Reproductive system in mammals - SS2 Biology Lesson Note

STRUCTURES AND FUNCTION OF THE MALE REPRODUCTIVE SYSTEM

The male reproductive system is responsible for producing and delivering sperm, the male gametes, to fertilize female eggs. It consists of several organs and structures that work together to facilitate reproduction. Here are the main structures and their functions in the male reproductive system:

 

1.       Testes:

·         Structure: The testes, also known as testicles, are paired oval-shaped glands located in the scrotum, a sac-like structure outside the body cavity. Each testis is surrounded by a tough fibrous covering called the tunica albuginea and contains many coiled tubules called seminiferous tubules.

·         Function: The testes are the primary male reproductive organs responsible for producing sperm and the male sex hormone testosterone.

2.       Scrotum:

·         Structure: The scrotum is a pouch of skin and connective tissue that holds and protects the testes. It is located outside the body cavity, which helps regulate the temperature of the testes, as sperm production is optimal at a temperature slightly lower than the body's core temperature.

3.       Epididymis:

·         Structure: The epididymis is a coiled tube located on the back of each testis. It is divided into three sections: the head, body, and tail.

·         Function: The epididymis serves as a storage and maturation site for sperm. Sperm produced in the seminiferous tubules of the testes move into the epididymis, where they gain motility and the ability to fertilize eggs.

4.       Vas Deferens:

·         Structure: The vas deferens is a muscular tube that extends from the tail of the epididymis and travels through the spermatic cord into the abdominal cavity. There, it joins with the duct of the seminal vesicle to form the ejaculatory duct.

·         Function: The vas deferens is responsible for transporting mature sperm from the epididymis to the ejaculatory duct, where they mix with seminal fluid before ejaculation.

5.       Seminal Vesicles:

·         Structure: The seminal vesicles are two sac-like structures located near the base of the bladder. They are glands that produce a thick, alkaline fluid that makes up a significant portion of semen.

·         Function: The seminal vesicles secrete a fluid rich in fructose, prostaglandins, and other substances that provide energy for sperm and help with their motility and viability.

6.       Prostate Gland:

·         Structure: The prostate gland is a walnut-sized gland located below the bladder and surrounding the urethra, the tube through which both urine and semen pass.

·         Function: The prostate gland secretes a milky, alkaline fluid that constitutes another significant portion of semen. This fluid helps neutralize the acidity of the male urethra and the female reproductive tract, enhancing the survival of sperm.

7.       Bulbourethral Glands (Cowper's Glands):

·         Structure: The bulbourethral glands are small glands located below the prostate gland and near the base of the penis.

·         Function: These glands produce a clear, lubricating fluid that is released into the urethra before ejaculation. This fluid helps neutralize any remaining acidity in the urethra and provides lubrication for sperm passage during ejaculation.

8.       Urethra:

·         Structure: The urethra is a tube that runs through the penis and carries both urine and semen out of the body.

·         Function: During ejaculation, the urethra serves as the conduit for sperm and seminal fluid to exit the body through the penis.

During sexual intercourse, the male reproductive system works together to produce, store, and deliver sperm into the female reproductive tract, facilitating the fertilization of eggs and reproduction.

(freepik.com)

 

STRUCTURES AND FUNCTION OF THE FEMALE REPRODUCTIVE SYSTEM

The female reproductive system in humans consists of several structures that work together to produce and nurture offspring. Here are the key structures and their functions:

1.       Ovaries: The ovaries are the primary reproductive organs in females. They produce and release eggs (ova) through a process called ovulation. The ovaries also secrete hormones such as estrogen and progesterone, which regulate the menstrual cycle and support pregnancy.

2.       Fallopian Tubes: Also known as uterine tubes or oviducts, the fallopian tubes are slender, tube-like structures that connect the ovaries to the uterus. They serve as the site of fertilization, where sperm and egg meet. The fertilized egg then travels through the fallopian tube toward the uterus for implantation.

3.       Uterus: The uterus, or womb, is a pear-shaped organ where a fertilized egg implants and develops into a fetus during pregnancy. The inner lining of the uterus, called the endometrium, thickens each month in preparation for potential pregnancy. If fertilization does not occur, the endometrium sheds during menstruation.

4.       Cervix: The cervix is the lower part of the uterus that connects to the vagina. It produces mucus that changes in consistency throughout the menstrual cycle, affecting sperm transport and acting as a barrier to prevent infection.

5.       Vagina: The vagina is a muscular canal that connects the cervix to the external genitalia. It serves as the birth canal during childbirth and receives the penis during sexual intercourse. The vagina also plays a role in menstruation, allowing the flow of menstrual blood to exit the body.

6.       External Genitalia: The external genitalia, also known as the vulva, include the labia majora, labia minora, clitoris, and vaginal opening. The labia protect the entrance to the vagina, while the clitoris is highly sensitive and involved in sexual arousal.

7.       Mammary Glands: Although not directly part of the reproductive system, the mammary glands in the breasts play a crucial role in nurturing offspring. During pregnancy, they undergo hormonal changes and prepare for milk production. After childbirth, they produce and release breast milk to feed the newborn.

The female reproductive system undergoes cyclical changes during the menstrual cycle, preparing for potential pregnancy each month. Hormones from the brain (hypothalamus and pituitary gland) regulate the release of hormones (estrogen and progesterone) from the ovaries, which influence ovulation, menstruation, and pregnancy.

(freepik.com)