A & P II Lab2

.What is the difference between the structure of the atrioventricular valves and the semilunar valves? What is the function of each type of valve?

Atrioventricular valves structure is like pockets while semilunar valves are like half-moons. The function of atrioventricular valves is to separate the atria from the ventricles and allow blood to flow from the atria to the ventricles in a one direction. The function of semilunar valves is to prevent backflow from the arteries to the ventricles and to help maintain pressure.

Why do peripheral veins have valves

They have them to prevent backflow or pooling of blood in the lower extremities

What are the unique features of cardiac contractile cells that separate them from skeletal and smooth muscle cells?

Cardiac muscle contains sarcomeres, which in themselves contain myofibril proteins, as well as actin and myosin filaments. Cardiac contractile cells have intercalated discs that permit ions to pass between the cells, which transmits the electrical impulse rapidly. These anatomical features that are necessary for the heart to beat are not found in smooth muscle cells.

What is the function of intercalated discs? What did the intercalated discs look like on the slide?

Cardiac muscle contains sarcomeres, which in themselves contain myofibril proteins, as well as actin and myosin filaments. Cardiac contractile cells have intercalated discs that permit ions to pass between the cells, which transmits the electrical impulse rapidly. These anatomical features that are necessary for the heart to beat are not found in smooth muscle cells. The intercalated discs are junctions that permit ions to pass between the cell, which transmits the electrical impulse rapidly. They also have desmosomes which propel the force from each contraction to the next cell. The intercalated discs appear as thin vertical strips along the band of the cell

List the differences that you saw between the artery and the vein cross sections. Why do those differences exist>

The arteries have a thicker lumen to withstand the higher blood pressure and greater forces created by the heart

How did the striations look on the cardiac muscle slide? Why are striations present in heart muscle?

The cardiac muscle had light and dark areas along the cells giving them a striped appearance. They are present because the myosin filaments of the muscle create the dark areas where as the the smaller actin filaments create the lighter areas.

Comparison of Ventricle Wall Thickness

The ventricles of the heart are thicker and have more muscular walls than the atria due to blood being pumped out of the heart. Greater pressure is needed from these chambers compared to the atria. The left ventricle wall is also thicker (more muscular) than the right ventricle since blood needs to be sent throughout the body from here.

Where are the papillary muscles of the heart, and what do they look like?

They are attached to the chordae tendinae and ventricle walls. They look like bands of string.

Compare and contrast your images of the left and right sides of the dissected heart. What is one similarity and what is one difference in the muscle tissue?

They both have chordae tendonae and the left ventricle has a much larger cavity.

Why do capillaries facilitate nutrient and gas exchange better than arteries and veins?

They consist of a single layer of cells and are specialized for gas and nutrient exchange