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Flashcards in Week 203 - Puberty Deck (37):
1

Week 203 - Puberty: Give a definition of puberty.

Puberty a series of physiological events that begin in late childhood, including the development of secondary sexual characteristics, somatic growth, bone maturation as well as psychological and behavioural changes.

2

Week 203 - Puberty: Give a definition of adolescence.

Adolescence is classed as the period between the ages of 10-24, and is when the person adapts neurologically and psychologically to physical changes of puberty, and to their changing social position.

3

Week 203 - Puberty: What is the basic endocrine system at the start of puberty?

• The hypothalamus stimulates the anterior pituitary gland to first release LH (leutinising hormone) and later FSH (Folicle stimulating hormone).
• LH acts on the gonads to produce the respective sex hormones, which in turn act on growth tissues.
• FSH acts on the gonads to produce either sperm or ova.

4

Week 203 - Puberty: What are the two main cell types in the testes, involved in puberty?

• Sertoli cells
• Leydig cells

5

Week 203 - Puberty: Which hormone acts on the Sertoli cells of the testes? What does it stimulate the release of?

• FSH leading to a release of inhibin and oestradiol.
• Testosterone also stimulates the sertoli cells.

6

Week 203 - Puberty: Which hormone acts on the Leydig cells of the testes?

• LH leading to the release of testosterone.

7

Week 203 - Puberty: What is the first stage of puberty in boys?

• Enlargement of the testes, puberty is said to have begun when they reach a volume <4ml.

8

Week 203 - Puberty: Explain the endocrine pathway that occurs during female puberty.

• The hypothalamus stimulates the anterior pituitary gland to release LH+FSH.
• These act on the ovary to produce oestradiol which causes the development of antral follicle.
• This directly releases oestrogen and causes the development of corpus luteum which releases progesterone.

9

Week 203 - Puberty: Which set of hormones cause the development of female pubic and axillary hair?

Androgens.

10

Week 203 - Puberty: Oestradiols produced by the ovary cause the development of which structure within the ovary?

Antral follicle.

11

Week 203 - Puberty: The two female sex hormones are oestrogen and progesterone, which two structures in the ovary produce them?

• Antral follicle - Oestrogen
• Corpus Luteum - Progesterone

12

Week 203 - Puberty: What is the first sign of puberty in females?

Breast development, deposition of fat on the hips and enlargement of uterus and vagina.

13

Week 203 - Puberty: What is the difference between growth of height in the patterns of female and male puberty?

In female puberty growth begins at the start of puberty, where as in males it does not develop until later when the testes of 10-12ml.

14

Week 203 - Puberty: The sex hormones stimulate the release of which hormones needed for growth? Where are they secreted from?

• GH (Growth hormone) - Anterior pituitary gland.
• IGF (Insulin-like growth factor) - Liver.

15

Week 203 - Puberty: There are two other hormones needed for the production and effect of GH and IGF, what are they and what is their effect?

• Thyroid hormone - Production and action of GH
• Insulin - Secretion of IGF and promotes protein synthesis.

16

Week 203 - Puberty: How much growth do males and females experience during puberty?

• Females - 25cm approx.
• Males - 28cm approx. (But since they start pubertal growth on average 2 years later, they have a further 10cm of normal growth)

17

Week 203 - Puberty: What causes the end of growth?

• Fusion of the epiphyseal plates, in response to oestrogen.

18

Week 203 - Puberty: What is consonance?

• This is the normal pattern that puberty follows, ie, testicular growth> penile growth> pubic hair> growth spurt.
• If someone is developing along with consonance, it suggests that the hypothalamus-pituitary-gonadal axis is working correctly.

19

Week 203 - Puberty: What is non-consonance?

• This is deviation from the normal pattern of puberty and suggests that there is production of sex hormones/androgens from a peripheral source (out of the hypo-pit-gonadal axis).
• The order of development can suggest the site that is driving puberty.

20

Week 203 - Puberty: The exact cause for the initiation of puberty is unknown, but what are the three main factors?

• Genetics
• Nutrition
• Environment

21

Week 203 - Puberty: What is adrenarche and what does it cause?

• Adrenarche is the normal maturation of adrenal glands causing increased secretion of the androgens (androstenedione and dehydroepiandrosterone (DHEA))
• The androgens cause the development of axillary and pubic hair.
• It normally coincides with the start of puberty but can start earlier or be delayed.

22

Week 203 - Puberty: The nocturnal secretion of which hormone at the end of the 1st decade of life heralds the start of gonadarche?

GnRH - Gonadtrophin releasing hormone.

23

Week 203 - Puberty: What is Thelarche?

Development of breast tissue, during puberty. (Females)

24

Week 203 - Puberty: What is the definition of delayed puberty and how can the diagnosis be confirmed?

• Complete absence of physical signs of puberty in girls after the age of 13 and aged 14 in boys.
• Bone age scan of hand and wrist.

25

Week 203 - Puberty: What are the two types of delayed puberty and what are the levels of FSH/LH in these?

• Central failure - Hypogonadtrophic failure - Low FSH/LH
• Primary gonadal failure - Hypergonadotrophic failure - High FSH/LH

26

Week 203 - Puberty: What are some of the causes of hypergonadotrophic failure?

Primary Gonadal Failure
- Genetic (Turner's, Klinefelter's XXY)
- Autoimmune
- Enzyme defects
- Androgen insensitivity
- Chemotherapy
- Pelvic radiation
- Bilateral cryptoorchidism in males. (Uncorrected before age 8)

27

Week 203 - Puberty: What are some of the causes of hypogonadotrophic failure?

Central Failure
- Constitutional
- Eating disorder
- Excessive physical activity
- Hypothyroidism
- Intracranial tumour
- Isolated GH or GnRF deficiency

28

Week 203 - Puberty: What is the system of staging for puberty?

Tanner staging 1-5 (5 being fully developed)

29

Week 203 - Puberty: What is precocious puberty?

This is the early onset of secondary sexual characteristics.
- <9yrs in boys

30

Week 203 - Puberty: Explain the two types of precocious puberty.

• True central precocious puberty
- Gonadotrophin dependant
- Consonant puberty occurring early, resulting from initiation of the hypothalamus.

• Peripheral precocious puberty
- Precocious pseudopuberty / Independent of gonadotrophin.
- Caused by abnormal secretion of sex-hormones independent of hypothalamus.
- May be non-concordant.

31

Week 203 - Puberty: What three themes of impact does precocious puberty have on the child?

• Low final height. (Early fusing of epiphyseal plates)
• Impact on fertility and age of menopause.
• Psychological impact.

32

Week 203 - Puberty: What are the causes of true central precocious puberty?

• Idiopathic
• Secondary;
- CP/Hydrocephalus, Tumours/Masses, Trauma, Chronic inflammatory conditions, Radiotherapy, Sexual abuse, Adoption.

33

Week 203 - Puberty: What are the causes of peripheral precocious puberty?

• Genetic
• Precocious breast development - Thelarche, ovarian cyst, hypothyroidism.
• Virilisation - Adrenarche, Cushings Disease, Adrenal Tumours
• Gonadotrophin/sex-hormone secreting tumours
• Exogenous steroids

34

Week 203 - Puberty: What investigations should be performed for precocious puberty?

• Auxology - multi-disciplinary approach.
• Parental heights
• LH/FSH tests
• Oestradiol/Testosterone
• Androgens
• Bone age
• Pelvic USS -Girls

35

Week 203 - Puberty: What is the treatment of central precocious puberty?

• An analogue of GnRH can be given which inhibits the secretion of LH/FSH, so delays puberty, this can then be stopped at a later age so puberty can resume.

36

Week 203 - Puberty: What is the treatment of peripheral precocious puberty?

Address the cause.

37

Week 203 - Puberty: What enzyme is responsible for breaking 17-OH-progesterone into cortisol? What effect can deficiency of this enzyme cause?

• 21-hydroxylase
• Deficiency of this enzyme pushes the pathway towards the sex-steroid pathway, commonly resulting in congenital adrenal hyperplasia (CAH).