Female reproductive system:Four functions• Produces female sex hormones: estrogen and progesterone

• Makes and stores reproductive egg cells, commonly referred to as eggs

• Provides a place for fertilization to occur

• Nourishes the fertilized egg, and the developing fetus until it has matured enough to live outside the mother’s womb (the gestation period)

Organs• The major organs are the two ovaries, the uterus, the fallopian

tubes and the vagina.. • The ovaries produce egg cells that move through the fallopian

tubes to the uterus.

• The uterus holds the egg after fertilization until birth. In the birthing process the vagina that connects to the uterus becomes the passageway for the baby to be born.

• If the egg is not fertilized, the lining of the uterus (the endometrium) is sloughed off and passes out of the body through the uterus.

Ovaries: • These two almond-shaped glands,

which are also a part of the endocrine system, release egg cells, or ova, and create the female sex hormones (estrogen and progesterone) that promote female sexual development.

• Located on either side of the uterus, the ovaries grow from one-two inches in length during puberty and consist primarily of immature eggs surrounded by hormone-producing cells and connective tissue.

• Females are born with 40,000 - 300,000 immature egg cells in each ovary.

• Fallopian tubes: Two fallopian tubes provide passageways for ova from the right and left ovaries to the uterus. After the ova are released from the ovaries they pass through the fallopian tubes to the uterus.

• Uterus: A pear-shaped, hollow organ that holds the fertilized egg until birth, the uterus has thick, muscle-tissue walls. The lower narrow portion of the uterus is the cervix, which joins the uterus to the vagina.

• Vagina: Passage from the uterus to the outside of the body. The vagina receives the sperm from the male before it moves into the uterus, serves as the birth canal when the baby is ready to leave the womb, and moves menstrual blood (the sloughed lining of the uterus) out of the body in the monthly cycle.

Menstrual Cycle• Ovaries produce one mature egg during each menstrual cycle,

usually in the midpoint of the cycle. This release of the mature egg is called ovulation. If the egg is not fertilized the thick uterine lining, the endometrium, leaves the body.

• Contraction of the muscles of the uterus causes the endometrium to be expelled. These muscle contractions may create an uncomfortable cramping sensation.

• The menstrual cycle encompasses the entire sequence of events from one menstruation to the next. The average cycle takes 28 days and occurs monthly until menopause.

Cycle Stages: Days 1 – 13: New egg is maturing in the ovary. Day 14: Ovulation occurs; new egg is released. Days 15 – 20: Egg moves through fallopian tube, where fertilization is most

likely to occur. Days 21 – 28: Egg enters uterus. If it is not fertilized, menstruation begins.

Menstrual flow lasts between five - seven days.

Sexual life in females:• Life span of females divided in three periods:1. First period: this extends from birth to puberty. During this

period, primary and accessory organs do not function. Puberty occurs at the age of 12 years.

2. Second period: it extends from the onset of the puberty to the onset of the menopause. The first menstrual cycle is known as ‘menarche’. The permanent stoppage of the menstrual cycle is known as ‘menopause’, which occurs at the age of about 45 to 50 years.

3. Third period: this period extends from menopause to the rest of life.

Placenta:• Placenta forms a link between the fetus and mother.• It is not only physical attachment between the fetus and mother,

but also forms the physiological connection between the two.Functions of the Placenta:1) Nutritive function: various nutrients and other substances

necessary for the development of the fetus diffuse from the mother’s blood into the fetal blood through placenta.

2) Excretory function: the metabolic end products and other waste products from the fetal body are excreted into the mother’s blood through placenta.

3) Respiratory function: fetal lungs are non functioning. So the placenta forms the respiratory organ for the fetus. Oxygen necessary for fetus is received from the maternal blood and carbon dioxide from the fetal blood diffuses into the mother’s blood through placenta.

Exchange of respiratory gases between fetal and maternal blood• Pressure gradient is responsible for exchange of respiratory

gases between fetal blood and maternal blood.• Partial pressure of oxygen in the maternal blood – 50 mm Hg Whereas partial pressure of oxygen in fetal blood – 30 mm Hg• Pressure gradient of 20 mm Hg causes diffusion of oxygen into

the fetal blood.• This pressure gradient is very low still adequate quantity of

oxygen remains available for the fetus because:

1. The hemoglobin in the fetal blood has got 20 times more affinity than the adult hemoglobin.

2. The concentration of hemoglobin is about 50% more in fetal blood than in adult blood

Endocrine function:Four hormones are secreted from the placenta namely1) Human Chorionic Gonadotropin also known as HCG:Functions: Effect on corpus luteum: HCG is responsible for the preservation and the secretary

activity of corpus luteum. Progesterone and estrogen secreted by corpus luteum are

essential for maintenance of pregnancy. Deficiency or absence of HCG during the first two months of

pregnancy leads to abortion, because of inovulation of corpus luteum.

Effect on fetal testes: It stimulates interstitial cells of Leydig and causes secretion of

testosterone. The testosterone is necessary for the development of sex organs in the male fetus.

2) Estrogen: Functions:• Effect on uterus: estrogen causes enlargement of uterus so

that, the growing fetus could be accommodated.• Effect on breasts: this hormone is responsible for the

enlargement of the breasts and growth of the duct system in the breasts.

• Effect on the external genitalia: it causes enlargement of the female external genitalia.

• Effect on pelvis: it causes relaxation of the pelvic ligaments. This facilitates the passage of the fetus through the birth canal at the time of labor.

Progesterone:FunctionsEffect on endometrium of uterus: It accelerates the proliferation and development of decidual

cells in the endometrium of uterus. The decidual cells are responsible for the supply of nutrition to

the embryo at the early stage. Effect on the movement of the uterus: It inhibits contraction of

muscles in the pregnant uterus and thereby it prevents expulsion of the fetus.

Effect on breasts: It is also responsible for development and preparation of the mammary glands for lactation.

Human Chorionic Somatomammatropin:• It is believed to act on mammary glands and to enhance growth

of the fetus by influencing the metabolic activities.FunctionsEffects on the breasts: in pregnant women this function is not

known.Effect on protein metabolism: it acts like growth hormone of the

pituitary gland and cause anabolism of proteins as well accumulation of the protein. Thus the growth of the fetus is enhanced.

Effect on the carbohydrate metabolism: it reduces peripheral utilization of glucose in the mother leading to availability of large quantity of glucose to growing fetus.

Effect on lipid metabolism: it mobilizes fat from the adipose tissue of the mother. Large amount of free fatty acids made available as the source of energy for mother’s body. This compensate loss of glucose from the mother’s blood to fetus.

Fetoplacental Unit:• Fetus and placenta interact with each other in the synthesis of

some steroid hormones.

• This is because some of the enzymes involved in steroid synthesis present in the fetus are absent in placenta and, those enzymes which are absent in the fetus are present placenta.

• Due to this interaction during synthesis of steroid hormones fetus and placenta are together called fetoplacental unit.

Function