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Patho. Cardio
Pathophysiology
| Question | Answer |
|---|---|
| Describe the heart. | A hollow, muscular organ located in the center of the thorax, where it occupies the space between the lungs and rests on the diaphragm. |
| How much does the heart weight? | 300 grams (10.6 oz). |
| How is the heart's weight determined? | By the patient's age, weight, exercise, and heart disease. |
| What is the function of the heart? | To pump blood to the tissues, supplying them with oxygen and other nutrients while removing carbon dioxide and other waste products of metabolism. |
| How much blood does the heart pump? | Varies according to body build, but is generally 70 ml per contraction. |
| What is the cardiac output per minute? | Approximately 5 liters. |
| Where is the mediasinum located? | The area in the middle of the chest between the two lungs; the bulk of the mediastinal space is occupied by the heart, which in encased in the pericardium. |
| What is the pericardium? | A thin, fibrous sac which encases the heart. |
| What is the pericardium protecting the heart against? | Trauma and infection. |
| Parietal pericardium | The tough, fibrous outer membrane. |
| Visceral pericardium | The thin, inner layer that closely adheres to the heart (next to the epicardium). |
| This membrane protects the surface of the heart, but is NOT essential for the heart to function properly. | Pericaridum |
| How much fluid is located between the heart and the pericardial lining and what are its functions? | 5-20 ml of fluid which lubricates the surface, cushions the heart, and reduces friction during contraction of the cardiac muscle. |
| What chambers make up the heart? | Atrium and ventricle. |
| What is the common wall between the right and left chambers called? | The septum. |
| What chamber is responsible for ejecting blood into the arteries? | The ventricles. |
| What are the functions of the atria? | To receive incoming blood from the veins and act as temporary storage reservoirs from which the blood empties into the ventricles. |
| How many valves are in the heart and what are their functions? | 4 valves wich ensure that blood does not flow in the wrong direction. |
| What are the valves composed of? | Thin, leaflets of fibrous tissue, open and close passively in response to pressure changes and blood movement. |
| Name the two types of cardiac valves. | Atrioventricular and semilunar. |
| Valves that separate the atria from the ventricles. | Atrioventricular valves. |
| What are the atrioventricular valves composed of? | Tricuspid valve, biscuspid valve, papillary muscles, and chordae tendineae. |
| What to components of the atrioventricular valves attach only to the bicuspid (mitral) and tricuspid valves? | Papillary muscles and chordae. |
| Named because it is composed of 3 cusps, or leaflets, separates the right atrium from the right ventricle. | Tricuspid valve. |
| 2 cusps whcih lie between the left atrium and the left ventricle. | Bicuspid (mitral) valve. |
| Muscle bundles located on the sides of the ventricular walls. | Papillary muscles. |
| Fibrous bands extending from papillary muscles to the edges of the valve leaflets. | Chordae tendineae. |
| Situated between each ventricle and its corresponding artery. | Semilunar valves. |
| What makes up the semilunar valves? | Pulmonic valve and aortic valve. |
| The valve between the right ventricle and the pumonary artery. | Pulmonic valve. |
| The valve between the left ventricle and aorta. | Aortic valve. |
| Coronary arteries. | The vessels that supply blood to the heart muscle, which has large metabolic requirements for oxygen and nutrients. |
| How much oxygen does the heart use? | 70-80% delivered by the coronary arteries. Other organs use about 1/4 of the oxygen. |
| Where do the coronary arteries arise from? | The aorta near its origin at the left ventricle. |
| Name the components of the coronary arteries. | Left main coronary artery (left anterior descending artery and cirumflex artery) and the right coronary artery. |
| What is the function of the left main coronary artery? | To supply blood to the left side of the heart by dividing into several large branches. |
| Runs down the left side of the heart. | Left anterior descending artery. |
| Runs across the left side of the heart. | Cirumflex artery. |
| What is the function of the right coronary artery? | To supply blood to the right side of the heart. The coronary arteries are perfused (passage of fluid) during diastole (period between contractions). |
| Specialized muscle tissue composing the wall of the heart. | Cardiac muscles. |
| How are cardiac muscle fibers arranged? | In an interconnected manner (syncytium) so that they can contract and relax in a coordinated manner. |
| What are the 3 cardiac muscles? | Myocardium, endocardium, epicardium. |
| The heart muscle itself. | Myocardium. |
| The inner lining of the myocardium which is in contact with the blood. | Endocardium. |
| The outer layer of the cells. | Epicardium. |
| What is the function of the conduction system? | Generate and coordinate the transmission of electrical impulses to the myocardial cells. |
| What is the result of the conduction system? | Sequential atrioventricular contraction, which provides for the most effective flow of blood, thereby optimiizing cardiac output. |
| Name the components of the conduction system. | SA node, AV node, Bundle of HIS, and purkinje fibers. |
| Located at the junction of the superior vena cave and the right atrium. The beginning of the conduction system. | SA node. |
| What is the function of the SA node? | Normally functions as the pacemaker for the entire myocardium. |
| How many pulses does the SA node initiate in a resting normal heart. | 60-100 impulses per minute. |
| Where does the electrical signale initiated by the SA node travel? | It is conducted along the myocardial cells of the atrium to the AV node. |
| Located in the right atrial wall near the trisucpid valve, but this group of specialized cells have an intrinsic rate of 40-60 impulses per minute. | AV node. |
| What does the AV node do? | Coordinates the incoming electrical impulses from the atria and, after a slight delay, relays an impulse to the ventricles. |
| How is the AV node's impulses conducted? | Through a bundle of specialized muscle fibers (bundle of HIS) that travel in the septum separating the left and right ventricles. |
| Bundle of HIS | Divides into the right and left bundle branches, which terminate in fibers called the Purkinje fibers. |
| Where does the right bundle of the Purkinje fibers lead? | Fans out into the right ventricular muscle. |
| What happens to the left bundle? | It divides again into the left anterior and left posterior bundle branches, which fan out into the left ventricular muscle. |
| How is the heart rate determined? | By the myocardial cells with the fastest intrinsic rate. Normally, the SA node is fastest. |
| What happens if the SA node malfunctions? | The AV node will take over the pacemaker function of the heart. |
| What if the AV and SA nodes fail? | The myocardium will continue to beat at a rate of less than 40 beats per minute, which is the intrinsic pacemaker rate of the ventricular cells. |
| The amount of blood pumped by the ventricles during a given period? | Cardiac output. |
| What is the cardiac output of a typical adult? | 4-8 L/min but varies greatly depending on the metabolic needs of the body. |
| Stroke volume (SV) x Heart rate (HR)=? | Cardiac output (CO). |
| Amount of blood ejected per heartbeat? | Stroke volume. |
| What is the average heart rate and stroke volume for an adult? | HR: 60-80 beats/minute. SV: 70 ml/beat |
| What are the 3 factors that control stroke volume? | Intrinsic contractility of the heart muscle, degree of stretch of cardiac muscle before contraction (preload), the pressure against which heart muscle has to eject blood during contraction (afterload). |
| What is the structure of blood vessels in systemic circulatio? | Tunica intima, tunica media, tunica adventitia. |
| Innermost layer of blood vessels. | Tunica intima. |
| Middle layer (smooth muscle) of blood vessels. | Tunica media. |
| Outermost layer (connective tissue) of blood vessels. | Tunica adventitia. |
| Example of the structure of blood vessels. | Tunica media of arteries close to the heart have a greater proportion of elastic fibers bc arteries must be able to distend during systole and recoil during diastole. |
| Example of the stucture of blood vessels. | Arteries further away from the heart contain a greater proportion of smooth muscle fibers bc arteries must be able to constrict and dilate to control BP and volume w/in capillary beds. |
| Blood flow: | ventricles-->aorta-->arteries-->arterioles & capillaries (smallest of arterial vessels) |
| Where do oxygen, nutrients, and other substances needed for cellular metabolism travel? | They pass from the capillaries into the interstitium. |
| Venules | Smallest veins; receive capillary blood. |
| Venous blood | Flows into larger and larger veins until it reaches the vena cava and then into the atrium. |
Created by:
shanhaup
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