B) Arteries and veins

Explanation: Arteries, arterioles, venules, and veins are the primary distributing and collecting tubes in the circulatory system, facilitating the flow of blood to and from the heart.

D) Carbon dioxide

Explanation: While carbon dioxide is a metabolic by-product that is removed by the circulatory system, it is not an essential substance that is transported for the body's functions.

C) Left ventricle

Explanation: Blood flows from the left ventricle (LV) to the right atrium (RA) due to the pressure gradient created by the beating heart, which is crucial for maintaining proper circulation.

C) To facilitate gas exchange in the lungs

Explanation: The primary function of pulmonary circulation is to transport cardiac output from the right heart to the lungs for gas exchange, allowing for oxygen uptake and carbon dioxide removal.

B) It halves

Explanation: If the cross-sectional area (A) is doubled while keeping the flow rate (Q) constant, the velocity (v) will halve, as per the equation v = Q/A.

C) Lower pressure in pulmonary circulation

Explanation: The pulmonary circulation is characterized as a lower pressure system compared to the systemic circulation, which is crucial for understanding the dynamics of blood flow in the body.

B) It is adjustable to match metabolic demand

Explanation: The distribution of cardiac output can be adjusted based on the metabolic demands of different tissues, ensuring that organs receive the appropriate amount of blood flow according to their activity levels.

B) Hypoxia

Explanation: Hypoxia, or a deficiency in the amount of oxygen reaching the tissues, can trigger referred pain, particularly in conditions like angina pectoris and myocardial infarction.

B) 5%

Explanation: The heart receives approximately 5% of the resting cardiac output, which is essential for its nourishment and function.

C) Coronary arteries

Explanation: The coronary arteries are specifically responsible for supplying blood flow to the heart muscle, ensuring it receives the necessary oxygen and nutrients.

B) To pump blood

Explanation: The heart serves as the pump of the circulatory system, responsible for circulating blood throughout the body to deliver oxygen and nutrients to tissues.

B) To exchange nutrients between tissue and blood

Explanation: Capillaries are extensive thin vessels that facilitate nutrient and gas exchange between blood and surrounding tissues, playing a crucial role in the circulatory system.

B) Right heart

Explanation: The right heart is responsible for pulmonary circulation, pumping deoxygenated blood to the lungs for gas exchange.

B) To regulate flow to individual vessel beds

Explanation: Vascular resistance plays a crucial role in regulating blood flow to specific vessel beds, allowing the body to direct blood where it is needed most based on various physiological demands.

C) Blood

Explanation: Blood is the primary fluid circulated by the cardiovascular system, transporting oxygen, nutrients, and waste products throughout the body.

B) By altering vessel diameter

Explanation: Vascular resistance can be adjusted primarily by changing the diameter of blood vessels, which affects the flow rate and distribution of blood throughout the body.

C) Higher resistance to flow in systemic circulation

Explanation: Cardiac output can be the same between pulmonary and systemic circulation because the systemic circulation has a higher resistance to flow, which compensates for the lower pressure in the pulmonary circulation.

B) Blood flow decreases

Explanation: An increase in vascular resistance typically results in a decrease in blood flow, as the higher resistance makes it more difficult for blood to pass through the vessels.

C) Carbon dioxide

Explanation: The circulatory system is responsible for the removal of metabolic by-products, with carbon dioxide being a primary waste product that needs to be expelled from the body.

B) To maintain a relatively constant blood pressure gradient

Explanation: Regulating blood flow distribution is crucial for maintaining a stable blood pressure gradient, which is essential for proper circulation and overall cardiovascular health.

C) Flow down a pressure gradient

Explanation: Bulk flow refers to the movement of liquid or gas in a direction determined by the pressure gradient, meaning it moves from areas of higher pressure to areas of lower pressure, which is essential for blood circulation.

B) By transporting heat throughout the body

Explanation: The circulatory system helps regulate body temperature by transporting heat generated by metabolic processes to different parts of the body, thus maintaining a stable internal temperature.

C) Brain and heart

Explanation: The brain and heart are critical organs that must always receive a continuous blood supply to function properly; any interruption can lead to serious consequences.

B) It beats harder

Explanation: During exercise, the heart beats harder to pump more blood and oxygen to the working muscles, which is essential for sustaining physical activity.

B) To supply oxygen to muscles

Explanation: The primary goal of increased blood flow during exercise is to supply oxygen to the muscles, which is necessary for energy production and performance.

C) By decreasing heart rate and blood flow

Explanation: After exercise, the heart function returns to normal as the heart rate and blood flow gradually decrease, allowing the body to recover from the physical exertion.

B) Angina pectoris

Explanation: Angina pectoris is a condition that arises from impaired blood flow in the coronary arteries, resulting in chest pain due to insufficient oxygen supply to the heart muscle.

B) Higher resistance to flow

Explanation: Systemic circulation is characterized by higher resistance to flow compared to pulmonary circulation, which is essential for maintaining adequate blood pressure and flow throughout the body.

D) Bacteria

Explanation: The circulatory system transports essential components like WBCs, hormones, nutrients, and platelets, but it does not transport bacteria as a normal function.

B) Pulmonary and systemic pumps

Explanation: The heart functions as two pumps in series: the pulmonary pump, which sends blood to the lungs, and the systemic pump, which distributes blood to the rest of the body.

C) Blood flow increases

Explanation: A decrease in resistance (R) to flow allows for an increase in blood flow (Q), as less hindrance means blood can move more freely through the vessels.

B) They affect the vessel's ability to contract and expand

Explanation: The varying amounts of tissue layers in blood vessels are significant because they affect the vessel's ability to contract and expand, which is crucial for maintaining proper blood circulation and pressure.

B) To facilitate gas exchange

Explanation: Exchange vessels, primarily capillaries, are designed for the exchange of gases, nutrients, and waste products between blood and tissues, making them crucial for metabolic processes.

B) By the blood supply from coronary arteries

Explanation: The heart muscle is nourished by the blood supplied through the coronary arteries, which deliver oxygen and nutrients necessary for the heart's function.

B) Parallel circuits have lower resistance than series circuits

Explanation: In parallel circuits, the total resistance is lower compared to series circuits, allowing for more efficient blood flow and distribution to various organs and tissues.

B) Blood can bypass certain organs if needed

Explanation: In a parallel circuit, blood can be directed to different organs independently, allowing for the possibility of bypassing certain organs based on the body's immediate needs.

C) Returns deoxygenated blood from the systemic circulation

Explanation: The vena cava is responsible for returning deoxygenated blood from the systemic circulation back to the heart, completing the circuit of blood flow.

D) Heart rate

Explanation: While heart rate affects overall blood flow, it is not a direct determinant of vascular resistance, which is influenced by factors such as vessel length, diameter, and blood viscosity.

B) It provides a continuous pressure gradient (ΔP)

Explanation: The beating heart generates a continuous pressure gradient (ΔP) that allows blood to flow from the left ventricle (LV) to the right atrium (RA), facilitating effective circulation throughout the body.

B) Myocardial infarction

Explanation: Myocardial infarction, commonly known as a heart attack, is a more severe condition that results from prolonged impaired blood flow, leading to significant tissue damage in the heart muscle.

C) Flow rate

Explanation: In the equation v = Q/A, 'Q' represents the flow rate, which can be measured in units such as mL/min or L/min.

A) Overview of the circulatory system

Explanation: Lecture 14 is specifically titled 'Overview of the circulation,' indicating that the main focus is on the circulatory system as a whole.

C) To control blood flow from the right ventricle to the pulmonary artery

Explanation: The Pulmonary (Semilunar) Valve is located between the right ventricle and the pulmonary artery, ensuring proper blood flow to the lungs.

B) Increased cross-sectional area leads to decreased velocity

Explanation: In the circulatory system, as the cross-sectional area of blood vessels increases (such as in capillaries), the velocity of blood flow decreases, allowing for more efficient exchange of substances.

C) In arteries

Explanation: Blood flow velocity is fastest in arteries due to their larger diameter and lower total cross-sectional area compared to other vessel types.

B) To receive venous return

Explanation: The atria are responsible for receiving venous return, collecting blood from the body and lungs before it is pumped into the ventricles.

B) To maintain homeostasis

Explanation: The circulatory system plays a crucial role in maintaining homeostasis by transporting and distributing essential substances throughout the body.

B) Fainting or heart attack

Explanation: If blood flow to the brain and heart is compromised, it can result in fainting or even a heart attack, highlighting the critical need for consistent blood supply to these vital organs.

B) Cholesterol build-up

Explanation: Cholesterol build-up in the arteries can lead to impaired blood flow, contributing to conditions such as angina pectoris and myocardial infarction.

B) The measure of hindrance to blood flow caused by friction

Explanation: Vascular resistance is defined as the measure of hindrance to blood flow that occurs due to friction between the moving blood and the vessel wall.

B) To transport oxygen and nutrients

Explanation: One of the main functional roles of the cardiovascular system is to transport oxygen and nutrients throughout the body, which is essential for maintaining cellular function and overall health.

C) Conduct blood flow

Explanation: Conduit vessels, such as arteries, are primarily responsible for conducting blood from the heart to various parts of the body, ensuring efficient blood flow.

C) Digestive tract

Explanation: Blood flow to the digestive tract decreases during exercise as the body prioritizes blood supply to the working muscles, skin, and heart.

C) Fighting infections

Explanation: Leukocytes, or white blood cells, play a crucial role in the immune system by fighting infections and protecting the body against foreign invaders.

B) To determine blood flow direction

Explanation: The valves in the heart ensure that blood flows in the correct direction, preventing backflow and maintaining efficient circulation.

C) Pressure gradient (ΔP)

Explanation: Blood always flows from regions of higher pressure to regions of lower pressure, which is defined as the pressure gradient (ΔP). This fundamental principle governs the movement of blood throughout the circulatory system.

B) Increased heart rate

Explanation: During exercise, such as doing jumping jacks, one of the most noticeable physiological responses is an increased heart rate, which helps supply more oxygen to the muscles.

B) Cholesterol-lowering drugs

Explanation: The treatment for impaired blood flow caused by cholesterol build-up often involves the use of cholesterol-lowering drugs, which help reduce the levels of cholesterol in the blood and improve arterial health.

B) To regulate blood flow and pressure

Explanation: Different tissue layers in blood vessels serve to regulate blood flow and pressure, adapting to the specific needs of the circulatory system.

C) Tricuspid Valve

Explanation: The Tricuspid Valve is specifically identified as the right atrioventricular (AV) valve, playing a crucial role in blood flow from the right atrium to the right ventricle.

C) The resistance of blood vessels

Explanation: Blood flow distribution is primarily determined by the resistance encountered in blood vessels, which can vary based on their diameter and elasticity, affecting how blood is directed to different tissues.

C) To meet the metabolic demands of active tissues

Explanation: The primary reason for the redistribution of blood flow during exercise is to ensure that active tissues, such as working skeletal muscles, receive adequate blood supply to meet their increased metabolic demands.

B) Series circuits

Explanation: Series circuits have higher overall resistance compared to parallel circuits, which can affect the efficiency of blood flow and the pressure required to maintain circulation.

B) To distribute blood to systemic circulation

Explanation: The aorta is the main artery that distributes oxygenated blood from the heart to the rest of the body, playing a crucial role in systemic circulation.

B) It is divided into many parallel circuits

Explanation: In systemic circulation, the cardiac output from the left heart is divided into multiple parallel circuits, allowing for efficient distribution of blood throughout the body.

D) Color of the blood

Explanation: The color of the blood does not influence the structure of blood vessels; rather, it is the function and type of the vessel that determine the number of tissue layers.

B) To support the heart valves

Explanation: The fibrous rings provide structural support to the four heart valves, ensuring they function properly during the cardiac cycle.

B) To pump blood throughout the body

Explanation: The primary function of the heart is to pump blood, ensuring that oxygen and nutrients are delivered to tissues and organs while also facilitating the removal of waste products.

D) Body temperature

Explanation: While body temperature can affect overall metabolism, it is not a direct factor influencing blood flow. Blood flow is primarily influenced by blood pressure, viscosity, heart rate, and the diameter of blood vessels.

B) Blood flows through one pathway to reach each organ

Explanation: In series circuits, blood flows through a single pathway, meaning it must pass through each organ sequentially, which can affect the overall efficiency of blood distribution.

C) They eject blood from the heart

Explanation: The ventricles contract to eject blood from the heart, sending it either to the lungs for oxygenation or to the systemic circulation.

B) The return of blood to the heart from the body

Explanation: Venous return refers to the process by which blood returns to the heart from the systemic circulation, completing the circuit of blood flow.

C) ΔP must increase

Explanation: To maintain the same blood flow (Q) when resistance (R) increases, the pressure difference (ΔP) must also increase, as described by the equation Q = ΔP / R.

B) Blood storage

Explanation: Capacitance vessels, such as veins, are primarily responsible for storing blood, which allows them to accommodate varying volumes of blood in the circulatory system.

D) Mitral (Bicuspid) Valve

Explanation: The Mitral Valve, also known as the Bicuspid Valve, is the left atrioventricular (AV) valve, facilitating blood flow from the left atrium to the left ventricle.

C) It remains unchanged

Explanation: Blood flow to the brain remains relatively unchanged during exercise, as the brain requires a constant supply of blood regardless of physical activity levels.

B) They allow for independent regulation of blood flow to different organs

Explanation: Parallel circuits enable the body to regulate blood flow independently to various organs, allowing for tailored responses to different physiological needs.

C) They act as resistance vessels

Explanation: Arterioles are known as resistance vessels because they regulate blood flow and pressure by constricting or dilating, thus controlling the resistance to blood flow.

C) Blood flow increases

Explanation: Blood flow (Q) is directly proportional to the pressure difference (ΔP) between two points; therefore, an increase in ΔP results in an increase in blood flow.

C) Q = ΔP / R

Explanation: The relationship is defined by the equation Q = ΔP / R, indicating that blood flow is directly proportional to the pressure difference and inversely proportional to resistance.

B) Science Hall 380E

Explanation: Dr. Ann Revill's office is located in Science Hall 380E, as mentioned in the provided text.

B) It varies based on vessel function

Explanation: The cross-sectional area and percentage of total blood volume in systemic blood vessels vary according to their specific functions, which is essential for maintaining proper circulation and blood flow dynamics.

B) Plasma

Explanation: The liquid portion of blood is referred to as plasma, which contains water, ions, proteins, nutrients, waste, gases, and hormones, serving as the medium in which cellular elements are suspended.

C) Blood clotting

Explanation: Platelets are essential for blood clotting, helping to prevent excessive bleeding when injuries occur.

C) Site of exchange

Explanation: Capillaries are the primary site of exchange for nutrients, gases, and waste products between blood and tissues, making them crucial for cellular function.

C) Velocity increases

Explanation: According to the principle that if flow through a tube is constant, the velocity increases as the cross-sectional area decreases, as described by the equation v = Q/A.

B) 10 cm/s

Explanation: Using the equation v = Q/A, if Q = 100 mL/min and A = 10 cm², then v = 100 mL/min ÷ 10 cm² = 10 cm/s.

C) Lungs

Explanation: While the lungs are crucial for gas exchange, they are not considered a component of the cardiovascular system, which primarily includes the heart, blood vessels, and blood.

B) To form an electrical insulator between atria and ventricles

Explanation: The fibrous skeleton acts as an electrical insulator, preventing direct electrical conduction between the atria and ventricles, which is essential for coordinated heart contractions.

D) Neurons

Explanation: Neurons are not a component of blood. The main components of blood include erythrocytes (red blood cells), leukocytes (white blood cells), platelets, and plasma.

B) It remains constant

Explanation: Despite the variations in blood flow velocity among different vessel types, blood flow itself remains constant throughout the systemic circulation.

C) Collect blood from capillary beds

Explanation: Venules are responsible for collecting blood from capillary beds and transporting it to veins, playing a key role in the return of blood to the heart.

B) The function of the vessel

Explanation: The number of tissue layers in each type of blood vessel is determined by its specific function, which influences its structural characteristics.

C) Arteries

Explanation: Arteries typically have the most tissue layers compared to other blood vessel types, allowing them to withstand and regulate high pressure from the heart's pumping action.

C) Right atrium → Right ventricle → Pulmonary artery → Left atrium

Explanation: Blood flows from the right atrium to the right ventricle, then to the pulmonary artery for oxygenation, before returning to the left atrium, illustrating the directional flow through the heart.

B) Semilunar valves

Explanation: The semilunar valves (pulmonary and aortic valves) prevent backflow of blood into the ventricles after contraction, ensuring that blood flows forward into the arteries.

C) Red blood cells

Explanation: Erythrocytes are commonly known as red blood cells (RBCs), which are responsible for transporting oxygen throughout the body.

B) They have a small diameter

Explanation: Capillaries are characterized by their small diameter, which facilitates the exchange of nutrients and gases between blood and tissues.

D) Capacitance vessel and blood reservoir

Explanation: Veins function as capacitance vessels, meaning they can hold a large volume of blood and act as a blood reservoir, helping to regulate blood flow back to the heart.

C) cm²

Explanation: The cross-sectional area (A) in the equation v = Q/A is measured in square centimeters (cm²).

B) To prevent backflow of blood

Explanation: The primary function of the heart valves is to ensure unidirectional blood flow through the heart, preventing backflow and maintaining efficient circulation.

B) Blood is pushed into the arteries

Explanation: During ventricular contraction, blood is pushed from the ventricles into the arteries, specifically the pulmonary artery and aorta, facilitating circulation throughout the body.

C) Kidneys

Explanation: Blood flow to the kidneys decreases during exercise, as the body redirects blood to areas that are more active, such as the skeletal muscles and skin.

C) It is larger than that of arteries

Explanation: The total cross-sectional area of all capillaries combined is very large compared to that of arteries, which contributes to the slower velocity of blood flow in capillaries.

C) To bring blood to the lungs for oxygenation

Explanation: The pulmonary arteries carry deoxygenated blood from the heart to the lungs, where it is oxygenated.

B) Dr. Ann Revill

Explanation: The lecture is conducted by Dr. Ann Revill, as indicated in the provided information.

C) They separate the atria from the ventricles

Explanation: The atrioventricular valves (tricuspid and mitral) separate the atria from the ventricles and ensure that blood flows in the correct direction, preventing backflow during ventricular contraction.

C) Working skeletal muscle

Explanation: During exercise, blood flow is redistributed to increase in working skeletal muscles, skin, and the heart to meet the heightened metabolic demands.

C) Capillaries

Explanation: Capillaries have the slowest blood flow velocity because they have a small diameter, allowing for efficient nutrient and gas exchange.

C) Rapid-transit passageways and pressure reservoir

Explanation: Arteries serve as rapid-transit passageways for blood and act as a pressure reservoir, allowing for efficient blood flow from the heart to various parts of the body.