This document discusses the physiology of puberty. It begins with definitions and notes that puberty is the transition from childhood to adulthood involving sexual maturation. It then discusses the endocrine control of puberty through the hypothalamic-pituitary-gonadal axis. The onset and sequence of pubertal changes are also outlined, beginning with breast development in girls and testicular growth in boys. Finally, it briefly discusses the physical growth and increased nutritional requirements that occur during puberty.

1. Physiology of Puberty
Guide : Dr. M.V. Patil
Dr.Nishant Mittal
Dr.Hardik A. Shah
23-03-2018 Department of Pediatrics , J N Medical College, Belagavi 1

2. Course of Presentation
• Definition
• Introduction
• Epidemiology
• Normal Puberty: Endocrine control
• Molecular level regulation
• Onset and sequence
• Physical growth & Nutritional Requirement
• Factor affecting Puberty
• Assessment
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3. Definition
Latin word : Puberatum
means age of maturity
Complex developmental process resulting in
Sexual maturity
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4. • Transition from the sexually immature child to
the mature, potentially fertile adolescent and
adult.
• begins in the late childhood (8-9years)
Also called as Pre pubertal Period
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5. characterized by..
1)maturation of the hypothalamic-pituitary-
gonadal axis, functional integrity with adrenal
cortex.
2)the appearance of secondary sexual
characteristics,
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6. • 3)acceleration of growth, and, ultimately, the
capacity for fertility,
• All pubertal changes follow the sequential
pattern..
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7. Introduction
• Puberty start from late childhood period to the
early half of the adolescence
Childhood Adulthood
Early Mid Late
(10-13yr) (14-16yr) (17-19yr)
• Puberty : marks the early half of adolescence
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8. Which involves mainly
─ Appearance of sexual characters
─ Cognition function development
─ Psychological development
In which Puberty refers to physical aspect
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9. Epidemiology
• Genetics
Play an important role,
• Ethnicity
• In India and south asia, it relates with adverse
factors like..
1) Prevalence of malnutirtion
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10. • 2) Chronic disease
• 3) Socio economical condition
• 4) environmental factors.
• Age of onset : highly variable
Boys : 9-14years
Girls : 8-13years
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11. • Influenced by…
-Optimal Nutrition
-Weight gain during mid childhood
with..
Genetics and environmental condition.
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12. • Average age at menarche : Secular trends
Urban indian Girl - decreased to 12.6year
Rural indian Girl - still around 15-16year
Age of thelarche also decreased in recent years
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13. Age of thelarche also decreased in recent years,
-for african and american girls..
In boys, the age at onset of puberty :
-attainment of testicular volume > 4ml
Secular trends
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14. • But industrial Chemical effluents and
pesticides,
Endocrinal disruptors
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15. Hypothalamus-
Pituitary-Gonadal Axis
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• Endocrinal reproductive
system:
• Controls and synchronizes
pubertal development
• Maturation adrenal gland
is an independent but
interrelated process.
Hypothalamus
Pituitary
glandGonads
Adrenal
Gland

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17. Normal Puberty:
Endocrine control
During early childhood / pre pubertal age
Hypothalamic-Pituitary-Gonadal axis is
Dormant,
Serum Concentration Of LH and Sex Hormones
(estradiol in girls, Testosterone in boys)
are undetectable
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18. • 1-3 year before onset of clinically evident
puberty , low serum levels of LH during sleep
become demonstrable.
• Sleep entrained LH secretion
Pulsatile fashion and demonstrate the discharge
of hypo gonadotropic GnRH release
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19. • As clinically puberty approaches..
Nocturnal release of LH continue to increase.
• Pulsatile secretion of gonadotropin is
responsible for
o enlargement and maturation of gonads
o secretion of sex hormones
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22. • Active interaction between hypothalamus,
pituitary gland and gonads happen in peri
pubertal period,
• By mid puberty, LH surge become evident
even during day time and occurs at approx. 90-
120 min intervals.
•
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inhibin?
GnRH
higher centres
hypothalamus
testosteroneoestradiol
Sertoll
cells
Leyding
cells
LH FSH

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GnRH
oestradiol (E ) granulosa
cells
androgen theca interna
cells
LH
higher centres
hypothalamus
FSH
2
inhibin?
aromatising
enzyme

25. • Second critical event occurs in
mid or late adolescence phase
in girls which is responsible for cyclicity and
ovulation.
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26. • Adrenocortical androgens also have role in
sexual maturation
• Level of DHEA and its sulphate DHEAS
Begins to increase at 6-8 years of age , before
any increase in LH or sex hormone.
This process is called as ADRENARCHE
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27. • DHEAs is the most abundant adrenal C-19
steroid in the blood,
• Its concentration remains constant over
24hours
• used as marker for adrenal androgen secretion
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28. • Adrenarche antedates the onset of gonadal
activity its called as GONADARCHE by few
years,
• 2 processes do not seen to be casually related ,
because adrenarche and gonadarche are
dissociated in condition such as central
precocious puberty and adreno cortical failure
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29. Molecular level regulation
• positive feedback mechanism
• Increase level of hypothalamic GnRH
Reveals in pulsatile manner so,
“GnRH Pulse Generator” will form.
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30. • GnRH Pulse Generator is regulated by
multiple neuropeptides
• Stimulatory Inhibitory
Glutamic acid Gamma butiric acid
Kisspeptin Preproenkephalin
Neurokinin B Dynorphin
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31. • Its also regulated by Factor produced by the
glial cell like
• Transforming growth factor alpha
• Increased its level cause central precocious
puberty in patient with hypothalamic
hamartoma
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32. • Loss of function of KISSI R also known as
GPR 54 gene which associated with G protein
coupled receptor whose ligand is kisspeptin
• Cause hypogonadotropic hypogonadism
which is autosomal recessive condition
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33. Onset and sequence
• Girls : between 8 -13 years
• Start with Breast development
(THELARCHE)
• Appearance of Pubic hair ( PUBARCHE)
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34. • Mestruation (Menarche) , Occurring at an
average of 12.6 years ( range 10-16years)
• Usually Menarche occurs after 2 or 2 1/2 yers
of thelarche
• Breast Buds may be tender and asymmetry in
breast size during early phase of puberty..
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35. • Growth spurt peaks before menarche
• Pubic and axillary hair growth: sign of adrenal
androgen secretion
• Starts at similar stage of apocrine gland sweat
production and associated with adult body
odour
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36. Menarche
• During puberty oestradiol levels fluctuate widely
(reflecting successive waves of follicular
development that fail to reach ovulatory stage)
• Endometrium affected by oestradiol. Undergoes
cycles of proliferation and regression until point
where withdrawal of oestrogen results in the first
menstrual bleed (menarche)
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37. Ovarian development
• Rising levels of plasma gonadotrophins
• Stimulate ovary to produce increasing amounts of
oestradiol
• Oestradiol
secondary sex characteristics
– Breast growth and development
– Reproductive organ growth and development
– Fat redistribution (hips,breasts)
– Bone Maturation
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38. Boys
: 9-14 years
• earliest change is increase in Testicular size
(its Volume reaching 4ml or length 2.5cm)
• Appearance of Pubic Hair and Lengthening of the
penis.
• Spermarche : Production of sperms start during
mid adolescence
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39. • Laryngeal growth, manifesting as cracking of
voice, begins in boys in mid puberty under the
androgenic stimulus,
• Deepening of voice is complete by the end of
puberty,
• Mild degree of breast enlargement is normally
seen in more than half of boys in early puberty
which subside spontaneously over several
months.
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40. Physical Growth & Nutritional
Requirements
• During Puberty, Boys gain about 20-30cm and
Girls about 16-28cm of height
• Peak growth velocity in girls occurs before
attainment of menarche,
• Where as in boys it happens later stage of
puberty.
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41. Growth spurts
• a rapid rise in height and weight — are most
visible in the first year of life and around
puberty, both periods when a tremendous
amount of growth takes place in a short time.
• But growth spurts can occur other times, too,
though they're less obvious.
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42. • Which affect the distal skeleton first , hence
enlargement of limb and extremities is
followed by increase in trunk size.
• In boys : Increase in Muscle mass and Bone
diameter and total bone mass in both sexes
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43. • Lean body mass increases during the early
stages in both sexes where as,
• Fat mass increase in girls at later stage of
puberty,
• Rapid calcium accretion occurs during puberty
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44. • Almost 50% of adult bone accretion occurs
during puberty,
• Estrogen and androgen enhance calcium
accretion by bone
• Cause early fusion of epiohysis.
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45. • Increase in body structure is paralleled by
increase in blood volume and muscle mass
• With starting of menstruation, nutritional
requirement of iron are higher.
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