Textbook Question
Physiologists often consider capillaries and postcapillary venules together.
a. What functions do these vessels share?
b. Structurally, how do they differ?
2
views
Ch. 19 The Cardiovascular System: Blood Vessels
Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091
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 Units24
- Ch. 4 Tissue: The Living Fabric19
- Ch. 5 The Integumentary System10
- Ch. 6 Bones and Skeletal Tissues19
- Ch. 7 The Skeleton11
- Ch. 8 Joints7
- Ch. 9 Muscles and Muscle Tissue26
- Ch. 10 The Muscular System26
- Ch. 11 Fundamentals of the Nervous System and Nervous Tissue23
- Ch. 12 The Central Nervous System26
- Ch. 13 The Peripheral Nervous System and Reflex Activity28
- Ch. 14 The Autonomic Nervous System18
- Ch. 16 The Endocrine System26
- Ch. 17 Blood27
- Ch. 18 The Cardiovascular System: The Heart22
- Ch. 19 The Cardiovascular System: Blood Vessels27
- Ch. 20 The Lymphatic System and Lymphoid Organs and Tissues16
- Ch. 21 The Immune System: Innate and Adaptive Body Defenses29
- Ch. 22 The Respiratory System20
- Ch. 23 The Digestive System30
- Ch. 24 Nutrition, Metabolism, and Energy Balance26
- Ch. 25 The Urinary System25
- Ch. 26 Fluid, Electrolyte, and Acid-Base Balance24
- Ch. 27 The Reproductive System23
Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091Not the one you use?Change textbook
Chapter 18, Problem 17
a. What blood vessels contribute to the formation of the hepatic portal circulation?
b. Why is a portal circulation a 'strange' circulation
Verified step by step guidance1
Step 1: Identify the blood vessels involved in the hepatic portal circulation. These primarily include the superior mesenteric vein, the splenic vein, and the inferior mesenteric vein, which all converge to form the hepatic portal vein. The hepatic portal vein then carries blood to the liver.
Step 2: Understand the anatomical pathway: blood from the gastrointestinal tract (including the stomach, intestines, pancreas, and spleen) drains into these veins, which then merge to form the hepatic portal vein, directing nutrient-rich blood to the liver for processing before it enters the systemic circulation.
Step 3: Define what a portal circulation is: it is a system where blood flows through two consecutive capillary beds before returning to the heart, unlike the typical circulation where blood passes through only one capillary bed between arteries and veins.
Step 4: Explain why the hepatic portal circulation is considered 'strange' or unique: because it carries blood from one capillary bed (in the digestive organs) through veins to a second capillary bed (in the liver) without first returning to the heart, allowing the liver to metabolize nutrients and detoxify substances directly.
Step 5: Summarize the functional significance: this arrangement ensures that substances absorbed in the intestines are first processed by the liver, which is crucial for maintaining metabolic homeostasis and protecting the body from toxins.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hepatic Portal Circulation
The hepatic portal circulation is a system of blood vessels that carries nutrient-rich blood from the gastrointestinal tract and spleen to the liver. It primarily involves veins such as the superior mesenteric vein, inferior mesenteric vein, splenic vein, and the gastric veins, which converge to form the hepatic portal vein. This circulation allows the liver to process and detoxify substances absorbed from the intestines before blood enters the systemic circulation.
Recommended video:
Guided course
02:52
What is Anatomy & Physiology? Example 1
Portal Vein Formation
The portal vein is formed by the convergence of several veins, mainly the superior mesenteric vein and the splenic vein. The inferior mesenteric vein usually drains into the splenic vein before this junction. These vessels collect blood from the stomach, intestines, pancreas, and spleen, directing it to the liver for metabolic processing.
Recommended video:
6:24Introduction to Veins
Strange or Portal Circulation
A portal circulation is termed 'strange' because it involves blood passing through two capillary beds in series before returning to the heart. In the hepatic portal system, blood flows from the capillaries of the digestive organs to the liver sinusoids via the portal vein, unlike typical circulation where blood passes through only one capillary bed. This unique arrangement allows the liver to regulate nutrient and toxin levels effectively.
Recommended video:
Guided course
10:02Anterior Pituitary
Related Practice
Textbook Question
Write an equation showing the relationship between total peripheral resistance, blood flow, and blood pressure.
2
views
Textbook Question
Distinguish between elastic arteries, muscular arteries, and arterioles relative to location, histology, and functional adaptations.
1
views
Textbook Question
How are nutrients, wastes, and respiratory gases transported to and from the blood and tissue spaces?
1
views
Textbook Question
a. Define blood pressure. Differentiate between systolic and diastolic blood pressure.
b. What is the normal blood pressure value for an adult?
1
views
Textbook Question
Describe the neural mechanisms responsible for controlling blood pressure.
1
views