fossa ovalis – an oval depression in the interatrial septum; it is a remnant of the foramen ovale
Right Atrium Tricuspid Valve – Blood passes from the right atrium into the right ventricle through here
Right Ventricle Forms most of the anterior surface of the heart
Right Ventricle Pulmonary semilunar valve - Blood passes from the right ventricle to the pulmonary trunk via this valve
Left Atrium Receives pulmonary venous blood from the pulmonary veins which is rich in oxygen and low in CO2
Left Atrium Mitral Valve – Blood passes from the left atrium to the left ventricle via this valve
Left Ventricle Thickest and strongest chamber
Left Ventricle Forms the apex of the heart
Left Ventricle Blood passes from the left ventricle through the aortic valve into the aorta
Left Ventricle During fetal life the ductus arteriosus shunts blood from the pulmonary trunk into the aorta
Left Ventricle At birth the ductus arteriosus closes and becomes the ligamentum arteriosum
Left Ventricle The left ventricle is separted from the right ventricle by the interventricular septum
Myocardial Thickness and Function The atria walls are thin because they only pump blood to the nearby ventricles
Myocardial Thickness and Function The ventricle wall are thicker because they pump blood greater distances
Myocardial Thickness and Function The right ventricle walls are thinner than the left because they pump blood to the nearby lungs
Myocardial Thickness and Function The left ventricle walls are thicker because they pump blood through the body
Function of Heart Valves Valves open and close in response to pressure changes as the heart contracts and relaxes
Myocardial Thickness and Function 1.
2.
Two types of valves; Atrioventricular Valves Semilunar
Atrioventricular Valves 1.
2.
Tricuspid (right side) Mitral or bicuspid (left side)
Atrioventricular Valves AV valves prevent blood flow from the ventricles back into the atria
Atrioventricular Valves Back flow is prevented by the contraction of papillary muscles and tightening the chordae tendinae
Semilunar Valves SL valves allow ejection of blood from the heart into the pulmonary arteries and aorta
Semilunar Valves Prevent back flow into the ventricles
Circulation of Blood 1.
2.
3.
Systemic Pulmonary Coronary
Systemic Circulation The left side of the heart pumps oxygenated blood from the left ventricle into the ascending aorta.
Systemic Circulation The coronary arteries arise off of the ascending aorta
Pulmonary Circulation The right side of the heart receives deoxygenated blood from the body.
Pulmonary Circulation The right side of the heart pumps blood from the right ventricle and sends it into the lungs via the pulmonary artery
Circulation of Blood Right atrium receives blood from the superior and inferior vena cava
Circulation of Blood The Left atrium receives blood from the pulmonary veins
Coronary Circulation It delivers oxygenated blood and nutrients to and removes CO2 and wastes from the myocardium
Coronary Circulation The
left and right coronary arteries
branch from the ascending aorta and carry oxygenated blood
Coronary Circulation 1.
2.
Left coronary artery branches into the; Left anterior descending artery Circumflex artery
Coronary Circulation 1.
2.
Right coronary artery branches into; Marginal artery Posterior descending artery
Coronary Circulation Deoxygenated blood returns to the right atrium through the coronary sinus
Histology of Cardiac Muscle In comparison to skeletal muscle fibers, cardiac muscle fibers are involuntary, shorter in length, larger in diameter, and squarish rather than circular in transverse section.
Histology of Cardiac Muscle They also exhibit branching
Histology of Cardiac Muscle Have same arrangement of actin and myosin, and the same bands, zones, and Z discs as skeletal muscles
Cardiac Conduction System There is an atrial and ventricular network
Cardiac Conduction System Fibers within the networks are connected by intercalated discs
Cardiac Conduction System The intercalated discs allow the fibers to work together so that each network serves as a functional unit
Cardiac Conduction System Cardiac muscle cells are autorhythmic cells because they are self-excitable.
Cardiac Conduction System They repeatedly generate spontaneous action potentials that then trigger heart contraction
Cardiac Conduction System 1.
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The components of this system are; Sinoatrial node (SA) Atrioventricular node (AV) Bundle of His Right and Left Bundle branches Purkinje fibers
Cardiac Conduction System SA node is the pacemaker
Cardiac Conduction System From the SA node, a cardiac action potential travels throughout the atrial muscle and down to the AV node
Cardiac Conduction System At the AV node the impulse is delayed (about 0.1sec)
Cardiac Conduction System This gives the atria time to completely contract before ventricular contraction begins
Cardiac Conduction System It then passes through the Bundle of His, Right and Left Bundle Branches, and the Purkinje fibers, resulting in ventricular contraction
Cardiac Cycle 1.
2.
Consists of; Systole (contraction) and Diastole (relaxation) of both atria Systole and Diastole of both ventricles
Atrial Diastole The atria are relaxed
Atrial Diastole They receive blood from three veins
Atrial Diastole The A-V valves are open, allowing for 70% of ventricular filling. The ventricles are therefore also in diastole.
Atrial Systole The SA node then fires; after this electrical event, atrial systole begins (a mechanical event)
Atrial Systole Atrial contraction accounts for 30% of ventricular filling
Ventricular Systole Shortly after the beginning of ventricular depolarization, ventricular systole begins
Ventricular Systole The ventricles contract. The ventricular pressure becomes higher than atrial pressures, causing the AV valves to close.
Ventricular Systole The SL valves open when the ventricular pressure becomes higher than aortic (pulmonary arterial) pressure.
Ventricular Systole Then blood is ejected into the aorta and pulmonary trunk.
Ventricular Diastole Begins when the ventricles relax
Ventricular Diastole Ventricular pressures drop below arterial pressures, causing the SL valves to close
Ventricular Diastole The ventricular pressures continue to drop below atrial pressures, causing the AV valves to open
Auscultation Listening to sounds within the body with a stethoscope
Auscultation The first heart sound (lubb) is created by the closing of the AV valves soon after ventricular systole begins
Auscultation The second heart sound (dupp) represents the closing of the SL valves close to the end of the ventricular systole.
Cardiac Output The volume of blood ejected from the left ventricle (or the right ventricle) into the aorta (or pulmonary trunk) each minute.
Cardiac Output Cardiac Output = Stroke volume X Heart Rate
Cardiac Output Stroke volume – the volume of blood ejected by the ventricle with each contraction
Cardiac Output Stroke Volume = End Diastolic Volume (130ml) – End Systolic Volume (60ml)
Cardiac Output Heart Rate – number of beats per minute
Regulation of Heart Rate Sympathetics impulses increase heart rate and force of contraction
Regulation of Heart Rate Parasympathetic impulses decrease heart rate
Tachycardia Heart Rate over 100 beats/min
Bradycardia Heart Rate below 60 beats/min
Fibrillation Prolonged tachycardia
Exercise And The Heart Sustained exercise increases oxygen demand in muscles
Exercise And The Heart Resting cardiac output 5.25 Liters/minute
Exercise And The Heart In sedentary people CO may go up to 22 liters/minute
Exercise And The Heart In trained athletes CO may go up to 40 liters/minute
Exercise And The Heart Sedentary people increase their CO during exercise by an increase in HR and SV
Exercise And The Heart Sedentary people Increase in HR more dramatic Stroke volume only goes up by 10-35%
Exercise And The Heart For a given activity, sedentary people’s maximum HR will be higher than in a trained athlete
Exercise And The Heart Trained athletes increase their CO during exercise by an increase in HR and SV
Exercise And The Heart Trained Athletes Increase in SV more dramatic than HR Their SV goes up to 60%
Exercise And The Heart Athletes have larger stroke volumes due to longer filling time
Electrocardiogram (ECG or EKG) Records the electrical currents of the body generated by the heart
Electrocardiogram (ECG or EKG) P= depolarization of the atria
Electrocardiogram (ECG or EKG) QRS= depolarization of the ventricles (repolarization of atria, but don’t see)
Electrocardiogram (ECG or EKG) T= ventricles repolarization
Electrocardiogram (ECG or EKG) PR interval= between beginning of atrial depolarization and ventrical depolarization
Electrocardiogram (ECG or EKG) ST segment= ventricle contraction
Electrocardiogram (ECG or EKG) QT interval = ventricle depolarization through ventricle repolarization