Tutor profile: Grace D.
Why are there very few "laws" in Psychology?
Psychology as a field is seen as subjective, and a scientific law is something that is generally considered to be true, in a more unquestionable sense than a theory. A scientific law much be repeatable under certain conditions, with the same outcome every time. Psychology has a wide, diverse range of theories, about behavior and reactions and everything in between, but it is very hard to quantify these things. Therefore, laws are not as firmly present in the field of Psychology as in other fields of science. This is not necessarily a bad thing; it only means that there are a lot of different perspectives one can take while studying Psychology.
Examine the following sentence, and choose the best word (in parenthesis). Then explain the choice. Though there were many impressive prizes, the suitcase was the one (who / whom / that) I really wanted.
"That" is the best word choice here, due to the fact that an object is being referred to. "Who" and "whom" will only be used in a sentence like this if a person is being referred to. "That" can be used to refer to people as well as objects.
Explain the purpose of the fossa ovalis and ductus arteriosus, the two structures of circulation found in the fetal heart.
Both the fossa ovalis and the ductus arteriosus exist in order to shunt blood away from the lungs, which do not function anywhere near capacity while the baby is in the womb. The placenta is the fetal organ of respiration and assists the fetus with the re-oxygenation of blood. The fossa ovalis is an opening between the right and left atria of the fetal heart. Normally, deoxygenated blood flows from the right atrium into the right ventricle, and eventually passes through the pulmonary trunk to travel to the lungs for re-oxygenation. However, since the lungs are largely non-functional in the womb, there is no reason for all of this blood to travel there. Instead, most of the blood passes through the fossa ovalis, skipping the right side of the heart (pulmonary circulation) altogether. The blood then ends up in the left ventricle of the heart, where it can then travel through the body and eventually to the placenta to be re-oxygenated there. The same principle applies to the ductus arteriosus, which is a shunt between the pulmonary trunk and the aorta. Some blood avoids the fossa ovalis and passes through pulmonary circulation. However, before it can reach the lungs through the pulmonary trunk, most of the remaining blood is shunted away from the pulmonary trunk and into the aorta, to join systemic (body) circulation and reach the placenta for re-oxygenation. This does cause the mixing of oxygenated and deoxygenated blood, which is not ideal, but it's better than the alternative - letting all the blood flow into the lungs and remain deoxygenated.
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