Human Reproductive System - Male and Female: Structure & Function

What is The Human Reproductive System?

The human reproductive system is a very complex and intricate system responsible for producing gametes, facilitating fertilisation, and developing offspring. It consists of primary and secondary sex organs and their accessory ducts or structures working together to ensure the continuation of the species. Understanding the anatomy and physiology of both the male and female reproductive systems explains how they function, and also important related issues such as fertility and sexual function.

Primary and Secondary Sex Organs

The primary sex organs, the gonads, are associated with the production of gametes and sex hormones. The male primary sex organs are the testes, and the female primary sex organs are the ovaries.

Primary Sex Organs

• Testes: Testes produce sperm and testosterone, the male sex hormone. They are located outside the body, wrapped in a membrane sac called the scrotum, which maintains them at the right temperature for the best production of sperm.

• Ovaries: The ovaries are the female gonads that produce eggs or ova and female sex hormones, the primary hormones being estrogen and progesterone. They are located within the pelvic cavity, one on either side of the uterus.

Secondary Sex Organs

The secondary sex organs are responsible for the secondary sexual features and conduct the function associated with sexual intercourse.

Male Secondary Sex Organs: These are the penis, prostate gland, and seminal vesicles. Only the penis is described here as the external urinary eliminative organ and the organ of sexual intercourse, while the other two, the prostate gland and seminal vesicles are part of the seminal fluid formation process.

Female Secondary Sex Organs: These are the uterus, vagina and external genitalia. The fallopian tube and the uterus are the sites of fertilisation and implantation of the ovum and development of the fertilised egg. It also forms the birth canal and serves as the receptacle for the penis during sexual intercourse.

The Male Reproductive System

The male reproductive system includes a series of structures and organs which function in coordination to produce and deliver sperm.

Testes

Testes are contained within the scrotum and primarily have the role of spermatogenesis and production of the hormone testosterone. They include the seminiferous tubules, where the production of sperm takes place.

Epididymis

This is a coiled tube at the back of each testis responsible for storing and maturing sperm. It also connects the sperm from the testes to the vas deferens.

Vas Deferens:

This is a muscular tube that carries mature sperm from the epididymis to the urethra. Aside from this, it also carries along with it the seminal fluid coming from the seminal vesicles.

Seminal Vesicles

The seminal vesicles are sac-like glands which produce a fructose-rich nutrient fluid, a type of food for the sperm to gain motility.

Prostate Gland

The prostate gland secretes fluids that nourish and protect the sperm. The fluids form part of the semen.

Urethra

The urethra is a tube through which the urinary bladder discharges urine, and the reproductive system discharges semen to the outside of the body via the penis.

Penis

The penis is the male external reproductive organ that conveys the sperm into the female reproductive tract during intercourse. It has erectile tissue, allowing it to engorge with blood, and therefore be erected.

The Female Reproductive System

The anatomy and physiology of the female reproductive system are structured and organised to produce eggs and provide the site of fertilisation of the egg, which supports the development of the fetus.

Ovaries

The ovaries produce eggs and hormones. During a part of the menstrual cycle, an egg is released from one of the ovaries each month.

Fallopian Tubes

The fallopian tubes take the egg from the ovary into the uterus. Fertilisation usually occurs within the fallopian tube.

Uterus

The uterus is a muscular organ in which a fertilised egg implants and grows into a fetus. Its lining is called the endometrium, and it thickens up anticipating pregnancy.

Cervix

The cervix is located at the lower end of the uterus and it opens into the vagina. This part of the uterus acts as a one-way passage because, despite allowing sperm to pass into the uterus, it does not allow menstrual blood to come out of it.

Vagina

The vagina is a muscular tube connecting the cervix to the external genitalia. It acts as a birth canal, and it is also the receptacle for the penis during sexual intercourse.

External Genitalia

The female external genitalia, or vulva, include the clitoris, labiae, and opening of the vagina. While they trigger sexual arousal, they also protect the internal organs.

MCQs on The Human Reproductive System

Q1. Statement A: Temperature in the scrotum is 2-3 degrees Celsius lower than that of the abdominal temperature.

Statement B: A lower temperature is required for active sperm production and its survival.

Option 1: Both statements are correct and statement B is the correct explanation for statement A.

Option 2: Both statements are correct and statement B is not a correct explanation for statement A.

Option 3: Both statements are incorrect

Option 4: Statement B is correct and statement A is incorrect.

Correct answer: 1) both statements are correct and statement B is the correct explanation for statement A.

Explanation:

The scrotum maintains the temperature of the testes 2- 3 degrees Celsius below the body temperature.

When the temperature of the testes falls the scrotum shrinks bringing the scrotum close to the body to attain the desired temperature.

When the temperature rises the scrotum is relaxed and the testes come down at a distance from the body.

Hence, the correct option is 1) both statements are correct and statement B is the correct explanation for statement A.

Q2. Seminal plasma in humans is rich in:

Option 1: Fructose and calcium have no enzymes.

Option 2: Glucose and certain enzymes but have no calcium.

Option 3: Fructose and certain enzymes but poor in calcium.

Option 4: Fructose, calcium and certain enzymes.

Correct answer: 4) Fructose, calcium and certain enzymes.

Explanation:

Components of Seminal Plasma:

1. Water: This acts as the fundamental solvent, facilitating sperm transportation.

2. Fructose:
Source: Seminal vesicles.
Role: Supplies energy essential for sperm motility.

3. Prostaglandins:
Source: Seminal vesicles.
Role: Induces contractions in the female reproductive tract's smooth muscles, thus promoting sperm movement.

4. Proteins and Enzymes:
Examples: Fibrinogen, and fibrinolysin.
Role: Semen coagulation and subsequent liquefaction to free sperm.

5. Alkaline Compounds:
Source: Prostate gland.
Role: Counteracts the acidic female reproductive environment.

6. Zinc, Citric Acid, and Calcium:
Source: Prostate gland.
Role: Ensures sperm chromatin stability and overall sperm health.

Hence, the correct answer is option 4) Fructose, calcium and certain enzymes.

Q3. Gamete mother cells in females are known as?

Option 1: Spermatogonia

Option 2: Oogonium

Option 3: Both 1 and 2

Option 4: None of the above

Correct answer: 2) Oogonium

Explanation:

Gamete mother cells in females are termed oogonia. These cells, located in the ovaries, are crucial for the creation of female gametes, also known as egg cells or ova. They are diploid and undergo oogenesis.

Key Notes:

1. Definition: Oogonia are precursor cells in female ovaries, responsible for producing gametes via oogenesis.
2. Location: Found in ovaries during early development, especially fetal stages in mammals.
3. Development: Oogonia multiply through mitosis during fetal growth. Some transform into primary oocytes, initiating meiosis but halting at prophase I until puberty.
4. Function: Oogonia are vital for forming ova, which are later released during ovulation.

Hence, the correct answer is option 2) Oogonium.

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