Test

What is the Tanner staging system?

A classification system that tracks the order of development of secondary sexual characteristics during puberty.

What are the five stages of Tanner staging for male external genitalia?

The five stages are: Stage 1 (Prepubertal) - testes less than 2.5cm; Stage 2 - Scrotum and testes enlarge with reddening of scrotal skin; Stage 3 - Continued growth of penis and testes; Stage 4 - Development of the glans, continued growth, and scrotal skin darkening; Stage 5 - Adult size and shape.

At what ages do males typically reach Tanner stages 1 to 5?

Typically, males progress from Tanner stage 1 to stage 5 between 11.5 years and 15 years for adult penis and testicular size, and reach adult pubic hair by their early 20s.

What is the Accelerator Hypothesis in relation to puberty?

The Accelerator Hypothesis suggests that puberty begins due to an increase in permissive signals that activate the hypothalamic stimulatory centers, leading to the induction of the pulsatile GnRH generator.

How does the hypothalamus influence the onset of puberty?

The hypothalamus releases Gonadotropin Releasing Hormone (GnRH) in a pulsatile manner, stimulating the anterior pituitary gland to release Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH).

What is the critical weight for the activation of the hypothalamo-pituitary-gonadal axis in females?

A critical weight of 47kg must be attained before the activation of the hypothalamo-pituitary-gonadal axis, which is essential for the onset of menarche.

How has the age at menarche changed in Western Europe and the USA over the past century?

Although the age at menarche has reduced over the past 100 years, the body weight at menarche has remained constant.

What hormones are involved in the Hypothalamic-Pituitary-Gonadal Axis (HPG)?

The HPG axis involves the release of Gonadotropin Releasing Hormone (GnRH), Follicle Stimulating Hormone (FSH), and Luteinizing Hormone (LH), which regulate the synthesis and release of sex steroid hormones.

What effects do FSH and LH have on the gonads?

FSH and LH stimulate the gonads to synthesize and release sex steroid hormones (estrogen/progesterone in females and testosterone in males) and support gametogenesis.

What is the role of sex steroid hormones in puberty?

Sex steroid hormones exert various effects on the reproductive system and provide negative feedback to the hypothalamus and pituitary gland to maintain stable circulating levels.

When do growth spurts typically begin for boys and girls?

Growth spurts typically begin at 10.5 years in girls and 12.5 years in boys.

At what ages do boys and girls typically reach their full adult height?

Girls typically reach their full adult height by 17 years, while boys reach their full adult height by 21 years.

What is the hormonal basis for growth spurts during puberty?

Growth spurts are driven by a complex interaction between gonadal sex steroids, growth hormone (GH), and insulin-like growth factor 1 (IGF-1).

How does growth hormone (GH) influence growth during puberty?

Levels of GH rise during puberty due to increased sex steroids, which positively affect the pulsatile release of GH from the anterior pituitary gland, leading to increased somatic growth.

What is the role of insulin-like growth factor 1 (IGF-1) in puberty?

IGF-1, stimulated by GH, promotes somatic growth through its metabolic actions, including increasing trabecular bone growth.

What is the significance of the pulsatile release of GnRH?

The pulsatile release of GnRH is crucial for stimulating the release of FSH and LH, which are essential for the onset of puberty and the regulation of reproductive hormones.

How do sex steroids provide feedback to the hypothalamus and pituitary gland?

Sex steroids exert negative feedback on the hypothalamus and pituitary gland to ensure that circulating hormone levels remain stable and prevent overproduction.

What physical changes occur in males during Tanner stage 3?

During Tanner stage 3, there is continued growth of the penis and testes, indicating further development of male secondary sexual characteristics.

What are the characteristics of Tanner stage 4 in males?

In Tanner stage 4, there is development of the glans, continued growth of the penis, and darkening of the scrotal skin, indicating advanced sexual maturation.

What is the relationship between body weight and menarche onset?

There is a direct relationship where a critical body weight must be achieved for menarche to occur, highlighting the importance of body composition in reproductive health.

What changes occur in the CNS leading up to puberty?

There is a progressive maturation of the central nervous system (CNS) and activation of hypothalamic stimulatory centers, which are essential for initiating puberty.