Download Heart of the Matter KEY

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The Heart of the Matter – 60 Informal Points & 5 Formal Points (2 for Maniken Build & 3 for Heart Box)
Introduction
Movement by muscles pulling on bones would not be possible if blood did not supply this tissue with the key
resource, oxygen. The flow of blood around the body ensures that essential nutrients are delivered and
wastes are moved away for disposal. At the center of this system is the amazing pump, the human heart.
The force your heart exerts at each pump is about the equivalent of your squeezing a tennis ball. Not exactly
easy, is it? In fact, the muscle in the heart works twice as hard as the leg muscles of a person who is
sprinting. We have looked in depth at skeletal muscle and how this tissue works with the nervous system to
contract and pull on bone. In this lesson, you will take a look at the types of muscle at work in the
cardiovascular system. What if you had to think every time your heart needed to beat? What if the signal had
to make its way to your brain, be processed and make its way back to the heart to cause a contraction? Most
likely, you would not last too long. For this reason, contraction of your heart muscle is involuntary. It happens
(or at least it should) without your ever having to think about it.
A series of tubes, or vessels, serve as the highways for the transportation of blood. Arteries are responsible
for carrying blood away from the heart and veins are responsible for returning blood back to the heart. By
looking at how blood is pumped in and out of the heart, you will begin to see how the structure of arteries and
veins relates to the stress each vessel has to endure.
In this activity, you will review the basic structure of the heart as well as identify the major blood vessels that
bring blood in and out of the heart’s chambers. Finally, you will really get to the “heart of the matter” and
create a clay heart for your beloved Maniken®.
Procedure
Part I: Blood Flow in the Heart
1. Find the heart box diagram you created last year in PBS. Review the chambers of the heart, major blood
vessels and pathway of blood flow through systemic and pulmonary circulation. Because this is a review
it is expected you have already mastered this material, but if you are a little rusty the next few questions
should help you review.
2. Imagine you are a red blood cell sitting in the right atria of the heart. On a separate sheet of paper, write a
paragraph that describes what happens to this red blood cell as it moves through the body. What
structures will it pass through? How will it interact with oxygen? Make sure to include the word
hemoglobin in your response. [THIS WILL BE AN UPCOMING ESSAY ON THE TEST]
The red blood cell is in the right atria, meaning it is currently deoxygenated and in the pulmonary
circulation circuit. At this time the hemoglobin is not binding O2, but the red blood cell is
carrying CO2 waste, in the form of bicarbonate, to the lungs to be exhaled. The red blood
cell moves from the right atrium to the right ventricle via the tricuspid valve. From there it
passes through the pulmonary valve into the pulmonary artery. The next stop is the lungs
where the respiratory system meets the circulatory system. The CO2 passes from the
capillaries in the circulatory system into the alveoli of the respiratory system so that it can be
exhaled. At the same time inhaled O2 passes from the alveoli into the capillaries to enter the
circulatory system. The O2 binds to the hemoglobin in the red blood cells. The blood is not
“oxygenated.” The red blood cell now enters the left side of the heart and systemic
circulation as it enters the pulmonary vein. From there it travels to the left atrium and then on
to the left ventricle via the mitral (also known as the bicuspid) valve. From there it passes
through the aortic valve and into the aorta. From here the red blood cell travels via the
circulatory system to all parts of the body where the O2 is unloaded by diffusing through the
capillary membranes as well as the cell membranes to enter the body cell. CO2 waste is
picked up from the body cell and loaded into the red blood cell in the form of bicarbonate.
The blood at this time is said to be “deoxygenated” and must travel back to the lungs so that
the CO2 may be exhaled. It travels back to the lungs via the right side of the heart and
pulmonary circulation. It flows through the superior (from top head and brain region) and
inferior vena cavas (from lower body) into the right atrium, which is where the story began so
the red blood cell has come full circle!
3. Label the structures and vessels listed on your heart box on the heart diagram below.
Part II: Giving Your Maniken® a Heart
4. Give your Maniken® a heart! Let’s get the blood pumping in your Maniken® and fuel the muscles you built
earlier in the unit. Later in this lesson, you will use your knowledge of blood flow to start hooking up the
vessels.
5. Form a ball of pink clay (about the size of a quarter) into a short fat carrot. Which chambers does the
pointed end of the carrot correspond to? The atria or the ventricles? Answer in the space below:
The pointed end of the carrot points towards the ventricles, specifically the left ventricle.
6. Lay the heart on the tabletop and flatten the back side of the heart just a bit.
7. Using what you know about the structure of the heart, sketch the four main chambers into the clay with a
pencil.
8. Remember that the heart is responsible for pumping blood to all of the organs of the body, but remember,
the tissue of the heart also needs to be bathed in blood. The hard-working muscle needs a constant
supply of oxygen. The muscle of the heart receives blood through tiny vessels called the coronary
arteries. Visualize the system of coronary arteries by looking at the following diagram:
9. Use your clay tools or a pencil to carve the following coronary arteries in your clay heart.
o
o
o
o
Left Coronary Artery (Left Main)
Left Anterior Descending
Circumflex Artery
Right Coronary Artery
10. Roll out a thick piece of pink spaghetti about 1in long. You will use this piece of clay to create the aorta.
11. Place the end of the spaghetti onto the top of the heart. This piece should stick up like a cherry stem,
bend back towards the dorsal side of the heart and run down the back of the organ.
12. Locate the diaphragm of your model. The heart will “sit” on the diaphragm.
13. Place the heart in the chest cavity. Pay attention to whether you have the right side or the left side of a
Maniken®. Think about how heart placement would be different in each case.
14. Press the heart against the wall to get it to stick. Do not worry about flattening the heart a bit.
Conclusion Questions
1. Explain how each of the three types of muscle assist with moving blood around the body.
2. What role do valves play in the heart?
Valves prevent blood from flowing in the wrong direction (or backwards) in the heart. The
valves are held in the proper place because of the chordae tendinae.
3. Which structure in the heart functions as the natural pacemaker? What does this term mean?
SA node (sinoatrial node) which is located in the right atrium. This node controls the pace of the heart; the
heart pace is NOT controlled by the brain.
4. How does the movement of the electrical impulse relate to the contraction of the chambers of the heart?
5. What is the difference between pulmonary circulation and systemic circulation?
Pulmonary circulation affects only the right side of the heart, pumping blood to the lungs where
the blood gives off CO2 and picks up O2. This is then returned to the left side of the heart which
then pumps the oxygenated blood out to the entire body in systemic circulation.
6. Thinking about function, explain why the left ventricle is much more muscular than the right ventricle.
The left ventricle is what must contract with more force than any other chamber because it has to pump blood
with enough force to send it all the way around the body.
7. Describe the role of smooth muscle in two human body systems other than the cardiovascular system.
Smooth muscle lines the digestive system and allows for movement down the esophagus, through the
stomach and intestines. Smooth muscle also lines the bronchii which is part of the respiratory system
and allows the tubes to expand and contract as air enters and exits the lungs.
8. How does electrical communication in the heart compare to electrical communication in skeletal muscles?
Skeletal muscles require outside forces for electrical communication to occur as action potential
must occur before any movement takes place. Electrical communication in the heart starts and
ends there without any help from other body systems.
The remainder of this packet are resources from last year that you are expected to know.
There will NOT be a key given for these because you are expected to have all the information
you need from last year.
Labeled Heart Diagram – Resource Sheet
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Apex – tip of the heart
Septum – muscle that divides left and right side
Atrioventricular Valves (AV) - these valves are located between the atrium and the ventricle
and prevents backward blood flow (ie, prevents blood from the ventricle from flowing back into the
atrium)
o Tricuspid - right side AV; between right atrium and right ventricle
o Mitral Valve (Bicuspid) - left side AV; between left atrium and left ventricle
Semilunar Valves (SV) – these valves are located between ventricles and arteries to regulate
blood flow and prevent backward blood flow (ie. Prevents blood from the arties from flowing back
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into the ventricles.)
o Aortic Valve – controls proper blood flow and direction from the left ventricle to the aorta
o Pulmonary Valve – controls proper blood flow and direction from the right ventricle to the
pulmonary artery
Superior Vena Cava - vessel that returns deoxygenated blood to the heart from the upper body
Inferior Vena Cava - vessel that returns deoxygenated blood to the heart from the lower body
Aorta – largest artery that delivers blood to the body
Chordae tendinae / Papillary Muscles - muscles and tendons that hold the heart valves in place
Sinoatrial Node (SA Node) – pacemaker of the heart
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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
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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
*Capillaries are very tiny cells with membranes only one
cell thick that gas exchange can easily occur across. This
is important because oxygen and carbon dioxide are
exchanged by diffusing across the capillary cell membrane
to enter or exit the bloodstream.
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.
Heart Study Questions – Answer on a separate sheet of paper.
1.
2.
Why does a diagram of the heart appear to have mixed up left and right sides?
Label the structures on the heart diagram below and trace the path of blood flow through the
heart.
3.
Label each of the following structures as being part of the right or left side of the heart?
a. Vena Cavas
b. Left Ventricle
c. Right Atrium
d. Pulmonary Vein
e. Pulmonary Artery
f. Right Ventricle
g. Left Atrium
h. Mitral Valve
i. Pulmonary Valve
j. Aortic Valve
k. Tricuspid Valve
l. Aorta
How are the superior and inferior vena cavas similar? How are they different?
What is the function of a valve? What four types of valves have we talked about and where are
they located? Name and describe the AV and SV valves we have discussed in class.
What is the apex of the heart?
What is the scientific name for the SA node and what is the function of the SA node?
What are the functions of the chordae tendinae and papillary muscles?
Describe the main differences between arteries and veins.
What are capillaries? What is the function of capillaries?
What is the difference between systemic and pulmonary circulation?
When does blood go from being oxygenated to deoxygenated?
When does blood go from being deoxygenated to oxygenated?
What are alveoli?
Describe how the respiratory system and circulatory system work together to ensure the body gets
the oxygen it needs.
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16. What is the ductus arteriosus and why does a baby in utero need this duct, but not need it once
he/she has been born?
17. Which chamber of the heart contracts the most forcefully? Why?