Ch 18 Blood And Cha 19 Heart

The sinoatrial (SA) node is the pacemaker that initiates each heart beat. It is a small cluster of cells located in the right atrium of the heart. The SA node generates electrical impulses that cause the atria to contract and pump blood into the ventricles. These impulses then travel through the atrioventricular (AV) node and the rest of the cardiac conduction system, causing the ventricles to contract and pump blood out of the heart. The autonomic nervous system, sympathetic division, and AV node are all involved in regulating and coordinating the heart's activity, but they do not serve as the primary pacemaker.

The myocardium is the correct answer because it is the muscular layer of the heart that performs the work of pumping blood. It is responsible for the contraction and relaxation of the heart, allowing it to effectively pump blood throughout the body. The other options listed are not directly involved in the functioning of the heart.

Albumin is the most abundant protein in plasma. It is synthesized in the liver and plays a crucial role in maintaining osmotic pressure, transporting various substances such as hormones, fatty acids, and drugs, and regulating pH balance in the blood. It also acts as a carrier protein for many molecules, assisting in their transportation throughout the body. Due to its abundance and multiple functions, albumin is considered the most prevalent protein in plasma.

Arrhythmia is the correct answer because it refers to any abnormal cardiac rhythm. It encompasses a wide range of conditions where the heart beats too fast, too slow, or irregularly. This can be caused by various factors such as heart disease, electrolyte imbalances, or medication side effects. Arrhythmias can have serious consequences and may require medical intervention to restore a normal heart rhythm.

The tendinous cords (TC) are not part of the cardiac conduction system. The cardiac conduction system consists of specialized cells that regulate the electrical impulses that control the heart's rhythm and coordinate its contractions. The Purkinje fibers, sinoatrial (SA) node, atrioventricular (AV) bundle (bundle of His), and atrioventricular (AV) node are all components of the cardiac conduction system. The tendinous cords, also known as the chordae tendineae, are fibrous cords that connect the cusps of the heart valves to the papillary muscles, helping to prevent the valves from inverting during ventricular contraction. They do not play a role in the conduction of electrical impulses.

Basophils are the least abundant formed elements in the given list. They are a type of white blood cell that plays a role in the immune response by releasing histamine and other chemicals. Basophils are involved in allergic reactions and help to defend against parasites. Compared to other formed elements like erythrocytes (red blood cells), neutrophils, eosinophils, and platelets, basophils are present in smaller numbers in the blood.

The P wave represents atrial depolarization, which is the electrical activation of the atria. This occurs during atrial systole, which is the contraction of the atria. Therefore, the correct answer is the P wave.

A deficiency of Vitamin B12 can cause pernicious anemia. Pernicious anemia is a type of anemia that occurs when the body is unable to absorb enough Vitamin B12 from the diet. Vitamin B12 is necessary for the production of healthy red blood cells, and a deficiency can lead to a decrease in the number of red blood cells and a decrease in their ability to carry oxygen. This can result in symptoms such as fatigue, weakness, and shortness of breath.

The buffy coat is a layer of blood that contains white blood cells and platelets. Erythrocytes, also known as red blood cells, are not found in the buffy coat. They are instead found in the bottom layer of blood called the packed cell volume (PCV) or hematocrit. Therefore, the correct answer is erythrocytes.

Mitral valve stenosis is a condition where the mitral valve, located between the left atrium and left ventricle, becomes narrowed. This narrowing prevents the valve from opening fully, causing blood to flow backward into the left atrium when the ventricles contract. Therefore, the correct answer is left atrium.

The correction of hypoxemia, which refers to low oxygen levels in the blood, is regulated by a negative feedback loop. In a negative feedback loop, the body detects low oxygen levels and triggers a response to increase oxygen levels. This response could include increasing the respiratory rate, improving blood flow to the lungs, or releasing hormones that stimulate the production of red blood cells. Once oxygen levels return to normal, the feedback loop is turned off to maintain homeostasis.

The cardiac output refers to the volume of blood that is pumped out by each ventricle of the heart in one minute. It is an important measure of the overall efficiency of the heart's pumping action and is influenced by factors such as heart rate and stroke volume. The cardiac output is a crucial parameter in assessing cardiac function and can be used to diagnose and monitor various cardiovascular conditions.

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A total count above 10,000 WBCs/L is considered leukocytosis. This means that if the number of white blood cells in a person's body exceeds 10,000 per liter of blood, it is classified as leukocytosis. Leukocytosis is often an indication of an underlying infection or inflammation in the body.

The correct path of an electrical excitation from the pacemaker to a cardiocyte in the left ventricle starts at the sinoatrial (SA) node, then goes to the atrioventricular (AV) node, followed by the atrioventricular (AV) bundle, and finally reaches the cardiocyte in the left ventricle through the Purkinje fibers. This sequence ensures that the electrical signal is properly transmitted from the pacemaker to the ventricles, allowing for coordinated contraction and efficient pumping of blood.

Cardiac muscle fibers have a different level of endurance compared to skeletal muscle fibers. While skeletal muscle fibers can sustain prolonged contractions and fatigue over time, cardiac muscle fibers have a much higher endurance and are capable of contracting continuously without fatigue. This is due to their reliance on aerobic respiration as the main source of energy, their abundance of mitochondria, and their high concentration of myoglobin, which facilitates oxygen storage. Additionally, cardiac muscle fibers are rich in glycogen, which provides a backup energy source during periods of increased demand.

Pericardial fluid is found between the parietal and visceral membranes. The pericardium is a double-layered membrane that surrounds the heart. The parietal pericardium is the outer layer, while the visceral pericardium is the inner layer that directly covers the heart. The space between these two layers is filled with pericardial fluid, which acts as a lubricant, reducing friction between the membranes as the heart beats.

Cardiac muscle fibers have striations, which means they have alternating light and dark bands. This feature is also present in skeletal muscle fibers. Striations are caused by the arrangement of contractile proteins within the muscle fibers, giving them a striped appearance. This allows for coordinated contraction and relaxation of the muscle fibers, enabling efficient pumping of blood in the case of cardiac muscle.

The plateau in the action potential of cardiac muscle is caused by the slow Ca2+ channels. These channels open during the plateau phase and allow the influx of Ca2+ ions into the cell. This influx of Ca2+ prolongs the depolarization phase and maintains the membrane potential, resulting in the plateau. This is important for the contraction of the cardiac muscle, as it allows for sustained contraction and efficient pumping of blood.

Neutrophils typically increase in response to bacterial infection. Neutrophils are a type of white blood cell that play a crucial role in the body's immune response against bacterial pathogens. They are highly effective at phagocytosis, the process of engulfing and destroying bacteria. When a bacterial infection occurs, the body releases signals that attract neutrophils to the site of infection. The increase in neutrophils helps to eliminate the bacteria and resolve the infection.

Anemia is a condition characterized by a decrease in the number of red blood cells or a decrease in the amount of hemoglobin in the blood. This leads to a reduced oxygen-carrying capacity of the blood. The potential consequences of anemia include lethargy due to inadequate oxygen supply to tissues, increased fluid transfer from the bloodstream to the intercellular space leading to edema, reduced blood osmolarity due to dilution of solutes, and reduced blood resistance to flow due to decreased viscosity. However, anemia does not cause an increase in blood viscosity, as the decrease in red blood cells or hemoglobin levels leads to a decrease in viscosity.

Lymphocytes are the most abundant agranulocytes in the body. They play a crucial role in the immune system, helping to defend against pathogens and foreign substances. Lymphocytes are responsible for the production of antibodies, which target specific antigens, and they also play a role in cell-mediated immunity. These cells are found in lymphoid tissues such as the lymph nodes, spleen, and thymus. Lymphocytes are diverse and can be further classified into B cells, T cells, and natural killer cells, each with their own specific functions in the immune response.

Type AB blood has both A and B antigens on the surface of its red blood cells (RBCs). This means that individuals with AB blood type have both A and B antigens present, making them universal recipients since they can receive blood from any blood type without their immune system attacking the transfused blood.

The long absolute refractory period refers to the period of time after a cardiac action potential where the cardiac muscle is unable to be stimulated again. This prevents tetanus, which is a sustained contraction of the heart muscle. During the refractory period, the heart muscle is able to relax and refill with blood before the next contraction, ensuring proper cardiac function.

The correct sequence of events in the cardiac cycle starts with ventricular filling, where blood flows from the atria to the ventricles. This is followed by isovolumetric contraction, where the ventricles contract but there is no change in volume. Next, ventricular ejection occurs, where blood is pumped out of the ventricles into the arteries. Finally, isovolumetric relaxation takes place, where the ventricles relax but there is no change in volume. This sequence accurately represents the different phases of the cardiac cycle.

The given answer SV=30 mL/beat, HR=80bpm is correct because stroke volume (SV) is the difference between end-diastolic volume (EDV) and end-systolic volume (ESV). In this case, EDV is 90 mL and ESV is 60 mL, so the SV is 90 mL - 60 mL = 30 mL. Cardiac output (CO) is calculated by multiplying SV and heart rate (HR), so if CO is 2,400 mL/min and SV is 30 mL/beat, we can solve for HR by dividing CO by SV: 2,400 mL/min / 30 mL/beat = 80 beats/min. Therefore, the correct answer is SV=30 mL/beat, HR=80bpm.

When the ventricles contract, the mitral valve closes, causing the first heart sound (lubb or S1) to be heard. Mitral valve prolapse (MVP) is a condition where the mitral valve does not close properly, allowing blood to leak back into the atrium. However, this does not affect the timing of the first heart sound, which still occurs when the ventricles contract. Therefore, the correct answer is lubb (S1); ventricles contract.

This individual with type B, Rh-positive blood has both B and D antigens. Therefore, they can produce antibodies against A antigens and D antigens.

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According to the Frank-Starling law of the heart, stroke volume is proportional to the end-diastolic volume. This means that the amount of blood pumped out of the heart with each heartbeat (stroke volume) increases as the volume of blood in the heart at the end of relaxation (end-diastolic volume) increases. This relationship is important because it allows the heart to adapt to changes in venous return and maintain an adequate cardiac output.

During atrial diastole, the atria are relaxed and the atrioventricular (AV) valves are open. This allows blood to flow from the atria into the ventricles, filling them up. Atrial diastole is the phase of the cardiac cycle when the atria are in a state of relaxation and are able to passively fill the ventricles with blood. During atrial systole, the atria contract to push any remaining blood into the ventricles. During ventricular systole, the ventricles contract to pump blood out of the heart. Isovolumetric contraction is the brief period when both the AV and semilunar valves are closed and no blood is being pumped out of the ventricles.

The term "homeostasis" refers to the body's ability to maintain internal stability and balance. While homeostasis is involved in many physiological processes, it does not specifically refer to the cessation of bleeding. "Hemeostats" is not a recognized term in biology or medicine. "Blood clotting" or "coagulation" is the process by which blood forms a clot to stop bleeding. "Vascular spasm" refers to the constriction of blood vessels to reduce blood flow, which can help in the cessation of bleeding. "Platelet plug formation" is the initial step in the formation of a blood clot, where platelets aggregate at the site of injury. Therefore, the correct answer is "blood clotting."

Isovolumetric contraction occurs during the R wave of the electrocardiogram. The R wave represents the depolarization of the ventricles, which leads to their contraction. During this phase, the ventricles contract while the atria are relaxed, and the blood volume within the ventricles remains constant as the valves between the atria and ventricles are closed. This contraction phase allows for the ejection of blood from the ventricles into the arteries.

The correct answer is "Venae cavae and pulmonary veins." The venae cavae are large veins that carry deoxygenated blood from the body back to the heart, specifically to the right atrium. The pulmonary veins, on the other hand, are responsible for carrying oxygenated blood from the lungs to the left atrium of the heart. Therefore, both the venae cavae and pulmonary veins carry oxygen-poor blood.

In this figure, option 2 indicates when calcium enters the myocytes.

An individual with blood type A, Rh-positive has Anti-B antibodies in their blood. When they receive blood from an individual with blood type AB, Rh-negative (who has B antigens on their red blood cells), the Anti-B antibodies in the recipient's blood will recognize the B antigens on the donor's red blood cells as foreign and cause them to agglutinate (clump together). This can lead to serious complications and is why an individual AB, Rh-negative cannot donate blood to an individual A, Rh-positive.

At 0.2 sec in the graph, the AV valve is open. This means that the atrioventricular valve, also known as the mitral valve or tricuspid valve, is open allowing blood to flow from the atria into the ventricles. This occurs during the diastole phase of the cardiac cycle when the ventricles are relaxed and filling with blood. The opening of the AV valve is an important step in the cardiac cycle as it allows for the efficient filling of the ventricles before they contract during systole.

In the cardiac cycle, the aortic valve opens to allow the blood to be pumped out of the left ventricle and into the aorta. This occurs during the phase known as systole. Therefore, "4" represents the opening of the aortic valve.