PBL 2 Flashcards
what is the scrotum?
a sac-like organ made of skin and muscles that houses the testis. its located inferior to the penis in the pubic region.
what is the importance of the smooth muscle that makes up the scrotum?
it allows regulation of the distance between the testes and rest of the body- stops testes getting too warm to support spermatogenesis
what are the testes
the make gonads responsible for the production of sperm and testosterone
how are each testes connected to the abdomen?
by the spermatic cord and cremaster muscle
what is the function of the cremaster muscle?
to contract and relax to regulate the temperature of the testes
describe the structure of the inside of each testes?
its divided into lobules and each lobule contains seminiferous tubules lined with epithelial cells. the epithelial cells contain many stem cells that divide and help spermatogenesis.
what is the epididymis?
the sperm storage area that wraps around the superior and posterior edge of the testes. the length of it delays the release of sperm and allows them time to mature
what does the spermatic cord contain?
the ductus deferens, nerves, veins, arteries and lymphatic vessels to support the function of the testes
what is the ductus vas deferens?
a muscular tube that carries sperm superiorly from the epididymis into the abdominal cavity to the ejaculatory duct
how does sperm move through the ductus deferens?
the smooth muscle of the walls of the ductus deferens are used to move sperm via peristalsis
what are seminal vesicles?
exocrine glands that store and produce some of the liquid portion of semen
what is in the liquid produced by the seminal vesicles?
contains proteins and mucus and has an alkaline pH to help the sperm survive the acidic environment of the vagina. it also contains fructose to feed sperm cells so they can survive long enough to fertilise the oocyte
what is the ejaculatory duct?
where the ductus deferens joins the urethra. it opens during ejaculation and expels sperm and the secretions from the seminal vesicles into the urethra
where is the urethra?
from the ejaculatory duct through the prostate to the tip of the penis
what are the 3 functional areas of the urethra?
prostatic (base of bladder and through prostate)
membranous (in the perineal membrane region) and spongy (part of urethra surrounded by erectile tissue)
what are the 3 regions of different histology in the urethra?
transitional epithelium in prostatic urethra
psuedostratified epithelium from membranous urethra to glans penis
stratified squamous epithelium in glans penis
what is the prostate?
an exocrine glands that borders the inferior end of the urinary bladder.
it has smooth muscle tissue that can constrict to prevent the flow of urine or semen
what does the prostate produce?
a large portion of the fluid that makes up semen.
what are Cowpers glands?
aka bulbourethral glands
exocrine glands located inferior to the prostate.
what do cowpers glands secrete?
a thin alkaline fluid into the urethra that lubricates it and neurtralises acid from urine remaining in the urethra after urination- prepares urethra for flow of semen
what is the penis?
the male external sexual organ.
how does the penis become erect?
it contains large pockets of erectile tissue which allow it to fill with blood and become erect
what is the perineal membrane?
a membrane covering the urogenital triangle
what is the deep perineal pouch?
a gap between the perineal membrane
what is the ischia-anal fossa?
two gaps between the diaphragmatic muscles and perineal membrane, filled by fat
what is the superficial perineal pouch?
between the perineal membrane and superficial fascia and skin. it contains erectile tissue
describe the erectile tissue found within the superficial perineal pouch?
the corpus cavernosus- one on each side (contains most of blood in erection)
corpus spongiosum - lines the midline
what is the blood supply of the perineum?
the internal pudendal artery (branch of internal iliac artery) and internal pudendal vein
what is the blood supply of the gonads?
branches off the abdominal aorta- because of descent of testes
what is the venous supply of the penis?
the deep dorsal vein which drains into the prostate plexus
what supplies the somatic motor and sensory innervation of the dorsal penis and scrotum?
the pudendal nerve S2-S4
what are the parasympathetic fibres for?
S2-S4
vasodilation, stimulation of erection, stimulation of bladder control
what are the sympathetic fibres for?
smooth muscle contraction of the internal urethral sphincter and reproductive tract and glands T10-L2
what is spermatogenesis?
when spermatozoa are produced from male primordial germ cells by mitosis and meiosis
why is there no spermatogenesis before puberty?
a lack of hormonal triggers
outline spermatogenesis?
it begins when LH triggers the production of testosterone and FSH triggers the maturation of germ cells
1) spermatocytogenesis
2) spermiogenesis
3) spermatogenesis
describe spermatocytogenesis?
spermatogonia (stem cells) divide to replace themselves and produce a population of cells destined to become mature sperm
describe spermiogenesis
maturation of spermatids into spermatozoa
- golgi phase (Golgi apparatus creates enzymes that will become the acrosome)
- acrosomal cap phase
- formation of tail (a centriole elongates)
- maturation phase (excess cytoplasm is phagocytosed by Sertoli cells)
describe spermination?
Mature spermatozoa are released from the sertoli cells into the lumen of the seminiferous tubule. unnecessary cytoplasm and organelles are removed. the are now mature but lack motility
where do the mature, non-mobile spermatozoa gain their mobility?
they move into the epididymis in testicular fluid by peristalsis and here they acquire motility.
what produces testosterone?
leydig cells
where do sperm develop?
between 2 Sertoli cells and shuffle down towards the lumen
what are the steps of spermatocytogenesis?
spermatogonium is the germ cell mitosis to form primary spermatocyte meiosis to form secondary spermtocytes meiosis 2 to form spermatids spermatids mature to form spermatozoa
what are the normal constituents of semen?
citric acid free amino acids fructose enzymes phosphorylchlorine prostaglandin zinc
where does the fluid from semen come from
mostly seminal vesicles
some prostate gland
small amount from testicles and epididymis
describe the histology of the testes?
Skin Dartos layer External spermatic fascia Cremaster muscle Internal spermatic fascia parietal tunica vaginalis visceral tunica vaginalis tunica albuginea
(Some Days Eddie Can Irritate People Very Thoroughly)
what is the dartos layer in the testes?
contains muscle fibres that contract when it’s cold which results in wrinkling of the scrotal skin and brings the testes closer to the body
where does the external spermatic fascia come from?
the external oblique muscle
where does the cremaster muscle come from?
the internal oblique muscle
where does the internal spermatic fascia come from?
the transversals fascia
what is the parietal and visceral tunic vaginalis?
a peritoneal sac that partially encloses the tests
what is the tunica albuginea?
fibrous envelope that extends the length of the corpora cavernosa and corpus spongiosum penis
what is erectile dysfunction?
a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual activity
how is a penile erection triggered?
in 2 ways…
1) the reflex erection which is achieved by directly touching the penile shaft
2) the psychogenic erection- achieved by erotic or emotional stimuli
describe the physiology of an erection?
stimulation of the penile shaft leads to secrete of nitric oxide which causes increases in cGMP which decreases intracellular calcium stores; this leads to the relaxation of smooth muscles of the corpora cavernosa which causes blood flow to penis to increase and the lacuna spaces can fill with blood. this pressure pushes against the tunica albuginea causing venous drainage to decrease= erection
what may impotence be due to?
hormonal deficiency
disorders of the neural system
lack of inadequate penile blood supply
psychological problems
what are some causes of erectile dysfunction?
drugs neurogenic disorders cavernosal disorders psychological e.g. performance anxiety surgery ageing diseases e.g. diabetes lifestyle e.g. smoking prostatectomy
name 3 drugs that can be used for treating erectile dysfunction?
sildenafil
vardenafil
alprostadil
describe the mechanism of sildenafil?
it selectively inhibits PDE5 from breaking down cGMP which therefore increases nitric oxide so that the smooth muscle around the corpus cavernous relaxes and blood flow can increase
describe the mechanism of alprostadil?
it directly acts on the penile and vascular smooth muscle cells to stimulate the production of cAMP which results in smooth muscle relaxation = erection
