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BIO169-Reproduction
Reproduction
| Question | Answer |
|---|---|
| What are the 4 different types of sex development? | 1) chromosomal sex 2) gonadal sex 3) pheontypic sex 4) psychological sex |
| What are the factors contritubing to chromosomal sex: | at conception, the sperm brings into the ovum either an X chromosome; the ovum contains an X chromosome |
| What is a chromosomal male? Female? | male if the fertilized single-egg ovum (zygote) contains XY chromosomes; if the zygote contains XX chromosomes it is a chromosomal female |
| what is gonadal sex? | it is determined by which type of gonad, ovary or testis, is present |
| what influences gonadal sex? | hormonal factors; |
| what is an indifferent gonad? | early embryos of both sexes have the exact same undifferentiated gonadal tissue |
| where is the indifferent gonad located? | inferior to the developing kidney |
| which structures will eventually develop into tubular genitalia? Are these specific to sex? | no, bot XX and XY embryos have these identical structures: Mullerian ducts, Wolfian ducts, urogenital sinuses, and genital tubercles |
| what is the SRY gene? | it is a gene on the Y chromosome; it is activated approximately 40 days after fertilization |
| what does the SRY gene do? For which type embryos? | the SRY gene is only on the chromosomal male (XY); it directs the gonad to become a testis |
| how is the testis formed? | a substance called Mullerian Regression Factor is produed which causes the Mullerian ducts to break down (i.e. the ducts atrophy) |
| what does the testis produce to stimulate the development of other male sex organs? | after the Mullerian ducts and the testis begins to form, it produces testosterone which causes the development of the Wolffian duct into the inner male structures |
| what does the Wolffian duct develop into in the male? | the epididymis, vas deferens, seminal vesicles, and ejaculatory duct |
| what does testosterone convert to, and what is its impact on male sex organs? | testosterone is converted by enzymes to dihydrotestosterone, which then stimulates the development of the urogenital sinus and genital tubercle (the external male genitalia) |
| what do the urogenital sinus and genital tubercles become in the male? | "urogenital sinus: prostate gland, Cowper's glands, penile urethra and scrotum; |
| in the XX embryo, what does the undifferentiated gonad become? What triggers this? | the undifferentiated gonad becomes an ovary; this occurs because there is no SRY gene activity |
| what do the Wolffian ducts become in the XX embryo? What triggers this? | the Wolffian ducts simply atrophies in the XX embryo; this occurs because of a lack of testosterone |
| what does the Mullerian duct become in the XX embryo? What triggers this? | the Mullerian duct differentiaties into the Fallopian tubes, uterus, and upper vagina; this occurs because of the absence of Mullerian Regression Factor |
| What do the urogenital sinus and genital tubercle become in the XX embryo? How? | "urogenital sinus: lower vagina, labia minora, and labia majora; |
| is estrogen required in the development of female genitalia? | no; it is the absence of the SRY gene, Mullerian regression factor, testosterone, and dihydrotestosterone that cause the development of female genitalia |
| what is involved with sexuality at a psychological level? | 1) sexual identification, 2) sexual preference, 3) libido |
| explain sexual identification: | an individual will develop a self-identity to one sex or the o ther; this is influenced both by genetics and environment |
| explain sexual preference: | the process of developing sexual preference is not completely understood from a physiologica standpoint; it is know that both genetics and environment play a role |
| explain libido: | libido is an individual's sex drive; this is strongly influenced by hormones, most specifically androgens; many psychological factors also play a role |
| what is phenotypic sex? | related to the development of sex organs, excluding ovaries & testis; these remaining sex organs develop into male organs in the presence of Mullerian regression factor, testosterone, and dihydrotestosterone; or into female organs in the lack of these |
| when does the reproductive system become fully functional? | during puberty |
| why is the reproductive system the last organ system in the body to become fully functional? | 1) it is not absolutely essential to supporting life; 2) it is delayed until the individual has completed most other processes related to growth & development and has a body mass & metabolism which can support the demands of reproduction |
| what prevents the hypothalamus from producing GnRF prior to puberty? | the hypersensitivity of the hypothalamus to low levels of sex hormones produced in the immature body; these low levels of sex hormones produce a negative feedback preventing the production of gonadotrophic releasing factors |
| what stimulates puberty? | as puberty approaches, the hypothalamus begins to lose its hypersensitivity and begins to produce increasing amounts of GnRF (FRF and LRF) |
| what is FRF? LRF? | FRF: follicle stimulating hormone releasing factor; LRF: luteinizing hormone releasing factor |
| What do the increased GnRF levels stimulate? | the anterior pituitary to release FSH and LH |
| What is the role of increasing levels of FSH in the female? | FSH stimulates the development of follicles in the ovary; the follicle cells begin to produce estrogen; estrogen stimulates the development of the female secondary sex characteristics |
| What is the role of FSH on the follicle? | it stimulates the maturation of the ovum within each follicle |
| What is the function of LH? | increasing levels of LH will induce ovulation (generally of one ovum); the ruptured follicle cells will produce a temporary endocrine structure called a corpus luteum |
| What does the corpus luteum produce? | large amounts of progesterone |
| When does the menstrual cycle begin in the female? | generally, several years after the onset of development of secondary sex characteristics |
| what is the role of increasing levels of FSH in the male? | it stimulates the seminiferous tubules of the testes to begin spermatogenesis |
| What is the role of LH in the male? What else is LH called in the male? | LH is aka interstitial cell stimulating hormone (ICSH); it stimulates the interstitial cells of the testes to produce testosterone |
| what is the role of testosterone in the male? | it causes development of the male secondary sex characteristics |
| what are the 3 phases of the menstrual cycle? | menstrual phase (days 1-4), proliferative phase (days 5-15), secretory yphase (days 16-28) |
| what occurs during the menstrual phase? | the endometrial lining is shed, FSH levels are rising, follicles develop; as estrogen levels rise, they feedback on the hypothalamus and anterior pituitary and FSH is shut off |
| what occurs during the proliferative phase? | estrogen causes proliferation of the endometrial lining; rising LH levels stimulate ovulation at approximately day 14 and development of the corpus luteum occurs |
| what occurs during the secretory phase? | progesterone from the corpus luteum stimulates the endometrium to become fully functional and able to support a pregnancy; as progesterone levels rise, the feedback on the hypothalamus & anterior pituitary and shut off LH |
| what triggers the end of the secretory phase, and accordingly, the beginning of the next menstrual cycle? | the lack of LH causes the corpus luteum to atrophy and progesterone levels to drop; as progesterone levels drop, it brings about the menstrual phase |
Created by:
debmurph
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