Introduction to Physiology - Blood Transport Systems
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Questions and Answers

What effect does a decrease in blood pressure have on baroreceptor function?

  • Decreases stretch of the baroreceptors (correct)
  • Causes vasodilation of the arterioles
  • Increases afferent baroreceptor signaling
  • Leads to increased parasympathetic activity

Where are peripheral chemoreceptors located?

  • In the carotid body and aortic arch (correct)
  • In the cerebral spinal fluid
  • In the lungs
  • In the medulla oblongata

What type of blood pressure change stimulates vasoconstriction via baroreceptors?

  • Hypertension leading to increased arterial pressure
  • Hypotension leading to decreased arterial pressure (correct)
  • Increased stroke volume reducing TPR
  • Decreased heart rate triggering increased BP

What is stroke volume primarily determined by?

<p>End-diastolic volume and end-systolic volume (A)</p> Signup and view all the answers

Which theory explains how an organ maintains blood flow despite changes in perfusion pressure?

<p>Myogenic theory (A)</p> Signup and view all the answers

Which factor does NOT stimulate peripheral chemoreceptors?

<p>Increased pH levels (C)</p> Signup and view all the answers

Which factor does NOT increase stroke volume?

<p>Decreased contractility (B)</p> Signup and view all the answers

What does the Frank-Starling law explain?

<p>The compensation of stroke volume with increased venous return (B)</p> Signup and view all the answers

What happens to vascular smooth muscle when perfusion increases?

<p>The muscle experiences increased stretching and constricts (A)</p> Signup and view all the answers

What role do metabolic byproducts play in blood flow?

<p>They lead to vasodilation (A)</p> Signup and view all the answers

Which of the following best estimates afterload?

<p>Mean arterial pressure (C)</p> Signup and view all the answers

What is one effect of decreased afferent baroreceptor signaling?

<p>Increased sympathetic nervous activity (C)</p> Signup and view all the answers

What is the normal ejection fraction (EF) percentage?

<p>Greater than 55% (A)</p> Signup and view all the answers

What phase of the cardiac cycle follows the rapid ejection phase?

<p>Isovolumetric relaxation (A)</p> Signup and view all the answers

Why does blood pressure decrease from arteries to veins?

<p>Pressure overcoming resistance in vessels (A)</p> Signup and view all the answers

What vessel type contributes most significantly to increased resistance in the circulatory system?

<p>Arterioles (A)</p> Signup and view all the answers

How does the radius of a tube affect the resistance to flow?

<p>Increasing radius decreases resistance (A)</p> Signup and view all the answers

What is the relationship between total resistance in series and parallel circuits?

<p>Total resistance in series equals the sum of individual resistances (D)</p> Signup and view all the answers

What happens to blood flow when resistance in a vessel increases?

<p>Blood flow decreases, especially across the constricted area (C)</p> Signup and view all the answers

According to the Poiseuille equation, how is flow calculated?

<p>Flow = (P1 - P2) / Resistance (A)</p> Signup and view all the answers

In a trauma situation with hemorrhage, what compensates for decreased cardiac output?

<p>Increased total peripheral resistance (D)</p> Signup and view all the answers

Which pressures are represented in the Poiseuille equation for pulmonary circulation?

<p>PAP and LAP (D)</p> Signup and view all the answers

What is the main function of baroreceptors in the cardiovascular system?

<p>Detect pressure changes (C)</p> Signup and view all the answers

Which nerve is associated with afferent signals from the carotids?

<p>Glossopharyngeal nerve (D)</p> Signup and view all the answers

What can cause edema due to an increase in capillary pressure?

<p>Heart failure (B)</p> Signup and view all the answers

What is the consequence of long-term increase in afterload due to hypertension?

<p>Concentric hypertrophy of the heart (B)</p> Signup and view all the answers

Which heart sound is typically associated with left-sided diastolic heart failure?

<p>S4 (A)</p> Signup and view all the answers

What condition can lead to dilated cardiomyopathy that may be reversible?

<p>Alcoholic cardiomyopathy (A)</p> Signup and view all the answers

In cardiogenic shock, what happens to the pulmonary capillary wedge pressure (PCWP)?

<p>It increases due to backup of blood (D)</p> Signup and view all the answers

What happens to systemic vascular resistance (SVR) during cardiogenic shock in response to low cardiac output?

<p>It increases (B)</p> Signup and view all the answers

What must a clinician consider if a patient has low blood pressure after a traumatic event?

<p>Possible blood loss (D)</p> Signup and view all the answers

What condition could lead to an increase in systemic vascular resistance (SVR) alongside an increase in cardiac output?

<p>Hemorrhagic shock (C)</p> Signup and view all the answers

How does the constriction of arterioles affect blood flow and pressure?

<p>Decreases blood flow and decreases blood pressure (A)</p> Signup and view all the answers

What happens to diastolic blood pressure (DP) during systole?

<p>It is at its lowest point (B)</p> Signup and view all the answers

What is the relationship between stroke volume and systolic blood pressure (SP)?

<p>As stroke volume increases, SP increases (C)</p> Signup and view all the answers

Which equation correctly represents mean arterial pressure (MAP)?

<p>MAP = DP + 1/3 (pulse pressure) (B)</p> Signup and view all the answers

What effect does increased arterial compliance have on pulse pressure?

<p>Decreases pulse pressure (B)</p> Signup and view all the answers

How does the velocity of blood relate to cross-sectional area in the vasculature?

<p>As cross-sectional area increases, velocity decreases (C)</p> Signup and view all the answers

What is the primary characteristic of the venous system regarding compliance?

<p>It is very compliant and stores a significant amount of circulating blood (A)</p> Signup and view all the answers

What does the equation for resistance (R) indicate about the relationship between vessel radius and resistance?

<p>Resistance decreases as vessel radius increases (C)</p> Signup and view all the answers

Which metabolite is primarily responsible for causing vasodilation in cerebral blood flow?

<p>Carbon Dioxide (B)</p> Signup and view all the answers

During exercise, which of the following substances primarily contributes to vasodilation in skeletal muscle?

<p>Hydrogen ions (D)</p> Signup and view all the answers

What effect does decreased arterial carbon dioxide have on cerebral vasculature?

<p>Vasoconstriction (B)</p> Signup and view all the answers

How does hypoxia affect blood flow in the lungs?

<p>Creates shunts away from poorly ventilated areas (B)</p> Signup and view all the answers

Which condition causes renal arterioles to constrict and potentially leads to loss of renal function?

<p>Severe hypotension (B)</p> Signup and view all the answers

What is the primary regulator of blood flow in the skin?

<p>Sympathetic stimulation (B)</p> Signup and view all the answers

Which of the following substances does NOT play a role in regulating cerebral blood flow?

<p>Hydrogen ions (B)</p> Signup and view all the answers

What role does potassium play during metabolic activity?

<p>Relaxes vascular smooth muscles (C)</p> Signup and view all the answers

Flashcards

Stroke Volume (SV)

The amount of blood pumped out of the heart with each beat.

Preload

The pressure inside the ventricle before contraction, caused by the amount of blood in the ventricle.

Afterload

The resistance the heart must overcome to pump blood out.

Contractility

The ability of the heart muscle to contract forcefully.

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Ejection Fraction (EF)

The percentage of blood ejected from the left ventricle with each beat.

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Cardiac Cycle

The cyclical phases of heart function, involving contraction and relaxation.

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Vasculature

The network of blood vessels that transports blood throughout the body.

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Vascular Resistance

The resistance to blood flow in the blood vessels, primarily in the arterioles.

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Diastolic Blood Pressure (DP)

The pressure in an artery during the relaxation phase of the heart cycle (ventricular filling). Directly proportional to Total Peripheral Resistance (TPR).

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Systolic Blood Pressure (SP)

The pressure in an artery during the contraction phase of the heart cycle (ventricular contraction). Directly related to stroke volume (SV).

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Pulse Pressure

The difference between SP and DP. Indicates the pressure difference due to the pumping action of the heart. Larger pulse pressure means stiffer arteries.

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Mean Arterial Pressure (MAP)

The average pressure in the arteries throughout the cardiac cycle. Closer to DP than SP.

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Total Peripheral Resistance (TPR)

The resistance to blood flow offered by the blood vessels. Higher resistance means less blood flow.

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Cardiac Output (CO)

The amount of blood pumped by the heart per minute. Determined by heart rate and stroke volume.

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Arterial Compliance

The tendency of a vessel to expand when pressure increases. Larger compliance means less increase in pressure for the same volume change.

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Viscosity

The resistance to flow caused by the blood's thickness or viscosity. Higher viscosity means higher resistance.

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Baroreceptors

Specialized sensory receptors located in the carotid sinus and aortic arch that detect changes in blood pressure.

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Hypotension

A drop in blood pressure, often caused by a decrease in blood volume.

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Autoregulation

The process by which the body maintains a stable blood flow to organs and tissues despite fluctuations in blood pressure.

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Myogenic Theory of Autoregulation

The intrinsic ability of vascular smooth muscle to contract or relax in response to changes in blood pressure.

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Metabolic Theory of Autoregulation

The theory that blood flow is regulated by the metabolic needs of tissues, where increased metabolism leads to vasodilation.

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Peripheral Chemoreceptors

Receptors that monitor oxygen levels, carbon dioxide levels, and the pH of the blood, located in the carotid body and aortic arch.

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Central Chemoreceptors

Chemoreceptors located in the medulla oblongata that monitor the pH and carbon dioxide levels in the cerebrospinal fluid.

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Hypertension

An increase in overall blood pressure.

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Heart Failure

A condition where the heart's ability to pump blood effectively is impaired, leading to fluid buildup in the lungs and other tissues.

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Cardiogenic Shock

A life-threatening condition where the heart is unable to pump effectively, resulting in shock and organ damage.

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Hypertrophy

Enlargement of the heart muscle, particularly the left ventricle. It can occur due to high afterload or other conditions.

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Resistance and Tube Length

The resistance of a tube increases as its length increases. This means that longer tubes have higher resistance to fluid flow.

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Resistance and Tube Radius

The resistance of a tube decreases as its radius increases. This means that wider tubes have lower resistance to fluid flow.

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Resistance in Series

The total resistance of vessels connected in series (one after another) is the sum of individual resistances. This means the resistance adds up.

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Resistance in Parallel

The total resistance of vessels connected in parallel (side by side) is calculated by the reciprocal of the sum of reciprocals of individual resistances. This means the overall resistance is lower than the individual resistances.

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Poiseuille Equation

The Poiseuille equation describes the flow of blood through a vessel, considering pressure difference and resistance. The greater the pressure difference, the greater the flow. The greater the resistance, the lower the flow.

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Resistance and Blood Flow

Increased resistance in a blood vessel, like a constricted arteriole, leads to decreased blood flow through that point. Additionally, the pressure drop across the constricted point is larger compared to less resistant areas.

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Resistance and Pressure Changes

Increasing resistance at a point in the circulatory system increases the pressure upstream of the point, but decreases the pressure downstream. This is because resistance obstructs flow and causes pressure to build up before the obstruction, while reducing pressure after it.

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Poiseuille Equation in Systemic Circulation

The Poiseuille equation can be applied to the systemic circulation to relate cardiac output (CO), mean arterial pressure (MAP), and total peripheral resistance (TPR). It essentially states that CO is proportional to MAP divided by TPR.

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What is Vasodilation?

Vasodilation is the widening of blood vessels, increasing blood flow to the area.

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What is Adenosine's role in vasodilation?

Adenosine is a molecule produced during metabolic activity, and it signals the surrounding tissues to vasodilate.

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How does Carbon Dioxide affect blood flow?

Carbon dioxide is a waste product of metabolism and its build-up triggers vasodilation. It's particularly important in regulating blood flow in the brain.

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What is Potassium's role in vasodilation?

Potassium levels increase in the blood as a result of muscle activity, and this directly leads to relaxation of smooth muscles, causing vasodilation.

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How does Low Oxygen affect blood flow?

Low oxygen, also known as hypoxia, triggers vasodilation as the body tries to deliver more oxygen to the area.

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What is Lactic Acid's role in vasodilation?

Lactic acid is a byproduct of anaerobic metabolism, meaning it's produced when cells don't have enough oxygen. Increased lactic acid leads to vasodilation.

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How do Hydrogen Ions (H+) affect blood flow?

Hydrogen ions (H+) increase with metabolic activity, contributing to vasodilation. However, they don't cross the blood-brain barrier and thus don't affect cerebral blood flow.

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What is the Starling Equation?

The Starling equation describes the movement of fluid between blood vessels and tissues. It explains how the balance of pressure and concentration differences drive the movement of fluid, which can ultimately affect blood flow.

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Study Notes

Introduction to Physiology - Blood Transport Control Systems

  • The heart pumps blood directly into arteries (aorta or pulmonary artery).
  • Blood vessels control blood flow to specific body parts.
  • Arteries carry blood away from the heart, branching into large and smaller arteries.
  • Large arteries are thick and elastic to withstand high pressure.
  • Arterioles have smooth muscle to regulate blood flow.
  • Arterioles have less elastic need due to lower blood pressure.
  • Capillaries branch off arterioles, with a single-cell layer for nutrient/gas exchange.
  • Veins carry blood back to the heart, preventing backflow with valves.

Cardiovascular Function

  • The cardiovascular system includes systemic and pulmonary circulations.
  • Systemic circulation delivers oxygenated blood and nutrients.
  • Pulmonary circulation oxygenates blood.
  • Cardiac output (CO) is stroke volume (SV) multiplied by heart rate (HR).
  • Stroke volume is the difference between end-diastolic volume (EDV) and end-systolic volume (ESV).
  • Increased contractility, preload, and decreased afterload increase stroke volume.
  • Catecholamines increase intracellular calcium and decrease extracellular sodium to increase left ventricular contractility.
  • Preload is the ventricular pressure due to EDV, stretching the ventricle, creating a larger stroke volume.
  • Afterload is the pressure the left ventricle must exceed to push blood forward (estimated by diastolic pressure).
  • Ejection fraction (EF) is the percentage of blood ejected from the ventricle (normal EF > 55%).
  • The cardiac cycle involves atrial contraction, mitral valve closure, isovolumetric phase, aortic valve opening, ejection phase, aortic valve closure, isovolumetric relaxation, and mitral valve opening.

Blood Vessel Function and Regulation

  • Blood pressure decreases from arteries to veins due to overcoming vascular resistance.
  • Arterioles have the largest resistance impact and largest pressure drop.
  • Arteriole constriction increases resistance and decreases flow.
  • Arteriole dilation decreases resistance and increases flow.
  • Diastolic pressure (DP) is the lowest pressure in the artery.
  • Systolic pressure (SP) is the peak arterial pressure during contraction.
  • Pulse pressure is the difference between systolic and diastolic pressure.
  • Mean arterial pressure (MAP) is the average pressure throughout the cardiac cycle (MAP=DP+(1/3) pulse pressure).
  • Systemic veins are compliant, holding up to 70% of circulating blood.

Pressure and Flow Regulation

  • Poiseuille's equation relates flow to pressure and resistance (Flow = (P1−P2)/R).
  • Increasing resistance reduces blood flow in a vessel.
  • Mean arterial pressure (MAP) is maintained by cardiac output (CO), total peripheral resistance (TPR).

Nervous System Regulation

  • Baroreceptors in the carotid sinus and aortic arch respond to blood pressure changes.
  • Decreasing blood pressure causes a decrease in baroreceptor stimulation. This leads to increased sympathetic activity and decreased parasympathetic activity.
  • These increases raise heart rate, contractility, and vasoconstriction to increase blood pressure and TPR.
  • Chemoreceptors in the carotid body and aortic arch are sensitive to oxygen, carbon dioxide and pH levels.

Autoregulation

  • Autoregulation is how organs maintain blood flow despite changes in perfusion pressure.
  • Myogenic theory: Vascular smooth muscle contracts or relaxes automatically in response to changes in pressure.

Metabolic Regulation

  • Metabolites such as adenosine, carbon dioxide, and potassium increase and are vasoactive.
  • Increased metabolic activity leads to increased blood flow.

Other Relevant Factors

  • Heart failure, cardiac tamponade, and hemorrhagic shock impact blood flow.
  • Coronary vasodilation is affected by adenosine, NO, carbon dioxide, and low oxygen.

Clinical Significance

  • Blood pressure is vital for assessing cardiovascular health.
  • Abnormal heart sounds (S3, S4, and murmurs) indicate potential issues.

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Description

Explore the basics of blood transport control systems in physiology. This quiz covers the functions of the heart, arteries, arterioles, capillaries, and veins, along with the concepts of systemic and pulmonary circulation. Test your understanding of how blood flows and the role of cardiovascular functions.

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