Zoology 142 Final-Ch 29: Fetal Development

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1. 
Order of prenatal development
 
zygote, cleavage, morula, blastocyst, embryo, fetus
 
2. 
process that makes it possible for sperm to penetrate the egg is called
 
capacitation
 
3. 
In the slow block to polyspermy, sperm penetration releases an inflow of ___________, which in turn stimulates the ________.
 
Ca2+; cortical reaction
 
4. 
In the fast block to polyspermy, binding of sperm opens up _________ channels, which depolarizes the egg membrane and _________
 
Na+; prevents the entrance of any more sperm
 
5. 
The optimal "window of opportunity" to conceive a child is
 
a few days before ovulation to less than a day after
 
6. 
The spheroidal stage of early prenatal development with about 16 to 64 cells is called a/an
 
Morula
 
7. 
Twins produced when a single egg is fertilized are called _____________ twins, and twins produced from two eggs ovulated at the same time are called ___________ twins
 
monozygotic; dizygotic
 
8. 
In the blastocyst, the trophoblast will become ____________, whereas the embryoblast will become __________
 
part of the placenta; the embryo
 
9. 
Primary germ layers are formed during
 
gastrulation
 
10. 
Mesenchyme gives rise to
 
muscle, bone and blood
 
11. 
During implantation, the trophoblast divides into a deep layer, the _________, composed of individual cells, and a superficial layer, the ___________, composed of a multinucleate mass of cytoplasm
 
cytotrophoblast; syncytiotrophoblast
 
12. 
By the time the conceptus arrives in the uterus
 
it consists of 16 or more cells
 
13. 
Out of the 300 million ejaculated sperm, only about ____________ reach the vicinity of the egg
 
3,000
 
14. 
Prior to ejaculation, __________ in the sperm plasma membrane prevents premature release of ______________
 
cholesterol; acrosomal enzymes
 
15. 
These are derivatives of ectoderm except
 
the dermis
 
16. 
The first body cavity is called the
 
coelom
 
17. 
By the end of 8 weeks, the individual is considered a fetus because
 
all of the organ systems are present
 
18. 
The ___________ completely encloses the embryo and provides a stable environment for it.
 
amnion
 
19. 
The ___________ encloses all the rest of the membranes and the embryo
 
chorion
 
20. 
The embryonic membrane that forms the fetal portion of the placent
 
the villous chorion
 
21. 
As it implants, the conceptus is nourished by means of
 
trophoblastic nutrition
 
22. 
The vessel that provides oxygenated blood to the placenta is
 
a maternal artery
 
23. 
In fetal circulation, the __________ bypasses the liver and the _________ bypasses the lung
 
ductus venosus; ductus arteriosus
 
24. 
In fetal circulation, blood bypasses the lungs by flowing through
 
the foramen ovale and ductus arteriosus
 
25. 
Which of the following major events of prenatal development happens first? -eyes are fully open-body covered with lanugo-bone calcification begins-central nervous system begins to form-meconium accumulates in intestines
 
the central nervous system begins to form
 
26. 
Oxygenated blood reaches the fetus through the
 
umbilical vein
 
27. 
The embryonic membranes include all of the following except the
 
placenta
 
28. 
_______ pass(es) from the maternal blood to the fetal blood; while fetal _________ pass(es) the other way
 
Oxygen and nutrients; wastes
 
29. 
The digital rays of a fetus give rise to
 
fingers and toes
 
30. 
The first 6 weeks of postpartum life constitute
 
the neonatal period
 
31. 
The fossa ovalis is a remnant of the ___________ of the fetus
 
foramen ovale
 
32. 
During birth, an infant is normally stimulated to breathe by
 
CO2 accumulating in the baby's blood
 
33. 
Which organ system shows the greatest anatomical change in the transitional period after birth?
 
Circulatory
 
34. 
Infant respiratory distress syndrome (IRDS) is caused by
 
deficiency of pulmonary surfactant.
 
35. 
Which organ system faces the greatest physiological challenge in the transitional period after birth?
 
Respiratory
 
36. 
A teratogen is most likely to cause
 
a deformity of the limbs.
 
37. 
These are have potentially teratogenic effects except-smoking-alcohol-infectious diseases-sunlight-x-rays
 

sunlight.
 
38. 
Down syndrome (trisomy-21) results from
 
nondisjunction.
 
39. 
The most likely outcome of nondisjunction is the production of a gamete receiving
 
22 chromosomes.
 
40. 
Only autosomal trisomies involving chromosomes 13, 18, and 21 are survivable. why would this be?
 
These are relatively gene-poor chromosomes.
 
41. 
Urine retention is a greater problem for elderly men than for elderly women because men
 

usually develop benign prostatic hyperplasia.
 
42. 
Muscular weakness tends to develop in old age for all of the following reasons except:-aged muscle has less glycogen, myoglobin, and creatine phosphate.-there are fewer motor neurons in the spinal cord.-aged muscle fibers have fewer myofibrils.-there are fewer and smaller mitochondria.-myocytes do not synthesize myosin anymore.
 
myocytes do not synthesize myosin anymore.
 
43. 
Older people may require lower drug doses than younger people because
 
they have lower rates of renal clearance.
 
44. 
Telomeres
 
are DNA segments at each end of a chromosome.
 
45. 
The observation that there is a limit to how many times a cell can divide is the basis for the
 
replicative senescence theory.
 
46. 
Clinical death is widely defined as
 
brain death.
 
47. 
Which of the following systems shows the least overall senescence?
 
endocrine system
 
48. 
Senescence of the immune system makes older people more subject to cancer and infectious disease because of a decline in
 
antigen-presenting cells and helper T cells.
 
49. 
Congenital anomalies can result from all of the following except-an infectious disease in the mother during pregnancy.-genetic disorder-exposure to teratogens during pregnancy-smoking during lactation-smoking during pregnancy
 
smoking during lactation.