B) The formation of new blood vessels

Explanation: Angiogenesis refers to the physiological process through which new blood vessels form from pre-existing vessels, playing a vital role in long-term control of blood flow and tissue perfusion.

C) Autoregulation mechanisms

Explanation: Basal blood flow is significantly influenced by autoregulation mechanisms, which allow organs to maintain a consistent blood supply despite fluctuations in systemic blood pressure.

B) Myogenic and Metabolic

Explanation: Autoregulation of blood flow involves both myogenic and metabolic theories, which work together to maintain consistent blood flow despite changes in perfusion pressure.

C) It influences vascular tone and blood flow

Explanation: The endothelium plays a crucial role in regulating blood flow by releasing various substances that influence vascular tone, thereby affecting blood flow dynamics.

C) It increases blood flow to active tissues

Explanation: Metabolic activity in tissues leads to the release of vasodilators, which increases blood flow to active tissues, ensuring they receive the necessary oxygen and nutrients to meet their metabolic demands.

C) Metabolic control

Explanation: Metabolic control of blood flow is primarily responsible for adjusting blood supply to tissues based on their metabolic needs, ensuring that areas with higher activity receive more blood.

B) A temporary occlusion of blood flow

Explanation: Reactive hyperemia occurs when there is a temporary blockage of blood flow, leading to a subsequent increase in blood flow to the affected area once the blockage is removed, compensating for the lost perfusion.

B) Blood flow is adjusted based on metabolic activity

Explanation: The metabolic theory of autoregulation posits that blood flow is regulated according to the metabolic needs of tissues, ensuring that areas with higher metabolic activity receive more blood supply.

B) To facilitate gas exchange

Explanation: Capillary beds play a crucial role in local blood flow control by facilitating gas exchange and nutrient delivery to tissues, which is essential for maintaining organ function.

C) They facilitate nutrient and gas exchange

Explanation: Capillary beds are integral to the circulatory system as they are the primary sites for nutrient and gas exchange between blood and tissues, ensuring that cells receive the necessary substances for metabolism.

B) Vasodilation

Explanation: Increased carbon dioxide levels in tissues lead to vasodilation, which enhances blood flow to those areas, facilitating the removal of carbon dioxide and the delivery of oxygen.

B) Nitric oxide

Explanation: Nitric oxide is a potent vasodilator produced by endothelial cells, playing a crucial role in regulating blood flow by relaxing smooth muscle in blood vessels.

B) Increased blood flow in response to increased metabolic activity

Explanation: Active hyperemia refers to the physiological response where blood flow increases in a tissue due to heightened metabolic activity, such as during exercise or increased organ function.

B) Maintenance of near constant blood flow for a particular metabolic level

Explanation: The primary function of autoregulation is to maintain a stable blood flow that corresponds to the metabolic needs of tissues, ensuring that they receive adequate oxygen and nutrients regardless of changes in systemic blood pressure.

B) It ensures adequate oxygen supply to tissues

Explanation: Local control of blood flow is significant because it ensures that organs receive an adequate supply of oxygen and nutrients based on their metabolic needs, which is vital for their proper functioning.

B) Supplying organs with oxygen and nutrients

Explanation: Basal blood flow is crucial for providing organs with the necessary oxygen and nutrients required for their normal functioning, ensuring metabolic processes are maintained.

C) It increases tissue blood flow

Explanation: Reduced oxygen levels lead to an increase in tissue blood flow, as the body compensates to deliver more oxygen to the tissues that need it.

B) It inhibits platelet aggregation and promotes vasodilation

Explanation: Prostacyclin is an endothelial factor that not only promotes vasodilation but also inhibits platelet aggregation, contributing to the regulation of blood flow and preventing thrombosis.

A) Vasodilation

Explanation: An increase in hydrogen ions (↑H+) typically leads to vasodilation, which helps to enhance blood flow to areas with high metabolic activity, as it indicates a need for more oxygen and nutrient delivery.

C) Metabolic regulation

Explanation: Acute local control of blood flow is primarily governed by metabolic mechanisms, which respond to the metabolic needs of tissues, ensuring adequate blood supply based on activity levels.

B) It decreases oxygen levels in tissues

Explanation: When blood flow bypasses the capillary bed, it limits the exchange of oxygen and nutrients, leading to decreased oxygen levels in the tissues, which can impair their function.

E) Temperature of the blood

Explanation: While metabolic activity, neural regulation, hormonal influences, and blood viscosity are all factors that can influence local blood flow, the temperature of the blood is not typically considered a direct factor in local control mechanisms.

B) Brain

Explanation: The brain typically receives the highest basal blood flow compared to other organs, reflecting its critical need for oxygen and nutrients to support its metabolic demands.

C) Blood flow increases

Explanation: When tissue metabolism increases, metabolic control mechanisms lead to vasodilation, resulting in increased blood flow to meet the heightened demand for oxygen and nutrients.

B) At the minimal level that meets the tissue's requirements

Explanation: Blood flow to each tissue is specifically regulated at the minimal level necessary to supply the tissue's requirements, ensuring efficient use of resources without excess.

B) Myogenic response

Explanation: The myogenic response is the mechanism by which blood vessels react to changes in pressure by constricting or dilating, allowing for immediate adjustments to blood flow in response to increased blood flow.

B) Increases blood flow

Explanation: Metabolic activity typically increases blood flow to tissues that are more active, ensuring that they receive adequate oxygen and nutrients to meet their metabolic demands.

C) Increases blood flow

Explanation: Increased levels of adenosine (↑Adenosine) are associated with vasodilation, which helps to increase blood flow to tissues that are metabolically active.

B) Blood flow changes during exercise

Explanation: Acute metabolic control refers to immediate adjustments in blood flow in response to metabolic demands, such as the increased blood flow that occurs during exercise to meet the heightened oxygen and nutrient requirements of active tissues.

B) Coordinating neural, hormonal, and local mechanisms

Explanation: The integrated control of blood pressure involves the coordination of neural, hormonal, and local mechanisms to maintain stable blood pressure and ensure adequate perfusion to tissues.

C) Blood viscosity

Explanation: While pH levels, temperature, lactic acid concentration, and adenosine levels are all factors that influence metabolic control of blood flow, blood viscosity is not directly involved in the metabolic regulation of blood flow.

C) Causes vasodilation

Explanation: Increased carbon dioxide concentration in tissues leads to vasodilation, which enhances blood flow to those areas, facilitating the removal of waste products and improving oxygen delivery.

C) Increase in K+

Explanation: During metabolic activity, there is often an increase in potassium ions (↑K+) in the extracellular fluid, which can contribute to vasodilation and increased blood flow to active tissues.

B) Vasodilation

Explanation: During active hyperemia, vasodilation occurs in response to increased tissue metabolism, allowing for greater blood flow to meet the metabolic demands of the tissues.

C) Vasodilation

Explanation: The buildup of metabolic waste during reactive hyperemia leads to vasodilation, which increases blood flow to the affected tissues, facilitating recovery and waste removal.

B) Increase in arterial pressure

Explanation: The Metabolic Theory of Autoregulation begins with an increase in arterial pressure, which subsequently leads to increased blood flow and oxygen delivery to tissues.

B) Blood vessels respond to changes in pressure

Explanation: The myogenic theory of autoregulation suggests that blood vessels can constrict or dilate in response to changes in intravascular pressure, helping to maintain consistent blood flow despite fluctuations in systemic blood pressure.

B) Pressure equals flow times resistance

Explanation: The equation P = Q x R describes the relationship between pressure (P), flow (Q), and resistance (R) in the circulatory system, indicating that pressure is directly proportional to flow and resistance.

B) Vasoconstriction

Explanation: Vasoconstriction is the mechanism that allows blood to bypass capillary beds by narrowing the blood vessels, redirecting blood flow away from certain areas, which can be crucial during times of stress or low oxygen demand.

B) It maintains constant blood flow despite changes in blood pressure

Explanation: Autoregulation is significant because it allows tissues to maintain a relatively constant blood flow despite fluctuations in systemic blood pressure, ensuring that metabolic needs are met.

C) It increases to meet metabolic demands

Explanation: During physical activity, basal blood flow increases to meet the heightened metabolic demands of active tissues, ensuring that they receive adequate oxygen and nutrients.

B) Myogenic mechanisms

Explanation: Myogenic mechanisms are a key component of autoregulation, where blood vessels respond to changes in pressure by constricting or dilating based on the stretch of the vessel walls.

B) Vasoconstriction

Explanation: Endothelin-1 is a potent vasoconstrictor produced by endothelial cells, leading to increased vascular resistance and reduced blood flow in response to various stimuli.

B) Exercise

Explanation: Exercise significantly increases metabolic activity in muscles, leading to a corresponding increase in blood flow to supply the necessary oxygen and nutrients.

D) Blood vessel constriction

Explanation: Blood vessel constriction would reduce blood flow, whereas active hyperemia is characterized by increased blood flow due to factors like increased carbon dioxide levels, decreased oxygen levels, and increased metabolic byproducts.

B) An increase in blood flow due to vasodilation after ischemia

Explanation: Reactive hyperemia is characterized by an increase in blood flow resulting from vasodilation that occurs after a period of ischemia, allowing for the removal of metabolic waste.

B) They are washed out during increased blood flow

Explanation: As blood flow increases due to elevated arterial pressure, tissue vasodilators are washed out, which contributes to the regulation of blood flow back to normal levels.

C) Increased metabolic activity leads to increased blood flow

Explanation: In the metabolic theory of autoregulation, higher metabolic activity in tissues results in the release of vasodilators, which increases blood flow to meet the heightened demand for oxygen and nutrients.

C) It serves as a vasodilator

Explanation: Nitric Oxide (NO) is primarily known for its role as a vasodilator, helping to relax blood vessels and improve blood flow, which is crucial for cardiovascular health.

D) All of the above

Explanation: Oxygen, carbon dioxide, and nitric oxide are all substances that play significant roles in metabolic control, influencing vasodilation and blood flow based on tissue demands.

A) Increased blood flow during exercise

Explanation: Active hyperemia refers to the increase in blood flow that occurs in response to increased metabolic activity, such as during exercise, where tissues require more oxygen and nutrients.

B) ↓O2

Explanation: During metabolic influences, oxygen levels typically decrease (↓O2) as it is consumed by tissues for cellular respiration, particularly in areas of high metabolic activity.

C) It promotes vasodilation

Explanation: Adenosine is a metabolite that accumulates in tissues during increased metabolic activity and promotes vasodilation, thereby increasing blood flow to meet the heightened metabolic demands.

B) It is inherent to vascular smooth muscle

Explanation: The statement highlights that the characteristics described, such as constriction and dilation in response to pressure changes, are inherent properties of vascular smooth muscle.

C) Endothelin-converting enzyme (ECE)

Explanation: The Endothelin-converting enzyme (ECE) is crucial for the conversion of precursor proteins into Endothelin-1 (ET-1), which plays a significant role in regulating blood flow and vascular tone.

C) Mechanisms that regulate blood flow to specific tissues

Explanation: The primary focus of local control of blood flow in cardiovascular physiology is to understand the mechanisms that regulate blood flow to specific tissues, ensuring that they receive adequate oxygen and nutrients based on their metabolic needs.

B) It remains constant under resting conditions

Explanation: Basal blood flow is characterized by its relative constancy during resting conditions, ensuring that organs receive a stable supply of blood regardless of external factors.

C) To match blood flow to tissue metabolic needs

Explanation: The metabolic control of blood flow is primarily aimed at ensuring that blood flow is adjusted according to the metabolic demands of tissues, allowing for efficient nutrient delivery and waste removal.

A) The formation of new blood vessels

Explanation: Angiogenesis refers to the process of forming new blood vessels from existing ones, which is crucial for supplying nutrients and oxygen to tissues, especially during growth and healing.

C) Flow of blood

Explanation: In the equation P = Q x R, 'Q' represents the flow of blood, which is a crucial factor in determining the pressure within the circulatory system.

C) Pressure increases

Explanation: According to the equation P = Q x R, if flow (Q) increases while resistance (R) remains constant, the pressure (P) will also increase, demonstrating the direct relationship between flow and pressure.

C) By producing substances that can either dilate or constrict blood vessels

Explanation: Endothelial factors influence blood flow by releasing various substances, such as Nitric Oxide and Endothelin-1, which can either promote vasodilation or vasoconstriction, thereby regulating blood flow effectively.

C) It synthesizes prostacyclin

Explanation: Cyclooxygenase (COX) is essential for the synthesis of prostacyclin (PGI2), converting arachidonic acid into this important compound that regulates blood flow.

D) Asthma

Explanation: Endothelin-1 (ET-1) is linked to cardiovascular issues such as coronary spasm, hypertension, pulmonary hypertension, and heart failure, but it is not associated with asthma.

C) It increases tissue blood flow

Explanation: Increased metabolism results in higher tissue blood flow, as the metabolic demands of the tissues require more oxygen and nutrients, prompting the body to enhance blood delivery.

A) Nitric oxide

Explanation: Nitric oxide is a key signaling molecule released during metabolic activity that causes vasodilation, thereby increasing blood flow to active tissues.

B) One focuses on pressure changes while the other focuses on metabolic needs

Explanation: The metabolic theory emphasizes the role of metabolic activity in regulating blood flow, while the myogenic theory focuses on the response of blood vessels to changes in pressure, highlighting their distinct mechanisms.

D) To release substances that influence vascular tone

Explanation: Endothelial cells play a crucial role in regulating blood flow by releasing various substances that can cause vasodilation or vasoconstriction, thereby influencing vascular tone and blood flow.

C) It causes vasodilation

Explanation: Prostacyclin is a substance released by endothelial cells that promotes vasodilation, helping to increase blood flow and reduce the risk of clot formation.

B) Cyclooxygenase (COX)

Explanation: Cyclooxygenase (COX) is the enzyme responsible for the synthesis of prostacyclin (PGI2) from arachidonic acid, highlighting its importance in the production of this vasodilatory compound.

B) It is involved in the pathogenesis of heart failure

Explanation: Endothelin-1 (ET-1) is implicated in the development of various cardiovascular conditions, including heart failure, coronary spasm, and hypertension, highlighting its significant role in cardiovascular pathophysiology.

B) The ability of tissues to maintain constant blood flow despite changes in perfusion pressure

Explanation: Autoregulation refers to the intrinsic ability of tissues to regulate their own blood flow, ensuring that it remains relatively constant despite fluctuations in systemic blood pressure.

B) CO2

Explanation: Metabolic activity leads to an increase in carbon dioxide (↑CO2) production as a byproduct of cellular respiration, which is a key indicator of tissue metabolism.

A) Decreased oxygen levels

Explanation: Decreased oxygen levels (hypoxia) are a significant stimulus for angiogenesis, as tissues signal for the formation of new blood vessels to improve oxygen delivery.

B) Blood flow increases due to high tissue activity

Explanation: Active hyperemia is characterized by an increase in blood flow that corresponds with heightened tissue activity, ensuring that active tissues receive the necessary blood supply.

B) Buildup of metabolic waste

Explanation: Following ischemia, there is a buildup of metabolic waste that triggers reactive hyperemia, leading to vasodilation and increased blood flow to the affected area.

B) Myogenic Theory

Explanation: The myogenic theory of autoregulation explains how blood vessels respond to changes in pressure by constricting or dilating, ensuring proper blood flow and pressure regulation.

B) Vasoconstriction in response to increased pressure

Explanation: The myogenic theory of autoregulation involves the intrinsic ability of vascular smooth muscle to constrict in response to increased intravascular pressure, thereby regulating blood flow.

B) Increased flow (shear stress)

Explanation: Nitric Oxide is released in response to increased blood flow, specifically due to shear stress, which plays a crucial role in regulating blood flow and vascular function.

B) Vasodilation

Explanation: Prostacyclin (PGI2) induces vasodilation, which helps to increase blood flow and reduce blood pressure, making it a key player in vascular health.

B) Increased tissue metabolism

Explanation: Active hyperemia refers to the increased blood flow that occurs in response to heightened tissue metabolism, ensuring that metabolically active tissues receive adequate oxygen and nutrients.

C) Increased blood flow

Explanation: Reactive hyperemia results in increased blood flow to an area following a period of ischemia, helping to clear metabolic waste and restore tissue health.

B) The vessel constricts

Explanation: According to the myogenic theory of autoregulation, a vessel constricts in response to an increase in pressure, which helps regulate blood flow and maintain homeostasis.

B) The vessel dilates

Explanation: The myogenic theory states that a vessel will dilate in response to a decrease in pressure, allowing for increased blood flow to the area.

D) All of the above

Explanation: Endothelial function can be influenced by various factors including exercise, diet, and smoking, all of which can affect the health and responsiveness of endothelial cells.

C) Enhanced vasodilation

Explanation: Increased levels of prostacyclin (PGI2) lead to enhanced vasodilation, which improves blood flow and reduces the risk of clot formation by inhibiting platelet aggregation.

B) Vasoconstriction

Explanation: Endothelin-1 (ET-1) primarily causes vasoconstriction, which can lead to increased blood pressure and is involved in various cardiovascular pathologies.

B) Buildup of metabolic waste

Explanation: Reactive hyperemia is primarily triggered by the buildup of metabolic waste in tissues, which leads to vasodilation and increased blood flow to restore normal conditions.

C) Blood flow increases

Explanation: An increase in arterial pressure leads to an increase in blood flow, which is a key aspect of the Metabolic Theory of Autoregulation.

B) Blood flow returns to normal

Explanation: The Metabolic Theory of Autoregulation ultimately aims to return blood flow to normal levels after an initial increase due to elevated arterial pressure.

B) Vasoconstriction

Explanation: Following the washout of tissue vasodilators, vasoconstriction occurs, which helps to regulate and normalize blood flow after it has initially increased.

C) Serving as a vasodilator

Explanation: Prostacyclin (PGI2) is primarily recognized for its role as a vasodilator, which helps to widen blood vessels and reduce blood pressure, contributing to overall vascular health.

A) The relationship between pressure, flow, and resistance

Explanation: The equation P = Q x R describes the fundamental relationship in hemodynamics, where pressure (P) is equal to flow (Q) multiplied by resistance (R), which is crucial for understanding blood circulation.

B) Nitric oxide

Explanation: Nitric oxide is a key substance released by endothelial cells that promotes vasodilation, helping to increase blood flow and reduce blood pressure.

C) It causes vasoconstriction

Explanation: Endothelin-1 is a potent vasoconstrictor released by endothelial cells, leading to a decrease in blood vessel diameter and an increase in blood pressure.

B) A response of blood vessels to changes in pressure

Explanation: The myogenic response refers to the ability of blood vessels to constrict or dilate in response to changes in pressure, helping to regulate blood flow and maintain homeostasis.

B) It promotes vasoconstriction

Explanation: Endothelin-1 (ET-1) is known for its potent vasoconstrictor properties, which means it narrows blood vessels and can increase blood pressure, playing a significant role in vascular regulation.

B) Acetylcholine

Explanation: Acetylcholine is noted as a stimulant for the release of Nitric Oxide, highlighting its role in the regulation of blood flow and vascular responses.

B) Resistance to blood flow

Explanation: In the equation P = Q x R, 'R' stands for resistance to blood flow, which affects how easily blood can move through the circulatory system and influences overall pressure.

B) To regulate blood flow

Explanation: Prostacyclin (PGI2) plays a crucial role in regulating blood flow by causing vasodilation and inhibiting platelet aggregation, which is essential for maintaining proper circulation.

A) Hypertension

Explanation: Endothelial dysfunction is often associated with hypertension, as it can lead to increased vascular resistance and elevated blood pressure.

B) Nitric Oxide

Explanation: Nitric Oxide is classified as a vasodilator, which helps to relax and widen blood vessels, contrasting with substances like Endothelin-1 that act as vasoconstrictors.

E) Insulin

Explanation: Insulin is not classified as an angiogenic factor. The other options, including VEGF, FGF, angiopoietins, and MMPs, are all involved in the process of angiogenesis.

B) Hypoxia

Explanation: Hypoxia, or low oxygen levels, is a key factor that stimulates the process of angiogenesis, leading to the growth of new blood vessels to supply oxygen to tissues with increased demands.

B) Angiogenesis

Explanation: Angiogenesis is the process that involves the migration, growth, and differentiation of endothelial cells to form new blood vessels, particularly in response to increased tissue demands or hypoxia.

B) Heart failure

Explanation: Increased levels of Endothelin-1 (ET-1) are often observed in heart failure, contributing to the pathogenesis of this condition and other cardiovascular diseases.

B) To act as a barrier between blood and tissues

Explanation: Endothelial cells line the blood vessels and serve as a crucial barrier between the blood and surrounding tissues, playing a significant role in regulating various functions including blood flow.

B) Nitric Oxide

Explanation: Nitric Oxide is a key signaling molecule released by endothelial cells that promotes vasodilation, helping to regulate blood flow and pressure.

D) All of the above

Explanation: Endothelial function can be influenced by various factors including diet, exercise, and hormones, which can affect vascular health and blood flow regulation.

C) It stimulates the release of nitric oxide

Explanation: Shear stress, which is the frictional force of blood flow against the endothelium, stimulates endothelial cells to release nitric oxide, promoting vasodilation and improving blood flow.

C) Smoking

Explanation: Smoking is a significant risk factor that can contribute to endothelial dysfunction by damaging the endothelium and impairing its function, leading to cardiovascular diseases.

C) It enhances vasodilation

Explanation: Nitric oxide is a crucial molecule produced by the endothelium that enhances vasodilation, helping to regulate blood flow and maintain vascular health.

C) It promotes vasoconstriction

Explanation: Endothelin is a potent vasoconstrictor released by endothelial cells, which leads to narrowing of blood vessels and an increase in blood pressure.

B) Impaired vasodilation

Explanation: Endothelial dysfunction is primarily characterized by impaired vasodilation, which affects the ability of blood vessels to relax and widen, leading to various cardiovascular issues.

E) Both B and C

Explanation: Both the nervous and endocrine systems are integral to the control of blood pressure, working together to regulate vascular resistance and blood volume.

B) To maintain homeostasis in blood flow

Explanation: The integrated control of blood pressure is crucial for maintaining homeostasis in blood flow throughout the body, ensuring that tissues receive adequate oxygen and nutrients.

B) They detect changes in blood pressure

Explanation: Baroreceptors are specialized sensors that detect changes in blood pressure and send signals to the central nervous system to initiate appropriate responses for regulation.

C) It increases blood pressure

Explanation: The sympathetic nervous system activates the 'fight or flight' response, which increases heart rate and constricts blood vessels, leading to an increase in blood pressure.

B) Increased risk of atherosclerosis

Explanation: A common consequence of endothelial dysfunction is an increased risk of atherosclerosis, as the impaired function of the endothelium can lead to plaque buildup in the arteries.

B) They degrade proteins in vessel walls

Explanation: Matrix metalloproteinases (MMPs) are enzymes that degrade proteins in vessel walls, facilitating the remodeling necessary for new blood vessel formation during angiogenesis.

C) Aldosterone

Explanation: Aldosterone is a hormone that plays a key role in increasing blood pressure by promoting sodium retention in the kidneys, which leads to increased blood volume.

B) It decreases blood pressure

Explanation: Vasodilation refers to the widening of blood vessels, which decreases vascular resistance and leads to a reduction in blood pressure.

B) It resupplies blood to affected tissue

Explanation: Collateral circulation refers to the alternative pathways of blood flow that develop to resupply blood to tissues with increased demands, ensuring adequate oxygen and nutrient delivery.

B) Neural regulation

Explanation: Neural regulation is a primary mechanism for short-term blood pressure control, involving the autonomic nervous system to quickly adjust blood vessel diameter and heart rate in response to changes in blood pressure.

B) It decreases blood pressure

Explanation: Vasodilation refers to the widening of blood vessels, which decreases resistance to blood flow and subsequently lowers blood pressure.

B) They detect changes in blood pressure

Explanation: Baroreceptors are specialized sensors located in blood vessels that detect changes in blood pressure and send signals to the nervous system to initiate appropriate responses for regulation.

B) Increased blood volume

Explanation: Increased blood volume can lead to higher blood pressure as more fluid in the circulatory system raises the overall pressure exerted on blood vessel walls.

C) Aldosterone

Explanation: Aldosterone is a hormone that plays a significant role in the long-term regulation of blood pressure by promoting sodium retention in the kidneys, which increases blood volume and pressure.

B) They detect changes in blood pressure

Explanation: Baroreceptors are specialized sensors located in blood vessels that detect changes in blood pressure and send signals to the brain to initiate appropriate responses for maintaining blood pressure homeostasis.

B) To maintain blood flow to vital organs

Explanation: The integrated control of blood pressure is crucial for ensuring that adequate blood flow is maintained to vital organs, which is essential for their proper functioning and overall homeostasis.

C) Aldosterone

Explanation: Aldosterone is a key hormone involved in long-term blood pressure regulation, as it promotes sodium retention in the kidneys, which increases blood volume and, consequently, blood pressure.

B) Nervous system

Explanation: The nervous system plays a key role in the short-term regulation of blood pressure through mechanisms such as baroreceptor reflexes, which quickly adjust heart rate and vascular resistance.