Explanation:

For normal incidence on a plane mirror identify which of these statements are true --

(I) Both the angles of incidence and reflection are 0 degree .

(II) Both the angles of incidence and reflection are 90 degree .

(III) The angles that both the incident ray and the reflected ray make with the mirror surface are 0 degree .

(IV) The angles that both the incident ray and the reflected ray make with the mirror surface are 90 degree ..

A) Only (I) is true .

B) Only (II) is true .

C) Both (I) and (III) are true .

D) Both (I) and (IV) are true ✔

Answer:

Pulmonary circulation is the system of transportation that shunts de-oxygenated blood from the heart to the lungs to be re-saturated with oxygen before being dispersed into the systemic circulation. Deoxygenated blood from the lower half of the body enters the heart from the inferior vena cava while deoxygenated blood from the upper body is delivered to the heart via the superior vena cava. Both the superior vena cava and inferior vena cava empty blood into the right atrium. Blood flows through the tricuspid valve into the right ventricle. It then flows through the pulmonic valve into the pulmonary artery before being delivered to the lungs. While in the lungs, blood diverges into the numerous pulmonary capillaries where it releases carbon dioxide and is replenished with oxygen. Once fully saturated with oxygen, the blood is transported via the pulmonary vein into the left atrium which pumps blood through the mitral valve and into the left ventricle. With a powerful contraction, the left ventricle expels oxygen-rich blood through the aortic valve and into the aorta: This is the beginning of systemic circulation.[1]

Development

Around fifteen days after fertilization, blood cell vessels begin to form outside of the implanted embryo which creates the initial placenta. This is vital to maintaining fetal life as it provides a mechanism that delivers oxygen and nutrients to the developing baby and discards waste products. By day seventeen, the fetus is forming red blood cell precursors and initial vasculature. Between three and four weeks after conception, the fetal heart develops all four chambers and begins beating on its own distinctly representative of its vitality separate from that of the mother.

Because the developing fetus uses the placenta to maintain oxygen saturation and exchange waste for nutrients, fetal circulation is designed to transfer blood around the organs not needed while the fetus is in the womb. Therefore, since blood does not need to enter the fetal lungs or liver, three shunts maximize the efficiency of blood flow. The placenta provides the fetus with oxygen-rich blood via the umbilical vein. Once inside the fetus, blood travels through the ductus venosus which directs blood from the umbilical vein around the liver and into the inferior vena cava. A portion of the blood from the inferior vena cava empties into the right atrium and is shunted through the foramen ovale which transfers it directly into the left atrium thus bypassing the right ventricle and the lungs. The remaining blood in the right atrium travels through the tricuspid valve into the right ventricle.[2] Instead of diverting into the lungs, blood in the right ventricle empties into the pulmonary artery which is connected to the aorta by the ductus arteriosus.[3]

Once the baby is delivered and takes his first breath, the high resistance in the lungs that was present during development drops dramatically. Since the baby is no longer reliant on the placenta for oxygenation, the umbilical vessels are ligated: blood can enter the lungs for oxygenation. The oxygen relaxes the pulmonary vessels and causes constriction and eventual closure of the portal shunts. Once these fetal shunts are fully closed, the neonate’s blood flow is identical to that of an adult