STRUCTURE AND FUNCTION OF THE FEMALE

1.  Sketch and label the ovarian cycle pg. 404 Figure 19.11.  (or the oogenesis diagram on your handout).  Note that this fig represents the sequences in 1 complete cycle (28 days) and that all these parts are not present at any one time.

Label this diagram of the female reproductive system.

Ovary, showing all phases of 28 day cycle

(1) The Ovaries - 2 Functions
	 I Produce eggs from follicles
	 II Produces estrogen (from follicles) & progesterone (from corpus luteum)

(2) Oviducts (AKA fallopian tubes)
- connected to uterus & lie close to ovaries
- lined with cilia & surrounded by circular muscles
- purpose - I to propel egg toward uterus
		II to serve as site of fertilization. 

(3) Uterus (womb) - thick-walled, muscle lining - pear-shaped
		    - lined with a layer called the endometrium
		    - site of development of embryo.
			
(4) Cervix
	- entrance to uterus
	- path for sperm to swim through
	- produces mucin strands to facilitate sperm
	- also holds baby in the uterus

(5) Vagina
	- birth canal
	- receptacle for male’s penis

(6) Clitoris
	- sensitive organ analogous to male’s penis
	
FEMALE CYCLES AND HORMONE CONTROL

1.  Anterior Pituitary  - makes 2 hormones that act on the ovaries

a) FSH - Follicle Stimulating Hormone - stimulates the follicle to mature and 			causes it to produce estrogen
b) LH - Lutinizing Hormone - maintains the corpus luteum and causes it to 				produce progesterone

	- these are the Gonadotrophic Hormones  (FSH & LH)
	- they regulate the ovary’s production of female sex hormones
2.  Ovary  - makes 2 hormones that act on the endometrium (uterus lining)

a) Estrogen (made by the follicle)
b) Progesterone (made by the corpus luteum)

PITUITARY FEEDBACK

Hypothalamus 

ant. pituitary

					FSH		          LH

OVARY

				   follicle			    corpus 
								      luteum

				Estrogen			Progesterone

These feedback controls are more complicated than the male and do not try to 	        maintain homeostasis. Hormone levels may vary.

The Female cycles
	- there are two cycles -> i) Ovarian cycle
				     ii) Menstrual cycle (Uterine Cycle)

i) Ovarian cycle (28 days average)

Days 1-14	Folicular Phase
	-FSH released from ant. pit.
	- stimulates the development of a follicle (unfertilized egg)
	- follicle begins to secrete estrogen , so the level of this hormone steadily 
increases

Day 14
	- Ovulation - follicle releases egg  (a peak of LH from ant. pit. stimulates this)

Day 15-28  Luteal Phase
	- follicle turns into corpus luteum
	- LH from ant. pit. stimulates the production of progesterone
	- as progesterone increases, ant. pit. decreased LH so corpus luteum begins 		   to degenerate
	- when corpus luteum is gone, menstruation occurs

ii) Menstrual Cycle

Days 1-5
	- low level of estrogen and progesterone
	- cause thickened uterine lining to degenerate and shed menstruation “period’

Days 6-13
- estrogen (from follicle) is increasing which causes a thickening of the uterus wall (endometrium)
	- extra blood vessels and glands

Day 14
	- Ovulation

Day 15-28
- increased levels of progesterone causes endometrium to thicken further (2x) and  thick mucous secretion
	- endometrium is ready to receive fertilized egg (zygote)

NORMALLY ->
	- egg is not fertilized therefore corpus luteum begins to degenerate therefore 		  progesterone falls
- low progesterone and estrogen cause endometrium to be  shed. Menstruation begins

Note: if pregnancy occurs, the zygote implants in the thick endometrium and prevents the corpus luteum from degenerating.  This keeps up progesterone levels and prevents the endometrium (and zygote from being shed).

 Put diagram. of cycles and hormones in notes  p.404 

FSH & LH

1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16 17 18 19  20  21  22  23 24  25 26 27  28   1   2   3

OVARIAN
CYCLE

1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16 17 18 19  20  21  22  23 24  25 26 27  28   1   2   3

ESTROGEN &
PROGESTERONE

1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16 17 18 19  20  21  22  23 24  25 26 27  28   1   2   3

ENDOMETRIUM

1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16 17 18 19  20  21  22  23 24  25 26 27  28   1   2   3	

IMPLANTATION
- fertilized egg attaches to endometrium (uterus wall) several days after fertilization
	- hormones are produced by the zygote to prevent menstruation
- HCG - Human Chorionic Gonadotrophin is the hormone, and it maintains the corpus luteum which continues to produce progesterone which prevents the endometrium from shedding.  Pregnancy test tests for this hormone.
	- corpus luteum persists for 3 - 6 months
- endometrium and fetus develop the placenta  (organ of exchange between maternal and fetal blood systems)
- the placenta continues production of HCG, and also produces progesterone and estrogen.  Higher levels of these 2 hormones shut off release of FSH from ant. pit. preventing ovulation and maintaining the endometrium. (Birth control pill also)

ESTROGEN
- has many affects on the body
- egg maturation
- growth of vagina and uterus at puberty
- pubic hair
- fat development and distribution
- widening of pelvic girdle
- breast development

OXYTOCIN - POSITIVE FEEDBACK

Oxytocin is a hormone produced by the Posterior pituitary gland.  It is the hormone that begins and controls birth contractions. (It is also involved in the milk letdown response in breast feeding).  It is one of the only examples of a hormone under control of a positive feedback system.

Positive Feedback:
	- very rare
	- leads to increasing instability
	- Oxytocin (Hormones ——› Labor contractions)

          +        OXYTOCIN
- This leads to stronger and more 							frequent contractions until the birth 
of the baby
				     +
           BIRTH CONTRACTION

Written Questions
1.	Identify the functions of each of the following structures: ovaries, oviducts, uterus, endometrium, cervix, vagina and clitoris. (7)
2.	Give the path of the egg.  Where does fertilization and implantation occur? (5)
3.	How do the male and female urethras differ in function? (2)
4.	Describe the events and hormonal control of the ovarian cycle.  Your answer should make reference to the three phases of this cycle (follicular, ovulation, luteal phase).  (6)
5.	Describe the events and hormonal control of the uterine cycle.   Your answer should include reference to the 3 phases of this cycle (menstruation, proliferative, and secretory phase). (6) 
6.	What hormonal changes occur because of implantation? (2)
7.	How is menstruation prevented if pregnancy occurs? (1)
8.	Describe the positive feedback mechanism involving oxytocin during childbirth. (2)