Sex Hormones and Reproductive Functions: Male and Female Sex Hormones

Sex Hormones are chemical structures that are classed as a group of steroidal hormones that are derived from cholesterol. The endocrine gland is responsible for the production of sex hormones which are then directly secreted into the bloodstream. It is essential for the growth and development of a human body and plays a major role in the sexual development of humans. Major sex hormones in females are estrogen, progesterone, and testosterone whereas in males, testosterone is the only sex hormone that is produced after the onset of puberty.

Read Also: Sexual and Asexual Reproduction

Key Terms: Sex Hormones, Reproduction, Puberty, Progesterone, Estrogen, Testes, Ovaries, Adrenal Glands, Reproductive organs, Endocrine gland

---

Sex Hormones and Their Role

[Click Here for Sample Questions]

Sex Hormones can be defined as a class of steroid hormones that regulate the growth and function of the reproductive organs. These hormones stimulate the development of secondary sexual characteristics when the person reaches puberty. Primarily, these hormones are produced in the gonads which are the ovaries in a female and in the testes in a male. These hormones are made up of fat-soluble molecules from cholesterol. The sex hormones produced in females are estrogen, progesterone, and testosterone whereas, in a male, the sex hormone produced is testosterone. However, these hormones are produced in both genders in variable amounts which greatly distinguish the secondary sexual features.

Read More: Population Interaction

---

Functions of Sex Hormones

[Click Here for Sample Questions]

Major functions of sex hormones are:

• Sexual Development – For any species, survival is dependent on reproduction. Sexual development, particularly in humans happens at a specific age for both males and females. The sex hormones which are testosterone for males and progesterone and estrogen for women play a major role in secondary sexual characteristics.
• Puberty – Puberty can be defined as a transition from childhood to adulthood. On average, girls become sexually mature between the ages of 10 and 14 whereas boys become sexually mature between the ages of 12 and 16. The first major signs seen during puberty are hair growth (both males and females) and breast changes (females). During puberty, a hormone called GnRH abbreviated as gonadotrophin-releasing hormone reaches a pea-shaped gland called the pituitary gland. This triggers two more hormones to be released into the bloodstream which are LH, abbreviated as Luteinizing Hormone, and FSH, abbreviated as Follicle Stimulating Hormone. While both males and females contain these hormones, how these hormones affect the respective bodies is different. Once these hormones are in the bloodstream, signals are given to the gonads to start the production of sex hormones which are testosterone, estrogen, and progesterone.
• Sex Hormones and Fat – Obesity-related conditions are mostly dependent on how fat is distributed in our body. After a certain age, hormones like estrogen are not produced in the gonads, but in the body fat. Once a woman surpasses her child-bearing age, most of the fat will get accumulated in the abdomen region contrary to when the body fat was mostly distributed in the lower body during child-bearing age. Therefore, women who take estrogen supplements tend not to store fat around the abdomen region because it has been observed that the lack of estrogen causes weight gain.

Also Read:

---

Male Sex Hormones

[Click Here for Sample Questions]

Two major glands responsible for the production of male sex hormones are the pituitary gland and the hypothalamus which is present at the base of the brain. The GnRH which is the gonadotropin-releasing hormone is produced in the hypothalamus which triggers the pituitary gland to release LH which is the luteinizing hormone and FSH which is the follicle-stimulating hormone in the bloodstream, which will cause the testicles to undergo some changes.

Testosterone

Testosterone is an androgen (male sex hormone) that is produced in the testicles. It is produced during puberty which causes changes like the development of penis and testicles, body hair growth, muscle growth, broad shoulders, deepening of the voice, and fat distribution. For bone health, some of the testosterone transforms into estrogen which is the female sex hormone. Although most of the testosterone is made in the testicles, a small amount is produced in the adrenal glands which are present on top of the kidneys.

Levels of Testosterone

Normal levels of testosterone in males range from 270-1070 ng/dL. Normal levels peak around the age of 20 and gradually dip as the male gets older.

Causes for Low Testosterone (Male Hypogonadism):

1. Alcohol and drug abuse
2. HIV/AIDS
3. Injury to the testes
4. Infections
5. Improper functioning of the pituitary gland

Causes for High Testosterone

1. Tumor in the adrenal glands or gonads
2. Ingesting Testosterone supplements

Read More: Reproductive System

---

Female Sex Hormones

[Click Here for Sample Questions]

In females, the onset of puberty starts around the age of ten or eleven. Prior to this age, the hormones LH and FSH are not significant in the individual’s body. When a female attains the age of ten or eleven, a hormone called GnRH abbreviated as a gonadotropin-releasing hormone produced in the hypothalamus of the brain triggers the pituitary gland to release the luteinizing hormone (LH) and the follicle-stimulating hormone (FSH). These two hormones are responsible for the sexual development of a female. Typically, the menstrual cycle starts about one to two years after the onset of puberty in females.

Estrogen

Estrogen is an important hormone that stimulates the growth and development of the egg follicles in the ovary of females. It is produced in the ovaries, fat tissues, and the adrenal gland. Not only is it important for sexual development, but it also helps to maintain cardiovascular and bone health.

Progesterone

Progesterone is another important female sex hormone that is produced mostly by the corpus luteum in the ovary. It is important for the regulation of the menstrual cycle in females. It is produced during the second half of the menstrual cycle. It prepares the body for a potential pregnancy. When pregnancy doesn’t happen, the progesterone levels plummet and cause a new menstrual cycle to begin. In case fertilization occurs, progesterone is responsible for the lining of the uterus. The role of progesterone is vital during the early stages of pregnancy and to form the placenta. The levels of progesterone increase gradually throughout the pregnancy.

Testosterone

Although abundant in the male sex, females also produce a small amount of testosterone. Testosterone plays an important role in the bone health, menstrual health and fertility of a woman. Most of the testosterone produced by the female body gets converted into estrogen.

Levels of Female Sex Hormones

The normal level of estrogen in a female during her reproductive age is around 17-200 ng/mL whereas after menopause it ranges from 7 to 40 ng/mL.

The normal progesterone level of women at the mid of her menstrual cycle is 5-20 ng/mL whereas for pregnant women during the first trimester is 11.2-90 ng/mL.

The normal level of testosterone in females ranges from 15 to 70 ng/dL.

Causes for Low Estrogen:

1. Age
2. Excessive exercise and diet
3. Drug abuse
4. Pituitary gland issues
5. Cancer

Causes for High Estrogen:

1. Body Fat
2. Certain types of medication
3. Stress
4. Certain products that contain estrogen or mimic estrogen, therefore, creating an imbalance

Causes for Low Progesterone:

1. Low Cholesterol
2. Thyroid
3. Excess prolactin hormone
4. Stress

Causes for High Progesterone:

1. Pregnancy
2. Ovarian Cysts
3. Cancer
4. Oral Contraceptives

Causes for Low Testosterone:

1. Menopause
2. Aging
3. Issues with adrenal or pituitary glands

Causes for High Testosterone:

1. Polycystic Ovarian Syndrome (PCOS)
2. Hirsutism
3. Hormonal Imbalance

Also Read:

---

Things to remember

[Click Here for Sample Questions]

1. Hormones can be defined as chemical substances that are used to maintain the regularity of our bodily functions. Sex hormones in particular are essential for the sexual development of humans and reproduction as well.
2. The main glands that produce sex hormones are the adrenal glands and the gonads (ovaries and testes).
3. The major function of sex hormones in both males and females is puberty when males and females become sexually mature.
4. The hypothalamus of the brain releases the GnRH hormone which triggers the pituitary gland to release the LH. These hormones once released into the bloodstream, the adrenal glands are signaled to start the production of sex hormones which are estrogen, progesterone, and testosterone in females and just testosterone in males.
5. Testosterone is responsible for secondary sexual characteristics in males like body hair growth, broad shoulders, deep voice, etc.
6. Estrogen and Progesterone are responsible for female sexual development like starting of the menstrual cycle, breast growth, pubic hair growth, etc.
7. Abnormal levels of hormones cause a lot of abnormalities like low muscle mass, low sperm count, etc. in men and PCOD, infertility, hirsutism, irregularities of the menstrual cycle, etc.

Check More: Micropropagation