1.Describe the similarities and differences between the fetal pig heart and the sheep
heart.
The fetal pig heart and sheep heart both have four
... [Show More] chambers, two upper chambers called atria, and two lower chambers called ventricles. The fetal pig heart and sheep heart were both shaped very similarly with the ventricle forming the lower part of the heart called the apex.
The main differences noted was the size; the sheep heart was nearly three times as large.
The sheep heart had a much thicker left ventricular wall than the fetal pig heart. The fetal pig heart also had a patent foramen ovale, an opening between the right and left atria as well as a patent ductus arteriosis, an opening between the right and left ventricle. This circulation is not noted in the sheep heart, as this opening should close shortly after the birth of the fetus.
2.Describe the four valves of the heart, including their name, location, and function.
Two valves sit between the atria and the ventricles, one on each side of the heart. The valve on the right side of the heart, sitting between the right atrium and the right ventricle is called the tricuspid valve. This valve has three cusps or flaps and prevents blood from flowing backward into the atrium during ventricular contraction. The valve on the left side of the heart that sits between the left atrium and left ventricle is referred to as the mitral valve.
There are two cusps or flaps in the mitral valve, making this a bicuspid valve. The mitral valve prevents backflow of blood from the left ventricle into the left atrium during ventricular contraction.
Two valves sit between the ventricles and the large arteries leaving the heart. The pulmonary valve is a semilunar valve; it sits between the right ventricle and the pulmonary artery. The pulmonary artery opens when the pressure in the right ventricle exceeds pulmonary
artery pressure, the ventricle contracts pushing blood into the pulmonary artery and the pulmonary circulation. When the pressure of the right ventricle drops, the pulmonary valve closes. The aortic valve sits between the left ventricle and the aorta; it is also a semilunar valve. The aortic valve prevents blood from flowing back from the aorta into the left ventricle as left ventricular pressure lowers. This allows the ventricle to fill from the left atrium and not backflow of blood from the aorta.
3.Discuss the similarities and differences between the left and right side of the heart.
The right and left side of the heart both have two chambers. The upper chambers, the atria and the lower chambers, the ventricles. The ventricles on both sides pump blood away from the heart. Although both ventricles are made up of muscle, the muscle wall on of the left ventricle is much thicker than the right side. The right side of the heart receives deoxygenated blood from the systemic circulation, and the left side of the heart receives oxygenated blood from the pulmonary circulation. The pressure in the left ventricle is much higher than the right ventricle as it must pump blood through the aorta and out into systemic circulation.
4.Compare the structure of the atrioventricular valves to the structure of the semilunar valves.
The atrioventricular or AV valves sit between the ventricles and the atria in the heart.
They have cusps that are held in place by fibrous tissue known as chordae tendineae; this attaches them to the papillary muscles on the inside walls of the ventricles. This construction prevents the AV valves from inverting into the atria during ventricular contraction. The closure of these valves is heard as the first heart sound, referred to a “lub.” The increased pressure of the atria as it is filled with blood causes the AV valve to open. As the ventricular pressure rises and the ventricle contracts, the pressure in the ventricles forces the AV valves to close. [Show Less]