reproductive system

Sex

Anatomical structure

“Male” organs/structures → sperm producing and sperm conducting

“Female” organs/structure → egg producing and gestational organs

Gender

How one identifies themself

What do sex and gender exist on?

A spectrum → a lot of variation between individuals

Primary sex organs (Gonads)

Testes and ovaries → produce gametes (sperm and ova) + secrete sex hormones

Testes

Lie within the scrotum (keeps testes out of pelvic cavity) → holds testes at 3 degrees Celsius less than rest of body > necessary for sperm production

Produces sperm

Surrounded by 2 tunics

Two tunics of testes?

Tunica vaginalis → outer derived from peritoneum

Tunica albuginea : forms fibrous capsule

What does each teste have?

~250 lobules each contains 1-4 seminiferous tubules

Seminiferous tubules

Have epithelium which contains spermatogenic cells (sperm forming cells) → embedded in support cells called (Sertoli cells)

Sperm pathway

From seminferous tubules → converge to form a straight tubule → rete testis → efferent ductules → epididymis (non fully motile sperm store here until eiaculation)

Interstitial endocrine cells (Leydig cells)

Located in tissue between seminiferous tubules

Produce testosterone

Blood supply to testes

Testicular arteries → arise from abdominal aorta

Testicular veins → from pampiniform venous plexus

Spermatic cord

Endoses nerve fibers, blood vessels, and lymphatics that supply testes (why testicular torsion is dangerous bc it cuts off blood supply)

Testicular cancer

Rare but most common cancer in men 15-35

Having mumps that leads to orchitis (inflammation of testis) can be risk factor + cryptorchudism is most common risk factor (non descent of testes)

90% cured by surgical removal and followed up by radiation or chemotherapy

Penis

copulatory organ (sexual inter course organ)

Consists of root and shaft that ends in glans penis + pepuce or foreskin

What is the penis made up of?

Spongy urethra and 3 cylindrical bodies of erectile tissue

Corpus spongiousum → surrounds urethra and expands to form the glans

Corpora cavernosa : paired dorsal erectile bodies

Erection

Érectile tissue fills with blood and becomes rigid and enlarged

Cause by sympathetic stimulation (vasodilation)

what do ducts do in penis/testes?

Carry sperm from testes to body exterior

Flow of ducts sperm takes?

Epididymis → ductus deferns → ejaculatory → urethra

Epididymis

Duct of it is ~ 6m in length

Microvilli absorb testicular fluid and pass nutrients to stored sperm

non motile sperm enter, pas slowly through (~20 days) become motile and can be stored for several months

Ejaculation

Sympathetic stimulation

Epididymis contracts, expelling sperm into ductus deferens

Ductus deferens

~45 cm long

Passes through inguinal canal to pelvic cavity → joins duct of seminal vesicle (ejaculatory duct)

Smooth muscle in walls propels sperm

Vasectomy occurs here

Vasectomy

Pinches tubes → cut and then corotize (burn it) → sperm can’t be passed then so semen is without sperm

Urethra

Conveys both urine and semen

3 regions

3 regions of urethra

Prostatic urethra : surrounded by prostate

Membranous urethra : in urofenial diaphragm

Spongy urethra : runs through penis → opens at external urethral orifice

Seminal glands

On posterior bladder surface

Produces viscous alkaline seminal fluid (fructose, coagulating enzyme and prostaglandins → need to provide sperm ATP to propel)

~60% of volume of semen

Duct of seminal gland joins ductus deferens to form ejaculatory duct

Prostate

Encircles urethra inferior to bladder

Smooth muscle will contract during ejaculation

Secretes milky slightly acid fluid → cleans out urethra from bacteria (contains prostate-specific antigen → very elevated levels for prostate cancer)

~30% of semen volume

Bulbo-urethral glands

Pea sized glands inferior to prostate

Produce thick clear mucus (lubricates glans penis + neutralizes traces of acidic urine in urethra)

Semen

Mixture of sperm and accessory gland secretions (like seminal fluid)

(2-5mL are ejaculated containing 20-150 million sperm/ml)

Contains fructose + alkaline fluid neutralizes acidity of urethra and vagina and enhances motility

Benign prostatic hyperplasia

Distorts urethra (reduced urine flow)

Treated with surgery but new options like drugs or radio frequency radiation

Prostate cancer

Second most common cause of cancer death in males

Treated with surgery + sometimes radiation

Erection

Artérioles are normally constricted → sexual excitement causes activation of parasympathetic neurons which release nitric oxide → causes vasodilation)

NO causes relaxation of local vascular smooth muscle → dilation

Corpora cavernosa expands + engorgement with blood and enlarges and stiffening penis

Ejaculation

Sympathetic NS → bladder sphincter muscle constricts preventing expulsion of urine + glands contract and cause expulsion of semen

Érectile dysfunction

Parasympathetic nerves of penis release too little NO (nitric oxide)

Possible causes : alcohol, drugs, hormones, blood vessels or NS problems, incompetent venous valves that fail to retain boood in penis