cardiovascular system: the heart - penguin prof
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Cardiovascular System: The Heart
Heart Development
I. Introduction
Functions of the Cardiovascular System:• Transportation:
• Respiratory gasses
• Nutrients
• Waste
• Hormones
• Regulation of temperature
• Protection (immune system)
Components of the Cardiovascular System
• Cardiovascular System = heart and the vessels
• Lymphatic system = lymph vessels, lymph nodes, lymph organs
Heart Anatomy
• General Features:
• Size
• It's a dual pump
Coverings of the Heart:
• Parietal pericardium
• Visceral pericardium (epicardium)
• Pericardial sac
Heart in Cross-Section
Epicardium (visceral pericardium)
Myocardium
Endocardium
Chambers of the Heart
• Atria receive blood
• Ventricles pump blood
• Right ventricle pumps blood to the pulmonary circuit
• Left ventricle pumps oxygenated blood to the systemic circuit
• NOTE: Arteries Always carry blood Away from the heart
Heart Valves
• Atrioventricular(AV) valves prevent backflow from ventricles to atria
• Tricuspid valve
• Bicuspid valve (mitral valve)
• Chordae tendineae originate from papillary muscles
• Semilunar valves
• Aortic semilunar valve
• Pulmonary semilunar valve
Cardiac Circulation
Electrical Events in the Heart
Compare and Contrast Skeletal vs. Cardiac Muscle
• Purpose
• Basic principles (all-or-none)
• Time
• Summation / Tetanus
• Refractory period
• Source of stimulus / role of NS
Extrinsic Regulation
Autonomic nervous system
• Sympathetic system
• Parasympathetic
Intrinsic regulation (nodal system)
• Sinoatrial (SA) node contains pacemakers
• Atrioventricular (AV) node
• Atrioventricular bundle (Bundle of His)
• Bundle branches
• Purkinje fibers
The Cardiac Cycle
• Cardiac cycle = contraction, relaxation cycle of the heart
• Systole = contraction
• Diastole = relaxation
• Stroke volume = volume of blood ejected by a ventricle as it contracts
• Cardiac Output = heart rate x stroke volume
The Cardiac Cycle
• 1. Atrial and Ventricular Diastole
• Atria are filling with blood, AV valves are open and blood passively fills the ventricles.
• 2. Early Ventricular Systole
• Ventricles begin to contract, forcing the AV valves to close
• Isovolumic ventricular contraction: ventricles contract, but AV and semilunar valves are closed
The Cardiac Cycle• 3. Ventricular Systole and Blood Ejection
• When ventricular contraction generates enough pressure to open the semilunar valves, blood enters the arteries
• 4. Ventricular Diastole
• Ventricles relax, pressure decreases
• Blood remaining in ventricles is called end-diastolic volume, EDV
• Blood flows back into the heart, closing the semilunar valves
Electrocardiogram (ECG)
• P wave = atrial depolarization
• QRS wave = depolarization of ventricles (and repolarization of atria).
• T wave = repolarization of ventricles
Arteriosclerosis and Cardiac Arrhythmia
• Plaques can clog the arteries, causing restricted blood flow
• Smoking, hypertension, and a diet high in cholesterol and fats contribute
• High ratio of HDL to LDL is desirable
• Myocardial ischemia
• Myocardial infarction = heart attack.
Tight stenosis of RCA. This can cause an inferior wall myocardial infarction. Since this is a short lesion, usually percutaneous coronary intervention will be used - balloon dilatation & stinting.
Cardiac Arrhythmias
• Arrhythmias
• Bradycardia = heart rate less than 60 beats/ min
• Tachycardia = heart rate more than 100 / min
• Flutter = rapid, controlled contractions of atria or ventricles
• Fibrillation = rapid, uncontrolled contractions
• Electrical defibrillation can sometimes re-regulate the myocardial cells to become synchronous again.
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