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# 5.3: Activities and Answer Keys

Difficulty Level: At Grade Created by: CK-12

## Activity 4-1: Making a Capillary Bed Model

### PLAN

Summary Students make models of capillary beds. They observe and describe the role of capillaries and capillary beds in bringing nutrients and oxygen to the cells and carrying away waste materials and carbon dioxide from the cells.

Objectives

Students:

\begin{align*}\checkmark\end{align*} show how a small artery brings blood to capillaries and a small vein takes blood away from capillaries.

\begin{align*}\checkmark\end{align*} differentiate between oxygenated and deoxygenated capillaries.

\begin{align*}\checkmark\end{align*} indicate where oxygen and nutrients leave the capillaries.

\begin{align*}\checkmark\end{align*} indicate where wastes and carbon dioxide enter the capillaries.

\begin{align*}\checkmark\end{align*} explain the role of capillaries in the maintenance of homeostasis.

Student Materials

• Activity Report
• Construction or drawing paper; Scissors; Glue or clear tape; Marking pens; Materials to represent arteries, veins, capillaries, and cells (Some examples include string, yarn, thread, and rope.)

Teacher Materials

• Photos of capillaries
• Diagrams or a model of the circulatory system

Collect the materials students will need to build their capillary bed models.

Estimated Time One \begin{align*}50-\mathrm{minute}\end{align*} class period.

Interdisciplinary Connection

Art Students can make their capillary bed models in art class.

Prerequisites and Background Information

None

Examples of materials that can be used in the models include the following.

Rope: colored/painted red to represent a small artery (arteriole) and colored/painted blue to represent a small vein (venule).

Yarn: red to represent capillaries carrying oxygenated blood and nutrients, and blue to represent capillaries carrying deoxygenated blood and carbon dioxide and other wastes.

Seeds or pasta: to represent body cells.

You can also use drinking straws to represent capillaries and smaller seeds or pasta that can pass through single file.

When representing capillaries in a body region, such as a leg, the direction of blood flow is from oxygenated (red) to deoxygenated (blue).

If they are using yarn, students can untwist ends of the yarn to show the close relationships of capillaries with each other and with neighboring cells. See diagram below.

### IMPLEMENT

Steps 1-2

Ask students to develop a key to show which materials represent which structures.

• capillaries carrying oxygen-rich blood and nutrients
• capillaries carrying oxygen-poor blood and wastes including carbon dioxide
• cells nourished by these capillaries
• small artery (arteriole) carrying oxygen-rich blood with nutrients to the capillaries
• small vein (venule) taking oxygen-poor blood with wastes away from the capillaries

Make sure students indicate the flow of blood using arrows.

Steps 3-4

When students have their models constructed, ask them as a Journal Writing assignment to take on the role of a component that travels in the blood through the capillaries (e.g., oxygen, carbon dioxide, food nutrients, hormone, or enzyme). Use the first person to write about a journey through the capillaries.

Conclude Activity 4-1 by having students refer to the models of the circulatory system they made in Activity 1-1: Pathway of Blood through Your Body to see where their capillary beds are located. Ask students to compare their models.

### ASSESS

Use the capillary bed model to assess if students can:

\begin{align*}\checkmark\end{align*} describe the role of capillaries in bringing nutrients and oxygen to the cells and carrying away waste materials and carbon dioxide from the cells.

\begin{align*}\checkmark\end{align*} compare and contrast oxygenated and deoxygenated capillaries.

\begin{align*}\checkmark\end{align*} identify where oxygen and nutrients leave the capillaries.

\begin{align*}\checkmark\end{align*} identify where wastes and carbon dioxide enter the capillaries.

\begin{align*}\checkmark\end{align*} explain the role of capillaries in the maintenance of homeostasis.

## Activity 4-1: Making a Capillary Bed Model Activity Report Answer Key

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. How did you decide on the design of your capillary bed model? In your answer, be sure you reflect the contributions of each lab group member.
2. Identify the materials you selected to represent each part of the capillary bed model. Indicate which material represents which model part.
3. Make a diagram of your constructed capillary bed model.
4. A. Label each part and indicate with arrows the direction of blood flow. B. Indicate where oxygen and nutrients leave the capillaries and where wastes and carbon dioxide enter.
5. Write a summary paragraph explaining how blood moves through capillaries and helps to maintain homeostasis in your body.

Transport of Nutrients: Exploring Diffusion

The process of diffusion plays an important role in the exchange of materials between the blood and the cells. Gather some materials together that students can use to try to answer one of the following questions. Ask students to design an experiment to answer one of these questions.

• What do you think would happen if you filled a small beaker with tap water and added one drop of food coloring?
• What would happen if you filled a small beaker with tap water and added a cube of sugar?
• How is diffusion affected by temperature?
• What happens when someone opens a container of perfume or uses a spray bottle of room deodorizer?

Ask students to compare this activity to diffusion of nutrients. How is diffusion described here like the diffusion of nutrients and wastes in your cells?

Pretend you are a red blood cell. Describe your journey as you pass through a capillary bed. How are you different leaving the capillary bed than when you entered the capillary bed?

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. How are capillaries different from arterioles?
2. Why do you have capillaries?
3. Describe the process by which substances enter and leave capillaries.

## Activity 4-1 Report: Making a Capillary Bed Model

1. How did you decide on the design of your capillary bed model? In your answer, be sure you reflect the contributions of each lab group member.

2. Identify the materials you selected to represent each part of the capillary bed model. Indicate which material represents which part.

3. Make a diagram of your constructed capillary bed model.

a. Label each part and indicate with arrows the direction of blood flow.

b. Indicate where oxygen and nutrients leave the capillaries and where wastes and carbon dioxide enter.

4. Write a summary paragraph explaining how blood moves through capillaries and helps to maintain homeostasis in your body.

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Subjects:
6 , 7 , 8
Date Created:
Feb 23, 2012