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50 terms

Chapters 27 & 28

STUDY
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Gonads begin to develop
5 to 6 weeks after fertilization
_____ determines whether an organism will be genetically male or female
the sperm
The gene that codes for the testis-determining factor (TDF) is found in or on
the Y chromosome
The penis is homologous to
the clitoris
The _____ is the gonad and the _______ is the gamete
Testis; sperm
When it is cold the _____ contracts and draws the testes closer to the body to keep them warm
cremaster muscle
The countercurrent heat exchanger that prevents arterial blood from overheating the testes is
the pampiniform plexus of veins
The blood testis barrier
prevents antibodies in the blood from getting to the germ cells
By volume most of the semen is produced in the
seminal vesicles
Why would an enlarged prostate gland interfere with urination
it compresses the urethra
The ______ are the sites of sperm maturation and storage
ductus epididymides
When do the testes start secreting testosterone
in the first trimester of fetal development
Which of the following hormones directly stimulates the development of male secondary sex characteristics
testosterone
Which of the following is an androgen
testosterone
____ stimulates the interstitial cells of the testes to secrete _____
Luteinizing Hormone(LH); testerone
Which hormone suppresses spermatogenesis without affecting testosterone secretion
inhibin
The ______ have no adrogen receptors and do not respond to it
germ cells
Testosterone inhibits
gonadotropin-releasing hormone (GnRH) secretion
Changes called male climacteric are a consequence of
decreased secretion of testosterone
In the process of sperminogenesis, ______ become______
spermatids; spermatozoa
In meiosis, each parent cell produces
four haploid cells
As a result of spermatogenesis and spermiogenesis, the final cells produced are called _____ but they and all the stages leading up to them can be called _______
gametes; germ cells
At the end of meiosis I there are ______, whereas at the end of meiosis II there are
two haploid cells; four haploid cells
The most important role of meiosis in sexual reproduction is
that it prevents the chromosome number from doubling in each generation
At what stage does a developing sperm cell begin to grow a tail
spermatid
Sperm cells get energy to power their movement from _____ contributed by the ______
fructose;seminal vesicles
Male infertility (sterility) refers to
the inability to fertilze an egg
The acrosome contains enzymes used to
penetrate barriers surrounding the ovum
____ have 46 chromosomes whereas _____ have 23
Primary spermatocytes; spermatids
A sperm count lower than _____ million sperm per mL of semen is usually associated with infertility (sterility)
20 to 25
The _____ arteries rhythmically constrict and dilate causing the uterine mucosa to blanch and flush with blood
spiral
After puberty the vaginal lining becomes ______ to ______
stratified squamous epithelium; resist abrasion
The ______ is the site of attachment of the embryo
endometrium
Mammary glands develop within the breast primarily
during pregnancy
Breast size is determined by
the amount of adipose tissue
The earliest sign of puberty in girls is
the onset of breat development
_____ are feminizing hormones
estrogens
_____ act primarily in the uterus
progesterone
The midlife change in estrogen and progesteron is called_____ whereas the cessation of menstruation is called______
climacteric;menopause
The ovum finalizes meiosis
during fertilization
Most ovulation homee test kits measure _____ surge, which happens about 24 hours before ovulation
LH
After expelling the oocyte, the follicle becomes the _____ and secretes______
corpus luteum; estrogen and progesterone
Oogenesis starts
during embryonic development
In the adult ovary, more than 90% of the follicles are found as
primordial follicles
During the follicular phase, granulosa cells secrete _____ which stimulates the secretion of ______
estradiol;LH
Which of these blood hormone levels reaches its maximum during the luteal phase
progesterone
______ inhibits the secretion of ______ during the female sexual cycle.
Estradiol and progesterone; FSH and LH
In early pregnancy _____ stimulates growth of the corpus luteum
human chorionic gonadotropin
The basis of pregnancy test kits is the presence of ______ which is secreted by ______
human chorionic gonadotropin (HCG); blastocyst and placenta
The basis for contraceptive pills is that they mimic the _____ feedback effect of _______
negative;estrogens and progesterone