Male Reproductive Physiology Flashcards
puberty describes
the anatomical and physiological changes in a boy’s body that are controlled by hormones and lead to his sexual maturation
male puberty typically begins at at
age 10 or 11; ends between age 15 and 17
the adrenal glands produce and release
low levels of testosterone before puberty begins
adrenal glands creates feedback inhibition
which prevents release of hypothalamic GnRH
hypothalamus plays an important role in
puberty
with the onset of puberty,
inhibition stops so hypothalamus can release GnRH
GnRH triggers antertior lobe of pituitary gland to produce and release
two gonadotropins
follicle stimulating hormone (FSH)
initiates sperm production
interstitial cell stimulating hormone (ICSH) stimulates the
interstitial cells of Leydig to synthesize and release testosterone
testosterone stimulates
spermatogenesis
testosterone triggers development
of secondary sex characteristics
testosterone stimulates growth of
growth of testes and scrotum and penis
testosterone cause production of
pubic hair, axillary hair, and facial hair
testosterone produces spontaneous
erections to occur and nocturnal emissions produce “wet dreams”
testosterone causes vocal cords
become longer and thicker and voice to become deeper
testosterone causes sebaceous glands to
produce more sebum which is the principle cause of acne
testosterone stimulates
male sex drive
secretion of gonadotropins is controlled by
a hypothalamic “gonadostat” that monitors testosterone levels in the blood
low levels of testosterone cause
hypothalamus to release GnRH
release of GnRH causes
pituitary gland to release ICSH, which triggers testes to produce and release more testosterone
rising levels of testosterone
inhibit release of GnRH
low levels of GnRH causes
testes to reduce synthesis and release of testosterone
the testes also produce and release the hormone
inhibin, which will inhibit the anterior lobe of the pituitary gland from releasing FSH
spermatogenesis
the process by which the testes produce haploid sperm
diploid spermatogonia line the ___________________ and divide by _________________
line the inner walls of the seminiferous tubules
divide by mitosis
resulting cells of spermatogonia mitosis
remain as spermatogonia or become primary spermatocytes
during the reduction division of meiosis, each primary spermatocyte
enlarges and divides to produce a pair of haploid secondary spermatocytes
During the equatorial division of meiosis, each secondary spermatocyte
divides to produce a pair of haploid spermatids
-4 haploid spermatids will be produced from each primary spermatocyte
spermiogenesis
a maturation process that converts spermatids into spermatozoa
spermatozoa remain attached to
Sertoli cells until they mature (break free and enter seminiferous tubule)
spermatozoa mature at a rate of
more than several hundred million per day
each functional sperm has
a head, midpeice, and a tail
head contains
nucleus and acrosome
acrosome contains
enzymes that help sperm penetrate an oocyte
midpiece contains
mitochondria that provide ATP from locomotion
tail
propels sperm through female reproductive tract
spermatogenesis takes an average of
74 days and starts when a male undergoes puberty and continues until he reaches an age when testosterone level become ineffective
the human sexual response can be divided into
4 or 5 arbitrary phases
sexual arousal is controlled by
the limbic system in the cerebrum, which is linked to centers throughout the brain where various stimuli can “turn on” the sex center to initiate the male sex drive
main event during male sexual arousal is
erection of the penis
erection of penis is controlled by
parasympathetic division of ANS
during erection, signals from spinal cord release
nitric oxide into the blood, causes smooth muscle in walls of penile arteries to relax and dilate
during erection, increased blood flow
fills corpora cavernosa penis with blood and penis becomes tumescent, increases in size, hardness, sensitivity
during arousal muscle tension
increases throughout body
during arousal dartos and cremaster muscles
contract and pull testes closer to body
during sexual arousal external urethral orifice
dilates
stimulation of an erect penis leads to the
plateau phase
during plateau skin
sex flush appears as skin becomes redder because of increased blood flow
during plateau testes are
drawn closer to body and may increase in size by up to 50%
during plateau parasympathetic division stimulates
bulbourethral glands to release fluids to lubricated glans penis in anticipation of sexual intercouse
during plateau phase, emission occurs when
sperm move through ejaculatory ducts into urethra
during emission seminal vesicles and prostate gland
secrete fluids into urethra to form semen
during emission urethral sphincters
contract to prevent bladder from releasing urine
continued stimulation of an erect penis may produce an
orgasm
orgasm
complete release of muscle tension usually accompanied by ejaculation
ejaculation is triggered by
the presence of semen in urethra
during ejaculation muscles in walls of male ducts
contract in response to signals from sympathetic division of ANS and propel semen through urethra
during ejaculation rhythmic contractions of skeletal muscles at
base of penis cause expulsion of semen out of urethra in a pulsating manner
ejaculation releases
several hundred million sperm
orgasm does NOT require
ejaculation, but most orgasms include an ejaculation
resolution
immediately follows an orgasm
refractory period occurs when
penis remains semi-erect, but cannot return to full erection
refractory period becomes
longer as male grows older
during resolution blood
leaves corpora cavernosa and penis returns to its flaccid state
testicular cancer
the most common cancer in males between ages of 15 and 34
males with a history of cryptorchidism
tend to be most susceptible for testicular cancer
most testicular cancers
are due to abnormal sperm producing cells
an early sign of testicular cancer
may be a lump in testis accompanied by discomfort or pain
a manual examination for testicular cancer
can be done by palpating testes to detect lumps
early stage of TC
may be asymptomatic
treatment for TC
involves orchiectomy followed by chemotherapy
inguinal hernia
can occur when a loop of the intestine descends into scrotum before inguinal canal closes
prostatitis
an inflammation of prostate gland caused by bacterial infection
acute prostatitis
tends to be common among sexually active men
symptoms and treatments of acute prostatitis
- prostate gland becomes swollen and tender
- antibiotics and increased fluid intake
benign prostatic hyperplasia
a non-cancerous, non-inflammatory enlargement of prostate gland that occurs in one of every three males over age of 60
BPH is probably due to
changing hormone levels
BPH may lead to
compression of urethra and obstruction of urine floq
symptoms of BPH
include painful or difficult urination, bed-wetting, and incomplete emptying
transurethral resection of the prostate (TURP)
surgically removes pieces of prostate gland
treatment for BPH
drugs, microwaves, or radio-frequency incineration
prostate cancer
the second leading cause of cancer death among males over 50
elevated blood levels
of acid phosphatase or phosphate specific antigen indicate a tumor has spread from prostate gland
tumors tend to
form near preiphery of prostate gland and metastasize
annual physical
with a digital rectal exam and/or blood test for PSA can detect prostate cancer in its early stages
treatment for prostate cancer
may involve prostatectomy followed by chemotherapy or radiation therapy
erectile dysfunction
the inability to attain and maintain an erection long enough to engage in satisfactory sexual intercourse
ED results from
insufficient release of nitric oxide
ED may be caused by
aging, cardiovascular disease, neruological disorders, medications, or psychological fctors
drugs for ED
viagra, cialis, and levita can supplement existing levels of ntric oxide within one hour
