1. Physiological Changes During Puberty & Menopause
بسم الله الرحمن الرحيم
Physiological Changes During Puberty & Menopause
Dr.Mohammed Sharique Ahmed Quadri
Assistant professor physiology
Al Maarefa College

2. Objectives Define puberty
List the factors that affect time of onset of puberty in boys and girls
Describe the hormonal changes that take place during puberty in boys and girls
Outline the functions of pituitary, gonadal and adrenal hormones during puberty
Define menopause
Distinguish the hormonal changes that takes place during menopause

3. Definition of Puberty:
Puberty is the stage of physical maturation in which an individual becomes physiologically capable of sexual reproduction.

4. Onset of Puberty Wide variation in the onset and duration of puberty
Males vs. females
Ethnic and racial groups
Individual difference(genetic factor)
On average It usually begins between the ages of years,( two years earlier in females than males )

5. Endocrine Regulation of Reproduction
Hypothalamus releases LHRH (GnRH) into hypothalamo-hypophyseal portal vessels.
Anterior pituitary secretes:
LH (luteinizing hormone).
FSH (follicle-stimulating hormone).
GnRH Secreted in pulsatile fashion to prevent desensitization and down regulation of receptors.

6. Endocrine Interactions
Anterior pituitary secretes LH and FSH.
Secretion of LH and FSH stimulated by LHRH (GNRH).
Primary effects of LH and FSH on gonads:
Stimulation of spermatogenesis and oogenesis.
Stimulation of gonadal hormone secretion.
Maintenance of gonadal structure.

7. Endocrine Regulation Negative feedback: Female: Male:
Inhibits GnRH from hypothalamus.
Inhibits anterior pituitary response to GnRH.
Inhibin secretion inhibits anterior pituitary release of FSH.
Female:
Estrogen and progesterone.
Male:
Testosterone.

8. Onset of Puberty
FSH and LH secretion is high in newborn, but falls to low levels in few weeks.
At puberty secretion of GnRH,FSH,& LH increases and become pulsatile.
Pulsatile pattern of hypothalamo pituitary axis is required for normal reproductive functions.

9. How does puberty begin ?
During childhood , the hypothalamus is extremely sensitive to the negative feedback exerted by the small quantities of estradiol & testosterone produced by the child's ovaries or testes .

10. As puberty approaches , the sensitivity of the hypothalamus is decreased and subsequently , it increase the pulsatile GnRH secretion initially at night .
The anterior pituitary responds by progressive secretion of FSH and LH associated with increased secretion of growth hormone .

11. In female
The ovaries respond to the increase Gonadotrophin secretion by follicular development & estrogen secretion .
Estrogen causes development of the genital organs and the appearance of the secondary sexual characters .
With increased estrogen secretion , menarche occurs.

12. Puberty in Girls The sequence of events in girls are as follows
THELARCHE: The development of breast
PUBARCHE: The development of axillary and pubic hairs
MENARCHE: The first menstrual period

13. Pubertal Changes in Females
Folliculogenesis proceeds
Ovulation for first time
Increase of Estradiol and progesterone
Secondary sexual characteristics:
Broadening of hips
Subcutaneous fat( buttocks, breast, thighs)
Growth of external genitalia
Pubic hair
Increased sebaceous gland secretions (adrenal androgens)

14. In Males
The testis respond to the increase Gonadotrophin secretion by increase in testicular size and increase testosterone secretion .
Testosterone causes development of the genital organs and the appearance of the secondary sexual characters .

15. Pubertal Changes in Males
Spermatogenesis initiates
Increased androgen secretion
Growth of accessory sex structures
Prostate
External genitalia
Male secondary sex characteristics
Facial and body hair
Growth of larynx( deepening of voice)

16. CHRONOLOGICAL ASPECT (changes in boys and girls at puberty)
Acceleration of growth rate
Development of breasts and pubic hair
Axillary hair
Menarche
BOYS
Increase of testicular volume
Increase of penile length
Pubic hair
Increased growth rate
Axillary hair
Deepening of the voice

17. What causes initiation of puberty in humans ?
The mechnismunderlyig the pulsatile GnRH secretion remain unclear. The theories proposed are
Melatonin secretion by pineal gland
Leptin secretion by adipose tissue

18. Factors responsible for initiating puberty Melatonin secretion
Melatonin is secreted by pineal gland .
Secretion decreases by exposure to light and increses during exposure to dark
It is suggested that , there is observed decrease in rate of melatonin secretion at puberty, particularly at night , when peak in GnRH secretion first occur- is the trigger for onset of puberty.

19. Factors responsible for initiating puberty Leptin secretion
A satiety producing hormone
Secreted by adipose tissue
May play role in hypothalamic maturation at puberty ( delayed onset of puberty in lean or caloric deprived girls )

20. Menopause Cessation of woman’s menstrual cycle
(Absence of menstrual cycle for at least 12 consecutive months)
Usually occurs between ages of 45 and 55

21. What Causes Menopause
Midlife hypothalamic change may trigger onset of menopause
limited supply of ovarian follicles present at birth. Once this reservoir is depleted ovarian cycle and menstrual cycle ceases
Follicular reserve provides an exhaustible source of oocytes that is established around the time of birth

22. Menopause
Preceded by period of progressive ovarian failure characterized by
Increasingly irregular cycles
Dwindling estrogen levels
Loss of estrogen primarily affects skeleton and cardiovascular system
Period of transition from sexual maturity to cessation of reproductive capability is called the climacteric or perimenopause.

23. Menopause (Reproductive Decline)
Cessation of menstrual cycle
Loss of ovarian function
Infertility
Drop in ovarian steroids (estrogen and progesterone)
Rise in gonadotropin hormones
Decrease in ovarian inhibin production

24. Risk of cardiovascular diseases and osteoporosis increases
Symptoms of Menopause
Hot flashes/flushes
Mood swings
Vaginal dryness
Depression
Incontinence
Change in sex drive
Risk of cardiovascular diseases and osteoporosis increases

25. Hormone Replacement Therapy
Estrogen is taken on a daily basis while progesterone is taken less regularly
Helps alleviate symptoms such as hot flashes, vaginal dryness and mood swings
Slows the progress of osteoporosis; decreased rate of fractures

26. Andropause Male reproductive aging Very gradual compared to menopause
Gradual decrease in sperm production and in testosterone production may occur after 45 to 50 years
Results from degenerative changes in small testicular blood vessels

27. References Human physiology by Lauralee Sherwood, seventh edition
Text book physiology by Guyton &Hall,11th edition
Text book of physiology by Linda .s contanzo,third edition