1. Physiology of the reproductive system
By Dr. Eman

2. The hypothalamus
The hypothalamus is composed of neural tissues its physicaly connected to the pituitary by the pituitary stalk, within this the anterior pituitary (adeno hypophysis) is connected to the hypothalamus by the pituitary portal system which are vesceles from the carotid and post. Communicating arteries.
The post. Pituitary (neurohypopysis) is connected to the hypothalamus by a rich plexus of nerves

3. Hypothalamus
: the hypothalamic nerve cells act both as neurones and as endocrine cells the, hormomnes are synthesised in the cytoplasm of the neurons and then passed in the axon of nerve terminals

4. Definitions & Functions Relative to Reproduction
Produces GnRH which stimulates the production of FSH & LH by the anterior pituitary gland initiating the ovarian cycle. Produces Oxytocin which is stored in the posterior pituitary gland.
Posterior Pituitary:
Stores & releases hormone Oxytocin to stimulate uterine contractions (Braxton Hicks) & the milk let-down reflex.
Since you will be required to give or recognize the function(s) of various things relative to reproduction, the next few slides will review these. *
The Hypothalamus * produces *
the hormone GnRH which stimulates production of FSH and LH by the anterior pituitary gland to initiate the ovarian cycle. * It also is where the hormone ocytocin is produced which is stored in the posterior pituitary gland. * The posterior pituitary * stores and relases ocytocin to stimulate uterine contractions during labor and delivery and the milk let-down reflex when initiated by a suckling baby. *

5. Hypothalamus and pituitary gland

6. Hormone Sources & Functions
Gonadotropin-releasing Hormone (GnRH) : Source: Hypothalamus
Targets & Functions:
Females & Males - Anterior Pituitary
Stimulates the production of Follicle Stimulating Hormone (FSH) & Leutinizing Hormone (LH)
Regulates the release of FSH & LH by the anterior pituitary gland
Gonadotropin-releasing Hormone (GnRH) * is produced by the hypothalamus. * * It’s target in both males and females is the anterior pituitary gland. * * which it stimulates to produce FSH and LH. * The Hypothalamus also regulates the release of FSH and LH by the anterior pituitary.* *

7. Hormone Sources & Functions
Follicle Stimulating Hormones FSH
Source: Anterior Pituitary
Targets & Functions:
Females - Ovaries
Stimulates follicle growth & maturation
Stimulates estrogen production
Males - Seminiferous Tubules
Promotes sperm production (Spermatogenesis) by establishing testosterone receptors on tubules
Follicle stimulating hormone (FSH) * is produced by the anterior pituitary gland. * * It’s target in females * is the ovaries * in which it stimulates the growth and maturation of a follicle * and causes the maturing follicle to produce the hormone estrogen. * The target of FSH in males is the seminiferous tubules. * The effect of FHS is to cause the development of testosterone receptors on the seminiferous tubules, promoting sperm production. * *

8. Leutenizing Hormone LH:
Source: Anterior Pituitary
Targets & Functions:
Females - Ovaries
Stimulates primary oocyte to complete first meiotic division to become secondary oocyte
Triggers ovulation of secondary oocyte
Transforms ruptured follicle into corpus luteum
Stimulates production of progesterone by corpus luteum
Leutenizing hormone (LH) * is produced by the anterior pituitary gland. * * It’s targets in the female are the ovaries. * The effect of LH within the ovaries is to stimulate a primary oocyte * to complete its first meiotic division to become a secondary oocyte. * It triggers ovulation (release) of the secondary oocyte, * the transformation of the ruptured follicle into a corpus luteum * and stimulates the production and release of the hormone progesterone from the corpus luteum. In Males, * the target of LH is the interstitial cells between the seminiferous tubules of the testes. Under the influence of LH, the interstitial cells produce and release testosterone * which binds to the receptors on the seminiferous tubules making possible sperm production (spermatogenesis). *
Males - Seminiferous Tubules
Stimulates sperm production (Spermatogenesis) by causing interstitial cells in testes to secrete testosterone
Corpus luteum

9. Prolactin: Source: Anterior Pituitary Targets & Functions breast:
Breasts
Stimulates alveoli of breasts to produce milk
Prolactin is a hormone stored by the anterior pituitary. * It’s targets * are the alveoli of the breasts, which it stimulates to produce milk. The release of prolactin is regulated by the hypothalamus. * *
Regulation
Release of prolactin by anterior pituitary is regulated by hypothalamus production of dopamine Prolactin Inhibiting Hormone (PIH)

10. Oxytocin: Targets & Functions:
Sources: Manufactured by hypothalamus. In the supraoptic and para ventricular gland Stored & released by Posterior Pituitary
Positive Feedback Mechanisms:
1. Childbirth - Stretching of uterus and cervix
2. Suckling - Milk letdown reflex
Targets & Functions:
Uterus
Stimulates contraction of uterine myometrium causing lowering of fetus & labor
The hormone onytocin is manufactured by the hypothalamus and is stored by the posterior pituitary. * It is involved in positive feedback mechanisms * including childbirth * and the milk letdown reflex. * The contractions associated with childbirth are triggered by stretching of the cervix and the uterus as term is reached. * Increasing amounts of oxytocin in the blood triggers the myometrium of the uterus to contract causing the lowering of the fetus and labor. * The suckling effect on the breast of a nursing baby * stimulates the release of oxytocin which when bound to the tissues of the milk ducts and sinuses of the breasts, stimulates the release of milk. *
Breasts
Stimulates contraction of milk ducts and sinuses, releasing milk

11. Hormonal Regulation of Ovarian & Menstrual Cycles
1. Hypothalamus releases GnRH.
2. GnRH stimulates anterior pituitary to release FSH.
Estrogen
FSH
3. FSH stimulates a follicle to grow & produce estrogen.
The ovarian cycle begins when rising levels of GnRH from the hypothalamus * * stimulate increased production and release of Follicle Stimulating Hormone (FSH) by the anterior pituitary. * * FSH stimulates one or more follicle cells within the ovaries to grow * * and begin producing estrogen. * *

12. Hormonal Regulation of Menstrual & Ovarian CyclesLH
4. Rising levels of estrogen cause anterior pituitary to increase production & storage of LH.
Estrogen
Estrogen
FSH
Rising estrogen levels in the blood * * inhibits further release of FHS while promoting increased production and storage of the hormone Leutinizing Hormone (LH) * within the anterior pituitary gland. *

13. Hormonal Regulation of Menstrual & Ovarian Cycles
5. High estrogen causes LH to be released in a burst & the endometrium to thicken (proliferative phase).
Estrogen
Estrogen
FSH
6. High LH stimulates first meiotic division of primary oocyte.
When estrogen levels in the blood become high enough, * * LH is released by the anterior pituitary gland in a burst. The high estrogen levels also cause the endometrium to thicken. * The sudden release of LH into the blood,* causes the primary oocyte in the mature follicle to undergo the first meiotic division. * * LH

14. Hormonal Regulation of Menstrual & Ovarian Cycles
7. High LH triggers ovulation.
Estrogen
Estrogen
8. High LH causes ruptured follicle to become a corpus luteum.
FSH
The high LH levels * also cause the mature follicle to release the primary oocyte (ovulation), * and the remains of the ruptured follicle * to become a corpus luteum. * * LH

15. Hormonal Regulation of Menstrual & Ovarian Cycles
9. Corpus luteum produces progesterone.
Estrogen
10. Progesterone inhibits the production of FHS & LH by the anterior pituitary & stimulates secretory phase (negative feedback mechnisim).
Progesterone X
Estrogen
FSH
The corpus luteum * * begins to produce and release the hormone progesterone * which inhibits the production of FHS and LH by the anterior pituitary * and stimulates the secretory phase of the ovarian cycle. * LH

16. Hormonal Regulation of Ovarian & Menstrual Cycles
11. Diminishing levels of FSH & LH cause corpus luteum to deteriorate & produce less progesterone.
12. Diminishing levels of estrogen & progesterone cause inhibition of FSH & LH to end & thickened endometrium to slough (menses). X
Estrogen
Progesterone
FSH LH
* Diminishing levels of FSH & LH cause the corpus luteum to deteriorate & produce less progesterone. * * * Diminishing levels of estrogen and progesterone * stop the inhibition of FSH & LH by the pituitary gland. * In the absence of adequate levels of progesterone, the thickened endometrium sloughs, causing menses to occur. * X

17. Hormonal Regulation of Ovarian & Menstrual Cycles
13. Increasing levels of FSH cause a new cycle to begin.
FSH
* Increasing levels of FSH * cause a new cycle to begin. *

18. Menstrual (Uterine) Cycle
Cyclic changes of the endometrium
Regulated by cyclic production of estrogens and progesterone
Stages of the menstrual cycle
Menses – functional layer of the endometrium is sloughed
Proliferative stage – regeneration of functional layer
Secretory stage – endometrium increases in size and readies for implantation
Slide 16.38
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

19. Hormonal Control of the Ovarian and Uterine Cycles
Figure 16.12a, b
Slide 16.39a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

20. Hormonal Control of the Ovarian and Uterine Cycles
Figure 16.12c, d
Slide 16.39b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

21. Hormone Production-Ovaries
Estrogens
Produced by follicle cells
Cause secondary sex characteristics
Enlargement of accessory organs
Development of breasts
Appearance of pubic hair
Increase in fat beneath the skin
Widening and lightening of the pelvis
Onset of menses
Slide 16.40
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

22. Hormone Production by the Ovaries
Progesterone
Produced by the corpus luteum
Production continues until LH diminishes in the blood
Helps maintain pregnancy
Slide 16.41
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

23. Progesterone: Source: Corpus Luteum & Placenta Targets & Functions:
Females - Uterus
Maintains thickened endometrium
Stimulates nutrient release
Quiets myometrium
Corpus luteum
Females - Breasts
Stimulates development of alveoli for milk production
Progesterone * is produced initially by the corpus luteum. * If pregnancy occurs, progesterone is also produced by the placenta as well. * It also has several targets and functions within the body. * One of the target organs of progesterone is the uterus. It maintains the thickened condition of the endometrium, stimulates nutrient release from the blood vessels in the walls of the uterus, and decreases muscular contractions of the myometrium. * Progesterone also affects the breasts by stimulating the development of the milk producing glands (alveoli). * Progesterone has the effect on the anterior pituitary gland of inhibiting the production and release of both FSH and LH. *
Females - Anterior Pituitary
Inhibits production & release of FSH & LH