S3) Puberty and HPG Axis Flashcards
What is puberty?
Puberty is a stage of human development when sexual maturation and growth are completed and result in ability to reproduce
Identify 3 forms of development that occur during puberty
- Morphological development
- Physiological development
- Behavioural development
Identify the primary sexual characteristics
- Gonads
- Genitals
Identify 4 secondary sexual characteristics
- Pubic hair
- Axillary hair
- Female breast development
- Male voice changes
Briefly, describe the reproductive system before and after puberty
- Primary sexual characteristics are established before birth
- Reproductive system inactive until puberty
Identify 4 events that occur in puberty for males and females
- Accelerated somatic growth
- Maturation of primary sexual characteristics
- Appearance of secondary sexual characteristics
- Menstruation and spermatogenesis begin
Describe the involvement of the pineal gland in puberty
- Triggered by changes in day length
- Varies with secretion of melatonin
- Pineal gland tumours influence puberty
Describe the variation in the menarche of puberty in western countries over the years
- Average age of menarche = 17 years (C 1800)
- Average age of menarche < 13 years (C 2000)
Explain how nutrition has a notable role in the onset of puberty
- Body weight most important factor
- Leptins may be involved in signalling
- Significant weight loss = menstrual cycles stop
What is the critical weight for puberty to begin in girls?
Weight = 47 kg
When does puberty begin in girls?
9 - 13 years
What is thelarche?
Thelarche is the onset of female breast development
What is pubarche?
Pubarche is the appearance of sexual hair
What is adrenarche?
Adrenarche is the onset of androgen-dependent body changes such as growth of axillary and pubic hair, body odor, and acne
Describe the sequence of events in female puberty
Breast bud growth → Pubic hair growth → Growth spurt → Onset of menstruation
Which hormones drive puberty in females?
- Oestrogen
- Testosterone
Describe the sequence of events in male puberty
Genital development → Pubic hair growth → Spermatogenesis → Growth spurt
Which hormone drives puberty in males?
Testosterone
Identify the stages of the following photos in the Tanner Scale:
Identify the stages of the following photos in the Tanner Scale:
Accelerated somatic growth occurs in both sexes. What drives this process?
- Growth hormone
- Sex steroids
What concludes the period of accelerated somatic growth in both sexes?
Epiphyseal fusion
If accelerated somatic growth occurs in both sexes, why are women generally smaller/shorter?
Provide 3 reasons
- Growth spurt in girls is shorter and earlier
- Growth spurt in boys is longer and slightly faster
- Oestrogen closes epiphyses earlier in girls