Male Reproductive System

The male reproductive system

It is a system that is responsible for producing, storing, transporting, and delivering sperm for fertilisation.

Main structures of the male reproductive system

• Testes

• Epididymis

• Vas deferens

• Accessory glands (seminal vesicles, prostate, bulbourethral glands)

• Penis

Structure of the Testes

• Two oval-shaped organs located inside the scrotum, outside the body

• Made up of coiled tubes (seminiferous tubules)

Function of the Testes

• Produce sperm cells needed to fertilise eggs.

• Produce the hormone testosterone, which stimulates sperm production and controls male sexual development during puberty.

Seminiferous tubules

Tiny, tightly coiled tubes located inside the testes where the body produces sperm

Structure of the Scrotum

A loose sac of skin that hangs outside the body and holds the testes.

Function of the Scrotum

Keeps the testes at a lower temperature than the body, which is essential for effective sperm production

Sperm duct system

It consists of the epididymis and the vas deferens

Structure of the Epididymis

A long, tightly coiled tube that sits on the back of each testis

Function of the Epididymis

• Stores immature and non-motile sperm until ejaculation.

• Allows them to mature and gain mobility, so that they can swim effectively.

Structure of the Vas deferens

A thick muscular tube connecting the epididymis to the urethra

Function of the Vas deferens

Transports sperm from the epididymis to the urethra during ejaculation

Another name for Vas deferens

Sperm duct

Vasectomy

A form of male contraception that involves cutting the vas deferens

Seminal Vesicles

• Pair of glands found in the male pelvis

• They produce the main ingredients of semen

• During ejaculation, the smooth muscle layer contracts, releasing the fluid.

Structure of Prostate gland

A small gland located below the bladder and surrounding part of the urethra.

Functions of the Prostate gland

• Adds a slightly alkaline fluid that protects sperm from acidic environments.

• Produces fluid that mixes with sperm to form semen.

• The fluid that mixes with sperm, also helps to nourish sperm and lubricate the urethra.

• Contains muscles which help to push semen through the urethra during ejaculation.

Structure of the Urethra

A tube that runs from the bladder through the penis, to the outside of the body.

Functions of the Urethra

• Carries urine out of the body

• Transports semen during ejaculation

Structure of the Penis

External organ made of erectile tissue, that can fill with blood

Function of the penis

• Delivers semen into the female reproductive system during sexual intercourse.

• To deliver the semen, it contains erectile tissue to make it firm enough to enter the vagina, to release the semen by the cervix, as close to the uterus as possible.

• Allows for the removal of urine from the body

Semen

The thick, whitish fluid released during ejaculation, which contains sperm, and fluids from seminal vesicles, prostate and bulbourethral glands.

Composition of Semen

• Contains sperm (about 5%)

• Contains fluids from seminal vesicles, prostate and bulbourethral glands (about 95%)

Functions of Semen

• Provides nutrients.

• Provides protection.

• Provides a medium for sperm transport.

Process of Ejaculation

1. Sperm movement: Sperm travel from the epididymis through the vas deferens.

2. Mix with Secretions: Sperm mix with fluids from accessory glands to form semen.

3. Ejection: Muscular contractions propel semen through the urethra and out of the penis.

The Key Hormones involved in the male reproductive system

Testosterone, FSH and LH.

Testosterone

Drives sperm production and development of secondary sexual characteristics.

FSH

• Follicle-Stimulating Hormone

• Stimulates spermatogenesis.

Spermatogenesis

The process of sperm cell development within the male reproductive organs, the testes.

LH

• Luteinising Hormone

• Triggers testosterone production by Leydig cells in the testes