Male Reproductive System Lecture Notes

Comprehensive vocabulary flashcards covering the anatomy, physiology, and regulation of the male reproductive system based on week 1 lecture notes.

Gametogenesis

The formation of germ cells.

Spermatozoon

The male gamete, which is usually much smaller and highly motile when mature.

Ovum

The female gamete, typically a large non-motile cell.

Fertilisation

The fusion of two gametes to form a zygote.

Parturition

The expulsion of the offspring once it is capable of surviving in the external environment.

Gonads

The organs responsible for gametogenesis, known as testes in males and ovaries in females.

Vas Deferens

A duct approximately $35\,cm$ long consisting of three smooth muscle layers that connect the epididymis to the urethra.

Ampulla

A small swelling of the vas deferens where it fuses with the duct from the seminal vesicle.

Seminal Vesicles

Glands approximately $5\,cm$ long on the posterior bladder that secrete seminal fluid into the ejaculatory duct.

Ejaculatory Duct

A short duct, around $2\,cm$ long, formed by the fusion of the vas deferens and the duct from the seminal vesicles.

Prostate Gland

A single dome-shaped gland made of glandular epithelium and smooth muscle that secretes prostatic fluid during ejaculation.

Bulbourethral (Cowper’s) Glands

A pair of small exocrine glands that secrete an alkaline mucus to neutralize acidity and act as a lubricant.

Epididymis

A C-shaped organ typically $3.5\,cm$ long that connects the testes to the vas deferens and is a site for extra-testicular maturation.

Urethra

A duct approximately $20\,cm$ long divided into three parts: prostatic, membranous, and penile.

Seminiferous Tubules

Double-ended tubules in the testes responsible for spermatogenesis, typically $200$ to $350$ microns in diameter.

Leydig (Interstitial) Cells

Cells located in the spaces between seminiferous tubules that are responsible for the production of testosterone.

Spermatogenesis

The process by which primordial germ cells are transformed into spermatozoa in the seminiferous tubules.

Cryptorchidism

The failure of the testes to descend from the pelvic cavity into the scrotum.

Sertoli Cells

Large cells attached to the peripheral edge of the seminiferous tubule that provide support, nourishment, and regulation for developing sperm.

Spermiogenesis

The final stage of spermatogenesis where spermatids metamorphose into mature spermatozoa through nuclear reorganization, acrosome formation, and tail assembly.

Acrosome

A structure formed from the Golgi apparatus that covers the anterior and lateral surfaces of the nucleus and is required for effective fertilisation.

Blood-Testes Barrier

Specialised tight junctions between adjacent Sertoli cells that prevent the movement of blood-borne substances into the seminiferous tubule lumen.

GnRH (Gonadotropin-releasing hormone)

A hormone from the hypothalamus that stimulates the anterior pituitary to secrete FSH and LH.

Follicle Stimulating Hormone (FSH)

A gonadotropin that acts on Sertoli cells to initiate spermatogenesis and stimulate the secretion of inhibin and ABP.

Luteinising Hormone (LH)

A gonadotropin that binds to Leydig cells to stimulate their development and the secretion of testosterone.

Inhibin

A hormone released by Sertoli cells that exerts negative feedback on the anterior pituitary to inhibit FSH secretion.

Androgen Binding Protein (ABP)

A protein secreted by Sertoli cells that binds testosterone to enhance its local concentration and stimulatory effect on spermatogenesis.

Nitric Oxide (NO)

An intercellular messenger released during sexual arousal that stimulates guanylate cyclase to produce cGMP, leading to smooth muscle relaxation and erection.

cGMP (cyclic guanosine monophosphate)

A messenger molecule that activates an intracellular cascade causing the relaxation of smooth muscle cells in penile erectile tissue.

PDE5 (phosphodiesterase type-5)

An enzyme that breaks down cGMP to inhibit smooth muscle relaxation, enabling the penis to become flaccid.

Emission

The transfer of spermatozoa and accessory gland secretions into the urethra, mediated by sympathetic activity.

Ejaculation

The rapid expulsion of semen from the urethra accompanied by rhythmic contractions of skeletal muscles at the base of the penis.

Semenogelin

A fibrinogen-like protein in seminal fluid responsible for coagulating semen into a gel-like mass after ejaculation.

PSA (Prostate Specific Antigen)

A proteolytic enzyme in prostatic fluid that breaks down the semenogelin clot to release spermatozoa.