Circulatory System Quiz

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Questions and Answers

What percentage of blood is found in the systemic arterial system?

  • 15%
  • 5%
  • 13% (correct)
  • 9%

Which of the following correctly identifies where blood is found in the pulmonary vessels?

  • 9% (correct)
  • 5%
  • 12%
  • 7%

In which component is a higher percentage of blood found: systemic capillaries or the heart?

  • Neither has significant blood volume
  • Heart
  • Both are equal
  • Systemic capillaries (correct)

Which of the following percentages represents blood in the heart?

<p>7% (B)</p> Signup and view all the answers

Identify the component with the lowest blood percentage based on the given information.

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

What is the term used to describe the intermittent contraction and relaxation of smooth muscle in pre-capillaries and met arterioles?

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

How many times per minute does vasomotion typically occur?

<p>5-10 times (A)</p> Signup and view all the answers

Which of the following factors is NOT involved in the regulation of vasomotion?

<p>Variations in blood viscosity (D)</p> Signup and view all the answers

What role do chemical signals play in vasomotion?

<p>They regulate vasomotion in response to internal conditions. (C)</p> Signup and view all the answers

Which statement accurately describes the flow pattern associated with vasomotion?

<p>It flows intermittently, turning on and off. (D)</p> Signup and view all the answers

What does cardiac output measure?

<p>The amount of blood pumped into the aorta each minute (B)</p> Signup and view all the answers

Which term refers to the speed at which blood moves along a specific segment of circulation?

<p>Blood flow velocity (C)</p> Signup and view all the answers

How is blood flow velocity expressed?

<p>In units of distance per time (C)</p> Signup and view all the answers

What is a distinguishing feature of sinusoidal capillaries?

<p>They have extensive intercellular gaps. (B)</p> Signup and view all the answers

Which of the following is NOT a factor that influences cardiac output?

<p>Respiratory rate (D)</p> Signup and view all the answers

If a person has a low cardiac output, what might this indicate?

<p>Possible heart issues affecting pumping (C)</p> Signup and view all the answers

What type of basement membrane do sinusoidal capillaries possess?

<p>Incomplete basement membranes (C)</p> Signup and view all the answers

Which of the following statements is true regarding the endothelium of sinusoidal capillaries?

<p>It consists of flattened cells. (D)</p> Signup and view all the answers

What is the prevalence of sinusoidal capillaries compared to other types?

<p>They are the least common type. (A)</p> Signup and view all the answers

Which structure of sinusoidal capillaries allows for greater exchange of substances?

<p>Their extensive intercellular gaps. (B)</p> Signup and view all the answers

What is a distinctive characteristic of laminar flow in blood vessels?

<p>Blood moves in concentric layers parallel to the vessel (C)</p> Signup and view all the answers

Why is laminar flow considered the most efficient pattern of flow?

<p>It exerts the least resistance to fluid movement (A)</p> Signup and view all the answers

Which of the following statements is NOT true regarding laminar flow?

<p>Laminar flow results in increased resistance in blood vessels (C)</p> Signup and view all the answers

In what manner does fluid behave during laminar flow?

<p>Fluid forms distinct layers moving at different velocities (C)</p> Signup and view all the answers

Which scenario is most likely to disrupt laminar flow in blood vessels?

<p>Abrupt changes in vessel diameter (B)</p> Signup and view all the answers

What does viscosity refer to in the context of fluid dynamics?

<p>The resistance of a fluid to flow due to internal friction (D)</p> Signup and view all the answers

What phenomenon is described as occurring due to high blood flow velocity?

<p>Bruit generation (C)</p> Signup and view all the answers

In the context of arterial walls, what condition might be indicated by a rough surface?

<p>Atherosclerosis or plaque buildup (D)</p> Signup and view all the answers

Which of the following best describes arteriovenous shunts?

<p>Connections between arteries and veins that divert blood flow (D)</p> Signup and view all the answers

Which of the following definitions did Isaac Newton provide for viscosity?

<p>Internal friction that opposes fluid flow (D)</p> Signup and view all the answers

Flashcards

Where is the majority of blood found?

The systemic arterial system is responsible for carrying oxygenated blood from the heart to the rest of the body. It holds a significant portion of the body's blood volume.

What system holds the least amount of blood?

The systemic capillary system is responsible for exchanging oxygen and nutrients with cells throughout the body. It plays a critical role in tissue perfusion.

Describe capillaries.

Capillaries are a vital component of the circulatory system responsible for exchanging materials between blood and tissues. They are highly branched and thin-walled to facilitate efficient diffusion of oxygen, nutrients, and waste products.

What system transports blood to and from the lungs for gas exchange?

The pulmonary system is responsible for transporting blood to and from the lungs for gas exchange, ensuring that oxygen enters the bloodstream and carbon dioxide is removed. It is crucial for respiration and oxygenation.

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What determines a high-pressure system?

A high-pressure system describes a part of the circulatory system where blood is pushed with more force. This is essential for efficient oxygen delivery and waste removal from the body.

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Laminar Flow

Blood flows in smooth, parallel layers, like a river in a straight channel.

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Most Efficient Blood Flow

The pattern of blood flow where layers move smoothly alongside each other, creating the least resistance.

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Cardiac Output

The amount of blood pumped by the heart into the aorta every minute.

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Blood Flow Velocity

The speed at which blood moves through any given segment of the circulatory system.

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Blood Flow Velocity Unit

The measurement of the distance traveled by blood over a specific period of time.

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Aorta

The aorta is the largest artery in the body and receives blood directly from the left ventricle of the heart.

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Left Ventricle

The left ventricle is one of the four chambers of the heart responsible for pumping oxygenated blood throughout the body.

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What is vasomotion?

Vasomotion is the rhythmic contraction and relaxation of small blood vessels, specifically the pre-capillary sphincters and met-arterioles, occurring approximately 5-10 times per minute.

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How is vasomotion regulated locally?

Vasomotion is primarily regulated by local metabolic factors, such as changes in oxygen, carbon dioxide, hydrogen ion, and lactic acid levels.

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How is vasomotion regulated by the sympathetic nervous system?

Vasomotion can also be influenced by the sympathetic nervous system, which can constrict or dilate blood vessels to adjust blood flow.

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Sinusoidal Capillary

A type of capillary with a discontinuous structure, featuring a flattened endothelium, incomplete basement membranes, and extensive intercellular gaps.

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What are pre-capillary sphincters?

The pre-capillary sphincters are tiny muscles that control the flow of blood into capillaries.

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Endothelium in Sinusoids

The thin layer of cells lining the inside of a capillary. In sinusoidal capillaries, this layer is flattened and creates gaps.

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What are met-arterioles?

Met-arterioles are small blood vessels that connect arterioles to capillaries.

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Basement Membrane in Sinusoids

A supportive layer beneath the endothelium of a capillary. It provides structural support and helps regulate the movement of substances. In Sinusoids, these are incomplete, allowing for more permeability.

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Intercellular Gaps in Sinusoids

Spaces between endothelial cells in a capillary. Sinusoids have large spaces, allowing for easy passage of substances.

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Discontinuous Structure of Sinusoids

Having a structure with large spaces, allowing for the free passage of materials.

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Viscosity

The force that opposes the flow of a fluid due to internal friction between its layers. It's like the 'stickiness' of a fluid.

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Bruit

A distinctive sound heard through a stethoscope when blood flow is turbulent or obstructed in an artery. It indicates increased blood flow velocity.

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Arterio-venous shunts

Direct connections between arteries and veins, bypassing the capillary bed. They allow for rapid blood flow and are often found in regions with high metabolic demands.

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Rough surface of arterial wall

The rough and uneven surface of an arterial wall. This can be caused by various factors like plaque buildup and inflammation.

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Viscosity (Newton's Definition)

The internal friction that occurs between layers of a fluid in motion. It is a measure of a fluid's resistance to flow, like the stickiness or thickness of a fluid.

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Study Notes

Vascular Physiology

  • Circulation is divided into pulmonary and systemic circulation
  • 84% of the blood is found in systemic circulation, including 64% in veins, 13% in systemic arteries, and 7% in systemic capillaries
  • 7% of blood is in the heart
  • 9% of the blood is in pulmonary vessels
  • Systemic circulation is a high-pressure system, including the arterial system and left ventricles
  • Systemic veins, pulmonary circulation, and heart chambers other than the left ventricle are part of the low-pressure system

Functional Morphology of Arteries

  • Arteries are categorized into large elastic arteries (windkessel vessels), medium muscular arteries (distribution vessels), and arterioles (resistance vessels)
  • Arterioles are the smallest branches of arteries and are under high pressure
  • Artery walls have layers to maintain structure and function

Arterioles

  • Arterioles are the primary regulators of blood flow into capillaries
  • Arterioles have a high smooth muscle content in walls
  • Arterioles are extensively innervated by autonomic nerve fibers
  • Alpha 1 adrenergic receptors are found on arterioles of skin, splanchnic organs, spleen, and kidney
  • Beta 2 adrenergic receptors are found on arterioles of skeletal muscle

Capillaries

  • Capillaries are exchange vessels with the largest total cross-sectional and surface area
  • Capillary walls are only one cell thick (simple squamous epithelium) with a basal lamina
  • Capillaries are thin-walled and have no muscle or elastic valve
  • Capillaries exchange nutrients, water, and gases
  • Capillaries have a small diameter (4-9 micrometers), allowing small molecules and cells to pass
  • Capillaries have a short transit time for blood flow, allowing for efficient exchange of materials within the tissues

Functional Morphology of Capillaries

  • Arterioles divide into smaller muscle or walled vessels called meta-arterioles, feeding into capillaries
  • A meta-arteriole is slightly larger than a capillary and has both arteriole and capillary characteristics
  • Has smooth muscle that is not continuous
  • Has individual smooth muscle cells placed short distances apart
  • Constricting narrows or shuts off blood flow through capillary beds

Capillaries (Exchange Vessels)

  • Capillaries have the largest total cross-sectional area and surface area compared to other vessels
  • Capillary wall is composed of a single layer of endothelial cells and a thin basal lamina
  • The main function of capillaries is the exchange of nutrients, waste products, and gases
  • Capillaries are the location of gas and nutrient exchange between blood and tissues
  • Due to their structure, there is a low pressure in capillaries compared to the arterial side

Types of Capillaries

  • Continuous capillaries have tight junctions between endothelial cells, allowing passage for small molecules and water but not large proteins
  • Fenestrated capillaries have pores (fenestrations) in their endothelial cells, allowing for faster exchange of fluids and molecules
  • Sinusoidal capillaries (discontinuous capillaries) have large intercellular gaps and incomplete basement membranes, resulting in the largest exchange ability, accommodating larger molecules

Venules

  • Venules are extremely small veins (8-100 micrometers) that collect blood from capillaries and progressively merge to form larger veins. The largest vein, the vena cava, returns blood to the heart
  • Venules are characterized by their thin walls, which are easily distended, and contain little elastic tissue or smooth muscles
  • Venules are under low pressure
  • Venules have á, -adrenergic receptors
  • Venules have valves

Blood Velocity and Viscosity

  • Blood flow is the amount of blood that passes a given point in the circulation in a set period
  • Blood velocity is the speed at which blood flows through a particular segment
  • Viscosity is the resistance to fluid flow due to internal friction between layers
  • Blood viscosity depends on plasma protein concentration, and hematocrit (packed red cell volume)

Turbulent Flow

  • Turbulent flow is characterized by crosscurrents (eddies) and the fastest velocities aren't necessarily in the center
  • High velocity and sudden changes in the diameter of the vessel contribute to turbulent flow
  • Large vessel diameter, sharp turns, and rough surfaces contribute to turbulent flow
  • Low viscosity and high-density fluids tend to resist turbulent flow

Murmurs and Bruits

  • Murmurs are abnormal heart sounds due to turbulent flow of blood in the heart, arising from valve problems or other heart defects
  • Bruits are abnormal sounds caused by turbulent blood flow in arteries, often associated with narrowing or blockage of arteries

Viscosity

  • Viscosity is a measure of the resistance of a fluid to flow
  • Viscosity is related to the thickness of the fluid
  • Some factors that affect viscosity include temperature and erythrocyte (red blood cell) count
  • Blood viscosity is higher than water's viscosity

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