Reproductive System Cont.

Female Anatomy & Physiology

Chapter 28

FEMALE ANATOMY• Ovaries = produce eggs

• Ovarian follicles = contain eggs in various stages of development and the cells that surround them; surrounding cells nourish the eggs & produce estrogen

• Corpus luteum = remnants of a mature follicle after ovulation (after egg is released); produces estrogen, progesterone, and relaxin

• Uterine tubes (oviducts/fallopian tubes) = transport eggs from the ovary to the uterus; fertilization occurs in the oviducts

• Uterus = organ in which the fetus develops

• Endometrium = uterine lining

• Cervix = lower end of uterus

• Vagina = passageway between the uterus and the outside

• Vulva = external genitals of the female

Female Reproductive

Cycles:1. Ovarian Cycle

& 2. Menstrual

(Uterine) Cycle

Female Reproductive CyclesFemale reproductive cycles prepare the female body for

pregnancy

1. Ovarian cycle = cyclic events that occur in the ovaries

2. Menstrual (uterine) cycle = cyclic events that occur in the uterus

• Last 28 days on average

• Influenced by

1. hormones secreted by pituitary gland: FSH and LH

2. hormones secreted by ovary: estrogen and progesterone

OVARIAN CYCLE1. Follicular phase – prior to ovulation:

• One ovarian follicle becomes the dominant follicle and begins to mature when the pituitary gland releases FSH

• Maturing follicle releases estrogen and causes the pituitary gland to release LH (this is an example of positive feedback: an increase in one hormone results in increase of another hormone)

2. Ovulation (day 14):

• levels of LH reach its peak and initiate ovulation

• Ovulation = egg is released from the dominant follicle

3. Luteal phase – after ovulation:

• Ruptured follicle becomes corpus luteum and secretes estrogen and progesterone

• High levels of estrogen and progesterone inhibit FSH and LH (this is an example of negative feedback: increase in one hormone results in decrease of another hormone)

MENSTRUAL CYCLE

• If the egg does not become fertilized, levels of estrogen and progesterone fall and cause endometrium to be shed = menstrual flow or menstruation (days 1-5)

• Starting with day 6, increasing levels of estrogen cause endometrium to thicken and prepare uterus for possible implantation of fertilized egg

FERTILIZATION

• Fertilization = union of sperm and egg; the resulting cell is called zygote

• Takes place in the uterine tube

IMPLENTATION

• Implentation = the zygote passes into the uterus where it attaches into the uterine lining (by the sixth day after fertilization)