ch 29 Development, Growth, Aging

Question 1

Prenatal Development:

1. • 3. What are the 3 sstages of prenatal development and their time frames?

Answer 1

1. Germinal Period: fertilization to 14 days after. Blastocyte.
2. Embryonic Period: 14-56 days after fertilization
3. Fetal Period: 56 days after fertilization until birth.

Question 2

Postnatal Development:

1. What are the 5 stages of human development after birth, and their time frames?

Answer 2

1. Neonatal Period: birth to 1 month
2. Infancy: 1 month to 1 or 2 years
3. Childhood: 1 or 2 years to puberty
4. Adolescence: Puberty until 20 years old
5. Adult: from 20 years until death

Question 3

Fertilization:

1. When does fertilization occur?
2. How do sperm reach the egg?
3. Once they arrive at the egg, sperm break through the …………… ………….. and bind to a receptor in the …………….. …………… that releases enzymes in the acrosomal cap on the sperm.
4. What do the enzymes releaaed by the zona pellucida allow the sperm to do?

Answer 3

1. When sperm fuses with egg.
2. By their tails and smooth muscle contraction (in female)
3. corona radiata, zona pellucida
4. bind to a receptor on the oocyte plasma membrane and fuse with the oocyte.

Question 4

Fertilization:

1. What is polyspermy and how is it prevented?
2. What are the fast and slow block?
3. What forms the male pronucleus?
4. How is the female pronucleus formed?
5. What is a zygote?

Answer 4

1. Polyspermy is more than 1 sperm fertilizing an egg. Prevented by the fast block (depolarization of the egg) first, and then the slow block after.
2. Fast block: egg depolarization once sperm binds to eggs membrane. Slow block: the water and molecule release from oocyte that inactivates receptors in the zona pellucida
3. The sperm head (the only part that enters the egg).
4. Female pronucleus forms when the egg is fertilized and it completes meiosis 2.
5. The zygote is the fusion of the male and female pronuclei.

Question 5

when does the oocyte give off the first and second polar bodies?

Answer 5

First polar body: upon completion of meiosis 1.

Second polar body: upon completion of meiosis 2 just after sperm enters egg.

Question 6

1. What is totipotent?
2. What is pluripotent?
3. What is a morula?
4. What is a blastocyst? What is the outer layer called? What will the inner part become?
5. How is the blastocyst nourished?

Answer 6

1. Totipotent: when fertilized egg starts to divide, each section of division has the ability to give rise to an individual. Identical twins happen here (prior to differentiation 1-3 days)
2. any cell has the ability to give rise to a wide range of tissues, but not a complete human. Cell has differentiated (around 4 days).
3. Once fertilized egg has divided into 12 or more cells, it’s a morula (around 5 days).
4. Once a hollow sphere in the middle of all the divided cells develops it’s a blastocyst (about 6 days). Outer layer: trophoblast. Inner part: becomes embryo.
5. Nourished by uterine secretions.

Question 7

Implantation and development of the placenta:

1. When does the embryo begin to implant?
2. What structure secretes enzymes that allow the blastocyst to burrow into the endometrium?
3. Name and describe the two layers that the trophoblast forms.
4. What hormone does the trophoblast secrete that mimics LH, maintaining the corpus luteum?

Answer 7

1. After roughly 6 days
2. The trophoblast
3. Syncytiotrophoblast: outer layer that invades the endometrium and protects embryo from implantation enzymes. Cytotrophoblast: the cellular layer closest to embryo.
4. hCG

Question 8

1. What does the placenta develop from?
2. What structure digests maternal blood vessels and forms lacunae that contain maternal blood?
3. How are the lacunae fed and drained?
4. Branches of the ………………. form chorionic villi around the lacunae
5. Where do embryonic blood vessels form?
6. T or F, there is a small distance between maternal and fetal blood for diffusion of nutrients, wastes, and respiratory gasses
7. What forms the chorion?

Answer 8

1. From the trophoblast and the endometrium.
2. The syncytiotrophoblast
3. fed by arterioles and drained by veins
4. Cytotrophoblast
5. In the trophoblast
6. the syncytiotrophoblast and its basement membrane

Question 9

1. What is gastrulation? When does it occur?
2. The embryonic disc forms the two layers of cells called ……………….. and …………………
3. In which of these two layers does the amniotic cavity form?
4. Which layer forms the yolk sac?

Answer 9

1. The formation of the 3 germ layers. Occurs around 14 days after fertilization.
2. Hypoblast and epiblast
3. epiblast
4. The hypoblast

Question 10

1. What do the 3 germ layers form?
2. What is the primitive streak?
3. What two layers does the epiblast form?
4. What is formed by the ectoderm?
5. What is formed by the mesoderm?
6. What is formed by the endoderm?

Answer 10

1. They form the tissues of the body.
2. A longitudinal groove that forms on the dorsal surface of the epiblast
3. the ectoderm, mesoderm, and endoderm
4. epidermis and nervous system
5. dermis, cardiovascular system, muscle, bone, and other tissues and organs.
6. epithelial lining of gut, respiratory, and some other organs

Question 11

1. A connecting stalk of extra-embryonic mesenchyme attaches the embryo to the trophoblast and will form the ……………. ………..
2. Name the structure who’s function is to induce further development of other cells
3. Where is the neural plate formed?
4. What does the neural plate form?
5. The neural tube will form the ……….. and ……….. ……….. .
6. The neural crest will form the ……….

Answer 11

1. umbilical cord.
2. notochord
3. In the ectoderm near the cephalic end
4. neural tube and neural crest cells
5. brain and spinal cord
6. PNS

Question 12

1. The placenta produces what hormones?
2. What are the effects of relaxin?
3. Name the hormone that helps prep mammary glands for lactation and regulates metabolism in mother and fetus

Answer 12

1. estrogen, progesterone, and hCG
2. increases flexibility of pubic symphysis and dilates cervix
3. human chorionic somatomammotrophin hCS.