chapt 27 male reproductive system Flashcards
sexual reproduction is __, meaning offspring receives genes form two parents
biparental
male and female gametes (sex cells) combine their genes to form a
zygote (fertilized egg)
parent with a Y chromosome is a
male
males have a __ for introducing their gametes into the female reproductive tract
copulatory organ (penis)
produces eggs, receives sperm, provides for gametes’ union, harbors fetus, and nourishes offspring
female
primary sex organs (gonads) produces __
gametes (testes or ovaries)
organs other than gonads that are necessary for reproduction
secondary sex organs
secondary sex organs of male
system of ducts, glands;penis delivers sperm cells
secondary sex organs of female
uterine tubes, uterus, and vagina receive sperm and harbor developing fetus
secondary sex characteristics (both)
develop at puberty and both sexes get pubic and axillary hair, scent glands, and pitch of voice
facial hair, hair on torso and limbs, muscular physique
male secondary sex characteristics
distribution of body fat, breast enlargement, hairless appearance of skin
female secondary sex characteristics
our cells contain 23 pairs of chromosomes:
22 pairs of autosomes and 1 pair of sex chromosomes (XY males; XX females)
males produce half Y carrying sperm and
half X carrying sperm
all eggs carry the
X chromosome
X carrying sperm fertilizes the egg:
female bby
Y carrying sperm fertilizes the egg:
male bby
develop high in the abdominal cavity and then migrate into the pelvic cavity (ovaries) or scrotum (testes)
gonads
embryonic connective tissue cord extending from gonad to pelvic floor cavity
gubernaculum
passes between the internal and external oblique muscles into the scrotal swelling
gubernaculum
fold of peritoneum that extends into the scrotum
vaginal process
pathway of low resistance through the groin created by gubernaculum and vaginal process
inguinal canal
descent of the testes begins as early as
6 weeks
accompanied by elongating testicular arteries and veins, lymphatic vessels, nerves, spermatic ducts, and extension of internal abdominal oblique muscle
testes
cryptorchidism is
undescended testes
external genitalia of the male-
scrotum and penis
diamond shaped area between the thighs
perineum
pouch of skin, muscle, and fibrous connective tissue containing the testes
scrotum
which testicle descends lower
left
skin has sebaceous glands, sparse hair, rich sensory innervation, dark pigmentation
scrotum
divides scrotum into right and left compartments
internal median septum
medial seam on scrotum surface that marks location of median septum
perineal raphe
extends anteriorly along ventral side of penis and posteriorly to anus
perineal raphe
bundle of fibrous connective tissue containing the ductus deferens, blood and lymphatic vessels, and testicular nerve
spermatic cord
inferior entrance to inguinal canal
external inguinal ring
superior exit to pelvic cavity
internal inguinal ring
human __ reside in the scrotum because of its cooler environment
testes
scrotum has 3 mechanisms to regulate the temperature of the testes:
cremaster, dartos fascia, pampiniform plexus
strips of the internal abdominal oblique muscle that enmesh the spermatic cord
cremaster
contracts and draws testes upward toward body
cold temps- cremaster
relaxes suspending testes further from body
warm temps- cremaster
subcutaneous layer containing the dartos muscle
dartos fascia
smooth muscle contracts when cold, wrinking the scrotum, holding testes against warm body
dartos fascia
reduces surface area of the scrotum and heat loss
dartos fascia
extensive network of veins from the testes that surrounds the testicular artery and spermatic cord
pampiniform plexus
without the pampiniform plexus, warm arterial blood would heat the testis and inhibit sperm production
countercurrent heat exchanger
combined endocrine and exocrine glands that produce sex hormones and sperm
testes (testicles)
teste shape is
oval and slightly flattened
covered anteriorly and laterally by tunica vaginalis
testes
white fibrous capsule on testes
tunica albuginea
divides testes into 250 to 300 wedge-shaped lobules
connective tissue septa
ducts where sperm are produced
seminiferous tubules
each tubule lined with a thick germinal epithelium of germ cells and nurse cells
seminiferous tubules
germ cells depend on what for nutrients, waste removal, growth factors
nurse cells
produces testosterone
interstitial endocrine cells
formed by tight junctions between nurse cells
blood-testis barrier
separates sperm from immune system, prevents antibodies from getting to sperm cells
blood testis barrier (BTB)
network that collects sperm from seminiferous tubules
rete testis
supplies each testis
testicular artery
low BP of testicular artery results in poor oxygen supply to the
testes
sperm develops __ to cope with poor oxygen supply and to help them survive hypoxic enviroment
large mitochondria
what leaves the testes through pampiniform plexus of veins which converge to form the testicular veins
blood
right testicular vein drains to
inferior vena cava
left testicular vein drains to
left renal veins
carries sensory fibers concerned with pain and sympathetic fibers regulating blood flow
testicular nerves
12 small ciliated ducts collecting sperm from rete testes and transporting it to epididymis
efferent ductules
site of sperm maturation and storage, sperm mature as they travel through duct
duct of the epididymis
passes through prostate to empty into urethra
ejaculatory duct
serves to deposit semen in the vagina
penis
leads to development of less sensitive epidermis on glans
circumcision
waxy secretion produced by the sebaceous glands
smegma
3 cylindrical bodies of erectile tissue fill with blood during sexual arousal and account for erection
single corpus spongiosum, two corpora cavernosa
diverge like arms of Y, each arm is called a ‘crus’
-covered with ischiocavernosus muscle
two corpora cavernosa
passing up from scrotum through inguinal canal to posterior surface of bladder
ductus (vas) deferens
pathway taken by sperm cell from its formation to its ejaculation
efferent ductules, duct of epididymis(head, body, tail), ductus (vas) deferens, ejaculatory duct
3 sets of accessory glands in male reproductive system:
seminal vesicles, prostate, bulbourethral glands
glands posterior to bladder, empties into ejaculatory duct, forms 60% of semen
seminal vesicles
surrounds urethra and ejaculatory duct inferior to the bladder, 30 to 50 compound tubuloacinar glands
prostate
empties through about 20 pores in the prostatic urethra, milky secretions forms 30% of semen
prostate
near bulb of penis, produces clear slippery fluid (pre-ejaculate)
bulbourethral glands
protects the sperm by neutralizing the acidity of residual urine in the urethra
bulbourethral glands
noncancerous enlargement of the prostate
benign prostatic hyperplasia
testes are __ until puberty
dormant
testes secrete __ in first trimester of fetal development
testosterone
as hypothalamus matures, it produces __ releasing hormone
gonadotropin (GnRH)
gonadotropin (GnRH) stimulates
anterior pituitary cells
stimulates interstitial endocrine cells to produce testosterone
luteinizing hormon
stimulates generalized body growth
testosterone
body cell doubles its DNA and then divides to produce two genetically identical daughter cells
mitosis
4 stages of mitosis
prophase, metaphase, anaphase, telophase
produces 4 gametes, each with only half the DNA of the diploid body cells
meiosis
sometimes called reduction division
meiosis
meiosis:
prophase, metaphase, telophase
before meiosis begins,
DNA is doubled
each pair of homologous chromosomes lines up side by side and forms a tetrad
prophase 1
creates new combination of genes
crossing-over in prophase 1
after __ each cells has 23 chromosomes, but each chromosomes is double stranded
meiosis 1
each of double stranded chromosomes divide into two chromatids, and these separate
meiosis 11
at the end, each cell contains 23 single stranded chromosomes
meiosis 11
meiosis 11 is much like
mitosis
random lining up of homologous pairs of each tetrad on either side of the cell’s midline, forming a double line of chromosomes
metaphase 1
homologous pairs of chromosomes are pulled to opposite ends of the cell, each chromosome still with 2 sister chromatids
anaphase 1
nuclear division finishes and nuclear envelopes re-form, cytoplasm divides, cytokinesis to produce 2 new cells
telophase 1
breaking of nuclear envelope, chromosomes collecting together, no crossing over
prophase 2
spindle fibers extending from centrioles to centromeres, single line along midline
metaphase 2
sister chromatids pulled apart, single stranded chromosomes separated
anaphase 2
reformation of nuclear membrane, formation of cleavage furrow, mature into sperm and oocytes
telophase 2
somatic cell division, produces 2 daughter cellsidentical to parent cells, diploid daughter cells, no crossing over
mitosis
includes crossing over, haploid daughter cells, produces 4 daughter cells different from parent cell, sex cell division
meiosis
lies ALONG PERIPHERY OF SEMINIFEROUS tubules and divide my mitosis
spermatogonia
one daughter cells remains in tubule wall as stem cell
type A spermatogonium
other daughter cell migrates away from wall and is on its way to producing sperm
type B spermatogonium
enlarges and becomes a primary spermatocyte
type B
primary spermatocyte undergoes __ which gives rise to two equal size
meiosis
each secondary spermatocyte undergoes __ dividing into two spermatids- a total of 4 each
meiosis 2
four spermatids undergo transformation in which they differentiate into a spermatozoa
spermiogenesis
when a primary spermatocyte undegoes __, it becomes genetically different and needs to be protected from the immune system
meiosis
the primary spermatocyte moves toward the lumen and a new tight junction between __ forms behind it, protect it from the bodys immune system
nurse cells
spermatozoon has two parts:
head and tail
head is pear shaped, nucleus contains haploid set of chromosomes
sperm cell
structure contains nucleus, acrosome, and basal body of tail flagellum
sperm cell
enzyme cap over the apical half of the nucleus that contains enzymes that penetrate the egg
acrosome of sperm cell
indentation in the basal end of the nucleus where flagellum attaches
basal body of sperm cell
contains mitochondria around axoneme of the flagella, produces ATP for flagellar movement
middle piece of tail on sperm cell
axoneme surrounded by sheath of supporting fibers
principal piece of tail on sperm cell (most of tail)
very narrow tip of flagella
endpiece of tail on sperm cell
composition of semen
60% seminal vesicle fluid, 30% prostatic fluid, and 10% sperm and spermatic duct secretions
normal sperm count
50 to 120 million
sperm count for infertility
20 to 25 million
prostate produces a thin, milky white fluid containing calcium, citrate, and phosphate ions
semen
stickiness of semen promotes
fertilization
two requirements for sperm motility
elevated pH and an energy source
prostatic fluid buffers vaginal acidity from pH of
3.5 to 7.5
seminal vesicles provide __ to the mitochondria of sperm for ATP production
fructose
active sperm proceeds up
vagina and uterus
may thin the mucus of the cervical canal and stimulate waves of contractions in uterus and uterine tubes to spread the semen
prostaglandins
environmental agents that interfere with hormones
endocrine disrupting chemical
enters root of the penis and divided in two branches
dorsal artery and deep artery
travels under skin on dorsal surface, supplies blood to fascia and corpus spongiosum
dorsal artery
when penis is flaccid, most blood comes from
dorsal artery
travels through the core of the corpus cavernosa
deep artery
dilation of deep artery fills cavernous spaces causing an
erection
deep dorsal vein drains blood
from penis
richly innervated by sensory and motor nerve fibers, the glans and foreskin have an abundance of tactile, pressure, and temperature receptors
penis
dorsal nerves of penis and internal pudendal nerves lead to sacral
spinal cord
carry impulses from spinal integrating center to penis
autonomic and somatic motor fibers
induce an erection in response to direct stimulation of the penis
parasympathetics
characterized by vasocongestion (swelling of genitals with blood), myotonia (muscle tension), and increases in heart rate, blood pressure, and pulmonary ventilation
excitement [phase
primarily due to parasympathetic triggering of nitric oxide (NO) secretion
erection
variables such as respiratory rate, heart rate, and blood pressure stay increased
plateau phase
ejaculation occurs in two stages
emission and expulsion
sympathetic nervous system stimulates peristalsis which propels sperm through ducts as glandular secretions are added
emission
semen in urethra activates somatic and sympathetic reflexes that stimulate muscular contractions that lead to
expulsion
constricts internal urethra sphincter so urine cannot enter urethra and semen cannot enter bladder
sympathetic reflex
body variables return to preexcitement state
resolution phase
constricts internal pudendal artery and reduce blood flow to penis
sympathetic signals
sexual stimulation triggers __ secretion, which activates cGMP, then increases blood flow into erectile tissue
nitric oxide
caused by human papillomavirus
genital warts
