PRACTICAL EXERCISE 4
HEART STRUCTURE AND CIRCULATION
Q.1 Describe the heart sounds you hear. Explain the origin of two sounds.
Two heart sounds are normally heard through a stethoscope on the chest wall, "lab" "dap". The first sound can be described as soft, but resonant, and longer then the second one. This sound is associated with the closure of AV valves (atrioventricular valves) at the beginning of systole. The second sound is louder and sharp. It is associated with closure of the pulmonary and aortic valves (semilunar valves) at the beginning of diastole. There is a pause between the each set of sounds. It is a period of total heat relaxation called quiescent period.
Q.2 Which structures are responsible for these sounds?
If these structures were damaged or functionally incorrectly, what do you think would happen to the heart sound?
The structures responsible for these sounds are: pulmonary, aortic and atrioventricular valves. These sounds are results of vibration caused by closure of these valves. Other sounds known as "heart murmurs" are sometimes a sign of heart disease. "Murmurs can be produced by blood flowing rapidly in the usual directions through an abnormally narrowed valve" (Vander, Sherman and Luciano, 1985, p.326) and in some cases, as mitral valve prolapse, the individual does not show any symptoms.
Q.5 If a glass probe is poked into the pulmonary trunk which chamber will it enter?
The glass probe poked into the pulmonary trunk will follow the cycle of blood from the pulmonary artery to the lungs and then through pulmonary veins will enter the left atrium.
Q.6 From which chamber does the aorta arise?
Aorta arises from the left ventricle. It is the largest artery in the body and it transports the oxygenated blood away from the heart.
Q.7 (a) Where do the coronary arteries start?
(b) Use this knowledge to explain how the coronary arteries only fill with blood during diastole.
The heart, like other organs, receives its blood supply through the smaller vessels of arterial branches. In this case, coronary arteries, which starts from the base of ascending aorta.
The blood circulates through coronary arteries and then to smaller vessels into cardiac muscle (myocardium). The blood flow is influenced by aortic pressure, which increases in systole, and the pumping activity of the ventricles. When the ventricle contracts, in systole, the coronary vessels are compressed by the contracted myocardium and partly blocked by the open aortic valve therefore the blood flow through the myocardium stops.
In this lab, I took two recordings of my heart using an electrocardiogram. An electrocardiogram, EKG pg. 628 Y and pg. 688 D, is a recording of the heart's electrical impulses, action potentials, going through the heart. The different phases of the EKG are referred to as waves; the P wave, QRS Complex, and the T wave. These waves each signify the different things that are occurring in the heart. For example, the P wave occurs when the sinoatrial (SA) node, aka the pacemaker, fires an action potential. This causes the atria, which is currently full of blood, to depolarize and to contract, aka atrial systole. The signal travels from the SA node to the atrioventricular (AV) node during the P-Q segment of the EKG. The AV node purposefully delays
The normal Mitral Valve controls blood flow between the upper (left atrium) and lower chamber (left ventricle) of the left side of the heart. The mitral valve allows blood to flow from the left atrium into the left ventricle, but not flow the other way. With each heartbeat, the atria contract and push blood into the ventricles. The flaps of the mitral and tricuspid valves open to let blood through. Then, the ventricles contract to pump the blood out of the heart. The flaps of the mitral and tricuspid valves close and form a tight seal that prevents blood from flowing back into the atria (nhlbi.nih.gov).
The Mayo Clinic’s book on High Blood Pressure was full of detailed facts about blood pressure and what it is. This is extremely significant to the experiment because blood pressure is one of the variables being tested. Understanding blood pressure is one of the key components to receiving accurate results from this experiment. Most of the book is on high blood pressure, which is not necessary for the experiment, but the book still had plenty of useful information about blood pressure itself. The book explains that when the heart beats, a surge of blood is released from the left ventricle. It also tells of how arteries are blood vessels that move nutrients and oxygenated blood from the heart to the body’s tissues. The aorta, or the largest artery in the heart, is connected to the left ventricle and is the main place for blood to leave the heart as the aorta branches off into many different smaller
of the heart: one chamber is on the top and one chamber is on the
Pulmonary arteries carry blood from the heart to the lungs where the blood picks up oxygen. The oxygen rich blood is then returned to the heart via the pulmonary veins. Systemic arteries deliver blood to the rest of the body. The aorta is the main systemic artery and the largest artery of the body. It originates from the heart and branches out into smaller arteries which supply blood to the head region brachiocephalic artery, the heart itself coronary arteries, and the lower regions of the body.
than 9 square centimeters, was placed on the patient's chest at various angles. The transducer delivered ultrasound waves into the body and these
The heart is divided into two halves, which are further divided into four chambers: the left atrium and ventricle, and the right atrium and ventricle. Each chamber on one side is separated from the other, by a valve, and it the closure of these valves that produce the “lubb-dubb” sound so familiar to us.
The ventricles send blood to the heart and are larger and stronger. Heart valves are another important aspect of the heart and body. We have atrioventricular and semilunar valves which help block regurgitation of blood. The heart has two states, it has a systole state where the heart is contracting to push blood out and diastole where the heart relaxes so the heart can fill back up with blood.
Another route of circulation is the fetal route of circulation. The fetal circulation is blood from the placenta that is helping the baby to live. The placenta accepts deoxygenated blood from the mother through blood vessels from the umbilical cord. According to heart.org, “Blood coming back from the fetus’s body also enters the right atrium,
The pattern of blood flow starts in the left atrium to right atrium, then into the left ventricle and right ventricle. During its course, blood flows through the mitral and tricuspid valves. Simultaneously, the right atrium is granted blood from the veins through the superior and inferior vena cava. The job of the superior vena cava is to transport de-oxygenated blood to the right atrium. When your heart beats, the first beat represents the AV valves closing to prevent the backflow of blood into the atrium.
The heart serves as a powerful function in the human body through two main jobs. It pumps oxygen-rich blood throughout the body and “blood vessels called coronary arteries that carry oxygenated blood straight into the heart muscle” (Katzenstein and Pinã, 2). There are four chambers and valves inside the heart that “help regulate the flow of blood as it travels through the heart’s chambers and out to the lungs and body” (Katzenstein Pinã, 2). Within the heart there is the upper chamber known as the atrium (atria) and the lower chamber known as the ventricles. “The atrium receive blood from the lu...
The process for an adult’s circulation system starts with non-oxygenated blood entering the right atrium from the inferior and superior vena cava. Once in the right atrium the tricuspid valve opens and drains the blood to the right
The arteries that take the blood to the head are found in something called aortic arch. After the blood goes through the arch, it’s distributed to the rest of the body. From the aorta, blood is sent to other arteries, where it gives oxygen to every cell.
The heart is a pump with four chambers made of their own special muscle called cardiac muscle. Its interwoven muscle fibers enable the heart to contract or squeeze together automatically (Colombo 7). It’s about the same size of a fist and weighs some where around two hundred fifty to three hundred fifty grams (Marieb 432). The size of the heart depends on a person’s height and size. The heart wall is enclosed in three layers: superficial epicardium, middle epicardium, and deep epicardium. It is then enclosed in a double-walled sac called the Pericardium. The terms Systole and Diastole refer respectively and literally to the contraction and relaxation periods of heart activity (Marieb 432). While the doctor is taking a patient’s blood pressure, he listens for the contractions and relaxations of the heart. He also listens for them to make sure that they are going in a single rhythm, to make sure that there are no arrhythmias or complications. The heart muscle does not depend on the nervous system. If the nervous s...
The heart beats when electrical signals move through it. Ventricular fibrillation is a condition in which the heart's electrical activity becomes disordered. When this happens, the heart's lower (pumping) chambers contract in a rapid, unsynchronized way. (The ventricles "flutter" rather than beat.) The heart pumps little or no blood therefore the probability of death is high.