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Chapter 20/the heart
The Heart
| Question | Answer |
|---|---|
| Know the 2 circuits of the cardiovascular system | The Pulmonary Circuit- carries blood to and from gas exchange surfaces of lungs. The Systemic Circuit- carries blood to and from the body, blood alternates between pulmonary circuit and systemic circuit. |
| Define pericardium | the fibrous sac that surrounds the heart, its inner serous lining is continuous with the epicardium |
| Know the different portions of this structure | Fibrous pericardium: tough, loose-fitting & inelastic sac around the heart, Serous pericardium: consists of 2 layers Parietal layer Lining inside of fibrous pericardium Visceral layer (epicardium) Adheres to outside of heart |
| Know and describe the 3 layers that make up the heart wall | Arteries Carry blood away from heart Veins Carry blood to heart Capillaries Networks between arteries and veins |
| Define syncytium | Cardiac muscle cells can pass an action potential from fiber to fiber along a large area of the heart wall |
| Know and describe the 4 chambers of the heart | 2 upper chambers = atria 2 lower chambers = ventricles “Receiving chambers” Receive blood from veins, Receive blood from atria and pump out of heart into arteries Primary “pumping chambers” |
| Know and describe the 4 valves of the heart | 2 atrioventricular (AV) valves Guard openings between atria and ventricles Have pointed flaps called cusps so they are known as cuspid valves 2 semilunar (SL) valves 1 is located where pulmonary artery joins R ventricle Pulmonary valve 1 is located |
| Know the function of the valves | |
| Describe flow of blood through the heart | R atrium thru R AV valve R ventricle pulmonary SL valve pulmonary trunk (first part of pulmonary artery) L and R branches of pulmonary artery lungs (gas exchange) pulmonary veins left atrium |
| know the 2 main arteries that supply the heart with blood | L and R coronary arteries |
| know the large venous structure that returns most of the blood from the heart back to the right atria | |
| Define anastomosis | 1 or more branches from the proximal part of an artery to a more distal part of itself or another artery |
| List 4 structures that make up conduction system of the heart | Sinoatrial (SA) node Atrioventricular (AV) node AV bundle (bundle of His) Subendocardial branches (Purkinje fibers) |
| Know how the structures of the conduction system of the heart differ in function from ordinary cardiac muscle | |
| Know how impulses travel through the conduction system of the heart (fig 20-12) | |
| Define electrocardiogram/electrocardiography | Impulse conduction generates tiny electrical currencies in the heart that eventually spread to the surface of the body/ A graphic record of heart’s electrical activity – its conduction of impulses |
| Know the different ECG waves | ECG composed of deflection waves called: P wave QRS complex T wave |
| P wave | Represents depolarization of the atria Deflection caused by the passage of an electrical impulse from SA node through the musculature of both atria |
| QRS complex | Represents depolarization of the ventricles Very complex process: Depolarization of interventricular septum Subsequent spread of depolarization by subendocardial branches (Purkinje fibers) Through the lateral ventricular walls |
| T wave | Reflects repolarization of the ventricles In atria, 1st part to depolarize is the 1st part to repolarize It is opposite in the ventricles 1st part to depolarize is the last to repolarize So, ECG deflections occur in the same direction |
| U wave | This can sometimes be seen in an ECG Appears as a tiny “hump” at end of the T wave Results from late repolarization of subendocardial branches Located in papillary muscle of ventricular myocardium |
| Know and describe the different phases of the cardiac cycle (fig 20-16) | A complete heart beat or pumping cycle Consists of: Contraction – systole Relaxation – diastole Of both atria and ventricles |
| Know what causes the heart sounds | Certain sounds are made during each cardiac cycle 1st systolic sound caused primarily by contraction of ventricles 2nd diastolic sound is short and sharp Caused by vibrations of closing semilunar valves |
| Define heart murmur | type of abnormal heart sound heard frequently |
| What is the primary principle of circulation? | A fluid does not flow when pressure is the same throughout A fluid only flows when its pressure is higher in one area than in another |
| Define pressure gradient | Difference between blood pressure in one structure and the blood pressure in another |
| Define perfusion pressure | local pressure gradient needed to maintain blood flow in a tissue Perfusion = “flow through” |
| List the 2 factors that influence arterial volume and pressure | Cardiac output Peripheral resistance |
| Define cardiac output | Amount of blood that flows from the ventricles per unit of time |
| Know how cardiac output is calculated | SV (volume/beat) X HR (beat/min) = CO (volume/min) |
| Define stroke volume | volume of blood pumped out of ventricle by each beat |
| Define starling’s law of the heart | Within limits, the longer (or more stretched) the heart fibers at the beginning of contraction, the stronger their contraction Compare to length-tension relationship in skeletal muscle |
| Define end-diastolic volume | Factor that determines how stretched the fibers are is amount of blood in heart at the end of diastole |
| Know relationship of ejection fraction to stroke volume | Ejection fraction (EF) is related to SV Ratio of SV to the EDV Often expressed as percent EF = (SV/EDV) x 100 As SV goes up, EF goes up Opposite is also true |
| Sympathetic nervous stimulation = stimulatory – releases norepinephrine | Sympathetic = cardiac nerve Stimulatory Release of NE |
| Parasympathetic nervous stimulation = inhibitory – releases ACh | Parasympathetic = chiefly, vagus nerve Inhibitory Release of ACh |
| Know locations of baroreceptors | Baroreceptors: sensitive to changes in pressure Located in 2 places near heart |
| Describe negative feedback loop that occurs with stimulation of baroreceptors | Operate with integrators in cardiac control centers in negative feedback loops called pressoreflexes (baroreflexes) Oppose changes in pressure by adjusting heart rate |
| Define dysrhythmia | Abnormal beating of the heart |
| Define bradycardia and tachycardia | Bradycardia Slow heart rhythm Below 60 beats/minute Tachycardia Rapid heart rhythm More than 100 beats/minute |
| Define atrial fibrillation and ventricular fibrillation | A-fib or AF Fibrillation in the atria Caused by mitral stenosis, rheumatic heart disease and infarction of atrial myocardium Life threatening Treated by defibrillation Application of electrical shock to force muscle fibers to contract together again |
| Define heart failure | Inability of heart to pump enough blood to sustain life Decline in EF below normal The more the decline, the more severe the heart failure |
| Define pericarditis | Inflammation of the pericardium |
| Define mitral valve prolapsed | Has genetic basis but can be caused by other factors Flaps of mitral valve extend back into the L atrium Causes the valve to be leaky |
| Define valvuloplasty | Procedure that replaces damaged or defective cardiac valves Artificial valves or valves taken from other mammals can be used as replacements |
| Define coronary artery disease, | Coronary Artery Disease A leading cause of death in US Caused by wide variety of factors Reduction in blood flow to myocardial tissue Can result in myocardial infarction (MI) |
| Define congestive heart failure | Inability of the L ventricle to pump blood effectively Most often caused by high blood pressure (hypertension) or MI caused by CAD “congestive” because causes body to retain fluid Due to decrease in pumping pressure |
| Define hypertension | high blood pressure |
| Define cardiomyopathy | Term for any heart disease that causes abnormal enlargement of the heart |
| Define atherosclerosis | Atherosclerosis One way coronary arteries can become blocked “Hardening of the arteries” Lipids build up on inner surface of the vessels and calcify Makes vessels hard and brittle |
| Define angina pectoris | Severe chest pain that accompanies MI Warning sign |
Created by:
coffeecake49
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