Female Reproductive System and Hormones

Female Reproductive System

• Ovaries• fallopian tubes• uterus• vagina• External

genitalia

External Genitalia (Vulva)

• Labia – skin folds– Labia majora– Labia minora

• Urethra- urination• Clitoris

– Contains erectile tissue– Corresponds to the male penis

Vagina

• Extends from cervix to exterior of body• Behind bladder and in front of rectum• Serves as the birth canal• Receives the penis during sexual

intercourse

Uterus• Located between the urinary bladder and

rectum• Hollow organ• Functions of the uterus– Receives a fertilized egg– Retains the fertilized egg– Nourishes the fertilized egg

• Fundus – area where uterine tube enters• Cervix – narrow outlet that protrudes into the

vagina

Female Reproductive System

Fallopian Tubes• Receive egg as it is released from the follicle

• Does not physically attach to the ovary

• Fimbriae – finger-like projections at the distal end that receive the egg

• Cilia inside the fallopian tube slowly move the egg towards the uterus (takes 3–4 days)

• Fertilization occurs inside the fallopian tube

Fallopian Tubes

Ovaries• Composed of ovarian

follicles• Structure of an ovarian

follicle– Oocyte (future egg)– Follicular cells

• Ovarian Follicle Stages:– Primary follicle –

contains an immature oocyte– Graafian follicle – growing follicle with a maturing oocyte– Ovulation – when the egg is mature the follicle ruptures

• Occurs about every 28 days– The ruptured follicle is transformed into a corpus luteum

(secretes hormones)

Oogenesis

Sexual Maturation & Reproduction• In females, the total supply of eggs are present at birth,

but the ability to release eggs only begins at puberty.• During fetal development the ovaries contain several

million immature oocytes• After birth, no new ones are formed, many degenerate

and only approximately one million remain• By puberty, only approximately 400,000 are left• Fewer than 400-500 are released throughout the

female reproductive life (on average one per month)• Female reproductive ability ends with menopause which

normally occurs in women between age 45 and 55.

Menstrual Cycle• Cyclic changes of the endometrium (uterine lining)

– Averages 28 days• Regulated by cyclic production of estrogens and

progesterone• Stages of the menstrual cycle– Proliferative stage – regeneration of functional

layer– Ovulation- the follicle is stimulated to release the

egg– Secretory stage – endometrium increases in size

and readies for implantation– Menses – functional layer of the endometrium is

sloughed

Hormone Production by the 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

• Progesterone– Produced by the corpus luteum– Production continues until LH diminishes in the

blood– Helps maintain pregnancy

• Work together to develop uterine lining

Hormone Production by the Ovaries

• Follicle Stimulating Hormone (FSH)– Stimulates the development of the follicle– Initiates the release of the egg from the follicle

• Luteinizing Hormone– Helps to stimulate egg production and release– Involved with the development of the

Endometrium

Walls of the Uterus• Endometrium– Inner layer (uterine lining)– Allows for implantation of a fertilized

egg– Sloughs off if no pregnancy occurs

(menstruation)• Myometrium – middle layer of smooth

muscle (contractions during labor)

Hormonal Control of the Ovarian and Uterine Cycles

Sexual Maturation & Reproduction

• Ovulation occurs about 14 days before the end of the cycle

• If no sperm is present in the fallopian tubes shortly after ovulation, there is no fertilization– ovaries stop releasing estrogen & progesterone • the endometrium breaks down & is shed as menses• causes irritability, depression, breast tenderness =

PMS

Sexual Maturation & Reproduction• If sperm is present in the fallopian tubes it joins with the

egg for fertilization– Fertilized egg travels down the fallopian tube– zygote implants in endometrium– corpus luteum continues to release progesterone & estrogen

• Supports the vascular & muscular development of uterus

– uterine wall develops placenta• Pouch or sac that grows around the embryo and connects the mother

and child• Important for gas exchange b/t mom & baby• Produces hormone (HCG) Human Chorionic Gonadotropin which

stimulates the corpus luteum to continue releasing hormones• Is the “afterbirth” after delivery