anatomy the heart
Define cardiac output
amount of blood pumped out by each ventricle in one minute
Identify the events of the cardiac cycle on an EKG reading.
A typical ECG tracing of the cardiac cycle (heartbeat) consists of a P wave (atrial depolarization ), a QRS complex (ventricular depolarization), and a T wave (ventricular repolarization). An additional wave, the U wave ( Purkinje repolarization), is often visible, but not always.
Describe the 3 layers common to veins and arteries.
Arteries and veins are composed of three tissue layers. ... It consists of circularly arranged elastic fibers, connective tissue, and smooth muscle cells. The inner layer ( tunica intima ) is the thinnest layer, comprised of a single layer of endothelium supported by a subendothelial layer.
Explain structural differences in each layer between veins and arteries and how those differences determine the function of the vessel.
Blood is carried through the body via blood vessels. An artery is a blood vessel that carries blood away from the heart, where it branches into ever-smaller vessels. Eventually, the smallest arteries, vessels called arterioles, further branch into tiny capillaries, where nutrients and wastes are exchanged, and then combine with other vessels that exit capillaries to form venules, small blood vessels that carry blood to a vein, a larger blood vessel that returns blood to the heart. Arteries and veins transport blood in two distinct circuits: the systemic circuit and the pulmonary circuit. Systemic arteries provide blood rich in oxygen to the body's tissues. The blood returned to the heart through systemic veins has less oxygen, since much of the oxygen carried by the arteries has been delivered to the cells. In contrast, in the pulmonary circuit, arteries carry blood low in oxygen exclusively to the lungs for gas exchange. Pulmonary veins then return freshly oxygenated blood from the lungs to the heart to be pumped back out into systemic circulation. Although arteries and veins differ structurally and functionally, they share certain features.
Explain how the unique structure of capillaries determines their function.
Capillaries are the smallest blood vessels in the body, connecting the smallest arteries to the smallest veins. ... Only two layers of cells thick, the purpose of capillaries is to play the central role in the circulation, delivering oxygen in the blood to the tissues, and picking up carbon dioxide to be eliminated.
Explain factors that affect CO
Factors affect cardiac output by changing heart rate and stroke volume. Primary factors include blood volume reflexes, autonomic innervation, and hormones. Secondary factors include extracellular fluid ion concentration, body temperature, emotions, sex, and age.
Explain the control of heart rhythm starting in the SA node and ending with the Purkinjie fibers.
Let's follow a signal through the contraction process. The SA node starts the sequence by causing the atrial muscles to contract. That's why doctors sometimes call it the anatomical pacemaker. Next, the signal travels to the AV node, through the bundle of HIS, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract. This signal creates an electrical current that can be seen on a graph called an electrocardiogram, or EKG. Doctors use an EKG to see how well the cardiac conduction system works. Any changes on the EKG can mean serious problems.
Identify major vessels of heart and describe type of blood and direction of blood flow in each.
Right Side Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium. Left Side The pulmonary vein empties oxygen-rich blood, from the lungs into the left atrium. Right Side Blood flows from your right atrium into your right ventricle through the open tricuspid valve. When the ventricles are full, the tricuspid valve shuts. This prevents blood from flowing backward into the atria while the ventricles contract (squeeze). Left Side Blood flows from your left atrium into your left ventricle through the open mitral valve. When the ventricles are full, the mitral valve shuts. This prevents blood from flowing backward into the atria while the ventricles contract (squeeze). Oxygen and carbon dioxide travels to and from tiny air sacs in the lungs, through the walls of the capillaries, into the blood. Right Side Blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs. Left Side Blood leaves the heart through the aortic valve, into the aorta and to the body. This pattern is repeated, causing blood to flow continuously to the heart, lungs and body. The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve. The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body.
Explain the relationship between blood volume and the force of contraction
The amount of blood in the ventricles, the amount of stretching, and the force of contraction are directly proportional--an increase in blood volume results in greater fiber stretching and then a more powerful contraction. This relationship is referred to as the Frank-Starling law.
Name and explain each phase of the cardiac cycle
The cardiac cycle therefore proceeds in four stages: Atrial systole: lasts about 0.1 seconds - both atria contract and force the blood from the atria into the ventricles. Ventricular systole: lasts about 0.3 seconds - both ventricles contract, blood is forced to the lungs via the pulmonary trunk, and the rest of the body via the aorta. Atrial diastole: lasting about 0.7 seconds - relaxation of the atria, during which the atria fill with blood from the large veins (the vena cavae). Ventricular diastole: lasts about 0.5 seconds - begins before atrial systole, allowing the ventricles to fill passively with blood from the atria
Explain function of the endocardium
The endocardium is the innermost layer of tissue that lines the chambers of the heart. Its cells are embryologically and biologically similar to the endothelial cells that line blood vessels. The endocardium also provides protection to the valves and heart chambers. it assists in forming the valves by its reduplications, and is continuous with the lining membrane of the large bloodvessels.
Explain what is happening to the heart during the P, QRS and T waves.
The first deflection is the P wave associated with right and left atrial depolarization. Wave of atrial repolarization is invisible because of low amplitude. The second wave is the QRS complex. Typically this complex has a series of 3 deflections that reflect the current associated with right and left ventricular depolarization. By convention the first deflection in the complex, if it is negative, is called a Q wave. The first positive deflection in the complex is called an R wave. A negative deflection after an R wave is called an S wave. A second positive deflection after the S wave, if there is one, is called the R' wave. Some QRS complexes do not have all three deflections. But irrespective of the number of waves present, they are all QRS complexes: Following the QRS complex is the ST segment, extending from where the QRS ends (irrespective of what the last wave in the complex is) to where the T wave begins. The junction between the end of the QRS and the beginning of the ST segment is called the J point. The T wave represents the current of rapid phase 3 ventricular repolarization (see diagram above). The polarity of this wave normally follows that of the main QRS deflection in any lead. The ventricles are electrically unstable during that period of repolarization extending from the peak of the T wave to its initial downslope. A stimulus (e.g. a run away heart beat called a premature beat) falling on this vulnerable period has the potential to precipitate ventricular fibrillation: the so call R-on-T phenomenon.
Explain the roles of the autonomic nervous system and the intrinsic conduction system in heart activty.
The function of the heart is to contract and pump oxygenated blood to the body and deoxygenated blood to the lungs. To achieve this goal, a normal human heart must beat regularly and continuously for one's entire life. Heartbeats originate from the rhythmic pacing discharge from the sinoatrial (SA) node within the heart itself. In the absence of extrinsic neural or hormonal influences, the SA node pacing rate would be about 100 beats per minute. Heart rate and cardiac output, however, must vary in response to the needs of the body's cells for oxygen and nutrients under varying conditions. In order to respond rapidly to the changing requirements of the body's tissues, the heart rate and contractility are regulated by the nervous system, hormones, and other factors. Here we review how the cardiovascular system is controlled and influenced by not only a unique intrinsic system, but is also heavily influenced by the autonomic nervous system as well as the endocrine system.
Describe each layer of the heart wall
The heart wall is divided into three layers: epicardium, myocardium, and endocardium. Epicardium: the outer protective layer of the heart. Myocardium: muscular middle layer wall of the heart. Endocardium: the inner layer of the heart.M
Identify valves of the heart and explain function of each type
The mitral valve and tricuspid valve, which control blood flow from the atria to the ventricles The aortic valve and pulmonary valve, which control blood flow out of the ventricles
Describe the coverings of the heart
The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made of serous membrane (serous pericardium).
Describe the pathway of a drop of blood as it travels through the systemic circulation beginning in the right atrium.
The systemic circulation provides the functional blood supply to all body tissue. It carries oxygen and nutrients to the cells and picks up carbon dioxide and waste products. Systemic circulation carries oxygenated blood from the left ventricle, through the arteries, to the capillaries in the tissues of the body. From the tissue capillaries, the deoxygenated blood returns through a system of veins to the right atrium of the heart.
Explain how heart rate and stroke volume influence cardiac output.
Your heart can also increase its stroke volume by pumping more forcefully or increasing the amount of blood that fills the left ventricle before it pumps. Generally speaking, your heart beats both faster and stronger to increase cardiac output during exercise. Given this stroke volume and a normal heart rate of 70 beats per minute, cardiac output is 5.25 L/min. When heart rate or stroke volume increases, cardiac output is likely to increase also. Conversely, a decrease in heart rate or stroke volume can decrease cardiac output.
Define diastole and systole
diastole is relaxation, systole is contraction
Identify the chambers of the heart.
left atrium, left ventricle, right atrium, right ventricle
Describe causes and treatments of blood vessel disorders
lifestyle changes, meds
where is the cavity of where the heart is located?
thoracic cavity The human heart is located within the thoracic cavity, medially between the lungs in the space known as the mediastinum
