Sunday, July 26, 2020

Human Reproduction - Notes | Class 12 | Part 2: Female Reproductive System

3. HUMAN REPRODUCTION


2. Female Reproductive System

It is located in the pelvic region.

It includes Ovaries, Accessory ducts & External genitalia.



a. Paired ovaries


-    Primary sex organs which produce ova (female gamete) & steroid ovarian hormones (estrogen & progesterone).

-    Each ovary is 2-4 cm in length.

-    They are located on both side of the lower abdomen and connected to the pelvic wall and uterus by ligaments.

-    Each ovary is covered by a thin epithelium which encloses the ovarian stroma.

-    The stroma has outer cortex and inner medulla.

-    Ovarian cortex contains groups of cells (Ovarian follicles). Each follicle carries a centrally placed ovum.


b. Accessory ducts (Duct system)


Include 2 oviducts (Fallopian tubes), a uterus & vagina.

Ø Oviducts: Each oviduct (10-12 cm long) has 3 parts: 

·   Infundibulum: Funnel-shaped opening provided with many finger-like fimbriae. It helps to collect the ovum.

·   Ampulla: Wider part.

·   Isthmus: Narrow part. It joins the uterus.

The ciliated epithelium lined the lumen of the oviduct drives the ovum towards the uterus.

Ø Uterus (womb):  It is inverted pear shaped. It is supported by ligaments attached to the pelvic wall.

Uterus has 3 parts: Upper fundus, middle body and terminal cervix. Cervix opens to vagina.

Cervical canal and vagina forms birth canal.

The uterine wall has 3 layers:

·     Perimetrium: External thin membrane.

·     Myometrium: Middle thick layer of smooth muscle.

·     Endometrium: Inner glandular and vascular layer.

Ø Vagina: It opens to the exterior between urethra & anus.


c. External genitalia (vulva or pudendum)


-    Consist of Mons pubis, labia majora, labia minora, hymen & clitoris.

-    Mons pubis: A cushion of fatty tissue covered by pubic hair.

-    Labia majora: Large, fleshy, fatty and hairy outer folds. Surrounds vaginal opening.

-    Labia minora: Small, thin and hairless inner folds.

-    Hymen (Maiden head): A membrane which partially cover the vaginal opening. It is often torn during the first coitus. It may also be broken by a sudden fall or jolt, insertion of a vaginal tampon; active participation in some sports items etc. In some women, hymen persists after coitus. So the hymen is not a reliable indicator of virginity or sexual experience.

-    Clitoris: A highly sensitive organ lying just in front of the urethral opening.


Mammary glands (breasts)


-    A pair of mammary glands contains glandular tissue & fat.

-    Glandular tissue of each breast has 15-20 mammary lobes containing clusters of cells (mammary alveoli).

-    Cells of alveoli secrete milk. It is stored in lumen of alveoli.

-    The alveoli open into mammary tubules.

-    The tubules of each lobe join to form a mammary duct.

-    Several mammary ducts join to form a wider mammary ampulla which is connected to lactiferous duct through which milk is sucked out.

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