Puberty and Sexual Response
Objective 12
Describe the role of the endocrine system and other factors in male and female puberty. Compare and contrast the male and female sexual response.
Puberty
The endocrine system plays a key role, but by no means the only role, in triggering puberty. At the onset of puberty, a number of factors combine to cause a burst of gonadotropin releasing hormone (GnRH) from the hypothalamus. GnRH causes release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. FSH and LH, in turn, “switch on” gamete production. In males, spermatogenesis begins; in females, menstrual periods begin, the first of which is called menarche.
In both genders, puberty is also marked by the development of secondary sexual characteristics. In short, primary sexual characteristics can be visualized at birth and define biological gender.
They are gender-related but not necessarily gender-specific. For example, males are generally more muscular and have deeper voices than do females, but these things do not make a person “male.” In other words, there are some women who are more muscular and have a deeper voice than some men.
Male secondary sexual characteristics include body hair (face, chest, pubic, axillary, arms, legs), deeper voice, more prominent thyroid cartilage (Adam’s apple), more muscular, and larger stature.
Female secondary sexual characteristics include body hair (pubic, axillary, arms, legs), higher voice, larger breasts, and wider hips.
Androgens and estrogens also alter the structure of the brain. It’s no secret that men and women tend to think differently, although this wasn’t supported scientifically until the late 1990s, when a landmark study showed clearly that male and female brains are different both structurally and physiologically.
Puberty is a cataclysmic event. The brain is changing, the body is changing, and interpersonal relationships are changing. It’s true that an internal developmental clock participates in the process, but scientists have also shown that internal cues and external cues have an effect as well. Sex steroids act on the brain to alter behavior, and other neurotransmitter systems change as well.
Internal cues, external cues, and input from the internal developmental clock are all fed into an “integrator,” a sort of funnel that collects the disparate sources of information. If/when the integrator reaches a predetermined set-point, it directs the hypothalamus to ramp up GnRH synthesis. Unfortunately, we don’t know what functions as the integrator, we don’t understand the internal developmental clock, the internal cues, the external cues, or how much weight each of them carries, and we don’t know the predetermined set-point.
Remember that menarche is the term for the beginning of menstrual flow in a female. The cessation of ovulation (and, therefore, cessation of monthly menstrual cycles) is called menopause. Menarche is a relatively sudden event; it is usually