3.1 Flashcards
What is puberty?
Sexual maturation and growth completed resulting in ability to reproduce.
What happens in puberty?
Accelerated somatic growth
Maturation of primary sexual characteristic
Appearance of secondary sexual characteristics
Menstruation and spermatogenesis
What the thelarche?
Development of the breast
What is menarche?
First menstrual period.
Equivalent in males is first nocturnal erection and first ejaculation.
What is adrenarche
Onset of an increase in secretion of androgens and pubic hair growth.
When does puberty occur for males and females?
Males: 9-14 years
Females: 8-13 years
What is the first sign of puberty in males? Why?
Increase in testicle size due to FSH induced increase in seminiferous tubules. TEsticular volume up to 4ml
Describe the changes in male puberty.
Genital development - testicle enlargement Adrenarche - pubic hair growth. Spermatogenesis begins Growth spurt (10cm/year) Genitalia adult Pubic hair adult
When does the growth spurt in males start? How fast is it?
About 12 months after the first signs of puberty.
10cm/year
Describe the female process of puberty.
What age does each occur at?
Thelarche - breast bud 8-11 Adrenarche - pubic hair growth 11-12 Grwoth spurt (9cm/year) 10-14 Menarche - onset of menstrual cycles 11-15 Pubic hair adult Breast adult
What is the first sign of puberty in females?
Brest bud appearance - thelarche
Why are men on average taller than women?
What are the growth spurt rates? What ends the growth spurt?
Growth spurt is longer and slightly faster. Men = 10cm/year. Women = 9cm/year.
Epiphyseal fusion
How is pubertal development classified in girls and boys?
Tanner standard:
Girls: breasts, pubic hair, axillary hair, menarche.
Boys: Testicular volume, penis enlargement, pubic hair, axillary hair, spermarche.
How does growth change in puberty compared to before?
Growth velocity is 2-3 times greater than prepubertal.
WhatHow do hormones control puberty?
GnRH secretion is too low for reproductive function before puberty.
Gradual activation of GnRH increases frequency and amplitude of LH pulses.
Gonadogrophins stimulate secretion of sexual steroids leading to sexual maturation.
Extragonadal hormonal changes lead to somatic growth.
A rise in what hormones is associated with the beginning of puberty?
GnRH, FSH, LH
Initiated by brain
Describe the puberty hormonal changes in males.
Hypothalamus releases GnRH LH and FSH release increases. Spermatogenesis and androgen secretion. Adrenals secrete androgens. Androgens initiate growth of sex accessory structures (prostate) and male secondary sexual characteristics. GH secretion increases Sertoli secrete some oestrogen TSH secretes increases: Promotes tissue growth and increases metabolic rate. Retention of minerals for growth.
Describe puberty hormonal changes in females.
Oestrogen induces secondary sexual characteristics:
Pelvis growth, subcutaneous fat
Growth of internal repro organs and external genitalia.
Androgen release by adrenal glands increases:
Growth of pubic hair
Lowering of voice
Growth of bone
Increased sebaceous gland secretion.
What initiates the first ovarian cycle?
LH surge
Usually insufficient to cause ovulation.
Describe the hormonal changes in the pre-follicular phase.
Corpus luteum absent Follicles only partly developed Secrete very little steroid or inhibin O and P low Little inhibition at hypothalamus or pituitary FSH levels rise
Describe the hormonal changes at the mid-follicular phase.
Oestrogen levels rise Inhibin levels rise. Selective inhibition of FSH No new follicles can develop. Oestrogen exerts positive feedback at hypothalamus and pituitary LH levels rise.
Describe the hormonal changes in ovulation
LH surge preceded by rise in oestrogen