Exercise 1: Microscopic Anatomy of Cardiac Muscle
Observations: Sketch and label your slide in the space provided. Include a description of the structures you observed on the slide.
Questions:
A.What are some unique structural features of cardiac muscle? Cardiac muscle is a specialized tissue designed around the beating of the heart. Cardiac muscle has to be able to expand and contract efficiently
B.What are intercalated discs and what do they do? Intercalated discs are connections between adjacent cardiac muscle cells that include gap junctions. These discs allow for the free flow of action potentials between cells that create muscle contractions.
C.Why does cardiac muscle have to be both elastic and strong? Cardiac muscle tissue is only in the heart. Its cells, striated and branched, are joined end-to-end, and interconnected in complex networks. Each cardiac muscle cell has a single nucleus. Cardiac muscle is controlled involuntarily. Cardiac muscle can continue to function without nervous stimulation. This tissue makes up the bulk of the heart and pumps blood through the heart chambers and into blood vessels.
D.Which of the three layers of the heart did the tissue used to make your slide originate from?
Myocardium, I believe
Exercise 2: The Pulmonary and Systemic Circuits
Draw a diagram showing pulmonary and systemic circulation. Color the deoxygenated side blue and the oxygenated side red. Use a regular pencil to draw arrows to indicate blood flow.
Questions:
A.Trace the flow of blood through the pulmonary and systemic circuits. Begin in the right atrium and end in the superior/inferior vena cava. Be sure to list every vessel, heart chamber, and heart valve the blood flows through. The blood flows through our body through a series of connected vessels and is driven by the heart. The pulmonary circuit takes blood from the right side of the heart and delivers it to the lungs for oxygenation. The oxygenated blood then returns to the left side of the heart where it is pumped out to the body. The systemic circuit takes the oxygenated blood from the heart out to the body through a series of arteries that decrease in size as they go down to the cellular level of all the tissues. The capillaries at the cellular level deliver the oxygen and nutrients and pick up carbon dioxide and wastes. The capillaries then return the blood back to the heart through a series of veins which increase in size as they approach the heart. Both of these circuits need to work properly to ensure homeostasis.
B.Explain what you learned from the online human heart dissection. I had much difficulty trying to view this video. My internet is not the best and I tried watching the smaller version of it but it just kept skipping and the picture was very choppy, kind of like satellite during a storm.
Exercise 3: Sheep Heart Dissection/Fetal Pig Comparison
Questions:
A.Compare the structure of the fetal pig and sheep heart. How are they similar? How are they different? Well for starters the pig’s heart is very tiny and the sheep heart is much closer to the size of a human heart. The sheep’s heart was much easier to identify certain parts of the heart rather than that of the pig’s heart. Because both animals are mammal’s they share mostly the same characteristics of a 4 chambered heart, other than size.
B.Why is the heart referred to as a double pump?
The heart is composed up of four chambers that move blood, your left and right atria’s and your left and right ventricle. The right ventricle pumps blood to the lungs using our pulmonary arteries while the left ventricle pumps blood to the rest of the body with our aorta. Hence the term double pump. .
C.There are four valves in the heart. Name each valve, list its location and give its function.
Tricuspid Valve- Located in the Right Atrioventricular orifice. This valve prevents blood from moving from right ventricle into right atrium during ventricular contraction.
Pulmonary Valve- Located in the entrance to the pulmonary trunk. This valve prevents blood from moving from pulmonary trunk into right ventricle during ventricular relaxation.
Mitral Valve- Located within the Left Atrioventricular Orifice. This valve prevents blood from moving from left ventricle into left atrium during ventricular contraction.
Aortic Valve- Located at the entrance to the aorta. This valve prevents blood from moving from aorta into left ventricle during ventricular relaxation.
D.Compare the left and right sides of the dissected heart. What differences do you see? It looks as if there is more papillary muscle on the Left Side. Both sides of the ventricles share 2 valves, further proving the double pump nickname. You can see the pulmonary opening on the Left side of the heart. I feel as if the left side is more detailed than the right.
E.Compare and contrast the functions of the atria and the ventricles. Internally the heart is divided into four hollow chambers, two on the left, and two on the right. The upper chambers, called atria, have thin walls and receive blood returning to the heart. Small, earlike projections called auricles extend anteriorly from the atria, slightly increasing atrial volume. The lower chambers, the ventricles, force the blood out of the heart into arteries.
F.Where is the myocardium located? The myocardium is the middle layer of the heart wall. It is located between the endocardium and the epicardium.
G.How does the heart supply blood to its own cells? The first two branches of the aorta, called the right and left coronary arteries, supply blood to the tissues of the heart.