Reproductive system Reproductive Systems Human reproductive system Produces

Reproductive system

Reproductive Systems • Human reproductive system – Produces, stores, nourishes and transports functional gametes • Fertilization – Fusion of sperm and immature ovum • Forms zygote

Reproductive System Components • • Gonads Ducts Accessory organs and glands External genitalia

Fig 27. 1 The scrotum is a pouch of skin Inside the scrotum there are two scrotal cavities that each contain a testis Male reproductive system

• Males – Testes produce sperm – Expelled from body in semen during ejaculation • Females • Ovaries produces eggs – Travel along uterine tubes to uterus – Vagina connects uterus with exterior

• • • Sperm produced in testes Travel along epididymus Ductus deferens Ejaculatory duct Urethra Male • Seminal vesicles • Prostate gland • Bulbourethral glands – Secrete into ejaculatory ducts and urethra • Scrotum – Encloses testes • Penis – Erectile organ

Fig 27. 1

Testes • Enclosed in scrotum – 2 inches by 1 inch • Descent of testes through inguinal canals – During 7 th month of development – Prior to descent, held in place by gubernaculum testis • No descent - cryporchidism - sterile

• Diagrammatical sectional view at representative stages of the descent of the testes.

Spermatic Cord • Layers of connective tissue, fascia and muscle • Encloses ductus (vas) deferens, testicular artery, testicular vein and nerves Thermoregulation by muscles in Scrotum • Dartos muscle wrinkles skin of scrotum • Cremaster muscle pulls testes closer to body

Seminiferous tubules • Site of sperm production – Sperm move to straight tubule – On to rete testis • Efferent ducts connect rete testis to epididymus • Interstitial cells – Between seminiferous tubules – Secrete androgens

Fig 27. 7 Sperm is produced in the seminiferous tubules of the testis

Histology of the Testes • Tunica vaginalis serous membrane cover • Tunica albuginea fibrous capsule that surrounds testis

Anatomy of Sperm • Head – Acrosomal cap • Neck • Middle piece • Tail – Flagellum

Teste Histology

Epididymus receives spermatozoa from testes Head, body and tail regions of epididymus Monitors and adjusts composition of tubular fluid Recycles damaged spermatozoa Stores spermatozoa Capacitation

Vas or Ductus Deferens • Begins at epididymus • Passes through inguinal canal • Enlarges near prostate to ampulla – Junction at base of seminal vesicle and ampulla • Ejaculatory duct • Empties to urethra • Transports and stores spermatozoa

Male Urethra Urinary bladder through penis • Three regions – Prostatic urethra – Membranous urethra – Penile urethra

Accessory Glands • Activate and provide nutrients to spermatozoa • Produce buffers to neutralize acidity of female tract • Include – Seminal vesicle – Prostate gland – Bulbourethral glands Semen • • Typical ejaculation releases 2 -5 ml Sperm count typically 20 – 100 million per ml Seminal fluid is mixture of accessory gland secretions Contains enzymes

Seminal Vesicles • Paired gland • 60% semen volume • Secretion high in fructose – Produces ATP for spermatozoa – Spermatozoa become active after contact with seminal fluids

Prostate Gland • • • Secretes prostatic fluid 20 -30% semen volume Prostaglandins Alkaline buffer prostate specific antigen (PSA)

Bulbourethral Gland • Paired glands • Alkaline mucus secretion • Lubricating properties

Penis • Root, body (shaft) and glans • Prepuce (foreskin) surrounds tip • • Three masses of erectile tissue – Two corpora cavernosa – One corpus spongiosum • Surrounds urethra Erection governed by smooth muscles in arterial walls – Erectile tissues become engorged with blood

Fig 27. 9

• Frontal and cross sections showing the structures of the penis.

penis Corpora caveronsa Corpus spongiosum urethra