Textbook Question
Physiologists often consider capillaries and postcapillary venules together.
a. What functions do these vessels share?
b. Structurally, how do they differ?
1209
views
Ch. 19 The Cardiovascular System: Blood Vessels
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch. 1 The Human Body: An Orientation24
- Ch. 2 Chemistry Comes Alive25
- Ch. 3 Cells: The Living Units21
- Ch. 4 Tissue: The Living Fabric20
- Ch. 5 The Integumentary System11
- Ch. 6 Bones and Skeletal Tissues19
- Ch. 7 The Skeleton14
- Ch. 8 Joints7
- Ch. 9 Muscles and Muscle Tissue26
- Ch. 10 The Muscular System26
- Ch. 11 Fundamentals of the Nervous System and Nervous Tissue19
- Ch. 12 The Central Nervous System26
- Ch. 13 The Peripheral Nervous System and Reflex Activity32
- Ch. 14 The Autonomic Nervous System19
- Ch. 15 The Special Senses26
- Ch. 16 The Endocrine System23
- Ch. 17 Blood25
- Ch. 18 The Cardiovascular System: The Heart24
- Ch. 19 The Cardiovascular System: Blood Vessels27
- Ch. 20 The Lymphatic System and Lymphoid Organs and Tissues14
- Ch. 21 The Immune System: Innate and Adaptive Body Defenses27
- Ch. 22 The Respiratory System21
- Ch. 23 The Digestive System31
- Ch. 24 Nutrition, Metabolism, and Energy Balance26
- Ch. 25 The Urinary System26
- Ch. 26 Fluid, Electrolyte, and Acid-Base Balance24
- Ch. 27 The Reproductive System24
- Ch. 28 Pregnancy and Human Development25
- Ch. 29 Heredity11
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
Chapter 19, Problem 21
Explain the reasons for the observed changes in blood flow velocity in the different regions of the circulation.
Verified step by step guidance1
Step 1: Understand that blood flow velocity varies throughout the circulatory system due to changes in the total cross-sectional area of the blood vessels in different regions.
Step 2: Recognize that blood flow velocity is inversely related to the total cross-sectional area, which means that as the total cross-sectional area increases, the velocity decreases, and vice versa. This relationship can be expressed as \(Q = A \times v\), where \(Q\) is the flow rate (constant), \(A\) is the cross-sectional area, and \(v\) is the velocity.
Step 3: Identify that arteries have a smaller total cross-sectional area compared to capillaries, so blood velocity is higher in arteries and slows down significantly in capillaries where the total cross-sectional area is much larger.
Step 4: Explain that the slow velocity in capillaries facilitates efficient exchange of gases, nutrients, and waste products between blood and tissues, which is essential for proper physiological function.
Step 5: Note that after capillaries, in the venous system, the total cross-sectional area decreases again, causing the blood flow velocity to increase as blood returns to the heart.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Blood Flow Velocity
Blood flow velocity refers to the speed at which blood moves through the vessels. It varies across different regions of the circulatory system due to changes in vessel diameter and total cross-sectional area, influencing how quickly blood reaches tissues.
Recommended video:
6:40
Relationship Between Blood Flow, Pressure, & Resistance
Cross-Sectional Area of Blood Vessels
The total cross-sectional area of blood vessels affects blood flow velocity; as blood moves from large arteries to numerous smaller arterioles and capillaries, the combined cross-sectional area increases, causing a decrease in velocity to facilitate nutrient exchange.
Recommended video:
4:59Blood Vessels
Hemodynamics and Vessel Structure
Hemodynamics studies the forces involved in blood circulation, including how vessel elasticity, diameter, and branching patterns influence resistance and flow velocity. Larger, elastic arteries maintain higher velocity, while smaller, more numerous vessels slow flow to optimize exchange.
Recommended video:
6:24Hemodynamics
Related Practice
Textbook Question
How does the control of blood flow to the skin for the purpose of regulating body temperature differ from the control of nutrient blood flow to skin cells?
869
views
1
rank
Textbook Question
A 60-year-old man is unable to walk more than 100 yards without experiencing severe pain in his left leg; the pain is relieved by resting for 5–10 minutes. He is told that the arteries of his leg are becoming occluded with fatty material and is advised to have the sympathetic nerves serving that body region severed. Explain how such surgery might help to relieve this man's problem.
1051
views
Textbook Question
Write an equation showing the relationship between total peripheral resistance, blood flow, and blood pressure.
89
views
Textbook Question
Distinguish between elastic arteries, muscular arteries, and arterioles relative to location, histology, and functional adaptations.
1272
views
Textbook Question
Describe neural and chemical (both systemic and local) effects exerted on the blood vessels when you are fleeing from a mugger. (Be careful, this is more involved than it appears at first glance.)
1093
views