The correct answer is Choice D.

Choice A rationale:

Vasoconstriction refers to the narrowing of blood vessels. When blood vessels constrict, they reduce the volume of blood that can flow through them, which increases the pressure. However, the flow is decreased, not increased.

Choice B rationale:

As explained above, vasoconstriction increases pressure but decreases flow.

Choice C rationale:

While vasoconstriction does increase pressure, it does not increase flow. Instead, it decreases flow.

Choice D rationale:

Vasoconstriction results in increased pressure and decreased flow. This happens because the narrowing of the blood vessels increases the resistance to blood flow, thereby increasing the pressure. At the same time, the reduced diameter of the blood vessels decreases the amount of blood that can flow through them.

Answer and explanation

The correct answer is Choice C.

Choice A rationale:

Baroreceptors are sensors located in the blood vessels that detect changes in blood pressure. However, they do not coordinate blood pressure control. They send signals to the brain about blood pressure changes, and the brain coordinates the response.

Choice B rationale:

The brainstem is a part of the brain that connects the cerebrum with the spinal cord. It contains structures that are involved in many vital body functions, including breathing and heart rate regulation. However, it is not the primary structure that coordinates blood pressure control.

Choice C rationale:

The medulla oblongata, a part of the brainstem, contains the cardiovascular centers that coordinate the regulation of heart rate and blood pressure.

Choice D rationale:

The thalamus is a part of the brain that is primarily involved in processing sensory information and regulating consciousness, sleep, and alertness. It does not coordinate blood pressure control.

Answer and explanation

The correct answer is Choice A.

Choice A rationale:

The conchae or turbinates are structures in the nasal cavity that increase the surface area of the mucosa exposed to the air. As air passes over the mucosa, it picks up moisture and heat, which helps to humidify and warm the air before it reaches the lungs.

Choice B rationale:

The sphenoid is a bone located at the base of the skull. It does not have a direct role in the heating or humidification of air.

Choice C rationale:

The nasopharynx is part of the pharynx that connects the nasal cavity to the throat. While it does play a role in the passage of air from the nose to the lungs, it is not the primary site where air picks up moisture and heat.

Choice D rationale:

The oropharynx is another part of the pharynx, located below the nasopharynx. It is involved in both respiratory and digestive processes, but it is not the main site where air picks up moisture and heat.

So, the correct answer is Choice A, after analyzing all choices.

Choice A rationale:

Increased blood viscosity is not typically associated with atherosclerosis. While high blood viscosity can contribute to cardiovascular problems, it is not a condition that you would expect to accompany atherosclerosis.

Choice B rationale:

Irregular heartbeat, or arrhythmia, is not typically a condition that accompanies atherosclerosis. While atherosclerosis can increase the risk of certain types of arrhythmias, it is not a direct result of the disease.

Choice C rationale:

High blood pressure, or hypertension, is often associated with atherosclerosis. The buildup of plaque in the arteries causes them to narrow and stiffen, which increases the resistance to blood flow and consequently increases blood pressure.

Choice D rationale:

Low blood pressure is not typically associated with atherosclerosis. Atherosclerosis tends to increase blood pressure rather than decrease it.

Choice A rationale:

Sinuses are indeed air-filled cavities. They are hollow spaces in the skull and the face bones around your nose.

Choice B rationale:

Sinuses are located in the skull and around the nose. There are four pairs of sinuses, named for the bones that they’re located in.

Choice C rationale:

One of the functions of the sinuses is to help lighten the head. The air-filled cavities provide a sort of crumple zone that can absorb impact and protect the brain.

Choice D rationale:

Gas exchange does not occur in the sinuses. The primary function of the sinuses is to produce mucus that moistens the inside of the nose. This mucus layer serves to trap dust and other particles that might otherwise reach the lungs.

Choice E rationale:

The sinuses do not directly help with hearing. The structures that are primarily responsible for hearing are the ears, specifically the eardrums and the bones of the middle ear. So, the correct answers are Choices A, B, and C, after analyzing all choices. .

Naturally acquired active immunity occurs when the body produces antibodies in response to an infection or vaccine. This is not the case for antibodies passed through the placenta.

Choice B rationale:

Artificially acquired passive immunity involves the injection of antibodies, not the transfer through the placenta.

Choice C rationale:

Innate immunity refers to nonspecific defense mechanisms that come into play immediately or within hours of an antigen’s appearance in the body. This does not describe the process of antibody transfer through the placenta.

Choice D rationale:

Natural passive immunity occurs when antibodies are passed from the mother to the fetus through the placenta. This matches the description in the question.

So, the correct answer is Choice D, after analyzing all choices.

The correct answer is Choice B.

Choice A rationale:

Venules are small vessels that collect blood from the capillaries and transport it to the veins. They are not primarily involved in the exchange of nutrients, wastes, and hormones.

Choice B rationale:

Capillaries are tiny vessels that branch out from arterioles to form networks around body cells. They are the primary sites for the exchange of gases, nutrients, and waste between blood and tissues.

Choice C rationale:

Arterioles are small branches of arteries that lead to capillaries. They primarily regulate blood pressure and blood flow, not the exchange of substances.

Choice D rationale:

Veins carry deoxygenated blood back to the heart. They are not the primary sites for substance exchange.

Choice A rationale:

Expiration, also known as exhalation, is the process of air leaving the lungs.

Choice B rationale:

Respiration is a broader term that includes both the inhalation and exhalation processes.

Choice C rationale:

Inhalation is the process of drawing air into the lungs, not exhaling.

Choice D rationale:

Inspiration is another term for inhalation, not exhalation.

Choice A rationale:

HIV invades various immune cells, most notably CD4+ T cells, eventually destroying them.

Choice B rationale:

D cells are not a recognized category of immune cells, and HIV does not specifically invade them.

Choice C rationale:

While B cells are part of the immune system, HIV primarily targets CD4+ T cells, not B cells.

Choice D rationale:

Helper C cells are not a recognized category of immune cells, and HIV does not specifically invade them.

Choice A rationale:

Vasodilation increases the diameter of blood vessels, which decreases resistance and thus decreases pressure. However, the increased diameter allows for increased blood flow, not decreased.

Choice B rationale:

Vasodilation decreases pressure due to the increased diameter of the blood vessels, and it increases flow because of the reduced resistance to blood flow.

Choice C rationale:

Vasodilation does not increase pressure; it decreases it.

Choice D rationale:

While vasodilation decreases pressure, it does not decrease flow; it increases it.

Choice A rationale:

Abdominal thrusts, also known as the Heimlich maneuver, are a first-aid technique used to treat conscious choking victims in which the rescuer delivers thrusts to a patient’s upper abdominal region. This motion pushes air from the lungs up through the throat to dislodge foreign objects and treat upper airway obstructions.

Choice B rationale:

Chest thrusts can also be used if needed. However, they are not the primary method for dislodging a foreign object in someone that is choking.

Choice C rationale:

Chest pumps are not a recognized method for dislodging a foreign object in someone that is choking.

Choice D rationale:

Bowel thrusts are not a recognized method for dislodging a foreign object in someone that is choking.

So, the correct answer is Choice A.

hoice A rationale:

Inspired gas passes through the convoluted air passages of the nasopharynx and pharynx which generates turbulence. This turbulence increases evaporative heat exchange between the air and the mucosa. The nasal mucosa is the lining of the nasal cavity. It moistens air that is coming into the body during inhalation.

Choice B rationale:

The sphenoid is a bone located within the skull and does not directly contribute to the heating and humidification of air.

Choice C rationale:

The nasopharynx is part of the pharynx, located above the soft palate. It serves as an air passage way connecting the nasal cavity to the throat and does not directly heat or humidify the air.

Choice D rationale:

The oropharynx is also part of the pharynx, located between the soft palate and the epiglottis. It serves as a passageway for both air and food but does not directly heat or humidify the air.

The correct answer is Choice B.

Choice A rationale:

Nitrogen is the most abundant gas in the atmosphere, but it is not the primary regulator of respiration.

Choice B rationale:

Carbon dioxide (CO2) is the main chemical regulator of respiration and the potent stimulus of the respiratory centers via the arterial chemoreceptors and directly on the central chemoreceptors.

Choice C rationale:

Oxygen is essential for cellular respiration, but it is not the primary regulator of respiration.

Choice D rationale:

Bicarbonate plays a role in maintaining the pH balance in the blood and is not the primary regulator of respiration.

Choice A rationale:

Sinusoids are a type of capillary found in some organs, such as the liver, bone marrow, and spleen. They are not vessels that carry blood away from the heart.

Choice B rationale:

Veins are blood vessels that carry blood from the body back into the heart.

Choice C rationale:

Capillaries are delicate blood vessels that deliver blood, nutrients and oxygen to cells throughout the body. They do not carry blood away from the heart.

Choice D rationale:

Arteries are blood vessels that carry oxygenated blood away from the heart to the body.

Choice A rationale:

Osmosis is the process by which water molecules move from an area of high concentration to an area of low concentration across a semi-permeable membrane. It does not directly involve the exchange of oxygen and carbon dioxide in capillaries.

Choice B rationale:

Diffusion is the process by which molecules move from an area of high concentration to an area of low concentration. At the respiratory membrane, where the alveolar and capillary walls meet, gases move across the membranes, with oxygen entering the bloodstream and carbon dioxide exiting.

Choice C rationale:

Filtration is a process that separates particles from a liquid or gas, and it does not directly involve the exchange of oxygen and carbon dioxide in capillaries.

Choice D rationale:

Colloid osmotic pressure refers to the pressure exerted by proteins in a blood vessel’s plasma that usually tends to pull water into the circulatory system. It does not directly involve the exchange of oxygen and carbon dioxide in capillaries.

Veins have valves that ensure blood flows toward your heart. They work hard, against gravity, to bring the blood that flowed down via arteries back up to your heart. This prevents the backflow of blood.

Choice B rationale:

Veins do not aid in the redirection of blood flow. Their primary function is to return deoxygenated blood from the body back to the heart.

Choice C rationale:

The function of preventing oxygenated blood from mixing with unoxygenated blood is not performed by the valves in veins but by the structure of the circulatory system itself.

Choice D rationale:

While veins do aid in the circulation of blood, they do not aid in the pumping of blood. The pumping action is performed by the heart.

Choice A rationale:

Capillaries are the smallest blood vessels that connect arteries and veins. They allow nutrients in the blood to diffuse to the body’s tissues.

Choice B rationale:

Arteries carry oxygen-rich blood from the heart to the tissues of the body. They do not connect the two sides of the vascular system.

Choice C rationale:

Venules are very small blood vessels that connect capillaries with veins throughout the body. They do not connect the two sides of the vascular system.

Choice D rationale:

Veins carry blood back toward the heart. They do not connect the two sides of the vascular system

Choice A rationale:

Low blood viscosity is not the primary reason blood constantly circulates. It is the heart that creates the pressure increase in arteries that pushes blood through the body.

Choice B rationale:

Vasoconstriction and dilation are not the primary reasons blood constantly circulates. They are mechanisms that help regulate blood flow and pressure, but the constant circulation of blood is due to the beating of the heart.

Choice C rationale:

Pressure gradients play a role in blood circulation, but they are not the primary reason blood constantly circulates. The heart is the organ that creates the pressure increase in arteries that pushes blood through the body.

Choice D rationale:

The beating of the heart is the primary reason that blood constantly circulates throughout the body.

The correct answer is Choice A.

Choice A rationale:

The pleural fluid functions by lubricating the space between the pleura, allowing the pleura to glide smoothly during inhalation and exhalation. This cushions delicate lung tissues against friction from the ribs and the chest wall itself.

Choice B rationale:

The fluid in the pleural cavity does not warm and moisten lung tissue. This is not one of its primary functions.

Choice C rationale:

The fluid in the pleural cavity does not prevent bacteria from entering lung tissue. This is not one of its primary functions.

Choice D rationale:

The fluid in the pleural cavity does not assist in the diffusion of oxygen across the respiratory membrane. This is not one of its primary functions.

Choice A rationale:

Veins do not always carry deoxygenated blood. The pulmonary veins are an exception as they carry oxygenated blood from the lungs to the heart.

Choice B rationale:

Veins do not carry blood away from the heart. They carry blood back toward the heart.

Choice C rationale:

Veins do not have a thick tunica media. The tunica media is thinner in veins than in arteries.

Choice D rationale:

Veins have valves. This is a true statement. The valves in veins prevent blood from flowing backward.

Choice A rationale:

Low blood viscosity is not the primary reason blood constantly circulates. It is the heart that creates the pressure increase in arteries that pushes blood through the body.

Choice B rationale:

Vasoconstriction and dilation are not the primary reasons blood constantly circulates. They are mechanisms that help regulate blood flow and pressure, but the constant circulation of blood is due to the beating of the heart.

Choice C rationale:

Pressure gradients play a role in blood circulation, but they are not the primary reason blood constantly circulates. The heart is the organ that creates the pressure increase in arteries that pushes blood through the body.

Choice D rationale:

The beating of the heart is the primary reason that blood constantly circulates throughout the body.

Choice A rationale:

The pleural fluid functions by lubricating the space between the pleura, allowing the pleura to glide smoothly during inhalation and exhalation. This cushions delicate lung tissues against friction from the ribs and the chest wall itself.

Choice B rationale:

The fluid in the pleural cavity does not warm and moisten lung tissue. This is not one of its primary functions.

Choice C rationale:

The fluid in the pleural cavity does not prevent bacteria from entering lung tissue. This is not one of its primary functions.

Choice D rationale:

The fluid in the pleural cavity does not assist in the diffusion of oxygen across the respiratory membrane. This is not one of its primary functions.

Choice A rationale:

Veins do not always carry deoxygenated blood. The pulmonary veins are an exception as they carry oxygenated blood from the lungs to the heart.

Choice B rationale:

Veins do not carry blood away from the heart. They carry blood back toward the heart.

Choice C rationale:

Veins do not have a thick tunica media. The tunica media is thinner in veins than in arteries.

Choice D rationale:

Veins have valves. This is a true statement. The valves in veins prevent blood from flowing backward.

Choice A rationale:

A pneumothorax, or collapsed lung, occurs when air leaks into the space between the lung and chest wall. This is not directly caused by pressure in the lungs dropping lower than atmospheric pressure.

Choice B rationale:

Bronchioles constricting could lead to respiratory distress, but this is not a direct result of the pressure in the lungs dropping lower than atmospheric pressure.

Choice C rationale:

When the pressure within the lungs drops lower than atmospheric pressure, air flows into the lungs. This is a fundamental principle of respiration.

Choice D rationale:

Air flows out of the lungs when the pressure within the lungs rises above atmospheric pressure, not when it drops.

Choice A rationale:

Arteries carry oxygen-rich blood away from the heart to various organs and tissues.

Choice B rationale:

Arteries do not carry blood away from the body. They transport blood within the body.

Choice C rationale:

While arteries do distribute blood throughout the body, this statement is too general and does not accurately describe the primary function of arteries.

Choice D rationale:

Arteries do not carry blood to the heart; this is the function of veins.