Sexual Reproduction

Question Answer
Early embryonic gonads can become either _______ or _______. Testes/ovaries
What chromosome induces the formation of the testes? Y
What hormone from the testes induces formation of the male sex organs and absence forms the female sex organs? Testosterone
What are formed in gonads by meiosis? Gametes
Each gamete has a ______ number of chromosomes (23) Haploid
Fusion of sperm and egg during ______ results in a _______ ______ with 43 chromosomes. Fertilizatio/dipoid zygote
Each zygote inherits __ chromosomes from mother and __ from father producing __ pairs of ____________ ___________. 23/23/23/homologous chromosomes
How many autosomal chromosomes are there? 22
the 23rd pair of chromosomes are _____ chromosomes. Sex
There are more genetic diseases causes by the _____linked gene. X
Only 1 of 2 Xs in the females becomes active in meiosis the other forms a clump of inactive heterochromatic called what? Barr body
What is used as a test for chromosomal sex? Barr body
What occurs in a gamete or zygote and causes differential expression of alleles? Genomic imprinting
In genomic imprinting each gene is represented either by the same or an alternative allele and both are usually expresses. In approximatelly ____ genes either the maternal or paternal allele is ___________. 80/silenced
Silencing of an allele is accomplished by _________ changes to the chromatin, such as by methylation of cytosine bases in DNA. Epigenetic
The 1st 40 days after conception, ganads of males and females are __________. Similar
Gonads have the potential to become testes or ovaries until what causes a conversion to testes which is produced by what gene? Testis-determining factor (TDF)/Sex-determining region of Y (SRY gene)
__________ tubules appear within 43-50 days following conception as opposed to _________ ________ that don't appear until day 105. Seminiferous/ovarian follicle
What masculinizes the embryonic structures? Leydig cells
In developing testes what cells begin secreting testosterone at 8 weeks of development and peak at 12-14 weeks and then decline to very low levels until puberty? Leydig cells
When do the testes descend into the scrotum? Shortly before birth
Spermatogenesis does not occur in males with undescended testes because it requires a 3 degrees C lower temperature than the body and is a condition called what? Cryptorchidism
Seminiferous tubules (STs) contain germinal cells which will produce _______ and nongerminal cells called __________ which appear at day 42. Sperm/Sertoli
At ~day 65, during the formation of testes, _______ cells (that produce testosterone) appear in cluster around the seminiferous tubules. Leydig
What develops in the absence of TDF? Ovaries
What ducts are male accessory sex organs derived from? Wolffian
What are the 4 wolffian ducts? Epididymis, vas deferens, seminal vesicles, and ejaculatory duct
What ducts are the female accessory organs derived from? Mullerian
What are the 2 mullerian ducts Uterus and fallopian tubes
Testosterone from _____ cells causes ______ ducts to give rise to male accessory organs. Leydig/Wolffian
At ~day 60, _______ cells secrete Mullerian inhibiting factor (MIF) which causes Mullerian ducts to regress. Sertoli
What secretions masculinize the external genitalia of men to form what 4 things? Testis/penis/urethra/prostate/scrotum
In the absence of testosterone _______ forms instead of a penis and the _____ forms instead of the scrotum. Clitoris/labia
What disorder occurs when individuals have both ovary and testis tissue? Hermaphroditism
What disorder occurs when the testes or ovaries are present (not both) but the accessory organs and external genitalia are incompletely developed or inappropriate for their chromosomal sex? Pseudohermaphrodites
The most common cause of female pseudohemaphroditism is what? Congenital adrenal hyperplasia
One cause of pseudohermaphroditism in males is caused by ______ ______ _____ in which the testes are normal but there are no receptors for testosterone. Testicular feminizing syndrome
What embryonic sexual development disorder causes a male to develop a very female appearance and is also infertile Testicular feminizing syndrome
In which trimester is there a lot of testosterone produced to masculinize the fetus? 1st
Ovaries don't produce much _____ ______ until puberty and both testes and ovaries remain inactive after birth until ________. Sex steroid/puberty
What part of the brain controls the release of LH and FSH from the anterior pituitary with GnRH. Hypothalamus
What 2 hormones stimulate the production of sperm and eggs, and gonadal sex steroids and maintains the size of the gonads? LH and FSH
Sex steroids provide what type of feedback on hypothalamus and the Ant. Pit.? Negative
What hormone does the gonads secrete which negatively feeds back on FSH secretion? Inhibin
At puberty the hypothalamus increases the secretion of what hormone which stimulates the increase of what 2 hormones? GnRH/LH/FSH
When is the secretion of FSH and LH low? Between the 6th month of life until puberty
What 2 hormones stimulates sex steroid seretion? LH and FSH
LH and FSH stimulates the secretion of sex steroids wich drives changes in __________ ______ characteristics and ____________. Secondary sex/Menarche
Growth of pubic and axillary hair is due to the secretion of what? Androgen
The growth of pubic and axillary hair is due to androgen secretion from what endocrine gland? Adrenal cortex
What is the 1st menstral flow called? Menarche
The age of puberty in girls depends on what 2 factors? % of body fat and physical activity
At the beginning of female puberty a high level of ____ stimulates growth? E
Melatonin inhibits the secreation of what hormone? Gonadotropin
What endocrine gland appears to play a role in seasonal reproduction in animals but the role in humans is unclear? Pineal
What are the 4 phases of sexual response? Excitation (arousal), plateau, organsm, and resolution
What phase of sexual response is characterized by increased muscle tone and engorgement of sexual organs with blood including nipples, clitoris, penis, and labia minor as well as vaginal lubricants? Excitation
During what phase of sexual human response is the clitoris partially hidden by the swelling labia, the areolae continues swelling and the outer third of the vagina engorges? Plateau phase
During what phase of human sexual response does the men ejaculate and the women have analogous contractions of the uterus and vagina? Orgasm
During what phase of sexual response does the body return to the preexcitation conditions and men enter a refractory period? Resolution phase

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