The Reproductive System Lesson 3: The Male Reproductive System 33 The Reproductive System Lesson 3: The Male Reproductive System

Lesson Objectives Upon completion of this lesson, students should be able to … Define and spell the terms to learn for this chapter. Explain the purpose and function of the male reproductive system. Identify the male external organs of reproduction and explain the function of each.

Lesson Objectives Identify and state the function of the testes, epididymis, ductus deferens, seminal vesicles, prostate gland, bulbourethral glands, and the urethra.

The Male Reproductive System The system consists of: Testes Various ducts Urethra Accessory organs Accessory glands include the: Bulbourethral Prostate Seminal vesicles Supporting structures and accessory sex organs, the scrotum, and the penis

The Male Reproductive Organs 5

External and Internal Organs Scrotum Penis Internal Testes Epididymis Ductus deferens (vas deferens) Two seminal vesicles Prostate gland Bulbourethral glands Urethra

External and Internal Organs 7

Scrotum Pouch-like structure behind the penis

Scrotum Pouch-like structure behind the penis Suspended from the perineal region Divided into two sacs by a septum Each sac contains one of the two testes along with the epididymis, a connecting tube Tissues of the scrotum have fibers of smooth muscle that contract in the absence of sufficient heat, giving the scrotum a wrinkled appearance

Scrotum This contractile action brings the testes closer to the perineum, helping them to absorb sufficient body heat to maintain the viability of the sperm

Penis Composed of erectile tissue covered with skin Size and shape of the penis vary; the average erect penis is about 15 to 20 cm in length Three longitudinal columns of erectile tissue in the penis are capable of significant enlargement when engorged with blood, such as during sexual stimulation

Penis Covered with a loose fold of skin called the foreskin or prepuce. Foreskin contains glands that secrete a lubricating fluid called smegma

Erectile State in the Penis Occurs when sexual stimulation causes large quantities of blood from dilated arteries supplying the penis to fill the cavernous spaces in the erectile tissue When the arteries constrict, the pressure on the veins in the area is reduced, allowing more blood to leave the penis than can enter it, and the penis returns to its normal size

Erectile State in the Penis The functions of the penis To serve as the male organ for intercourse or copulation The site of the orifice through which urine and semen are eliminated from the body

The Testes: Location and Structure Two testes Contained in scrotum Scrotum: thin-walled muscular pouch 15

Critical Thinking Question Can a man be potent if he has only one functioning testicle? 16

The Testes: Location and Structure 17

Function of Testes Testes Produce male hormone – Testosterone Responsible for development of the male secondary sex characteristics Necessary for the reproductive act 18

Epididymis Coiled tube lying on the posterior aspect of the testes. Between 13 and 20 feet in length Coiled into a space less than 5 cm in length, and ends at the ductus deferens Function is to serve as the: Storage site for the maturation of sperm First part of the duct system through which the sperm pass as they travel to the urethra 19

Ductus Deferens (vas deferens) Slim, muscular tube about 45 cm in length that is continuous with the epididymis Excretory duct of the testes Extends from a point adjacent to the testes and enters the abdomen at the inguinal canal A duct from the seminal vesicle joins the ductus deferens at the inguinal canal 20

Ductus Deferens (vas deferens) Between the testes and the internal inguinal ring (part of the abdomen), the ductus deferens is contained within a structure known as the spermatic cord – The spermatic cord also contains arteries, veins, lymphatic vessels, and nerves 21

Two Seminal Vesicles Connected by a narrow duct to the ductus deferens Forms the ejaculatory duct, a short tube that penetrates the base of the prostate gland and opens into the prostate portion of the urethra Produce an alkaline fluid that becomes part of the seminal fluid or semen 22

Prostate Gland Lies behind the urinary bladder Wraps around the first 2.5 cm of the urethra About 4 cm wide Composed of glandular, connective, and muscular tissue Secretes an alkaline fluid that aids in maintaining the viability of the spermatozoa 23

Bulbourethral Glands Also known as Cowper’s glands Two small, pea-sized glands Located inferior to the prostate and on either side of the urethra A 2.5-cm duct connects them with the wall of the urethra Secrete a mucous secretion into the seminal fluid before ejaculation 24

Male Urethra Approximately 20 cm long Divided into three sections: Prostatic Membranous Penile Extends from the bladder to the urethral orifice at the end of the penis Functions in the male are the expulsion of urine and semen from the body 25

Questions? 26