the male reproductive system
a sperm count any lower than ____ million sperm per mL of semen is usually associated with infertility (sterility)
20 to 25
gonads begin to develop
5 to 6 weeks after fertilization
heart rate, blood pressure, and respiratory rate peak during the
climax (orgasm)
the ____ is an example of the female external genitalia.
clitoris
the ____ is the gonad and the ____ is the gamete.
testis; sperm
_____ stimulates the descent of the testes.
testosterone
which of the following hormones directly stimulates the development of male secondary sex characteristics?
testosterone
which of the following is an androgen?
testosterone
the most important role of meiosis in sexual reproduction is
that it prevents the chromosome number from doubling in each generation
the gene that codes for the testis-determining factor (TDF) is found in or on
the Y chromosome
all of the following play a role in thermoregulation of the testes except
the bulbospongiosus muscle
the penis is homologous to
the clitoris
_____ is/are generally accepted as a secondary sex characteristic.
the enlargement of the breasts
male infertility (sterility) refers to
the inability to fertilize an egg
the countercurrent heat exchanger that prevents arterial blood from overheating the testes is
the pampiniform plexus
_____ determine/s whether an organism will be genetically male or female.
the sperm
at the end of meiosis I there are _____, whereas at the end of meiosis II there is/are _____.
two haploid cells; four haploid cells
which of the following is a secondary sex organ?
vagina
which hormone suppresses spermatogenesis without affecting testosterone secretion?
inhibin
sidlenafil (viagra) prolongs erection by
inhibiting degradation of cGMP
in meiosis, each parent cell produces
four haploid cells
sperm cells get energy to power heir movement from _____ contributed by the ____.
fructose; seminal vesicles
in spermatogenesis, only the final cells are called ____, but they and all the stages leading up to them can be called
gamete; germ cells
the _____ has/have no androgen receptors and do not respond to it.
germ cells
testosterone inhibits
gonadotropin-releasing hormone (GnRH) secretion
when do the testes start secreting testosterone?
in the first trimester of fetal development
changes called male climacteric are a consequence of
increased secretion of FSH and LH
erection is
an autonomic reflex mediated predominantly by parasympathetic nerve fibers
this image shows a sagittal section of the male reproductive system. what does "4" represent?
bulbourethral gland
_____ are not found in the siminiferous tubules.
corpus cavernosum cells
the penile urethra is enclosed by the
corpus spongiosum
this image shows a sagittal section of the male reproductive system. what does "3" represent?
corpus spongiosum
when it is cold, the ____ contracts and draws the testes closer to the body to keep them warm.
cremaster muscle
dilation of the ____ causes the lacunae to fill with blood and the penis to become erect.
deep arteries
this image shows a section of the testis and scrotal contents. what does "2" represent?
ductus (vas) deferens
the orgasm-emission phase of the male sexual response is stimulated by
efferent sympathetic signals from the lumbar region of the spinal cord
the ____ is/are the site(s) of sperm maturation and storage.
epididymides
why would an enlarges prostate interfere with urination?
it compresses the urethra
_____ stimulates the interstitial cells of the testes to secrete _____.
luteinizing hormone (LH); testosterone
which of the following are primary sex organs?
ovaries
the acrosome contains enzymes used to
penetrate the egg
the blood-testis barrier
prevents antibodies in the blood from getting to the germ cells.
_____ have 46 chromosomes, whereas _____ have 23.
primary spermatocytes; spermatids
this image shows a sagittal section of the male reproductive system. what does "3" represent?
prostate gland
men have only one ____ but have two of all the rest of these.
prostate gland(s)
this image shows spermatogenesis. What does "3" represent?
secondary spermatocyte
by volume, most of the semen is produced in the
seminal vesicles
from their formation to ejaculation, sperm cells take the following pathway:
seminiferous tubule, rete testis, epididymis, ductus deferns, ejaculatory duct, urethra.
at what stage does a developing sperm cell begin to grow a tail?
spermatid
in the process of spermiogenesis, ____ become _____.
spermatids; spermatoza