Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

19. The Blood Vessels

Capillaries

Anatomy & Physiology

19. The Blood Vessels

Capillaries

Previous problemNext problem

Problem 11

Textbook Question

Capillaries consist of:
a. Three thin tunics
b. Only a thin tunica intima with a well-developed internal elastic lamina
c. A thin sheet of endothelium with a basal lamina
d. Stratified epithelium

Verified step by step guidance

Step 1: Understand the structure of capillaries. Capillaries are the smallest blood vessels in the body and are specialized for the exchange of gases, nutrients, and waste products between blood and tissues.

Step 2: Recall the layers of blood vessel walls. Larger blood vessels typically consist of three layers: tunica intima (inner layer), tunica media (middle layer), and tunica externa (outer layer). However, capillaries are unique in their structure.

Step 3: Focus on the composition of capillaries. Capillaries lack the tunica media and tunica externa layers found in larger vessels. Instead, they are composed of a single layer of endothelial cells supported by a basal lamina.

Step 4: Eliminate incorrect options. For example, capillaries do not have three tunics (option a), nor do they have a well-developed internal elastic lamina (option b). Additionally, capillaries are not made of stratified epithelium (option d).

Step 5: Identify the correct answer. Capillaries consist of a thin sheet of endothelium with a basal lamina, which matches option c.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Capillary Structure

Capillaries are the smallest blood vessels in the body, primarily composed of a single layer of endothelial cells. This thin structure allows for efficient exchange of gases, nutrients, and waste products between blood and surrounding tissues. Unlike larger blood vessels, capillaries lack a tunica media and tunica externa, making them uniquely suited for their role in microcirculation.

Tunica Intima

The tunica intima is the innermost layer of blood vessels, including capillaries. In capillaries, this layer consists solely of endothelial cells and a basal lamina, which provides structural support. This simplicity is crucial for facilitating the rapid exchange of substances, as it minimizes the distance that molecules must travel.

Endothelial Cells

Endothelial cells line the interior surface of blood vessels, including capillaries. They play a vital role in maintaining vascular health, regulating blood flow, and controlling the permeability of the vessel wall. In capillaries, the thinness of these cells is essential for allowing the diffusion of oxygen, carbon dioxide, and other small molecules between blood and tissues.