Download Varicose Veins KEY - Belle Vernon Area

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Varicose Veins – 40 Informal Points
Introduction
An estimated 62,000 miles of blood vessels ensure that oxygen and nutrients are delivered to the trillions of
cells in your body, and that waste products are taken away for disposal. If all of these blood vessels were laid
out end to end, they would wrap around the Earth twice! This transportation system within your body consists
of a series of tubes that branch out and come back together, making sure to service even the tiniest of tissues.
Arteries carry blood away from the heart while veins transport blood back to the heart. Connecting these two
types of vessels are tiny branches called capillaries, the site of gas exchange. Just like everything in the body,
structure is highly linked to function. Since arteries and veins work in opposite directions, their structures have
key differences that support what they do for the human body.
Your grandmother has noticed that she is starting to see her veins popping out on the back of her legs. Her
doctor tells her that the development of these spider veins, or varicose veins, is normal for her age. She is
prepared to “grow old gracefully,” but she does want more information about the cause of these annoying,
wiggly veins. She knows you are taking Human Body Systems, so she comes to you for advice.
In this activity, you will explore the structure and function of veins and arteries by investigating the cause of
spider veins or varicose veins. You have probably heard of varicose veins, but why haven’t you ever heard of
varicose arteries?
Procedure
1. Use a microscope to view a prepared slide of a cross section of an artery, a vein and a capillary. In the
table below, use colored pencils to draw what you see. Label each vessel and make sure to note the
magnification.
Artery
Magnification:
Vein
Magnification:
Capillary
Magnification:
2. Use the Internet to research the structure of arteries and veins as well as the science behind
varicose vein formation. Pay attention to the structural differences between the vessels and
think about the force of blood flow in each type. As you complete your research answer the
questions in numbers 3 – 7.
3. How do arteries and veins differ in structure?
Blood Vessel Types
Arteries



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Carries oxygenated blood AWAY
from the heart
o Exception: Blood flowing
through the pulmonary artery
is deoxygenated.
Thick, elastic muscle layer that can
handle high pressure as blood pulses
through it
Red vessels
Aorta  Artery  Arteriole 
Capillary
Veins




Carries deoxygenated blood TO the
heart
o Exception: Blood flowing
through the pulmonary vein is
oxygenated.
Thin, elastic muscle layer
Blue vessels (although the blood is
NOT blue)
Vein  Venule  Capillary
4. What are varicose veins?
Arteries carry blood from your heart to the rest of your tissues. Veins return blood from the rest of
your body to your heart, so the blood can be recirculated. To return blood to your heart, the veins
in your legs must work against gravity.
Muscle contractions in your lower legs act as pumps, and elastic vein walls help blood return to
your heart. Tiny valves in your veins open as blood flows toward your heart then close to stop
blood from flowing backward.
5. How do varicose veins form?
Veins have valves that act as one-way flaps to prevent blood from flowing backwards as it moves up your
legs. If the valves become weak, blood can leak back into the veins and collect there. (This problem is
called venous insufficiency.) When backed-up blood makes the veins bigger, they can become varicose.
6. Why is it that people develop varicose veins, but not varicose arteries?
Varicose arteries do not exist because not only are they located much deeper in the skin than
veins, but they are also equipped to handle blood with a higher pressure due to their thick elastic
muscular walls. Also, arteries are not working against gravity as much; most arteries are taking
blood downward from the heart and work with gravity, not against it like most veins.
7. How is blood helped in its return back to the heart? You must mention the role of at least two other body
systems.
Both the superior and inferior vena cava allow blood to be taken back into the heart. Veins do not
have thick muscular walls with which to send the blood though, so they must rely on other
muscles throughout the body to help them get the blood back to where it needs to be. The
skeletal system helps them push the blood back to the heart.
Conclusion Questions
1. What do you notice about the width of an artery wall versus the width of a vein wall? Why does this make
sense given the function of the vessels?
Arteries have much thicker muscular walls than veins. This makes sense since arteries are transporting high
pressure blood throughout body; the pressure in veins is much lower.
2. Capillaries function in gas exchange. Describe at least two ways capillary structure is related to this
function.
Capillaries have membranes that are one cell thick making the gas exchange of O2 and CO2 quick and
efficient. They are also small and numerous to reach all parts of the body effectively.
3. How do capillaries interact with the respiratory system? Make sure to mention specific structures of the
respiratory system.
Description of how circulatory System and Respiratory System work together



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Gas exchange (O2 <--> CO2) occurs through the cell membranes of capillaries (smallest cell in
the circulatory system) and alveoli (smallest cell in the respiratory system.)
o Alveoli are the tiny “grape-like” cell structures in the lungs that expand when inhaling
and contract when exhaling during breathing.
The cell membranes of capillaries and alveoli touch.
When deoxygenated, blood carrying CO2 enters the capillaries in the lungs, the CO2 diffuses
across the capillary membrane and the alveoli membrane to leave the circulatory system and
enter the respiratory system to be exhaled out of the body.
When a person inhales they bring O2 into their alveoli, which diffuses across the alveoli
membrane and the capillary membrane to enter the blood stream. The blood is then sent to
the heart to be pumped out to the body.
4. Which artery do you think is made of thicker muscle, the aorta or the pulmonary artery? Why? Refer back
to your heart box to visualize the path of these vessels.
Aorta because it must hold and send blood long distances throughout the entire body whereas the pulmonary
artery only has to send blood a short distance to the lungs.
5. Explain why a person who spends most of the day on his/her feet is more likely to develop varicose veins.
A person that spends most of the day on his/her feet is constantly subjecting their legs to gravity, which
veins are fighting against to move blood back to the heart.