Test your knowledge of capillaries with this quiz on their structure and functio...

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Questions and Answers

What is the approximate volume of plasma in the standard person?

2.75 L (correct)

4.50 L

5.50 L

3.25 L

What is the approximate volume fraction of formed elements in the blood?

0.45 (correct)

0.65

0.55

0.35

What is the approximate length of the vasculature in the human body?

19,000 km (correct)

30,000 km

25,000 km

12,000 km

What is the approximate percentage of total body water in women?

60% Signup and view all the answers

What happens to the volume of distribution (Vd) when there is stronger binding to tissue proteins and membranes?

It increases because this binding lowers the unbound fraction of drug in tissues (fUOi) Signup and view all the answers

How does stronger binding to plasma proteins affect the volume of distribution (Vd)?

It decreases Vd because this binding lowers the unbound fraction of drug in plasma (fUP) Signup and view all the answers

What does Equation 4 indicate about the volume of distribution (Vd) in relation to protein binding?

If binding occurs in tissues, it increases Vd; if binding occurs in plasma, it decreases Vd Signup and view all the answers

What is the relationship between the volume of plasma (VP) and the corrected volumes of organs (VOCi) in the calculation of Vd?

Vd is the sum of VP and corrected volumes of organs (VOCi) Signup and view all the answers

What is the impact of protein binding on drug metabolism and excretion?

Protein-bound drug molecules are prevented from metabolism and excretion Signup and view all the answers

In the context of drug distribution, how does the drug amount in plasma (mg) relate to the amount in tissues (mg)?

The drug amounts in plasma and individual organs are in the same ratio as the volumes V and V Signup and view all the answers

For the standard patient, if VP = 3 L, what is the ratio of drug amounts in plasma to the amount in tissues (mg)?

3:7 Signup and view all the answers

What is the primary role of protein binding in drug distribution?

Protein binding serves as a depot for drug molecules and attracts the molecules to the given compartment Signup and view all the answers

What is the composition of blood in large veins?

Plasma, erythrocytes, and leukocytes Signup and view all the answers

What is the average diameter of capillary cross-sections?

8 mm Signup and view all the answers

Which component is part of capillary structure?

Endothelial layer Signup and view all the answers

What is the function of glycocalyx in capillaries?

To enhance nutrient exchange Signup and view all the answers

In which organ is capillary density high?

Lungs Signup and view all the answers

How does the distance of living cells from capillaries impact drug absorption?

It increases drug absorption Signup and view all the answers

What is the ratio used to define Volume of Distribution (Vd)?

Drug amount to drug concentration in plasma Signup and view all the answers

Which factor influences the Volume of Distribution (Vd)?

Protein binding Signup and view all the answers

In what circumstances can the Volume of Distribution (Vd) be equal to body volume?

When drug is evenly distributed in all tissues Signup and view all the answers

What percentage of cardiac output do the lungs receive?

100% Signup and view all the answers

How does capillary wall porosity affect permeability?

Higher porosity leads to higher permeability Signup and view all the answers

What is the minimum value of Volume of Distribution (Vd)?

Volume of plasma Signup and view all the answers

Study Notes

Capillaries: Structure and Function

Blood contains 8 liters (3 liters in large veins) with 50% in large veins
Blood composition includes plasma (rich in proteins such as albumin and lipoproteins), erythrocytes (5 million/μL), leukocytes (5 thousand/μL), and platelets (500 thousand/μL)
Capillaries consist of an endothelial layer, basement membrane, and glycocalyx
Capillary cross-sections have an average diameter of 8 mm, with minimum and maximum diameters of 4 mm and 40 mm, respectively
Capillary walls can be continuous, fenestrated, or discontinuous (sinusoids) with varying porosities and permeabilities
Capillary density varies among organs, with high density in lungs and low density in muscles and fat
Distance of living cells from capillaries affects drug absorption and distribution
The number of cell layers served by a capillary varies by organ and impacts drug penetration
Blood flow through organs varies, with lungs receiving 100% of cardiac output and fat and muscle receiving 0.04% and 0.03%, respectively
Volume of Distribution (Vd) is defined as the ratio of drug amount to drug concentration in plasma at any given moment
Vd is influenced by membrane accumulation, protein binding, and organ volume, with the minimum value being the volume of plasma
Vd can be equal to body volume in rare circumstances when certain conditions are met

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Description

Test your knowledge of capillaries with this quiz on their structure and function. Explore topics such as blood composition, capillary types, density in organs, drug absorption, and volume of distribution.