Download HAP Discovery 14

Name:
Cary Academy Human Anatomy and Physiology
Discovery 14 – The Cardiovascular System
Objectives
Students will be able to:
1. Describe and identify the location of the heart in the body as well as identify its major anatomical areas.
2. Trace the pathway of blood flow through the human heart- including all anatomical terms with a focus
on valve function.
3. Compare pulmonary and systemic blood circulation.
4. Understand blood pressure- systole, diastole, stroke volume, and cardiac cycle.
5. Dissect a pig heart and sheep pluck as well as any other dissection materials.
Part I. Resources
Internet Resources: Overview of Cardiovascular System- http://en.wikipedia.org/wiki/Human_heart,
http://youtu.be/NJzJKvkWWDc, https://www.youtube.com/watch?v=VUtehbgbpRk, and
https://www.youtube.com/watch?v=qWti317qb_w
Interactive Physiology- Cardiovascular System
Many Other Resources on the Internet
Key points will be reviewed in class.
Part II. Review Heart Anatomy (See 11.2 a and b)
b. Annotate the cut away of the human heart (photo) using Figure 11.2 as a guide.
Part III. Read the dissection guide!
Dissection Guide
This lab activity is designed for you to begin understanding the anatomy of the mammalian heart. In short, it is important
to remember that we are only dissecting these hearts for an educational purpose- to learn about and understand heart
structure. The heart that you will dissect was obtained from a pig that was slaughtered for food. The living animal in
which this heart came from was not sacrificed for this laboratory. You are going to be dissecting a heart that would have
been discarded or used for some other purpose.
Dissection Guide:
Procedure- External Anatomy of the Heart
1.
Position the heart on in your dissection pan such that the pointed end is towards you and the wide end is toward
the top of the dissection pan. The pointed tip is called the apex and the top of the heart is called the base.
***THE KEY TO ORIENTING THE HEART CORRECTLY IS TO LOOK FOR THE PULMONARY ARTERY AT THE TOP
(BASE) OF THE HEART. It is a large, floppy vessel that is fairly thin.
2. Orient the heart with the right and left auricles pointing upwards in the dissection pan. There will be cleft that runs
from the bottom right side of the heart to the upper left hand side of the heart, this is called the sulcus.
3. At this time you should locate the positions of the right atrium, right ventricle, left atrium, and left ventricle. There
is a large artery that emerges from the left ventricle at the base of the heart. This is called the aorta. It is the
largest artery in the human body.
4. Notice that there are blood vessels covering the exterior of the heart. These are the vessels that nourish the
heart muscle with blood such that it can pump blood throughout the body. Locate some of these blood vessels.
These are called the coronary veins and coronary arteries. When a coronary artery becomes blocked with plaque,
this is when a heart attack occurs as the heart muscle cannot get its own blood for nourishment.
5. You will see a large number of vessels emerging from the base of the heart. Try to find the: 1.) aorta (it emerges
from the left ventricle) 2.) the pulmonary artery (it emerges from the right ventricle) 3.) the pulmonary veins
(these enter the left ventricle) 4.) the superior vena cava (this enters the right atrium) 5.) the inferior vena cava
(this enters the right atrium)
Procedure- Internal Anatomy of the Heart
The Superior and Inferior Vena Cava
1. Begin the dissection by finding the superior vena cava. Place your probe into the superior vena cava and feed it
into the right atrium.
Now carefully take your dissecting scissors and cut along the line of the probe thereby opening up the vena cava into
the top part of the right atrium.
Figure 2. First Incision into the right atrium
The Right Atrium
2. Now observe the superior vena cava and the right atrium. The superior vena cava returns unoxygenated blood
from the head, neck and upper extremities. The inferior vena cava returns unoxygenated blood from the lower
body. The blood enters into the heart into the right atrium. Observe the right atrium. Now probe down through
the right atrium into the right ventricle. Your probe will push through a valve called the tricuspid valve. This
valve has three flaps.
Figure 3. Probe into the right ventricle.
3. Notice the thickness of the wall of the right atrium. The walls of the vena cava as well as the right atrium are
relatively thin compared to the arteries which emerge from the heart and the ventricles of the heart as the blood
pressure in the vena cava and right atrium is rather low since blood is returning to the heart in these areas.
The Right Ventricle and Pulmonary Artery
4. Now you will examine the right ventricle. The next incisions will create a window into the right ventricle. Make
an incision parallel to the coronary groove and then along the sulcus. This will create a triangular “window” in
which you can view the right atrium.
Figure 4. Make an incision parallel to the coronary groove and then along the sulcus. This will create a triangular
“window” in which you can view the right atrium.
5. Once you have created this “window” observe the right ventricle. How thick is it? Use your probe to find the
tricuspid valve from the prospective of the right ventricle.
6. Unoxygenated blood flows into the right atrium and then moves into the right ventricle through the tricuspid valve.
When the right ventricle contracts, the tricuspid valve is closed such that blood can not backflow into the atrium,
and therefore blood can only move forward through the pulmonary valve into the pulmonary artery. As the right
ventricle contracts, the right atrium fills with blood. Then as the right ventricle relaxes, the right atrium pushes
blood through the tricuspid valve into the ventricle. Notice the chords of tissue that are attached to the valve.
These are called the chordae tendinae. When blood is pumped from the right ventricle to the pulmonary artery
out to the lungs, the tricuspid valve closes as its leaflets come together. A sound is created in this process- the
“lub” of the “lub dub” sound of the heart.
7. Using your probe again, find the pulmonary artery which leads out of the right ventricle. Notice the pulmonary
valve which separates the right ventricle from the pulmonary artery. When the right ventricle contracts, this valve
is open. When the right ventricle relaxes and re-fills with blood from the right atrium, the pulmonary valve
closes, preventing blood from backflowing from the pulmonary artery. The closing of the pulmonary valve causes
a “dub” sound of the “lub dub”. Note that all of the blood at this point in time is unoxygenated blood. Thus the “lub
dub” sounds of the heart as heard through the stethoscope are created by the AV valve and the pulmonary valve
as they prevent blood from back flowing in the heart and only moving forward- towards the lungs.
Figure 5. Using your probe again, find the pulmonary artery which leads out of the right ventricle.
The Lungs
8. Once unoxygenated blood enters the lungs, it travels through many miles of capillaries in each of the lungs. In
the smallest of capillaries, the red blood cells exchange carbon dioxide (a product of cellular respiration, CO 2) with
oxygen (O2) in small air sacs called the alveoli. Once the red blood cells contain oxygen, they begin their journey
back to the heart through many miles of veins and eventually into the pulmonary veins which lead from each of
the lungs.
The Pulmonary Veins and the Left Atrium
9. Find a pulmonary vein. Using your scalpel create an incision on the left side of the heart. To do this, create an
incision from one of the pulmonary veins into the left atrium.
10. Then turn your blade and cut across the left atrium. Using your probe, locate a number of pulmonary veins and
probe into them. Your probe should emerge in the left atrium as you look through the muscle tissue. Create an
incision along the same path as your probe. Observe the thickness of the walls of the right atrium. Now find the
mitral valve which separates the left atrium and left ventricle. Also locate the chordae tendinae.
Figure 6. Using your probe, locate a number of pulmonary veins and probe into them. Your probe should emerge in
the left atrium as you look through the muscle tissue. Create an incision along the same path as your probe.
The Left Ventricle and Aorta
11. Now locate the left ventricle.The next incisions will create a window into the left ventricle. Make an incision
parallel to the coronary groove and then along the sulcus. This will create a triangular “window” in which you
can view the right atrium.
Figure 7. Make an incision parallel to the coronary groove and then along the sulcus. This will create a triangular
“window” in which you can view the right atrium.
12. Observe the thickness of the wall of the left ventricle. Blood enters the left side of the heart through the
pulmonary veins from each of the lungs where it has been oxygenated.
13. As it fills the left atrium, the left ventricle contracts and pushes blood into the aorta. When the left ventricle
contracts, the mitral valve closes, thereby preventing blood from backflowing into the left atrium. Once blood
enters the atrium, the left ventricle relaxes, and the aortic valve closes. Find the aortic valve by locating the
aorta and pushing your probe down through it into the left ventricle. The valve you push the probe through is the
aortic valve.
14. Figure 8. Find the aortic valve by locating the aorta and pushing your probe down through it into the left
ventricle. The valve you push the probe through is the aortic valve.
15. Once oxygenated blood enters the aorta it travels through many miles of arteries and capillaries until it reaches
the smallest capillaries where oxygen diffuses out of the red blood cells through the walls of the capillaries into the
surrounding cells where carbon dioxide is exchanged with it. Once the red blood cells have obtained the carbon
dioxide they begin their journey back to the heart via many miles of veins. Eventually the blood reaches the
superior or inferior vena cava and the journey begins again!
16. Re-trace the entire path of blood through your dissected heart using the terms in Part II of this Discovery.