Anatomy: Heart and Major Vessels

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Questions and Answers

How does the fibrous skeleton contribute to the function of heart valves?

  • It conducts electrical signals to coordinate valve timing
  • It prevents the backflow of blood by anchoring the valve cusps. (correct)
  • It produces lubricating fluid to reduce friction during valve movement.
  • It facilitates the diffusion of nutrients to the valve leaflets.

During ventricular diastole, what facilitates the elasticity that blood vessel walls exert a force on the blood, contributing to arterial blood pressure?

  • Contraction of smooth muscle
  • Elastic recoil (correct)
  • Increased blood viscosity
  • Increased heart rate

Why are changes in the percentage of cardiac output supplied to each organ primarily caused by alterations in the vascular resistance?

  • It decreases compliance of veins.
  • It increases the elasticity of the blood vessels.
  • It increases stroke volume.
  • The body can ensure each section and organ receives a proper need of blood flow. (correct)

What would occur if there was a significant reduction in the concentration of plasma proteins, such as albumin?

<p>Increased filtration of fluid out of the capillaries into the interstitial space. (A)</p> Signup and view all the answers

A patient with advanced liver disease experiences a significant decrease in the production of plasma proteins. What effect would this have on Starling forces and capillary fluid exchange?

<p>Decreased plasma colloid osmotic pressure, leading to increased fluid filtration out of capillaries. (B)</p> Signup and view all the answers

Following a severe hemorrhage and a subsequent drop in blood pressure, what compensatory mechanism is initiated to maintain adequate cerebral blood flow?

<p>Selective vasoconstriction in skeletal muscle and splanchnic circulation coupled with vasodilation in cerebral circulation. (D)</p> Signup and view all the answers

How do local metabolic changes cause vasodilation and influence blood flow in an organ?

<p>Increased carbon dioxide concentration and decreased oxygen levels promoting smooth muscle relaxation. (B)</p> Signup and view all the answers

After prolonged standing, blood pools in the veins of the lower extremities. How does the body counteract this effect to maintain adequate venous return?

<p>Activating the skeletal muscle pump in the legs to propel blood back towards the heart. (C)</p> Signup and view all the answers

What adjustments occur in response to an increased venous return? (Select all that apply.)

<p>Increased contractility (B), Increased stroke volume (C), Increased end-diastolic volume (D)</p> Signup and view all the answers

During a heart transplant, the nerves innervating the heart are severed. How does this affect the regulation of heart rate and cardiac output during exercise?

<p>The heart depends on circulating hormones and intrinsic mechanisms for rate and contractility adjustments. (A)</p> Signup and view all the answers

A patient has a stiffened left ventricle due to long-standing hypertension. How does this condition affect ventricular filling and cardiac output?

<p>Reduced ventricular filling due to decreased compliance, leading to decreased cardiac output. (B)</p> Signup and view all the answers

What is the functional significance of the elastic properties of large arteries, such as the aorta?

<p>To maintain continuous blood flow during ventricular diastole. (B)</p> Signup and view all the answers

How would an increase in blood viscosity caused by polycythemia (increased red blood cell count) affect blood flow and vascular resistance?

<p>Decrease blood flow and increase vascular resistance. (A)</p> Signup and view all the answers

In a capillary bed, what determines the net filtration pressure (NFP) and influences fluid movement across the capillary wall?

<p>The balance between hydrostatic and colloid osmotic pressures in the capillary and interstitial fluid. (A)</p> Signup and view all the answers

What are the mechanisms that promote vasodilation in response to increased metabolic activity?

<p>Decreased oxygen levels, increased carbon dioxide levels, and increased hydrogen ion concentration. (D)</p> Signup and view all the answers

A patient is diagnosed with mitral valve stenosis (narrowing of the mitral valve). How does this condition affect blood flow through the heart?

<p>Obstructs blood flow from the left atrium to the left ventricle, potentially leading to pulmonary congestion. (D)</p> Signup and view all the answers

What is the primary function of the pulmonary circulation, and how does it differ from the systemic circulation?

<p>To facilitate gas exchange in the lungs; it operates at lower pressures than systemic circulation. (D)</p> Signup and view all the answers

If the aortic valve is stenotic, creating increased resistance to blood flow, how is afterload affected, and what compensatory mechanisms might the heart employ?

<p>Increased afterload; increased contractility and hypertrophy of the left ventricle. (C)</p> Signup and view all the answers

How does the anatomical arrangement of microcirculation (i.e., the total cross-sectional area of capillaries compared to that of arterioles) contribute to its function?

<p>The larger cross-sectional area of capillaries reduces blood velocity, facilitating efficient exchange. (C)</p> Signup and view all the answers

How do changes in blood flow affect total blood volume and arterial pressure?

<p>Rapid responses are local control and slow responses are total blood volume. (D)</p> Signup and view all the answers

A person with hypertension (chronic high blood pressure) often has a decreased arterial compliance. How does decreased compliance change the relationship between arterial volume and arterial pressure?

<p>A smaller change in arterial volume is needed to cause a larger change in arterial pressure. (A)</p> Signup and view all the answers

What differences exist between vessel compliance in arteries and veins?

<p>Arteries are not very compliant, whereas veins are highly compliant. (D)</p> Signup and view all the answers

What happens when ventricles contract and eject blood?

<p>Arteries expand as they receive the blood. (A)</p> Signup and view all the answers

What is a main function of arterioles with regard to blood flow?

<p>Arterioles make blood flow variable depending on which capillary bed is involved. (D)</p> Signup and view all the answers

How does gravity have an affect on venous blood pressure while standing?

<p>Gravity causes an increase particularly in lower body blood pressure. (A)</p> Signup and view all the answers

If the nervous connection to the heart is severed in a heart transplant, how is functionality preserved and altered, if at all?

<p>The heart relies more upon hormones to have an affect. (A)</p> Signup and view all the answers

In a scenario involving local control of an organ's blood flow, increased levels of carbon dioxide would cause what?

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

Which vessels contain endothelium?

<p>All of these options (C)</p> Signup and view all the answers

Flashcards

Pulmonary Circulation

Circulation that involves blood flow between the heart and the lungs.

Systemic Circulation

Circulation that involves blood flow between the heart and the rest of the body.

Heart

Hollow organ that pumps blood throughout the body, located in the thoracic cavity and mostly to the left.

Pericardium

Protective sac that surrounds and anchors the heart.

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Atria

The two upper chambers of the heart that receive blood.

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Ventricles

The two lower chambers of the heart that pump blood out.

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Heart Valve

Structure that ensures blood flows in only one direction through the heart.

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Blood flow rate

The rate of liquid flow is equal to the pressure gradient divided by the resistance.

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Endothelium

Thin, innermost layer of epithelial cells in blood vessels that actively participates in vascular functions.

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Blood viscosity

The major determinant of blood viscosity, affecting vascular resistance.

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Arterioles

Vessels that have the function of delivering blood to the capillaries.

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Vasoconstriction

Contraction of smooth muscle that increases resistance and blood pressure.

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Vasodilation

Relaxation of smooth muscle that decreases resistance and blood pressure.

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Capillaries

Sites of nutrient and waste exchange; regulated by metarterioles and precapillary sphincters.

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Starling Forces

The combination of hydrostatic and osmotic pressures that drive fluid movement in capillaries.

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Venules and Veins

Elastic vessels that function as blood reservoirs.

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Cardiac Cycle

The heart's repeating cycle of contraction (systole) and relaxation (diastole).

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Elastic Arteries

The function of major blood vessels to expand and contract because of the thickness of arterial walls, coupled with the abundance of elastic tissue.

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Stroke Volume

The amount of blood ejected from the ventricles with each beat.

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Cardiac Output

Amount of blood pumped by each ventricle per minute.

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Mean Arterial Pressure (MAP)

The average pressure in the aorta throughout the cardiac cycle.

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Compliance

A measure of the relationship between pressure and volume changes.

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Low Compliance

A small increase in blood volume results in a large increase in blood pressure.

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Systolic pressure

The maximum pressure that occurs during systole.

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Study Notes

Heart Overview

  • Hollow organ, approximately the size of a fist
  • Located in the thoracic cavity
  • Lies mostly to the left

Pericardium

  • Protects and anchors the heart

Heart Chambers

  • 4 chambers create 2 pumps; right and left sides
  • 2 atria
  • 2 ventricles
  • The right side facilitates the pulmonary circuit.
  • The left side facilitates the systemic circuit

Atria Details

  • These are the top two chambers
  • Great vessels lead blood here
  • Right atrium receives blood from the superior vena cava and inferior vena cava
  • Left atrium receives blood from the pulmonary veins

Ventricles Details

  • Bottom two chambers
  • Great vessels lead blood away
  • Right ventricle sends blood via the pulmonary trunk
  • Left ventricle sends blood via the aorta

Heart Valves

  • Valves ensure one-way blood flow
  • Right side contains the tricuspid atrioventricular valve (AV) and pulmonary semilunar valve
  • Left side contains the bicuspid atrioventricular valve (AV) and aortic semilunar valve
  • Fibrous skeleton prevents backflow

Vasculature Layers and Function

  • Endothelium: Innermost, thin layer of epithelial cells, actively participates in multiple vascular functions
  • Smooth muscle: Regulates blood vessel diameter through vasodilation and vasoconstriction
  • Connective tissue: Includes elastic and fibrous components

Blood Flow and Pressure

  • Flow rate of liquid through a pipe is directly proportional to the pressure difference and inversely proportional to resistance
  • Formula: Flow = pressure gradient/resistance = ΔP/R
  • ΔP (pressure gradient) is the driving force
  • R is the resistance to flow

Systemic Circuit Pressure

  • Mean arterial pressure (MAP) in the aorta is approximately 85 mm Hg.
  • Central venous pressure (CVP) is about 2-8 mm Hg.
  • Vena cava pressure outside the right atrium is about 0 mm Hg
  • Pressure gradient (ΔP) drives blood flow

Resistance Factors

  • Vessel radius
  • Vessel length
  • Blood viscosity: Vascular resistance increases as viscosity increases, due to cell and protein concentration

Arteries

  • Walls have thickness and elastic tissue
  • They act as pressure reservoirs, ensuring continuous blood flow even between heartbeats (during diastole)
  • They have low compliance, meaning a small volume increase causes a large pressure increase.

Arterial Blood Pressure

  • Aorta receives blood from the ventricle, increasing pressure
  • Aorta walls recoil, exerting force
  • Pressure varies with cardiac cycle
  • Systolic pressure is maximum during systole.
  • Diastolic pressure is minimum

Arterioles

  • Deliver blood to capillaries
  • Act as resistance vessels
  • Blood flow resistance changes with diameter.
  • Vasoconstriction increases resistance and blood pressure
  • Vasodilation decreases resistance and blood pressure
  • Regulate flow to capillary beds and MAP

Microcirculation

  • Capillaries have a smaller radius than arterioles, but collectively offer less resistance due to greater total cross-sectional area.

Blood Distribution

  • Blood flow is unequal and depends on needs
  • Organs regulate their own flow through local control.
  • Vascular resistance changes affect the supply of CO.
  • The contraction or relaxation of smooth muscle in arterioles can change vascular resistance
  • Intrinsic control mechanisms are important in the heart, brain, and skeletal muscles

Tissue Blood Flow

  • Tissues sense adequate blood flow through vascular smooth muscle
  • Vascular smooth muscle responds to chemical concentrations, including oxygen, carbon dioxide, potassium ions, and hydrogen ions
  • Increased metabolic activity causes vasodilation
  • Decreased metabolism causes vasoconstriction.

Capillaries

  • Nutrient and waste exchange sites
  • Walls are thin with pores
  • They form beds at tissues
  • Flow is regulated by metarterioles and precapillary sphincters

Venules and Veins

  • Function as blood reservoirs

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