Chapter 29- Take 2

The hepatic vein is responsible for carrying blood from the liver to the vena cava. The liver receives blood from the hepatic artery and the hepatic portal vein, and the hepatic vein then drains this blood from the liver and returns it to the vena cava. This allows the liver to process and filter the blood before it is returned to the rest of the body.

The pulmonary veins carry oxygenated blood from the lungs back to the heart. After the blood is oxygenated in the lungs, it is transported through the pulmonary veins into the left atrium of the heart. From there, it is pumped into the left ventricle and then circulated to the rest of the body. Unlike the other options listed, the pulmonary veins specifically carry oxygenated blood, making them the correct answer.

When the sympathetic nervous system stimulation of the heart predominates over parasympathetic nervous stimulation, it leads to an increase in heart rate. The sympathetic nervous system releases neurotransmitters like adrenaline that stimulate the heart to beat faster. This response is commonly known as the "fight or flight" response, where the body prepares for intense physical activity or stress. Therefore, the correct answer is that the heart will increase its rate.

The QRS complex of the ECG represents ventricular depolarization. This is the electrical activation of the ventricles, causing them to contract and pump blood out of the heart. It is an important event in the cardiac cycle and is typically the largest and most prominent waveform on the ECG. The QRS complex is preceded by the P wave, which represents atrial depolarization, and followed by the T wave, which represents ventricular repolarization. Atrial repolarization is not visible on the ECG as it occurs at the same time as the QRS complex.

The SA node, also known as the sinoatrial node, is responsible for initiating the heartbeat. It is located in the right atrium of the heart and acts as the natural pacemaker. The SA node generates electrical impulses that spread throughout the atria, causing them to contract and pump blood into the ventricles. This electrical signal then travels to the AV node, which acts as a relay station, allowing the ventricles to contract and pump blood out of the heart. Therefore, the SA node is the correct answer as it is the initial source of the heartbeat.

The correct answer is "Both a and b are correct." This is because a cardiac cycle can have a duration that changes if the heart rate changes, and it usually requires less than 1 second to complete. Both statements are true, so the answer is that both options a and b are correct.

The two distinct heart sounds, lubb and dubb, are most directly related to the turbulence from the closing of the valves. These sounds occur as a result of the closing of the heart valves during the cardiac cycle. The first sound, lubb, is caused by the closure of the atrioventricular valves (mitral and tricuspid valves) at the beginning of ventricular contraction. The second sound, dubb, is caused by the closure of the semilunar valves (aortic and pulmonary valves) at the end of ventricular contraction. The turbulence created by the closing of these valves produces the characteristic heart sounds.

During atrial systole, the AV valves are open. This is because atrial systole refers to the contraction of the atria, which pushes blood into the ventricles. The AV valves, also known as the atrioventricular valves, are located between the atria and ventricles. When the atria contract, the pressure inside them increases, causing the AV valves to open and allowing blood to flow from the atria into the ventricles. This is an important step in the cardiac cycle, as it allows for the filling of the ventricles before they contract during ventricular systole.

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The presence of a heart murmur does not significantly affect heart rate because a heart murmur is an abnormal sound caused by turbulent blood flow in the heart. It does not directly impact the heart's ability to contract and pump blood, which is what determines heart rate. Factors such as temperature, age, and the levels of sodium (Na+) and potassium (K+) ions in the body can all have a direct effect on heart rate.

Insulin protects vascular tissue by increasing endothelial cell production of nitric oxide. Nitric oxide is a signaling molecule that helps to relax and dilate blood vessels, promoting proper blood flow and reducing the risk of vascular damage. By increasing the production of nitric oxide, insulin helps to maintain vascular health and protect against conditions such as atherosclerosis and hypertension.

Veins have a larger diameter compared to arteries. This is because veins carry blood back to the heart at a lower pressure, so they do not need to withstand the same amount of force as arteries. Additionally, veins have thinner walls and are less elastic than arteries, allowing them to expand and accommodate larger volumes of blood.

When the intraventricular pressure becomes greater than the pressure in the pulmonary arteries, the semilunar valves will open. This is because the semilunar valves are designed to open when there is higher pressure in the ventricles compared to the arteries. Opening the semilunar valves allows blood to be pumped out of the ventricles and into the pulmonary arteries.

A decreased number of capillaries would increase resistance to the flow of blood through the blood vessels. Capillaries are the smallest and thinnest blood vessels, responsible for the exchange of oxygen and nutrients with tissues. When the number of capillaries decreases, the available pathways for blood flow are reduced, leading to increased resistance. This means that blood will have a harder time flowing through the vessels, causing a decrease in overall blood circulation.

The correct sequence of an electrical impulse through the heart's conduction system starts with the SA node, which is responsible for initiating the electrical signal. The impulse then travels to the AV node, where it is delayed to allow for proper ventricular filling. From there, the impulse travels through the bundle of His, which branches into the right and left bundle branches. Finally, the impulse reaches the Purkinje fibers, which distribute the electrical signal throughout the ventricles, causing them to contract. Therefore, the correct sequence is d, b, a, e, c.

The Frank Starling law of the heart states that the strength of contraction of the heart is directly proportional to the length of the cardiac muscle fiber. This means that when the muscle fibers are stretched, they generate a stronger contraction, leading to an increased stroke volume and cardiac output. This relationship is important in regulating the pumping capacity of the heart and ensuring an adequate blood supply to the body.

The correct sequence of blood flow as it travels through the given structures is: right ventricle (d) pumps blood into the pulmonary arteries (b), which carry the deoxygenated blood to the lungs (c). In the lungs, oxygen is exchanged for carbon dioxide and the oxygenated blood returns to the heart through the pulmonary veins (a). Finally, the oxygenated blood enters the left atrium (e) before being pumped out to the rest of the body.

Blood pressure is measured by the pressure exerted on arteries by the blood. This is because blood pressure refers to the force exerted by the blood against the walls of the arteries as it is pumped through the circulatory system. By measuring this pressure, healthcare professionals can determine the health and functioning of the cardiovascular system.

The correct answer is that lymph from the entire body, except the upper right quadrant, eventually drains into the thoracic duct. The thoracic duct is the largest lymphatic vessel in the body and it collects lymph from the lower body, left side of the head and neck, and the left upper limb. The lymph from the upper right quadrant drains into the right lymphatic duct. So, the statement is true as it correctly identifies the drainage pattern of lymph in the body.

The pericardial space is found between the visceral and parietal pericardia. The visceral pericardium is the inner layer of the pericardium that covers the heart, while the parietal pericardium is the outer layer that forms the sac around the heart. The pericardial space contains a small amount of fluid that acts as a lubricant, allowing the heart to beat and move within the sac without friction.

The factors that assist the return of venous blood to the heart include venous valves, respiratory movements, and contraction of skeletal muscles. Venous valves prevent the backflow of blood, ensuring that it moves in one direction towards the heart. Respiratory movements, such as inhalation and exhalation, create pressure changes in the thoracic cavity, helping to propel blood towards the heart. Contraction of skeletal muscles, especially in the legs, acts as a pump, squeezing the veins and pushing blood towards the heart. These factors work together to facilitate the return of venous blood to the heart.

During the normal cardiac cycle, the two atria contract simultaneously while the two ventricles relax. This is known as atrial systole. After this, the two ventricles contract simultaneously while the two atria relax, which is known as ventricular systole. This sequence of contraction and relaxation allows for efficient blood flow through the heart, as the atria fill with blood while the ventricles relax, and then the ventricles pump the blood out to the rest of the body while the atria relax.

The normal end-diastolic pressure within the left ventricle is in the range of 4-12 mmHg. This means that during diastole, when the ventricle is relaxed and filling with blood, the pressure within the left ventricle should be between 4 and 12 mmHg. This range is considered normal and indicates that the ventricle is able to adequately fill with blood before the next contraction.

Nitric oxide is a potent vasodilator, meaning it relaxes and widens blood vessels, allowing for increased blood flow. It is also known as endothelium-derived relaxing factor (EDRF), indicating that it is produced by the endothelium and contributes to its relaxing effects. Therefore, both options a and c are correct as they describe different aspects of nitric oxide's functions.

Adrenomedullin (ADM) is a peptide hormone that is known to exhibit powerful vasodilation activity. This means that it causes the blood vessels to relax and widen, resulting in an increase in blood flow and a decrease in blood pressure. ADM is not involved in vasoconstriction, which is the narrowing of blood vessels, and it is not limited to cardiovascular tissue. Therefore, the correct answer is that ADM exhibits powerful vasodilation activity.