Circulatory System

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Questions and Answers

What percentage of the blood volume is in the systemic circulation?

60%

80% (correct)

90%

70%

What is the approximate percentage of arterial blood in the pulmonary circulation?

20%

30%

46.5% (correct)

55%

What is the approximate concentration of red blood cells per cubic millimeter of blood?

5×103 RBC/mm3 (correct)

10×103 RBC/mm3

15×103 RBC/mm3

1×103 RBC/mm3

What is the primary function of platelets in the blood?

Clotting Signup and view all the answers

What is the approximate percentage of blood volume made up of plasma?

55% Signup and view all the answers

What device is used to count red blood cells?

Coulter counter Signup and view all the answers

What is the approximate distance a molecule will travel after 10^12 collisions with other molecules in tissue?

10^-5m Signup and view all the answers

What is the primary location of oxygen and carbon dioxide exchange in the body?

Arterioles and capillary networks Signup and view all the answers

What is the name of the device used in the direct method of measuring blood pressure?

Pressure transducer Signup and view all the answers

What is the unit of pressure expressed in according to Bernoulli's principle?

dyne/cm2 Signup and view all the answers

What is the name of the sound heard when the cuff is deflated during the indirect method of measuring blood pressure?

Korotkoff sound Signup and view all the answers

What is the law that relates the transmural pressure to the radius of a tube and the pressure of the liquid?

Laplace law Signup and view all the answers

What is the unit of tension (transmural pressure) in Laplace law?

dyne/cm Signup and view all the answers

What is the major factor that affects the flow rate of blood in vessels according to Poiseuille's law?

Pressure difference between the two ends of the tube Signup and view all the answers

What is the approximate diameter of the smallest blood vessels, the capillaries?

20 um Signup and view all the answers

What is the principle that explains the increase in velocity of a fluid flowing through a narrow section of a tube?

Bernoulli's principle Signup and view all the answers

What is the type of energy converted into kinetic energy according to Bernoulli's principle?

Potential energy Signup and view all the answers

What is the unit of viscosity of blood?

Pas Signup and view all the answers

According to Poiseuille's law, what is the exponent of the radius (r) in the flow rate equation?

4 Signup and view all the answers

Why do capillaries not burst despite their thinness?

Because of their small radius Signup and view all the answers

What type of flow occurs when blood passes through constrictions, obstructions, or bending?

Turbulent flow Signup and view all the answers

What is the result of the skimming effect in blood flow?

Hematocrit is lower in small branches than in main vessels Signup and view all the answers

What is the effect of increasing temperature on the viscosity of blood?

Viscosity decreases Signup and view all the answers

What is the difference in hematocrit between the body's extremities and other parts of the body?

10% higher in extremities Signup and view all the answers

What is the main purpose of the systemic circulation?

Oxidization of food and production of energy Signup and view all the answers

What is the pressure exerted by the left ventricle during contraction?

120 mmHg Signup and view all the answers

Why is the muscular wall of the left ventricle thicker than the right ventricle?

To exert the higher pressure required for the general circulation Signup and view all the answers

What is the shape of the cross-section of the left ventricle?

Circular Signup and view all the answers

What is the function of the heart valves?

To permit the blood to flow in one direction Signup and view all the answers

How much blood does each ventricle of the heart pump on each contraction?

80 ml Signup and view all the answers

What percentage of the body mass is the mass of the blood?

7% Signup and view all the answers

How long does it take for the average red blood cell to make one complete cycle around the body?

1 minute Signup and view all the answers

What is the primary factor that determines the frequency of heart sounds?

The turbulent flow of blood through constrictions Signup and view all the answers

What is the advantage of laminar flow over turbulent flow?

It is more efficient Signup and view all the answers

What is the range of frequencies for normal heart sounds?

20 to 200 Hz Signup and view all the answers

What is the purpose of phonocardiography?

To record heart sounds graphically Signup and view all the answers

What is the effect of bends or obstructions on the value of K in Reynolds' law?

It decreases the value of K Signup and view all the answers

What is the primary cause of heart sounds?

The opening and closing of the heart valves Signup and view all the answers

What is the effect of amplifying heart sounds using an electronic stethoscope?

It distorts the heart sounds and affects their quality Signup and view all the answers

What is the formula for critical velocity in Reynolds' law?

Vc = (K η / ρ R) Signup and view all the answers

Study Notes

Heart Function and Circulation

The heart is a double pump system that circulates blood through two major circulatory systems: systemic circulation and pulmonary circulation.
Systemic circulation involves the oxygenated blood being pumped by the left ventricle to all body tissues for oxidation of food and energy production in capillary networks.
Pulmonary circulation involves the non-oxygenated blood being pumped by the right ventricle to the lungs for oxygenation.

Heart Structure and Function

The muscular wall of the left ventricle is three times thicker than the right ventricle, necessary for exerting higher pressure for general circulation.
The cross-section of the left ventricle is circular, while the right ventricle is crescent-like, allowing for higher pressure for general circulation.
Heart valves permit blood to flow in one direction, and can be replaced with artificial heart valves if they become insufficient.

Blood Composition and Circulation

A typical adult has about 4.5 liters of blood, with each ventricle pumping about 80 ml on each contraction.
About 1 minute is needed for the average red blood cells to make one complete cycle around the body.
The mass of blood is about 7% of the body mass.
About 80% of blood volume is in the systemic circulation (15% arterial, 75% venous, and 10% in capillaries), and about 20% is in the pulmonary circulation (46.5% arterial, 46.5% venous, and 7% in pulmonary capillaries).

Blood Components

Red blood cells (RBCs) make up about 45% of blood volume (5 x 10^3 RBC/mm^3).
White blood cells (WBCs) play an important role in combating disease, and their types need a differential count.
Platelets are responsible for clotting function (3 x 10^5 platelets/mm^3).
Plasma makes up about 55% of blood volume.

Oxygen and Carbon Dioxide Exchange

O2 and CO2 exchange occurs between the oxygen-rich blood of arterioles and capillary networks for oxidation of food and energy production.
The law of diffusion states that the most probable distance a molecule will travel after collisions with other molecules is D = λ √N.

Blood Pressure Measurement

There are two methods to measure blood pressure: direct method using a pressure transducer, and indirect method using a sphygmomanometer.

Laplace Law and Bernoulli's Principle

Laplace law states that the passage of a liquid through a tube imparts a tension to the wall of the tube, given by T = R x P (dynes/cm).
Bernoulli's principle states that the velocity of a fluid flowing through a frictionless tube increases in the narrow section.

Poiseuille's Law and Blood Flow

Poiseuille's law states that the rate of flow through a tube of constant radius is given by flow rate = (PA - PB) π r^4 / 8 η L.
The viscosity of blood is 3 x 10^-3 to 4 x 10^-3 Pas, and increases with an increasing percentage of RBCs in the blood and decreasing temperature of blood.
Laminar flow is a slow and silent flow, and turbulent flow is a rapid and noisy flow.

Heart Sounds and Phonocardiography

Heart sounds can be heard with a stethoscope and are caused by the vibrations resulting from the opening and closing of the heart valves, and by the turbulent flow caused by the passage of blood through constrictions, obstructions, and bendings.
Phonocardiography is the graphic recording of heart sounds, enabling examination of heart sounds by the eye in addition to hearing with a stethoscope.

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Description

Learn about the heart's double pump system, including systemic circulation and pulmonary circulation, and their roles in oxygenating the body and producing energy.