Human Circulatory System Quiz
29 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What primarily drives the movement of blood through the vessels?

  • Vessel diameter
  • Heart contractions
  • Pressure gradient (correct)
  • Blood viscosity

How is blood pressure defined in relation to blood vessels?

  • It is the resistance encountered by blood in the vessels.
  • It is the speed of blood flow through the vessels.
  • It is a measure of force exerted against vessel walls. (correct)
  • It is the amount of blood in circulation.

Which of the following factors does NOT influence blood flow through the vessels?

  • Gravity
  • Blood temperature (correct)
  • Pressure gradient
  • Vessel elasticity

What effect does increased pressure within a vessel have on blood flow?

<p>It increases blood flow. (C)</p> Signup and view all the answers

Which statement is true regarding the relationship between blood pressure and vessel walls?

<p>Pressure indicates the force that blood exerts against vessel walls. (A)</p> Signup and view all the answers

What phenomenon occurs when red blood cells (RBC) accumulate along the axis of a blood vessel?

<p>Reduced hematocrit (C)</p> Signup and view all the answers

How does plasma skimming affect blood viscosity?

<p>It decreases the viscosity by reducing RBC aggregation (C)</p> Signup and view all the answers

What happens to hematocrit levels as blood approaches a micro-vessel due to plasma skimming?

<p>Hematocrit levels decrease as RBCs are pushed towards the center (B)</p> Signup and view all the answers

What role does plasma skimming play in microvascular blood flow?

<p>Promotes more streamlined flow through micro-vessels (C)</p> Signup and view all the answers

What is the mean pulmonary arterial pressure in the pulmonary circulation?

<p>16 mm Hg (A)</p> Signup and view all the answers

What is the mean left atrial pressure in the pulmonary circulation?

<p>2 mm Hg (C)</p> Signup and view all the answers

What is the net pressure difference calculated in the pulmonary circulation?

<p>14 mm Hg (B)</p> Signup and view all the answers

Which statement about mean pressures in pulmonary circulation is correct?

<p>Mean pulmonary arterial pressure is higher than mean left atrial pressure. (B)</p> Signup and view all the answers

How does the mean pulmonary arterial pressure relate to blood flow in the pulmonary circulation?

<p>Higher pressure promotes increased blood flow. (B)</p> Signup and view all the answers

What happens to blood flow when the pressure falls below critical closing pressure?

<p>Blood flow ceases because intramural pressure is insufficient. (A)</p> Signup and view all the answers

What is the average diameter of red blood cells (RBC) mentioned in the context?

<p>7.5μm (B)</p> Signup and view all the answers

Why is intramural pressure significant for blood flow through capillaries?

<p>It is necessary to overcome the resistance against RBC passage. (A)</p> Signup and view all the answers

What occurs when the intramural pressure is inadequate in the circulatory system?

<p>Blood flow may stop completely. (C)</p> Signup and view all the answers

What is the average diameter of capillaries compared to red blood cells?

<p>Capillaries are smaller than RBC. (D)</p> Signup and view all the answers

What type of resistance do vascular components exhibit?

<p>Both in-series and parallel resistance (A)</p> Signup and view all the answers

What initiates blood distribution to major organs?

<p>Blood leaves the heart through the aorta (D)</p> Signup and view all the answers

Where do the large arteries that supply major organs originate from?

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

How is the resistance in a vascular bed characterized?

<p>Combined in both in-series and parallel arrangements (C)</p> Signup and view all the answers

Why do vascular components have resistance?

<p>Due to the structure of the vascular bed (A)</p> Signup and view all the answers

What does blood flow through the largest artery equal to?

<p>Total blood flow through all of the capillaries (B)</p> Signup and view all the answers

Which statement best describes the relationship between blood flow in different vessels?

<p>Blood flow is constant across all vessel types (D)</p> Signup and view all the answers

How does total blood flow compare through all arterioles and the capillaries?

<p>It is equal through both arterioles and capillaries (B)</p> Signup and view all the answers

What can be inferred about total blood flow in the circulatory system?

<p>The largest artery has the same total blood flow as all smaller vessels combined (A)</p> Signup and view all the answers

What is a characteristic of blood flow in the circulatory system?

<p>Blood flow remains the same regardless of vessel size (B)</p> Signup and view all the answers

Flashcards

Blood Viscosity

The thickness or resistance of blood to flow.

Plasma Skimming

The process where red blood cells (RBCs) concentrate in the center of a blood vessel, leading to a lower hematocrit (percentage of RBCs) towards the smaller vessels.

Hematocrit

The percentage of red blood cells (RBCs) in a given volume of blood.

Microvessels

Smaller blood vessels, often with diameters less than 100 micrometers.

Signup and view all the flashcards

RBC Accumulation

The tendency for RBCs to concentrate in the center of blood vessels, especially as the vessels become smaller.

Signup and view all the flashcards

Pressure in blood vessels

The force with which blood pushes against the vessel walls.

Signup and view all the flashcards

Pressure gradient

The difference in pressure between two points in a blood vessel that causes blood to flow from the higher pressure area to the lower pressure area.

Signup and view all the flashcards

How pressure gradient affects blood flow

The direction of blood flow is determined by this gradient, moving from areas of higher pressure to areas of lower pressure.

Signup and view all the flashcards

How pressure is measured

A measurement of the force that blood exerts on the walls of the blood vessels. It is typically measured in millimeters of mercury (mmHg).

Signup and view all the flashcards

Systolic pressure

The pressure exerted by the blood against the walls of the blood vessels when the heart is contracting. It is the highest pressure during the cardiac cycle.

Signup and view all the flashcards

Pulmonary Circulation

The flow of blood through the lungs, where it picks up oxygen and releases carbon dioxide.

Signup and view all the flashcards

Mean Pulmonary Arterial Pressure

The average pressure in the arteries that carry blood from the heart to the lungs.

Signup and view all the flashcards

Mean Left Atrial Pressure

The average pressure in the left atrium, the chamber of the heart that receives oxygenated blood from the lungs.

Signup and view all the flashcards

Net Pressure Difference (Pulmonary Circulation)

The difference between the mean pulmonary arterial pressure and the mean left atrial pressure, which drives blood flow through the lungs.

Signup and view all the flashcards

Pulmonary Circulation Pressure Difference

The average net pressure difference in pulmonary circulation, typically around 14 mmHg, which is relatively low compared to the systemic circulation.

Signup and view all the flashcards

Critical Closing Pressure

The minimal pressure required to keep blood flowing through a capillary. It is the pressure at which the capillary collapses and blood flow ceases.

Signup and view all the flashcards

Perfusion Pressure

The force that pushes blood through the capillaries. It is influenced by the pressure difference between the arteriole and venule ends of the capillary.

Signup and view all the flashcards

Intramural Pressure

The pressure inside the capillary wall that resists the flow of blood. It is caused by the tension of the capillary wall.

Signup and view all the flashcards

Intramural Force

The squeezing force required to get red blood cells through the narrow capillaries. This force is necessary because red blood cells are larger than the capillaries.

Signup and view all the flashcards

In-Series Resistance

The total resistance offered by individual, connected vascular sections within an organ. Imagine a series of pipes, one after the other, each having some resistance to water flow - this is similar to blood flow in organs.

Signup and view all the flashcards

Parallel Resistance

The overall resistance to blood flow offered by multiple parallel blood vessels within an organ. Imagine a network of pipes each flowing into a common destination - this is similar to blood flow in an organ.

Signup and view all the flashcards

Aorta

The major artery that carries oxygenated blood from the heart to other parts of the body, branching out to various organs.

Signup and view all the flashcards

Major Arteries

Large arteries that branch off from the aorta and supply blood to specific organs.

Signup and view all the flashcards

Blood Distribution

The distribution of blood from the aorta to different organs via the major arteries.

Signup and view all the flashcards

Conservation of Blood Flow

The total amount of blood flowing through a specific point in the circulatory system remains constant, regardless of the size of the vessel.

Signup and view all the flashcards

Blood Flow Distribution

The total blood flow through the largest artery in the body is equal to the total blood flow through all the arterioles, capillaries, and veins.

Signup and view all the flashcards

Capillary Cross-Sectional Area

The sum of the cross-sectional areas of all capillaries is significantly larger than the cross-sectional area of the aorta.

Signup and view all the flashcards

Blood Flow Velocity

The velocity of blood flow decreases as blood moves from larger arteries to smaller capillaries.

Signup and view all the flashcards

Blood Flow Regulation

This principle emphasizes that blood flow is distributed throughout the circulatory system in a regulated and coordinated manner.

Signup and view all the flashcards

Study Notes

Vascular Physiology Lecture 2

  • Concept 3: Blood Viscosity
  • Viscosity is defined as internal friction in fluids, or the lack of slipperiness.
  • Viscosity measures the fluid's thickness and its resistance to flow.
  • Viscosity can be measured in vitro using a viscometer.
  • The unit of measure for viscosity is the Poise (after Poiseuille)
  • A fluid with 1 poise viscosity has a force of 1 dyne/cm² of contact between layers when flowing at a 1 cm/sec velocity gradient
  • 1 Poise = 0.100 kg⋅m⁻¹.s⁻¹= 1g⋅cm⁻¹.s⁻¹
  • 1 Pa⋅s = 1 kg⋅m⁻¹.s⁻¹= 10 P
  • Relative viscosity is more commonly used, indicating a fluid's viscosity relative to water at body temperature (37°C).
  • Water viscosity at 21°C is 0.01 poise (or 1 centipoise).
  • Water viscosity at 37°C is 0.695 centipoise
  • Plasma viscosity at 37°C is 1.2 centipoise with a relative viscosity of 1.7
  • Blood viscosity at 37°C is 2.8-3.8 centipoise with a relative viscosity of 4-5.

Factors Affecting Blood Viscosity

  • Blood Composition Changes
    • RBC mass: Increased RBCs and Hemoglobin increase viscosity. Anemia decreases viscosity. Polycythemia increases viscosity.
    • Plasma proteins: Increased plasma protein increases viscosity. However, changes in plasma proteins have less effect than RBC changes.
  • Cells Deformation
    • Hereditary spherocytosis and sickle cell diseases increase viscosity.
  • Clotting Mechanisms
    • If clotting mechanisms are stimulated platelets aggregate and interact with plasma proteins. This entraps red cells, forming clots and dramatically increasing blood viscosity.
  • Temperature
    • A decrease in body temperature increases blood viscosity. Blood viscosity increases 2% for each 1°C decrease.
  • Shear Rate or Blood Flow Velocity Gradient
    • Viscosity decreases as shear rate or blood flow increases.
  • Plasma Skimming
    • The concentration of RBCs decreases as blood approaches smaller blood vessels. Larger branches have higher flow rates, more RBCs, and higher hematocrits, whereas smaller branches (with lower flow rates) have less RBCs and lower hematocrits.
  • Diameter of Blood Vessel (Fahraeus-Lindquist Effect)
    • Viscosity decreases with decreasing vessel diameter. This effect disappears at diameters greater than 0.5 mm. In small vessels, a cell-free plasma layer forms adjacent to the vessel walls.

Blood Flow: A New Equation

  • Overview
    • Cardiac output, flow, and resistance.
    • Compliance and elasticity
  • Effective Perfusion Pressure
    • Arterial pressure minus venous pressure.
  • Pressure Gradient
    • Drives blood from high pressure area to a lower pressure area
  • Critical Closing Pressure
    • The point at which the vessel collapses, flow ceases, and the lumen closes. For whole blood: 20mmHg; For Plasma: 5-10mmHg.
  • Flow and Resistance
    • Flow is inversely proportional to resistance.
    • Resistance cannot be directly measured
  • Total Peripheral Resistance (TPR) -Total resistance in circulatory system
  • Local Resistance
    • Resistance specific to local vessel conditions (varies with vessel constriction and dilation).
  • Poiseuille-Hagen Formula -Flow (conductance) is directly related to the fourth power of the vessel radius, and inversely related to viscosity and vessel length.

Compliance and Elasticity

  • Compliance is the ability of a vessel to expand or change volume in response to pressure changes.
  • Elastance is the ability of a vessel or hollow organ to recoil toward its original dimensions.
  • Compliance for Blood Vessels
    • The relationship between change in volume and change in pressure is usually non-linear
    • The slope of the volume-pressure curve decreases as volume increases.
    • Vein compliance is greater than artery compliance at lower pressures.
  • Compliance of the Ventricles
    • The relationship between change in volume and change in pressure is not linear
  • Laplace Law Describes the relationship between tension in a vessel wall, internal pressure, radius, and overall wall thickness.
  • Vascular Distensibility -Measurement of the vessel's ability to stretch relative to changes in pressure and volume.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Vascular Physiology Lecture 2 PDF

Description

Test your knowledge on the dynamics of blood flow, pressure, and circulation in the human body. This quiz covers key concepts such as blood vessel movement, plasma skimming, and the effects of pressure on blood behaviors. Perfect for students studying physiology or healthcare-related fields.

More Like This

Autoregulation of Renal Blood Flow
10 questions

Autoregulation of Renal Blood Flow

EntertainingArtDeco avatar
EntertainingArtDeco
Human Physiology Lecture 14: Cardiovascular System
21 questions

Human Physiology Lecture 14: Cardiovascular System

EasiestBowenite3090 avatar
EasiestBowenite3090
Functions and Pressures of Veins
10 questions

Functions and Pressures of Veins

BrainiestSard2626 avatar
BrainiestSard2626
Human Physiology: Blood Flow and Pressure
48 questions

Human Physiology: Blood Flow and Pressure

IndustriousRelativity avatar
IndustriousRelativity
Use Quizgecko on...
Browser
Open
Browser
Browser