Title: Adolescent Sexual Development: The Endocrine System, Puberty, Anatomy, and Physiology
1Adolescent Sexual Development The Endocrine
System, Puberty, Anatomy, and Physiology
- FCS 438 Adolescents in the Family Context
- Wendy Hill Williams, MA, LMFT
2Puberty
- Puberty is the time in life when a child changes
into a young man or young woman capable of having
children - Begins earlier in girls than boys (girls usually
between 8 13 boys between the ages of 9 - 14
years old) - Triggered by the pituitary gland which sends a
signal to the ovaries or testicles to produce
testosterone or estrogen - Understanding puberty requires an understanding
of the endocrine system
3The Endocrine System
- The endocrine system is a complex system
consisting of numerous glands that secrete more
than 50 different hormones into the bloodstream
to target tissues throughout the body - Hormones are chemical substances/messengers that
affect the activity of almost every cell in the
human body - The hormones of the endocrine system function to
maintain homeostasis, regulate growth and
metabolism, promote sexual development and sexual
function, balance sugar, and perform many other
physiological and metabolic functions many that
are essential to life (Daruna, 2004 Farabee,
2001 Rieser Kemp, 2005).
4The Major Endocrine Glands of the Human Body
- Each gland secretes one or more hormones
- pituitary gland
- pineal gland
- thyroid gland
- parathyroid gland
- adrenal gland
- pancreas
- ovaries or testes
The Internet Encyclopedia of Science
5The Hypothalamus Pituitary Gland
Many of the chemical processes begin in the
hypothalamus ? the pituitary gland
6The Hypothalamic-Pituitary-Adrenal Axis and the
Hypothalamic-Pituitary-Gonadal Axis
- The hormones of the hypothalamic-pituitary-adrenal
axis (HPA) and the Hypothalamic Pituitary
Gonadal (HPG) axis are regulated by a negative
feedback loop, involving the hypothalamus,
pituitary gland, and the target organs (Daruna,
2004 Morley 2005).
7Hypothalamic Pituitary Gonadal Adrenal Axes
8The Hormones of the Endocrine System
- Pituitary gland The Master Gland it secretes
releasing hormones to target gland and other
hormones such as oxytocin - Pineal gland secretes melatonin, regulates
sleep - Thyroid gland secretes thyroxine (T4) and
triiodothyronine (T3) and calcitonin functions
in metabolism - Parathyroid glands secretes PTH regulates
calcium, Vitamin D, and bone metabolism - Adrenal glands the outer cortex secretes
aldosterone which regulates salt and water
balance cortisol is secreted by the middle
cortex and is essential for life the adrenal
medulla produces epinephrine and norepinephrine -
the fight or flight response - Pancreas the islet cells of the pancreas
secrete insulin to balance blood sugar - Ovaries or Testes the gonads produce estrogen,
progesterone and testosterone and are responsible
for sexual development and reproduction
9Major Male Female Sex Hormones
- Estrogen is the major female hormone
- Testosterone is the major male hormone
- Both hormones are present in both genders but in
different quantities men produce 6-8 mg of
testosterone daily women produce .5 mg - Testosterone plays a role in sexual desire it
can also increase aggression
10Primary Sex CharacteristicsRelated to
reproduction and present at birth
- Men testes and other reproductive organs
- Women ovaries, uterus, and other reproductive
organs
11Secondary Sex Characteristics Appear at puberty
- Recall that puberty begins when the pituitary
signals the gonads to produce the sex hormones
testosterone and estrogen - The first sign of puberty is often a growth spurt
in both boys and girls - Boys penis and testicles enlarge, larger
skeletal structure, stronger muscles, shoulders
broaden, thicker skin, hair distribution (face,
chest, back, legs, arms, pubic area and
underarms), voice deepens, spontaneous erections
and wet dreams - Girls breasts develop, hair develops in pubic
area and underarms, extra layer of fat beneath
the skin which makes the womans body softer and
more rounded, hips widen, and menstruation begins - Increased hormone production, overactive oil
glands and sebum production can clog the pores
and cause acne in some teens
12Stages of Puberty
- The process of puberty begins at different ages
for each individual - Puberty occurs in five stages and can take
between two five years depending on the person - These stages are called The Tanner Stages of
Development
13Tanner Stages of Male Development
From Always Changing Fifth Grade Puberty
Education Program (2009)
14Stage One Up to ages 9 to 13 Stage Two May begin ages 9 to 15 Stage Three May begin ages 11 to 16 Stage Four May begin ages 12 to 17 Stage Five May begin ages 14 to 18
Childhood stage no visible signs of pubertal development Testicles and scrotum grow larger Fine, straight hair starts growing at the base of the penis Testicles and scrotum continue to growPenis grows larger Pubic hair becomes darker, thicker and curlier Vocal cords increase in size, causing voice to deepen Height and weight may start to increase noticeably Growth spurt continues Shoulders begin to broaden and physique becomes more muscular Penis grows in width as well as length Pubic hair coarsens and takes on a triangular shape Underarm hair appears Traces of hair may appear on upper lip and chin Testicles start to produce sperm ejaculation occurs for the first time Adult stage overall look is that of a young man Growth spurt slows down Facial hair growth becomes heavier Body hair growth, especially on the chest, may continue into the 20s
From Always Changing Fifth Grade Puberty
Education Program (2009)
15Tanner Stages of Female Development
From Always Changing Fifth Grade Puberty
Education Program (2009)
16 Stage One Up to ages 8 to 12 Stage Two May begin ages 8 to 14 Stage Three May begin ages 9 to 15 Stage Four May begin ages 10 to 16 Stage Five May begin ages 12 to 19
Childhood stage no visible signs of pubertal development Height and weight increase rapidly Breast buds appear nipples become raised and this area may be tender Fine, straight hair starts growing close to the labia Height continues to increase Breasts become rounder and fuller Pubic hair becomes darker, thicker and curlier Hips may start to widen in relation to waist, giving a softer, more rounded shape Vagina begins secreting a clear, whitish fluid called vaginal discharge For some girls, ovulation and menstruation begin late in this stage Underarm hair appears The nipple and the dark area around it (areola) may stick out from the rest of the breast Pubic hair starts to form a triangular patch in front and around sides of the genital area For many girls, ovulation and menstruation begin during this stage Adult stage overall look is that of a young woman Areola rejoins breast contour and breast development is complete Pubic hair forms a thick, curly, triangular patch Pubic hair forms a thick, curly, triangular patch Adult height is probably reached Ovulation and menstruation occur regularly
From Always Changing Fifth Grade Puberty
Education Program (2009)
17Sex Hormones (female)
- Estrogen the principal female hormone serves
multiple functions - Helps to promote sex differentiation in the fetus
- Promotes maturation of reproductive organs and
the development of secondary sex characteristics
during puberty - Has effects on other organs such as the breasts,
uterus, brain, bone, and other tissues - Facilitates the buildup and thickening of the
lining of the uterus during the proliferative
phase of the menstrual cycle - Progesterone
- serves multiple functions
- plays a major role in the luteal phase of
menstruation, and in maintaining pregnancy
18Sex Hormones (male)
- Testosterone principal male hormone, serves
multiple functions - The amount of testosterone seems to correlate
with sexual response - Can cause aggression
- Promotes development of secondary sex
characteristics in puberty - Facilitates muscle and bone growth (in both men
and women) - Both men and women have testosterone and estrogen
although not in the same quantities
19Gonadotropins
- FSH - Follicle Stimulating Hormone is secreted by
the pituitary gland and is responsible for
stimulating the development of the ova in the
ovary and for sperm production. - LH - Luteinizing Hormone is also secreted by the
pituitary gland and stimulates the production of
sex hormones by the ovaries and testes. LH
causes ovulation to occur.
20Menstruation and the Menstrual Cycle
- Complex endocrine, ovarian and uterine changes
characterize each of these phases - Menstrual Phase
- Proliferative Phase
- Ovulation
- Luteal Phase
21Phases of the Menstrual Cycle Regulated by
the Hypothalamic-pituitary-gonadal axis of the
endocrine system The menstrual cycle is
measured from the first day of menstrual flow to
the last day before the next flow begins
- The Menstrual Phase The sloughing off of the
uterine lining (the endometrial lining) that
takes place if conception has not occurred - Proliferative Phase The endometrial lining is
built up to prepare for a possible pregnancy.
Egg follicles develop. Estrogen plays a vital
role in this phase - Ovulation The release of a developed ovum (egg)
from the ovary. Usually occurs midway through
the cycle on day 14 of a 28 day cycle - Luteal Phase Postovulatory phase between
ovulation and the next menstrual cycle
22Menstrual PhaseDay 1
- The first day of your period is considered the
onset of your new cycle - The onset of menstruation during which the
endometrial lining is sloughed off and discharged
if pregnancy hasnt occurred
23Proliferative Phase
- The hypothalamus releases a hormone called
gonadotropin releasing hormone (GN-RH) - The lining of the uterus thickens as the
pituitary gland increases production of
gonadotropins - GNRH stimulates the pituitary to produce two
hormones follicle-stimulating hormone (FSH) and
luteinizing hormone (LH) FSH cause the ovarian
follicles to mature - LH causes the ovary to release a mature ovum and
stimulates the development of corpus luteum, the
mass of cells left in the ovary after the
follicle ruptures and an ovum is released
24Ovulation Phase
- Ovulation is the release of mature ovum from the
ovary and marks the transition from the
proliferative phase to the luteal phase of the
menstrual cycle - Pregnancy occurs during this phase if a viable
sperm meets and fertilizes a viable ovum - This usually takes place mid-cycle (on day 14 in
a 28 day cycle)
25 26Luteal Phase
- Postovulatory phase lasting from ovulation until
menstrual flow begins again - The corpus luteum is formed during this phase
producing large amounts of progesterone - Progesterone (along with estrogen produced by the
ovaries) causes the uterus to prepare for the
possible implantation of a fertilized egg and
regulates the production and release of other
hormones in the body - If implantation does not occur, the pituitary
gland decreases - production of LH and FSH causing the corpus
luteum to degenerate and estrogen and
progesterone production drop abruptly - This causes endometrial cells to die initiating
the next menstrual phase
27Conclusion
- Hormones are vital and necessary chemicals for
sexual development, maturation, desire,
reproduction, and some are essential for
maintaining health and life - Sex Hormones involve a complex interplay of the
hypothalamic-pituitary-gonadal axis to promote
sexual development, sexual desire and the ability
to propagate