A And P II - Midterm Lecture Practice Test

Helper T cells recognize antigens when they are bound to a major histocompatibility complex (MHC) protein. MHC proteins are found on the surface of antigen-presenting cells, such as macrophages and dendritic cells. These proteins act as receptors and display antigens to the T cells. When an antigen binds to the MHC protein, it forms a complex that can be recognized by the T cell receptor on the helper T cell. This recognition is crucial for the activation of the immune response and the coordination of the immune system's attack against the antigen.

T cells achieve immunocompetence in the thymus. The thymus is a primary lymphoid organ located in the chest, where T cells mature and develop their ability to recognize and respond to foreign antigens. T cells undergo a process of selection and education in the thymus, which ensures that they can distinguish between self and non-self antigens. This process is crucial for the proper functioning of the immune system. The liver, spleen, bone marrow, and blood stream also play important roles in immune responses, but they do not specifically contribute to the development of immunocompetence in T cells.

Large arteries have the thickest tunica media. The tunica media is the middle layer of the arterial wall and is composed of smooth muscle fibers. Large arteries, such as the aorta and the pulmonary artery, have a thicker tunica media compared to smaller arteries and veins. This is because large arteries need to withstand the high pressure and force of blood flow from the heart. The thick tunica media provides strength and elasticity to the arterial wall, allowing it to expand and contract with each heartbeat.

Antigen-presenting cells are specialized immune cells that capture, process, and present antigens to T cells to initiate an immune response. Lymph nodes are small bean-shaped structures found throughout the lymphatic system. They act as filters for lymph fluid and are a primary site for immune cell activation and interaction. Lymph nodes contain high concentrations of T cells, B cells, and antigen-presenting cells, making them an ideal location for the display of processed antigens to T cells. Therefore, lymph nodes are the most likely site for antigen-presenting cells to present processed antigens to T cells.

Congestive heart failure can result in ischemic hypoxia. Ischemic hypoxia occurs when there is a decrease in blood flow, leading to inadequate oxygen supply to tissues. In congestive heart failure, the heart is unable to pump blood effectively, causing reduced blood flow to various parts of the body. This can lead to ischemic hypoxia, as the tissues do not receive enough oxygen due to the compromised blood flow.

Interleukins are a type of chemical signals that immune cells use to communicate with each other. They are proteins produced by various immune cells and play a crucial role in regulating immune responses. Interleukins act as messengers, transmitting signals between different immune cells to coordinate their activities and responses to infections or diseases. They help in activating and directing immune cells to the site of infection, promoting inflammation, and enhancing the immune system's ability to fight off pathogens. Therefore, interleukins are essential for effective immune cell communication and overall immune system function.

Basophils are a type of white blood cell that plays a role in the immune response. They release certain substances to help other immune cells reach the site of infection or injury quickly. Heparin is an anticoagulant that prevents blood clotting, allowing immune cells to move freely. Histamine is a vasodilator that widens blood vessels, increasing blood flow to the site and facilitating the movement of immune cells. Therefore, the correct answer is heparin; histamine.

The mean arterial pressure is calculated by adding one-third of the difference between the systolic and diastolic pressures to the diastolic pressure. In this case, the difference between the systolic and diastolic pressures is 110 - 65 = 45 mm Hg. One-third of 45 mm Hg is 15 mm Hg. Adding 15 mm Hg to the diastolic pressure of 65 mm Hg gives us a mean arterial pressure of 80 mm Hg.

The medulla oblongata is responsible for controlling blood vessels throughout the body. It is a part of the brainstem and plays a crucial role in regulating various autonomic functions, including blood pressure and heart rate. The vasomotor center, located in the medulla oblongata, receives signals from the hypothalamus and adjusts the diameter of blood vessels to regulate blood flow and maintain homeostasis.

Myocardial infarction, also known as a heart attack, can lead to cardiogenic shock. This occurs when the heart is unable to pump enough blood to meet the body's needs, resulting in inadequate blood flow and oxygen delivery to the organs and tissues. Cardiogenic shock is a serious condition that can be life-threatening and requires immediate medical intervention.

Autoimmune diseases occur when the immune system mistakenly targets and attacks the body's own cells and tissues. In these disorders, the immune system fails to distinguish "self-antigens" from foreign antigens. Antigens are substances that can trigger an immune response, and "self-antigens" are normally present in the body. In autoimmune diseases, the immune system mistakenly identifies these self-antigens as foreign and launches an immune response against them, leading to inflammation and damage to the body's own tissues.

Tuberculosis is a bacterial infection caused by Mycobacterium that primarily affects the lungs. It leads to the formation of fibrous nodules in the infected lungs. This condition can cause various symptoms such as dyspnea (shortness of breath) due to the compromised lung function. Therefore, tuberculosis is the most appropriate answer for the given question.

Eosinophils are a type of white blood cell that are primarily found in the mucous membrane. They play a crucial role in the immune system by defending against parasites and allergens. These cells release toxic substances that help to kill parasites and regulate allergic reactions.

When the viscosity of blood increases, it means that the blood becomes thicker and less fluid. This increased thickness hinders the smooth flow of blood through the vessels, causing the velocity of blood flow to decrease. As a result, it takes longer for the blood to travel through the circulatory system, leading to a decrease in velocity.

In tuberculosis, the lungs are infected with Myocobacterium and produce fibrous nodules around the bacteria, leading to progressive pulmonary fibrosis.

Varicose veins are caused by the failure of the venous valves. When the valves in the veins of the lower limbs do not function properly, blood is not effectively pumped back to the heart and instead pools in the veins. This pooling of blood leads to the enlargement and twisting of the veins, resulting in varicose veins. An aneurysm or weak point in an artery or vein, as well as a ruptured aneurysm in a vein, are unrelated to the development of varicose veins. Failure of the lymphatic valves is also not a cause of varicose veins.

Dehydration would not increase capillary filtration because when the body is dehydrated, there is a decrease in blood volume, which leads to a decrease in blood pressure. Low blood pressure reduces the force pushing fluid out of the capillaries and into the surrounding tissues, resulting in decreased capillary filtration.

Atrial natriuretic peptide (ANP) is a hormone released by the heart in response to high blood pressure. Its main function is to promote the excretion of sodium and water, leading to a decrease in blood volume and blood pressure. Therefore, ANP does not increase blood pressure. On the other hand, angiotensin II, antidiuretic hormone (ADH), norepinephrine, and aldosterone all have vasoconstrictive effects and can increase blood pressure.

Epinephrine and angiotensin II are powerful vasoconstrictors, meaning they cause blood vessels to constrict or narrow. This leads to an increase in blood pressure. Additionally, epinephrine also increases heart rate, which further contributes to an increase in blood pressure.

A person who is HIV-positive and has a helper T (TH) cells count lower than 200 cells/μL has AIDS. This is because a low helper T cell count indicates a weakened immune system, which is a defining characteristic of AIDS.

The explanation for the correct answer is that specificity is a characteristic of the immune response, meaning that immunity is directed against a particular pathogen. This means that the immune system is able to recognize and target specific pathogens, such as bacteria or viruses, in order to mount an effective immune response. This specificity allows the immune system to differentiate between different pathogens and respond accordingly, leading to a more targeted and effective immune response.

B cells are a type of white blood cell that play a crucial role in the immune response. Before B cells secrete antibodies, they undergo a process called differentiation. During this process, B cells transform into plasma cells. Plasma cells are specialized B cells that produce and secrete large amounts of antibodies, which are proteins that help to identify and neutralize pathogens. Therefore, the correct answer is plasma cells.

Dalton's law states that the total pressure of a gas mixture is equal to the sum of the partial pressures of its individual gases. This means that in a mixture of gases, each gas exerts its own pressure independent of the others. The total pressure is simply the sum of these individual pressures. This law is important in understanding the behavior of gases in various mixtures and is widely used in fields such as chemistry and physics.

Carbonic anhydrase is the correct answer because it is the enzyme responsible for breaking down H2CO3 (carbonic acid) into water and carbon dioxide in red blood cells.

Lymph nodes are small, bean-shaped organs located throughout the body that play a crucial role in the immune system. They filter lymph fluid, trapping and destroying harmful substances such as bacteria and viruses. Lymph nodes receive lymph fluid through afferent lymphatic vessels, which carry lymph from the surrounding tissues to the node for filtration. The other options listed, such as the thymus, red bone marrow, tonsils, and spleen, are also lymphatic organs but do not have afferent lymphatic vessels as their primary function.

Neutrophils are a type of white blood cell that play a crucial role in the immune response. They are known for their ability to perform a "respiratory burst," which involves the production of bactericidal chemicals like hydrogen peroxide and hypochlorite. This respiratory burst helps neutrophils effectively kill bacteria and other pathogens. Therefore, neutrophils are the cells that employ a respiratory burst to produce bactericidal chemicals like hydrogen peroxide and hypochlorite.

Vaccination stimulates artificial active immunity because it involves the administration of a weakened or inactivated form of a pathogen or its components. This triggers the immune system to produce a specific response, including the production of antibodies and memory cells. As a result, the individual develops immunity to the pathogen, providing protection against future infections. This type of immunity is considered artificial because it is induced through a deliberate intervention, such as vaccination, rather than through natural exposure to the pathogen.

Each immunoglobulin (Ig) has two antigen-binding sites. These sites are located on the variable regions of the heavy and light chains of the Ig molecule. The antigen-binding sites are responsible for recognizing and binding to specific antigens, allowing the immune system to target and neutralize foreign substances. Having two antigen-binding sites allows for greater specificity and versatility in antigen recognition, enhancing the immune response.

The internal carotid artery supplies 80% of the cerebrum. This artery is a major blood vessel that provides oxygenated blood to the brain. It branches off from the common carotid artery and enters the skull through the carotid canal. Once inside the skull, it gives rise to several branches, including the middle cerebral artery, which supplies a large portion of the cerebrum. Therefore, the internal carotid artery is responsible for delivering a significant amount of blood to the cerebrum, making it the correct answer.

The pulmonary artery is the correct answer because it carries deoxygenated blood from the heart to the lungs. The alveoli in the lungs are responsible for gas exchange, where oxygen is taken in and carbon dioxide is released. The deoxygenated blood from the body is pumped into the pulmonary artery and then transported to the lungs, where it enters the capillaries surrounding the alveoli. In the alveoli, oxygen diffuses into the blood while carbon dioxide diffuses out, allowing for the exchange of gases. Therefore, the alveoli are surrounded by a basket of blood capillaries supplied by the pulmonary artery.

When CO2 enters the bloodstream, it combines with water to form carbonic acid. This carbonic acid then dissociates into bicarbonate ions and hydrogen ions. The majority of CO2 in the blood is transported in the form of bicarbonate ions. This is because bicarbonate ions are highly soluble in water and can easily be transported throughout the body. Additionally, bicarbonate ions can be converted back into CO2 in tissues where it is needed for cellular respiration. Therefore, bicarbonate ions play a crucial role in the transportation and regulation of CO2 in the bloodstream.

The correct answer is the pressure generated by the heart. The heart acts as a pump that creates pressure in the circulatory system, including the veins. This pressure pushes the blood forward, aiding in venous flow. While the other options, such as one-way flow due to valves, the thoracic pump, cardiac suction, and the skeletal muscle pump, also contribute to venous flow, the pressure generated by the heart is the most important force.

The brachiocephalic arteries, also known as the innominate arteries, are large arteries that arise from the aortic arch. In humans, there is only one brachiocephalic artery, which then branches into the right subclavian artery and the right common carotid artery. There is no left brachiocephalic artery in humans. Therefore, the correct answer is "right and left brachiocephalic arteries" because there are no brachiocephalic arteries on both sides in humans.

The correct answer is blood colloid osmotic pressure. When blood enters the capillaries, it contains proteins and other solutes that create an osmotic pressure. This osmotic pressure is higher in the blood compared to the tissue fluid, causing water and solutes to be drawn back into the capillaries from the interstitial space. This process is essential for maintaining fluid balance and preventing the buildup of excess fluid in the tissues. The other options mentioned, such as interstitial hydrostatic pressure and blood hydrostatic pressure, play a role in capillary filtration rather than reabsorption.

A mean arterial pressure (MAP) below 60 mmHg can cause syncope, which is a temporary loss of consciousness due to a lack of blood flow to the brain. On the other hand, a MAP above 160 mmHg can cause cerebral edema, which is the swelling of the brain due to increased pressure.

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Chronic bronchitis is a lung disease characterized by the reduction in the number and motility of cilia, which are hair-like structures that help in clearing mucus and foreign particles from the airways. The condition also leads to the enlargement of goblet cells, which produce excessive mucus, and the thickening of sputum. These changes result in the obstruction of the airways and difficulty in breathing. Oat-cell carcinoma is a type of lung cancer, atelectasis refers to the collapse of lung tissue, emphysema is characterized by the destruction of lung tissue, and asthma involves inflammation and narrowing of the airways.

Cytotoxic T (TC) cells are like natural killer (NK) cells because they both secrete granzymes and perforin. Granzymes are enzymes that induce apoptosis (cell death) in target cells, while perforin is a protein that forms pores in the target cell membrane, allowing granzymes to enter and initiate cell death. This mechanism is important in eliminating infected or cancerous cells. This similarity in function suggests that TC cells and NK cells play a similar role in the immune response.

The hypothalamus is responsible for regulating blood flow to various parts of the body. It helps maintain a stable blood flow to the organs and tissues, even when there are fluctuations in mean arterial pressure (MAP). This is because the hypothalamus can adjust the diameter of blood vessels and control blood flow accordingly. Therefore, blood flow to the hypothalamus remains quite stable despite changes in MAP.

The question asks for the tributaries of the inferior vena cava that are not included in the given options. The correct answer is "the vertebral veins". The other options - the internal and external iliac veins, the hepatic veins, the lumbar veins, and the inferior phrenic veins - are all tributaries of the inferior vena cava. Therefore, the vertebral veins are the only option that is not a tributary of the inferior vena cava.

Complement C3b protein coats bacteria and stimulates phagocytosis by neutrophils and macrophages in a process called opsonization. Opsonization is the process of marking pathogens for destruction by immune cells, such as neutrophils and macrophages, by coating them with molecules that enhance their recognition and uptake. This coating helps the immune cells recognize and bind to the bacteria more efficiently, leading to their engulfment and destruction.

Positive selection is a process that occurs in the thymus, where T cells are tested for their ability to recognize self-antigens. T cells that can recognize self-antigens with moderate affinity undergo positive selection. These selected T cells then multiply and form clones of identical T cells, which helps to ensure a diverse and specific T cell repertoire capable of recognizing a wide range of antigens. Therefore, the correct answer is that T cells undergo positive selection in the thymus, leading to the multiplication and formation of clones of identical T cells.

When a bee stings, it injects venom into the body. This venom can cause a massive release of histamine, which is a chemical that triggers an inflammatory response. Histamine causes blood vessels to widen, a process known as vasodilation. This widening of blood vessels leads to a decrease in arterial blood pressure. Therefore, the correct answer is "vasodilation; decrease."

The correct answer is celiac trunk, superior mesenteric artery, renal arteries, gonadal arteries, inferior mesenteric artery, and common iliac arteries. This is the correct order of the major branches of the abdominal aorta from superior to inferior. The celiac trunk is the first branch, followed by the superior mesenteric artery, renal arteries, gonadal arteries, inferior mesenteric artery, and finally the common iliac arteries.

The most important force driving filtration at the arterial end of a capillary is blood hydrostatic pressure. This pressure is exerted by the blood pushing against the walls of the capillary, forcing fluid and solutes out of the capillary and into the interstitial space. Oncotic pressure, blood colloid osmotic pressure, and tissue fluid colloid osmotic pressure all play roles in regulating fluid movement, but they are not the primary force driving filtration at the arterial end of a capillary.

The correct answer is the azygos system. The azygos system is responsible for draining blood from the thoracic organs. It is a network of veins that runs parallel to the vertebral column and collects blood from various organs, including the lungs, esophagus, and chest wall. The blood then flows into the superior vena cava, which carries it back to the heart. The other options mentioned, such as the coronary and pulmonary veins, mesenteric circulation, branches of the celiac trunk, and the hepatic portal system, are not primarily involved in the venous drainage of the thoracic organs.

The inspiratory reserve volume refers to the additional amount of air that can be inhaled with maximum effort, beyond the normal tidal volume. It represents the maximum amount of air that can be inhaled after a normal inhalation. This is different from inspiratory capacity, which is the total amount of air that can be inhaled after a normal exhalation. Expiratory reserve volume refers to the additional amount of air that can be exhaled with maximum effort, while vital capacity is the maximum amount of air that can be exhaled after a maximum inhalation. Residual volume is the amount of air that remains in the lungs after a maximum exhalation.

The medullary ischemic reflex is a physiological response that occurs when there is a decrease in blood flow to the brain. This reflex aims to increase circulation to the brain in order to maintain adequate perfusion and oxygenation. It does not result in increased circulation to the adrenal medulla or hormone secretion by the adrenal medulla. Ischemia of the medulla oblongata refers to a lack of blood supply to this region of the brain, which is not the outcome of the medullary ischemic reflex. Therefore, the correct answer is increased circulation to the brain.

The correct answer is vestibular and vocal ligaments. These two ligaments extend from the thyroid cartilage to the arytenoid cartilages. The vestibular ligaments, also known as false vocal cords, help to protect the vocal cords and assist in closing the glottis during swallowing. The vocal ligaments, also known as true vocal cords, are responsible for producing sound when air passes through them. Together, these ligaments play a crucial role in phonation and protecting the airway.

Bronchiole diameter will have the greatest influence on resistance to pulmonary airflow in a healthy person. The diameter of the bronchioles determines the amount of air that can flow through them. If the bronchioles are constricted or narrowed, it will increase resistance to airflow and make it more difficult for air to pass through. On the other hand, if the bronchioles are dilated or widened, it will decrease resistance to airflow and allow for easier breathing. Therefore, changes in bronchiole diameter can significantly affect the resistance to pulmonary airflow.