Answer to Question #50841 in Biology for abby

Question

1. a) About how this pregnancy week do luteum he begins to degenerate? Justify your answer.

b) About how this pregnancy week do parturition is triggered? Justify your answer.

c) What structure is responsible for the secretion of HCG?

d) Which structure is responsible for the secretion of progesterone and estrogen?


2. a) What organogenesis?

b) At what stage of pregnancy the embryo he now carries the fetus name? Why?

c) What is the duration of a typical pregnancy?

d) In which quarter there he has the most development and differentiation?

e) What is the minimum age (in weeks) to which a premature fetus could survive without much critical care?

3.Décris briefly the three stages of parturition. Why they say it is a phenomenon of retro activation.

4. How is it that lactation is it controlled by hormonal secretions of the pituitary gland? What is the external factor that indirectly stimulates the production of milk by the mammary glands?

Answer 1

1. a) About how this pregnancy week do luteum he begins to degenerate? Justify your answer. It begins to degenerate after the middle of pregnancy, when plasma progesterone remains high.

b) About how this pregnancy week do parturition is triggered? Justify your answer. The onset of parturition is thought to be triggered by release of cortisol by the fetus into the maternal circulation. This results in increased production and release of estrogen by the placenta. Estrogen causes the muscular wall of the uterus (myometrium) to begin contracting and preparing to expel the fetus.

c) What structure is responsible for the secretion of HCG? It is a hormone produced by the syncytiotrophoblast, a portion of the placenta following implantation.

d) Which structure is responsible for the secretion of progesterone and estrogen? During pregnancy progesterone is released by the corpus luteum in increasing amounts while estrogen is secreted by placenta.

2. a) What organogenesis? It is the developmental process by which the ectoderm, endoderm, and mesoderm develop into the internal organs of the organism.

b) At what stage of pregnancy the embryo he now carries the fetus name? Why? The term fetus is used after the first 8 weeks following conception, and subsequently until birth. Before there is the process of embyogenesis when all necessary primal tissues develop.

c) What is the duration of a typical pregnancy? Childbirth usually occurs about 38 weeks after conception.

d) In which quarter there he has the most development and differentiation? At the first quater it takes place. By the end of fifth week, the embryo has all of its internal organs.

e) What is the minimum age (in weeks) to which a premature fetus could survive without much critical care? Currently the limit of viability is considered to be around 24 weeks although the incidence of major disabilities remains high at this point.

3.Décris briefly the three stages of parturition. Why they say it is a phenomenon of retro activation. The first stage of parturition is dilation of the cervix. The second stage of parturition is defined as the delivery of the newborn. The third stage of parturition is the shedding of the placenta or fetal membranes.

4. How is it that lactation is it controlled by hormonal secretions of the pituitary gland? What is the external factor that indirectly stimulates the production of milk by the mammary glands? In humans, prolactin is produced both in the front portion of the pituitary gland (anterior pituitary gland) and in a range of sites elsewhere in the body. Lactotroph cells in the pituitary gland produce prolactin, where it is stored in small containers called vesicles. One of the main regulators of the production of prolactin from the pituitary gland is the hormone called dopamine, which is produced by the hypothalamus, the part of the brain directly above the pituitary gland. Dopamine restrains prolactin production, so the more dopamine there is, the less prolactin is released. The main external factors, estrogens and progesterone, stimulate alveolar and ductal proliferation, respectively. Estrogens also cause deposition of adipose tissue within the mammary gland.