S3) Puberty and HPG Axis Flashcards Preview

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Flashcards in S3) Puberty and HPG Axis Deck (59)
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1

What is puberty?

Puberty is a stage of human development when sexual maturation and growth are completed and result in ability to reproduce 

2

Identify 3 forms of development that occur during puberty

- Morphological development

- Physiological development 

- Behavioural development 

3

Identify the primary sexual characteristics 

- Gonads

- Genitals

4

Identify 4 secondary sexual characteristics

- Pubic hair

- Axillary hair

- Female breast development

- Male voice changes

5

Briefly, describe the reproductive system before and after puberty

- Primary sexual characteristics are established before birth

- Reproductive system inactive until puberty 

6

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 

7

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

8

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)

9

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 

10

What is the critical weight for puberty to begin in girls?

Weight = 47 kg

11

When does puberty begin in girls?

9 - 13 years

12

What is thelarche?

Thelarche is the onset of female breast development

13

What is pubarche?

Pubarche is the appearance of sexual hair

14

What is adrenarche?

Adrenarche is the onset of androgen-dependent body changes such as growth of axillary and pubic hair, body odor, and acne

15

Describe the sequence of events in female puberty 

Breast bud growth → Pubic hair growth → Growth spurt → Onset of menstruation

16

Which hormones drive puberty in females?

- Oestrogen

- Testosterone 

 

17

Describe the sequence of events in male puberty

Genital development → Pubic hair growth → Spermatogenesis → Growth spurt

18

Which hormone drives puberty in males?

Testosterone

19

Identify the stages of the following photos in the Tanner Scale: 

20

Identify the stages of the following photos in the Tanner Scale: 

21

Accelerated somatic growth occurs in both sexes. What drives this process?

- Growth hormone

- Sex steroids

22

What concludes the period of accelerated somatic growth in both sexes?

Epiphyseal fusion 

23

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 

24

Compare and contrast puberty in males and females in terms of the following:

- Onset

- First sign of puberty

- Growth velocity

- Duration of puberty

25

Outline the HPG axis in females

26

Outline the HPG axis in males

27

Identify the 4 events which succeed increased stimulation of the hypothalamo-pituitary-gonadal axis 

- Gradual activation of GnRH

- Increased frequency and amplitude of LH pulses

- Stimulated secretion of sexual steroids

- Extragonadal hormonal changes

28

GnRH -1 gene is primarily responsible for mammalian GnRH.

What happens when GnRH is blocked?

- Lack of gonadotrophin synthesis and secretion

- Lack reproductive development occurs 

29

Identify 5 characteristic functions of hypothalamic releasing hormones

- Act on specific membrane receptors

- Transduce signals via second messengers

- Stimulate release & synthesis of stored pituitary hormones

- Stimulates hyperplasia & hypertrophy of target cells

- Regulates its own receptor 

30

How are hypothalamic releasing hormones secreted?

Secretion in pulses tied to internal biological clock