Chapter 19 Flashcards
What do the Reproductive Systems do?
- Produces and unites gametes
- Harbors the fetus and gives birth
- Nourishes the infant
What are Gametes?
Sex cells that meet and combine their genes in a “zygote” (fertilized egg). The gametes require motility to establish a contact, and nutrients for the embryo. Require sperm and Egg
What are Gonads?
Primary sex organs that produce the gametes
Man –> Testes
Woman –> Ovaries
What are the External Genitalia?
- Located in perineum between thighs
- Most externally visible or superficially beneath skin.
What is the Internal Genitalia?
- Located mainly in pelvic cavity, except for testes and some scrotal ducts
What does a Surge of pituitary gonadotropins signal?
Onset of Puberty. Begins preparing system for adult reproductive function.
Boys –> 10-12
Girls –> 8-10
What is Puberty?
- first few years of adolescence
- until first menstrual period in girls
- first ejaculation of viable sperm in boys
- around age 12 in girls; 13 in boys in U.S.
What is Adolescence?
- from puberty onset to attainment of adult height. ends late teens to early twenties
What is Gonadotropin-releasing hormone (GnRH)?
- Secreted by hypothalamus as brain matures
- Stimulates anterior pituitary gland to secrete FSH and LH
What are the Effects of Testosterone?
- Growth of sex organs and sperm production (Testes and scrotum; later the penis and internal ducts and glands)
- Burst of body growth (elongation of limb bones, increasing muscle mass, enlargement of larynx and deepening of voice, elevated metabolic rate and appetite)
- Hair and sweat glands
- Awakening of libido (sex drive)
- sustains male reproductive tract, sperm production, and libido
Testosterone peaks at what age?
20
After age 50, declining levels of testosterone is accompanied by what?
rising levels of FSH and LH which produces andropause
How long to men normally produce sperm?
To the end of life although in reduced numbers.
Female puberty begins at what age?
age 9 or 10
Elevations is FSH and LH in the female do what?
- stimulate development of ovarian follicles
- secrete estrogens, progesterone, inhibin, and a small amount of androgen
What are Estrogens?
Feminizing hormones with wide-spread effects on the body
The earliest noticeable sign of puberty in girls is _________?
Breast development. Complete by around age 20
What is Menarche?
- first menstrual period
- around age 12 in U.S.
- regular ovulation about a year later