A&p II Exam 2 Part 1

Damage to the venous valve can lead to decreased venous return of blood to the heart. The venous valve plays a crucial role in preventing the backflow of blood in the veins. When the valve is damaged, it may fail to close properly, allowing blood to flow backwards and reducing the efficiency of venous return. This can result in decreased blood flow back to the heart, leading to a decrease in venous return.

The correct answer is that all the options mentioned are correct. Arterial blood pressure increases in response to catecholamine release from the adrenal medulla, an increase in stroke volume, an increase in heart rate, and atherosclerosis. Catecholamines, such as adrenaline, cause vasoconstriction and increased cardiac output, leading to increased blood pressure. An increase in stroke volume and heart rate also contribute to increased blood pressure. Atherosclerosis, the buildup of plaque in the arteries, narrows the blood vessels and increases resistance, leading to higher blood pressure.

The left side of the heart receives oxygenated blood from the lungs, not deoxygenated blood. Deoxygenated blood returns to the right atrium.

The AV node, or atrioventricular node, is located in the interatrial septum and is responsible for transmitting electrical signals from the atria to the ventricles of the heart. It acts as a gatekeeper, delaying the transmission of signals to allow for proper coordination of atrial and ventricular contractions. The other options mentioned, such as the SA node, tricuspid node, and Purkinje fibers, are not located in the interatrial septum and do not perform the same function as the AV node. Therefore, the AV node is the correct answer.

Veins carry both oxygenated and deoxygenated blood, so the statement "all veins carry deoxygenated blood" is not accurate. Veins that carry blood from the lungs to the heart, such as the pulmonary veins, carry oxygenated blood. On the other hand, veins that carry blood from the body tissues back to the heart, such as the systemic veins, carry deoxygenated blood. Therefore, not all veins carry deoxygenated blood.

Smooth muscle is responsible for vasoconstriction of blood vessels. Unlike skeletal muscle, smooth muscle is not under voluntary control and is found in the walls of blood vessels. When the smooth muscle contracts, it narrows the diameter of the blood vessels, leading to vasoconstriction. This helps regulate blood flow and blood pressure in the body. Elastic tissue provides elasticity to blood vessels, tunicca externa provides structural support, collagen tissue provides strength, and adipose tissue is responsible for fat storage.

The chemoreceptors in the carotid and aortic bodies are sensitive to changes in CO2, pH, and O2 blood levels. These chemoreceptors play a crucial role in regulating respiration by detecting alterations in the levels of these gases. When there is an increase in CO2 or a decrease in O2, the chemoreceptors send signals to the brain, which in turn stimulates an increase in respiration rate to remove excess CO2 and replenish O2 levels. Similarly, changes in blood pH also affect respiration, as the chemoreceptors respond to deviations from normal pH levels to maintain homeostasis. Therefore, the chemoreceptors in the carotid and aortic bodies are sensitive to these changes in blood gas levels.

Peripheral tissue and vascular resistance is inversely related to the diameter of the arterioles, meaning that as the diameter of the arterioles decreases, the resistance to blood flow in the peripheral tissues increases. Additionally, an increase in blood viscosity can also lead to an increase in vascular resistance. The length of the vascular bed is directly proportional to peripheral tissue and vascular resistance, meaning that as the length of the vascular bed increases, so does the resistance. Finally, sympathetic stimulation causes vasoconstriction, which leads to an increase in peripheral tissue and vascular resistance. Therefore, all of the given statements are correct.

Freshly oxygenated blood is first received by the left ventricle. The left ventricle is responsible for pumping oxygenated blood to the rest of the body. After receiving oxygenated blood from the lungs through the pulmonary veins, the left atrium contracts and pushes the blood into the left ventricle. From there, the left ventricle contracts and pumps the oxygenated blood out through the aorta to supply oxygen and nutrients to the various organs and tissues of the body.

The structure of a capillary wall differs from that of a vein or an artery because it has a single tunic, only the tunica interna. Unlike veins and arteries, capillaries do not have a tunica media or tunica externa. The tunica interna of capillaries is composed of a single layer of endothelial cells, allowing for the exchange of gases, nutrients, and waste products between the blood and surrounding tissues. This unique structure enables capillaries to facilitate the exchange of substances at the cellular level, making them essential for the functioning of various organs and tissues in the body.

The myocardium, which is the muscular tissue of the heart, receives its blood supply directly from the coronary arteries. These arteries branch off from the aorta, the largest artery in the body, and supply oxygenated blood to the heart muscle. The coronary arteries ensure that the myocardium has a constant supply of oxygen and nutrients, allowing the heart to function properly.

Extrinsic stimulation of the heart refers to the activation of nerves outside the heart that regulate its function. In this case, sympathetic stimulation refers to the activation of the sympathetic nervous system, which increases the force of contraction of the heart. This is because sympathetic stimulation releases norepinephrine, which binds to receptors in the heart, leading to an increase in calcium levels and subsequent stronger contractions. Therefore, the statement "sympathetic stimulation increases force of contraction" is true.

The blood flow in the capillaries is slow and intermittent due to the large cross-sectional area of the total capillary bed. This means that the total area of all the capillaries combined is much larger than the area of the arteries or veins. As a result, the blood flow is distributed over a larger surface area, causing it to slow down. Additionally, the slow and intermittent flow allows for exchange of nutrients, gases, and waste products between the blood and the surrounding tissues.

Baroreceptors located in the carotid sinus and aortic arch are responsible for sensing changes in arterial pressure. These specialized sensory receptors detect alterations in the pressure of the blood flowing through the arteries. When the arterial pressure increases or decreases, the baroreceptors send signals to the brain, which then initiates appropriate physiological responses to regulate and maintain blood pressure within a normal range. This helps to ensure adequate blood flow to various organs and tissues in the body.

When a depolarization wave travels through the myocardium, there is an increased influx of sodium ions (Na+), which helps to depolarize the cell. This is followed by an increased influx of calcium ions (Ca+), which triggers the release of more calcium from the sarcoplasmic reticulum, leading to muscle contraction. Finally, there is an increased efflux of potassium ions (K+), which helps to repolarize the cell and restore its resting membrane potential. Therefore, the correct answer is increased Na+ influx, increased Ca+ influx, increased K+ efflux.