Capillaries Worksheets & Facts | Functions, Conditions, Disorders - Free Printable

Problem Overview:

The task is to compare the structure and function of three types of blood vessels: capillaries, arteries, and veins. The goal is to fill in the provided table based on their structural and functional differences.

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Solution:

#### 1. Capillaries
- Structure:
- Extremely thin walls, consisting of a single layer of endothelial cells.
- Very small diameter, allowing only one red blood cell to pass at a time.
- Highly branched and form a dense network throughout the body.

- Function:
- Facilitate the exchange of substances (oxygen, nutrients, carbon dioxide, waste) between the blood and surrounding tissues.
- Serve as the site for diffusion of gases and other molecules due to their thin walls and slow blood flow.

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#### 2. Arteries
- Structure:
- Thick, muscular walls with a strong layer of smooth muscle and elastic fibers.
- Relatively large diameter compared to capillaries but smaller than veins.
- Have valves in some cases (e.g., semilunar valves in arteries near the heart).

- Function:
- Transport oxygenated blood away from the heart to various parts of the body.
- Maintain high pressure to push blood through the circulatory system.
- Distribute blood to different organs and tissues.

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#### 3. Veins
- Structure:
- Thinner walls compared to arteries but thicker than capillaries.
- Contain valves to prevent backflow of blood.
- Larger diameter than arteries and capillaries to accommodate more blood volume.

- Function:
- Return deoxygenated blood from the tissues back to the heart.
- Collect blood from capillaries and transport it to the heart via larger veins.
- Use valves to ensure unidirectional flow of blood against gravity.

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Filling the Table:

| Blood Vessel | Structure | Function |
|-------------------|------------------------------------------------------------------------------|------------------------------------------------------------------------------|
| Capillaries | Extremely thin walls (single layer of cells), very small diameter, highly branched. | Exchange of substances (oxygen, nutrients, waste) between blood and tissues. |
| Arteries | Thick, muscular walls with elastic fibers, relatively large diameter, high pressure. | Transport oxygenated blood away from the heart to tissues under high pressure. |
| Veins | Thinner walls than arteries, larger diameter, contain valves to prevent backflow. | Return deoxygenated blood from tissues back to the heart using valves. |

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Final Answer:

\boxed{
\begin{array}{|c|c|c|}
\hline
\textbf{Blood Vessel} & \textbf{Structure} & \textbf{Function} \\
\hline
\text{Capillaries} & \text{Extremely thin walls (single layer of cells), very small diameter, highly branched.} & \text{Exchange of substances (oxygen, nutrients, waste) between blood and tissues.} \\
\hline
\text{Arteries} & \text{Thick, muscular walls with elastic fibers, relatively large diameter, high pressure.} & \text{Transport oxygenated blood away from the heart to tissues under high pressure.} \\
\hline
\text{Veins} & \text{Thinner walls than arteries, larger diameter, contain valves to prevent backflow.} & \text{Return deoxygenated blood from tissues back to the heart using valves.} \\
\hline
\end{array}
}