The Circulatory System: Student Sheet 1
Name: _________________________________________________ Date: ______________
Part 1 – Preview – Video Clip “From the Heart”
http://nj.pbslearningmedia.org/resource/tdc02.sci.life.stru.circulator/from-the-heart/
Answer the following discussion questions with your small group. Be prepared to share your
group’s responses.

What is the job of the circulatory system? Be specific.

What does blood circulate that the body needs? (more than one thing!)

How does the circulatory system keep each cell in an organism alive and healthy?
Part 2 – Interactive “Cellular Service”
http://nj.pbslearningmedia.org/resource/tdc02.sci.life.stru.bloodtrekweb/cellular-service/
1. Play the interactive.
2. Read the instructions about how the interactive works. The instructions are located on the
bottom left hand side of the interactive.
3. Now click “BEGIN.”
4. Read the information in the bottom box about the lung.
5. Check off the appropriate boxes in the interactive and click “OK.” (It is possible to leave
some items unchecked.)
6. Fill in your paper chart. (Next page)
7. Then click “NEXT LOCATION”. Repeat steps 4 – 7 for each organ.
The Circulatory System: Student Sheet 1 pg 2
Circle the correct answer from what you learn by completing the “Cellular
Service” interactive.
Organ
Lungs
Pick up?
Deliver?
Oxygen
Oxygen
Nutrients
Nutrients
Carbon Dioxide
Carbon Dioxide
Hormones
Hormones
Bacteria
Bacteria
Oxygen
Oxygen
Nutrients
Nutrients
Carbon Dioxide
Carbon Dioxide
Hormones
Hormones
Bacteria
Bacteria
Pancreas /
Oxygen
Oxygen
Endocrine Gland
Nutrients
Nutrients
Carbon Dioxide
Carbon Dioxide
Hormones
Hormones
Bacteria
Bacteria
Oxygen
Oxygen
Nutrients
Nutrients
Carbon Dioxide
Carbon Dioxide
Hormones
Hormones
Bacteria
Bacteria
Oxygen
Oxygen
Nutrients
Nutrients
Carbon Dioxide
Carbon Dioxide
Hormones
Hormones
Bacteria
Bacteria
Small Intestines
Target Cells
Lymph Nodes
Name: _____________________________
Circulatory System – Cellular Service Homework
Background Essay – Read and answer the questions that follow.
What would it be like to be a cell? The answer depends on the type of cell you
happened to be. If you were, say, an amoeba, a single-celled organism, you would use
your pseudopod ("false foot") to crawl through your environment in search of food.
Along the way you would absorb oxygen and get rid of carbon dioxide. But what if you
were a cell that was part of a larger, more complex organism -- say, one of the ten
trillion cells that make up the human body? Assuming that you were not a red or white
blood cell, you'd be stuck in one place. You would still have the same needs as the
amoeba -- to get food and get rid of wastes -- but you wouldn't be able to move around
to take care of those needs. How, then, would you survive?
In order to stay alive and healthy, most of the cells that make up a multi-celled
organism rely on blood and related fluids to make pick-ups and deliveries. Blood
carries oxygen, mainly within red blood cells, from the lungs to all of the stationary cells
in the body. Plasma, the liquid portion of the blood, carries some oxygen as well as
nutrients from the small intestine and hormones from various endocrine glands. The
blood absorbs waste products produced by the body's cells, such as carbon dioxide,
and delivers them to various organs, which then expel the waste products from the
body.
Most of the body's cells do not come in direct contact with the blood, which is inside
blood vessels, so substances to be delivered and taken away must somehow travel
from the blood to the cells. These substances travel through a clear fluid that
surrounds all of the body's stationary cells. Actually, that fluid is the plasma portion of
the blood. Plasma passes through the walls of tiny blood vessels, called capillaries, in
the same way that sweat passes through your shirt on a hot day. When plasma moves
through a blood vessel wall, it carries with it the nutrients and hormones it contains.
Oxygen also moves from the blood through the capillary walls.
It might sound as though plasma "knows" that it is supposed to move through a
capillary and even what substances need to be delivered to a cell and what ones need
to be taken away. This is not so. There is a reason why plasma and the substances it
contains move in the "right" direction. There is less oxygen in the plasma that
surrounds the cells because that oxygen quickly moves into the cells as the cells burn
food (nutrients) for energy. The same is true for the hormones that the cells use to help
absorb the nutrients, and it's true for the nutrients as well. When the concentration of
oxygen, hormones, and nutrients is greater in the blood than it is in the fluid, or greater
in the fluid than it is in the cells, the substances move to where the concentration is
lower. At the same time, as cells metabolize food, they create waste products such as
carbon dioxide. When the concentration of carbon dioxide is greater in the cells than it
is in the plasma, the carbon dioxide moves into the plasma. It then moves from the
plasma into the blood vessels for the same reason. This process, by which a
substance moves from an area of higher concentration to an area of lower
concentration, is called diffusion.
So where does the plasma go after picking up wastes from the cells? It drains through
the lymphatic system -- a network of vessels separate from the blood vessels of the
circulatory system. Along the way, it passes through lymph nodes, which filter out
unwanted substances such as bacteria. The lymphatic system connects to the
circulatory system, where it returns the plasma to the blood.
Discussion Questions
1. What are some of the many functions of blood?
2. How does the blood distribute what the body needs?
3. What needs are met by:
Oxygen?
Nutrients?
Enzymes?
Bacteria?
Hormones?