10.7 Reproductive Hormones Flashcards
The Reproductive Hormones
- The gonads are the sex glands in males
(testes) and females (ovaries) - These glands produce androgens,
estrogens and progestins - These hormones regulate the development
of male and female reproductive systems,
sex characteristics, and mating behaviour
The Male Reproductive System
Male sex hormones, androsterone, and testosterone, are made in the interstitial cells of the testes
Testosterone Stimulates:
Spermatogenesis or the development of Sperm
Also promotes the development of secondary male
sexual characteristics
(Deepening Voice, Facial Hair etc.)
Negative Feedback
- The hypothalamus and pituitary gland control the
production of sperm and male sex hormones - At puberty the hypothalamus secretes
gonadotropin-releasing hormone (GnRH) which activates the pituitary gland to secrete follicle-stimulating hormone
(FSH) and lutenizing hormone (LH). - FSH acts directly on sperm producing cells stimulating sperm production
- LH stimulates the production of TESTOSTERONE which
then increases sperm production
The Female
Reproductive System
The female reproductive system is far more
complicated than that of the male
- While males produce sperm cells at a
relatively constant rate, females follow a
complicated sexual cycle in which one egg
matures every month
Oogenesis and Ovulation
Eggs develop in the ovary in a collection of
cells called follicles
- Follicles are made up of the primary oocyte
(the egg) and cells called granulosa which
nourish the developing egg
- Approximately 400 eggs will mature in the
lifetime of a female (That’s a lot of eggs!)
Ovulation
The developing follicle eventually releases the egg
into the fallopian tube; this process is called
ovulation
- The remaining follicle cells form the CORPUS
LUTEUM which begins to secrete hormones
essential for pregnancy
- If pregnancy does not occur the corpus luteum
degenerates and the cycle begins again
Menstrual cycle
- Avg of 28 days
- 4 distinct phases
1) Flow - Shedding of endometrium
2) Follicular - Follicles develop within the ovary. Estrogen is secreted
3) Ovulatory - Egg bursts from the ovary and travels into the uterus
4) Corpus luteum develops. Estrogen and progesterone are secreted
Estrogen
Stimulates the development of female secondary sex characteristics (pubic hair, breasts), also causes thickening of the endometrium
Progesterone
Stimulates the endometrium and prepares uterus for embryo. Also inhibits further ovulation and prevents uterine contractions.
If fertilization doesn’t occur the decrease in progesterone
causes weak uterine contractions to help shed the endometrium
Hormones/female reproductive system
Hypothalamus-pituitary complex regulates production of estrogen/progesterone (made in ovary)
- FSH/LH (from pituitary) regulate the control of these hormones
- However all 4 of these hormones are involved in a negative feedback system
Post-ovulation
- Estrogen/progesterone continue to increase
- This inhibits LH/FSH secretion which eventually causes corpus luteum to deteriorate and stop producing estrogen and progesterone
- The drop in these hormones signals the beginning of menstration
Male/female secrete same hormones, but have different sexual characteristics?
- Answer lies in the AMOUNT of hormone produced. Men produce more androgens (male sex hormones) then female sex hormones.
Negative feedback
GnRH released from hypo.
- GnRH stimulates pituitary to release LH/FSH
- FSH stimulates follicle development in ovaries
- LH promotes ovulation and the formation of the corpus luteum
- Follicle development initiates estrogen secretion which eventually turns off FSH secretion
- After ovulation LH turns the follicle cells into the corpus luteum which secretes estrogen and progesterone to ready the endometrium
