Textbook Question
Which of the following is greater?
(a) The osmotic pressure of the interstitial fluid during inflammation
(b) The osmotic pressure of the interstitial fluid during normal conditions
(c) Neither is greater
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Ch. 21 Blood Vessels and Circulation
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology26
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization30
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure36
- Ch. 7 The Axial Skeleton11
- Ch. 8 The Appendicular Skeleton17
- Ch. 9 Joints13
- Ch. 10 Muscle Tissue12
- Ch. 11 The Muscular System28
- Ch. 12 Nervous Tissue18
- Ch. 13 The Spinal Cord, Spinal Nerves, and Spinal Reflexes22
- Ch. 14 The Brain and Cranial Nerves20
- Ch. 15 Sensory Pathways and the Somatic Nervous System17
- Ch. 16 The Autonomic Nervous System and Higher-Order Functions30
- Ch. 17 The Special Senses16
- Ch. 18 The Endocrine System20
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation29
- Ch. 22 The Lymphatic System and Immunity31
- Ch. 23 The Respiratory System12
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes32
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance23
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089Not the one you use?Change textbook
Chapter 21, Problem 20
Which of the following conditions would have the greatest effect on peripheral resistance?
(a) Doubling the length of a vessel
(b) Doubling the diameter of a vessel
(c) Doubling the viscosity of the blood
(d) Doubling the turbulence of the blood
(e) Doubling the number of white cells in the blood
Verified step by step guidance1
Understand that peripheral resistance in blood vessels is primarily influenced by vessel length, vessel diameter (radius), blood viscosity, and blood flow characteristics such as turbulence.
Recall the formula for resistance in a blood vessel based on Poiseuille's law: \(R = \frac{8 \eta L}{\pi r^{4}}\), where \(R\) is resistance, \(\eta\) is blood viscosity, \(L\) is vessel length, and \(r\) is the radius of the vessel.
Analyze how each condition affects the variables in the formula: (a) Doubling length \(L\) will double resistance linearly; (b) Doubling diameter means doubling radius \(r\), which affects resistance to the fourth power, so resistance changes by a factor of \(2^{4} = 16\); (c) Doubling viscosity \(\eta\) doubles resistance linearly; (d) Doubling turbulence increases resistance but is not directly in Poiseuille's formula and generally has a less predictable effect; (e) Doubling white blood cells has minimal effect on viscosity or flow properties.
Compare the magnitude of changes: since resistance is inversely proportional to the fourth power of radius, changes in diameter have a much greater effect than changes in length or viscosity, which are linear.
Conclude that doubling the diameter of a vessel (option b) would have the greatest effect on peripheral resistance due to the exponential relationship between radius and resistance.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Peripheral Resistance
Peripheral resistance refers to the resistance to blood flow offered by the blood vessels, primarily the arterioles. It is influenced by factors such as vessel diameter, length, blood viscosity, and flow characteristics. Understanding peripheral resistance is essential to grasp how changes in these factors affect blood pressure and circulation.
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3:33
Peripheral Nervous System
Effect of Vessel Diameter on Resistance
Vessel diameter has a powerful inverse effect on resistance; according to Poiseuille’s law, resistance is proportional to the fourth power of the radius. This means even small changes in diameter cause large changes in resistance, making diameter the most significant factor in controlling blood flow.
Recommended video:
8:32Altering Resistance in Blood Vessels
Blood Viscosity and Turbulence
Blood viscosity is the thickness of blood, affecting how easily it flows through vessels; higher viscosity increases resistance. Turbulence refers to chaotic blood flow, which also raises resistance by disrupting smooth laminar flow. Both factors influence peripheral resistance but generally less dramatically than vessel diameter.
Recommended video:
6:11Functions of Blood
Related Practice
Textbook Question
A major difference between the arterial and venous systems is that
(a) Arteries are usually more superficial than veins.
(b) In the limbs there is dual venous drainage.
(c) Veins are usually less branched compared to arteries.
(d) Veins exhibit a much more orderly pattern of branching in the limbs.
(e) Veins are not found in the abdominal cavity.
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Textbook Question
Why do capillaries permit the diffusion of materials, whereas arteries and veins do not?
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Textbook Question
What are the primary forces that cause fluid to move?
(a) Out of a capillary at its arterial end and into the interstitial fluid
(b) Into a capillary at its venous end from the interstitial fluid?
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Textbook Question
Relate the anatomical differences between arteries and veins to their functions.
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Textbook Question
What cardiovascular changes occur at birth?
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