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What are chromosomes having the same or allelic genes with genetic loci usually arranged in the same order?
homologous
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How many chromosomes make up the human karyotype?
46 in 23 homologous pairs
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What is a karyotype?
the species-specific chromosomal characteristics of a cell
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What are the chromosome other than the sex chromosomes?
autosomes
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What sex chromosomes occur in humans?
X & Y
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What are the sex chromosomes in male and female humans?
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Why are X-linked genetic diseases in humans more common in mans?
Males have about 1,000 genes that are only represented by a single allele from the X chromosome.
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What sex chromosome(s) may an egg carry?
X
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What sex chromosome(s) may a sperm carry?
X or Y
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Which gamete determines sex at conception?
the sperm
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Only one of two X chromosomes in females becomes active. What does the other one form?
A clump of inactive heterochromatin called a Barr body.
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What is the immediate cause of gonads differentiating into testes in males?
testis-determining factor (TDF)
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What genetic factor causes the formation of testis-determining factor?
the sex-determining region of Y (SRY) gene
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What structures within the testes produce sperm?
seminiferous tubules
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What cells within the testes produce testosterone?
Leydig cells
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When is testosterone produced during the prenatal period?
It begins at 8 weeks, peaks at 12-14 weeks, and then declines to very low levels until puberty.
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What is the medical term for undescended testes?
cryptorchidism
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Why do testes occur in the scrotum outside of the pelvic cavity?
Spermatogenesis requires about a 30 C lower temperature than that of the body core.
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From what structures are male accessory organs derived?
wolffian ducts
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From what structures are female accessory organs derived?
Mullerian ducts
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How do testes and ovaries compare in their activity before birth?
Testes produce testosterone during the first trimester. Ovaries donít produce much sex steroid until puberty. Both testes and ovaries remain inactive after birth until puberty.
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What group of hormones produced by the hypothalamus controls the release of LH and FSH?
gonadotropic releasing hormones
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What is the full term for LH?
luteinizing hormone
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What is the complete term for FSH?
follicle-stimulating hormone
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What hormone stimulates follicle maturation in the ovary and sperm production in the testes?
follicle-stimulating hormone
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What hormone stimulates the production of estrogen and progesterone in the ovary and testosterone in the testis?
luteinizing hormone
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What hormone produced by the testes negatively feeds back on FSH secretion?
inhibin
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At puberty what hormone produced by the hypothalamus stimulates an increase in the production of LH and FSH?
gonadotropic releasing hormone
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At the beginning of female puberty, what hormone stimulates growth?
estrogen
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At what age do girls normally experience their greatest growth spurt?
about 12 years
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At what age do boys normally experience their greatest growth spurt?
about 14
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How does the onset of puberty in girls with low body fat and high activity levels compare with girls with normal body fat and activity levels?
It occurs at an older age.
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List the four phases of human sexual response.
- arousal
- plateau phase
- orgasm
- resolution phase (includes a refractory period in men)
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Within what microscopic structures of the testes does spermatogenesis take place?
seminiferous tubules
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Within what cells and tissue of the testes is testosterone formed?
Leydig cells of the interstitial tissue
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What cells within the testes respond to FSH?
Sertoli cells
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What cells within the testes respond to LH?
Leydig cells
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What cells within the testes produce inhibin?
Sertoli cells
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At what age does the level of testosterone begin to decline?
about 50 years
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In males what hormone and its derivatives are responsible for body changes such as growth of the larynx, bone, muscle mass, hemoglobin levels and the onset of spermatogenesis?
testosterone
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What are the stem cells for sperm?
spermatogonia
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What process allows spermatogonia to replicate themselves?
mitosis
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What process gives rise to haploid sperm?
meiosis
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What is the cap of digestive enzymes on the head of a sperm?
acrosome
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What cells prevent the autoimmune destruction of developing sperm?
Sertoli cells
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Developing sperm are embedded in what cells?
Sertoli cells
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What part of a sperm propels it forward?
the flagellum
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What part of a sperm contains a large concentration of mitochondria?
midpiece
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What part of a sperm contains the genetic material?
the head
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In what anatomical structure do spermatozoa mature and become motile?
the epididymis
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What structures carry sperm into the pelvic cavity?
vas deferens
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What male accessory organs add fluid to the sperm leaving the epididymis and provide fructose as an energy source for sperm?
seminal vesicles
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The vas deferens converge to form what structure?
the ejaculatory duct
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What accessory glands of the male reproductive system lies at the base of the urinary bladder and has the urethra passing through it?
the prostate
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What is the name of the fluid emitted during ejaculation?
semen
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What are the two main components of semen?
sperm and seminal fluid
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What are the functions of seminal fluid?
to provide a fluid medium for sperm; to provide an energy source for sperm; to protect sperm from the acidic environment of the vagina; to provide prostaglandins to produce contraction of the uterus
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What division of the ANS is responsible for erection of the penis?
the parasympathetic
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What neurotransmitter is involved in erection of the penis?
nitrous oxide (NO)
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List the three columns of erectile tissue in the penis.
two dorsal columns (corpora cavernosa) and a ventral column (corpus spongiosum)
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What is the movement of semen in the urethra?
emission
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What is the forcible expulsion of semen from the urethra out of the penis?
ejaculation
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Emission and ejaculation are stimulated by what division of the ANS?
the sympathetic
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What is the normal volume of the ejaculate?
1-5 ml
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How many sperm normally occur in each milliliter of ejaculate?
60-150 million
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List three factors that may cause a low sperm count.
- heat
- lead or arsenic poisoning
- drugs (marijuana, cocaine, anabolic steroids)
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What surgical procedure cuts the vas deferens to produce sterility?
vasectomy
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What structures carry the egg from the ovary to the uterus?
the oviducts (fallopian tubes)
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What is the outermost layer of the uterus?
the perimetrium
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What is the muscular layer of the uterus?
the myometrium
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What is the inner most, hormonally-responsive layer of the uterus?
the endometrium
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What portion of the uterus projects into the vagina?
the cervix
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What is the anatomical term for the birth canal?
the vagina
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What are the lateral folds of the vulva?
the labia majora
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What are the medial folds of the vulva?
the labia minora
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What structure within the vulva is homologous with the penis?
the clitoris
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When are oocytes formed?
before birth
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At what stage of meiosis are oocytes arrested in their development?
prophase 1
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About how many oocytes exist at puberty?
400,000
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When is meiosis completed by oocytes?
only after fertilization
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Meiosis of oocytes is an assymetric division. What is the small daughter cell produced by this
uneven division?
a polar body
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What two layers surround an ovulated ovum?
the cellular corona radiata and the zona pellucida
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In the menstrual cycle, what hormone is produced in the largest quantity by the ovary before ovulation?
estrogen
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How long is the menstrual cycle on average?
28 days
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What is considered the first day of the menstrual cycle?
the first day of menstruation
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What day does ovulation normally occur on?
14
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What becomes of a follicle after ovulation?
It becomes a corpus luteum
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What hormone does a corpus luteum produce in the largest quantity?
progesterone
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If fertilization does not take place, what becomes of the corpus luteum?
It becosme as scar tissue
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What is the shedding of the endometrial lining of the uterus?
menstruation
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The menstrual cycle consists of two separate cycles. What are they?
the ovarian cycle and the uterine cycle
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What phase of the ovarian occurs from day 1 through ovulation?
the follicular phase
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What phase of the ovarian cycle occurs from ovulation to menstruation?
the luteal phase
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What phase of the uterine cycle occurs from the end of menstruation to ovulation?
the proliferative phase
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What phase of the uterine cycle occurs from ovulation to menstruation?
the secretory phase
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What phase of the ovarian cycle occurs as the follicle is maturing before ovulation?
the follicular phase
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What part of the ovarian cycle occurs when the follicle ruptures to release the egg?
ovulation
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In what phase of the ovarian cycle is the most estrogen produced?
the follicular phase
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In what phase of the ovarian cycle is the most progesterone produced?
luteal phase
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In what phase of the uterine cycle is lining of the uterus increasing in thickness but is not yet secreting its products?
the proliferative phase
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In what phase of the uterine cycle is the lining of the uterus producing a product to capture the fertilized egg?
the secretory phase
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What structure produces inhibin in females?
the corpus luteum
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What is the function of inhibin in females?
It suppresses FSH
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What phase of the uterine cycle occurs during the follicular phase of the ovarian cycle?
proliferative phase
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What phase of the uterine cycle occurs during the luteal phase of the ovarian cycle?
the secretory phase
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What causes the dormitory effect in the menstrual cycles of female roommates?
The olfactory system sends information to the hypothalamus in response to pheromones from roommates
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What are two causes of functional amenorrhea?
stress and low body weight
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