7.3 - Secondary Sexual Characters

In the process of adolescence, various physical and hormonal changes occur in the human body. One of the key aspects of these changes is the development of secondary sexual characters, which are physical traits that distinguish males from females but are not directly involved in reproduction. These traits appear during puberty and play a crucial role in the maturation of an individual.

Secondary sexual characters are primarily influenced by sex hormones, such as testosterone in males and estrogen in females. These hormones trigger changes in the body that help in distinguishing the two sexes.

Secondary Sexual Characteristics in Males

In males, secondary sexual characteristics are primarily driven by the hormone testosterone, which is produced by the testes. Some key changes that occur in males during puberty are:

• Growth of facial and body hair: Males develop facial hair such as a beard and mustache. Body hair also increases, particularly under the arms and around the genital area.
• Deepening of voice: The larynx (voice box) grows larger, and the vocal cords thicken, causing the voice to become deeper.
• Increased muscle mass: Testosterone leads to the development of greater muscle mass and strength in males.
• Broadening of shoulders: The chest and shoulders become wider, resulting in a more V-shaped body.
• Enlargement of the Adam's apple: The Adam's apple becomes more prominent due to the growth of the larynx.

Secondary Sexual Characteristics in Females

In females, secondary sexual characteristics are mainly influenced by the hormone estrogen, which is produced by the ovaries. The key changes in females during puberty include:

• Development of breasts: The breasts start to enlarge, and the mammary glands develop to prepare for breastfeeding in the future.
• Widening of hips: The pelvic region broadens, and the body develops a more rounded shape.
• Growth of body hair: Females develop hair under the arms and in the pubic region, though it is usually finer and less abundant than in males.
• Menstruation: The onset of menstruation, or the menstrual cycle, is an important sign of sexual maturity in females.

Changes During Puberty

Puberty marks the transition from childhood to adulthood. It is during puberty that the primary and secondary sexual characteristics develop. The major events during puberty include:

• Onset of menstruation in females: Menarche, the first menstrual period, is a significant milestone in female puberty.
• Voice changes in males: The voice deepens due to changes in the larynx.
• Growth spurts: Adolescents experience rapid growth in height during puberty, usually starting earlier in females than in males.
• Development of sexual organs: While primary sexual characteristics include the development of the reproductive organs (like the testes in males and ovaries in females), secondary sexual characteristics enhance the sexual differentiation of the body.

Role of Hormones in Sexual Development

The development of secondary sexual characteristics is controlled by sex hormones, which are secreted by the gonads (testes in males and ovaries in females). The pituitary gland in the brain also plays an important role by stimulating the gonads to release these hormones. The primary hormones involved are:

• Testosterone: The primary male sex hormone responsible for the development of male secondary sexual characteristics.
• Estrogen: The primary female sex hormone responsible for the development of female secondary sexual characteristics.
• Progesterone: Also involved in females, especially in regulating the menstrual cycle and pregnancy.

The onset and development of these secondary sexual traits vary from individual to individual. Genetics, nutrition, and environmental factors play significant roles in determining the exact timing and progression of puberty.