Question

question 22
1 pts
during pregnancy, what happens to the oxygenated blood returned from the placenta via the umbilical vein?
it flows into the inferior vena cava.
it flows into the superior vena cava.
it flows into the ductus venosus.
none of the above is correct.
question 23
1 pts
the outermost layer of the larger blood vessels is the tunica
media.
intima.
adventitia.
intermedia.
question 24
1 pts
starlings law of the heart states that, within limits, the longer, or more stretched, the heart fibers are at the beginning of the contraction, the
weaker the contraction.
slower the heart rate.
faster the heart rate.
stronger the contraction.

Explanation:

• Question 22: During pregnancy, oxygenated blood from the placenta via the umbilical vein flows into the ductus venosus. The ductus venosus is a fetal vessel that shunts oxygen - rich blood from the umbilical vein to the inferior vena cava.
• Question 23: The outermost layer of larger blood vessels is the tunica adventitia. The tunica media is the middle layer (smooth muscle), the tunica intima is the inner layer (endothelium), and there is no tunica intermedia in standard blood - vessel anatomy.
• Question 24: Starling's law of the heart states that, within limits, the longer or more stretched the heart fibers are at the beginning of contraction, the stronger the contraction. This is because a greater stretch (up to an optimal point) allows for better actin - myosin interaction in the cardiac muscle fibers.

Answer:

• Question 22: It flows into the ductus venosus.
• Question 23: adventitia.
• Question 24: stronger the contraction.