Tuesday, January 8, 2013

Female Reproductive Organs Anatomy



female reproductive system

Internal female reproductive organs

Vagina

The vagina is a muscular, hollow tube that extends from the vaginal opening to the cervix of the uterus. It is situated between the urinary bladder and the rectum. It is about three to five inches long in a grown woman. The muscular wall allows the vagina to expand and contract. The muscular walls are lined with mucous membranes, which keep it protected and moist. A thin sheet of tissue with one or more holes in it, called the hymen, partially covers the opening of the vagina. The vagina receives sperm during sexual intercourse from the penis. The sperm that survive the acidic condition of the vagina continue on through to the fallopian tubes where fertilization may occur.
The vagina is made up of three layers, an inner mucosal layer, a middle muscularis layer, and an outer fibrous layer. The inner layer is made of vaginal rugae that stretch and allow penetration to occur. These also help with stimulation of the penis. microscopically the vaginal rugae has glands that secrete an acidic mucus (pH of around 4.0.) that keeps bacterial growth down. The outer muscular layer is especially important with delivery of a fetus and placenta.
Purposes of the Vagina
  • Receives a male's erect penis and semen during sexual intercourse.
  • Pathway through a woman's body for the baby to take during childbirth.
  • Provides the route for the menstrual blood (menses) from the uterus, to leave the body.
  • May hold forms of birth control, such as a  FemCap, Nuva Ring, or female condom.

Cervix

The cervix (from Latin "neck") is the lower, narrow portion of the uterus where it joins with the top end of the vagina. Where they join together forms an almost 90 degree curve. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall.
During menstruation, the cervix stretches open slightly to allow the endometrium to be shed. This stretching is believed to be part of the cramping pain that many women experience. 
Uterus
The uterus is a hollow, pear-shaped organ that is the home to a developing fetus. The uterus is divided into two parts: the cervix, which is the lower part that opens into the vagina, and the main body of the uterus, called the corpus. The corpus can easily expand to hold a developing baby. A channel through the cervix allows sperm to enter and menstrual blood to exit.
Fallopian Tubes
There are two fallopian tubes, also called the uterine tubes or the oviducts.The fallopian tubes are a pair of muscular tubes that extend from the left and right superior corners of the uterus to the edge of the ovaries. The fallopian tubes end in a funnel-shaped structure called the infundibulum, which is covered with small finger-like projections called fimbriae. The fimbriae swipe over the outside of the ovaries to pick up released ova and carry them into the infundibulum for transport to the uterus. The inside of each fallopian tube is covered in cilia that work with the smooth muscle of the tube to carry the ovum to the uterus where it implants into the lining of the uterine wall.
external female genitaliaExternal female genitals
Vulva
The external female genitalia is referred to as vulva. It consists of the labia majora and labia minora (while these names translate as "large" and "small" lips, often the "minora" can protrude outside the "majora"), mons pubis, clitoris, opening of the urethra (meatus), vaginal vestibule, vestibular bulbs, vestibular glands.
Mons Veneris
The mons veneris is the soft mound at the front of the vulva (fatty tissue covering the pubic bone). It is also referred to as the mons pubis. The mons veneris protects the pubic bone and vulva from the impact of sexual intercourse. After puberty, it is covered with pubic hair.
Labia Majora
The labia majora are the outer "lips" of the vulva.  The labia majora wrap around the vulva from the mons pubis to the perineum. The labia majora generally hides, partially or entirely, the other parts of the vulva.  These labia are usually covered with pubic hair. 
Labia Minora
Medial to the labia majora are the labia minora. The labia minora are the inner lips of the vulva. They are thin stretches of tissue within the labia majora that fold and protect the vagina, urethra, and clitoris.  The labia minora protect the vaginal and urethral openings. Both the inner and outer labia are quite sensitive to touch and pressure.
Clitoris
The clitoris, visible as the small white oval between the top of the labia minora and the clitoral hood, is a small body of spongy tissue that functions solely for sexual pleasure.
During sexual excitement, the clitoris erects and extends, the hood retracts, making the clitoral glans more accessible. 
Urethra
The opening to the urethra is just below the clitoris. Although it is not related to sex or reproduction, it is included in the vulva. The urethra is actually used for the passage of urine. The urethra is connected to the bladder. 
Hymen
The hymen is a thin fold of mucous membrane that separates the lumen of the vagina from the urethral sinus. Sometimes it may partially cover the vaginal orifice. The hymen is usually perforated during later fetal development.
Perineum
The perineum is the short stretch of skin starting at the bottom of the vulva and extending to the anus. It is a diamond shaped area between the symphysis pubis and the coccyx. This area forms the floor of the pelvis and contains the external sex organs and the anal opening.

Mammary glands


Cross section of the breast of a human female.
Mammary glands are the organs that produce milk for the sustenance of a baby. These exocrine glands are enlarged and modified sweat glands. 
The basic components of the mammary gland are the alveoli (hollow cavities, a few milli metres large) lined with milk-secreting epithelial cells and surrounded by myoepithelial cells. These alveoli join up to form groups known as lobules, and each lobule has a lactiferous duct that drains into openings in the nipple. The myoepithelial cells can contract, similar to muscle cells, and thereby push the milk from the alveoli through the lactiferous ducts towards the nipple, where it collects in widenings (sinuses) of the ducts. A suckling baby essentially squeezes the milk out of these sinuses.
The development of mammary glands is controlled by hormones. The mammary glands exist in both sexes, but they are rudimentary until puberty when - in response to ovarian hormones - they begin to develop in the female. Estrogen promotes formation, while testosterone inhibits it.
At the time of birth, the baby has lactiferous ducts but no alveoli. Little branching occurs before puberty when ovarian estrogens stimulate branching differentiation of the ducts into spherical masses of cells that will become alveoli. True secretory alveoli only develop in pregnancy, where rising levels of estrogen and progesterone cause further branching and differentiation of the duct cells, together with an increase in adipose tissue and a richer blood flow.
Colostrum is secreted in late pregnancy and for the first few days after giving birth. True milk secretion (lactation) begins a few days later due to a reduction in circulating progesterone and the presence of the hormone prolactin. The suckling of the baby causes the release of the hormone oxytocin which stimulates contraction of the myoepithelial cells.
The cells of mammary glands can easily be induced to grow and multiply by hormones. If this growth runs out of control, cancer results. Almost all instances of breast cancer originate in the lobules or ducts of the mammary glands. 

STRUCTURELOCATION & DESCRIPTIONFUNCTION
BreastsUpper chest one on each side containing alveolar cells (milk production), myoepithelial cells (contract to expel milk), and duct walls (help with extraction of milk).Lactation milk/nutrition for newborn.
CervixThe lower narrower portion of the uterus.During childbirth, contractions of the uterus will dilate the cervix up to 10 cm in diameter to allow the child to pass through. During orgasm, the cervix convulses and the external os dilates
ClitorisSmall erectile organ directly in front of the vestibule.Sexual excitation, engorged with blood.
Fallopian tubesExtending upper part of the uterus on either side.Egg transportation from ovary to uterus (fertilization usually takes place here).
HymenThin membrane that partially covers the vagina in young females.
Labia majoraOuter skin folds that surround the entrance to the vagina.Lubrication during mating.
Labia minoraInner skin folds that surround the entrance to the vagina.Lubrication during mating.
MonsMound of skin and underlying fatty tissue, central in lower pelvic region
Ovaries (female gonads)Pelvic region on either side of the uterus.Provides an environment for maturation of oocyte. Synthesizes and secretes sex hormones (estrogen and progesterone).
PerineumShort stretch of skin starting at the bottom of the vulva and extending to the anus.
UrethraPelvic cavity above bladder, tilted.Passage of urine.
UterusCenter of pelvic cavity.To house and nourish developing baby.
VaginaCanal about 10-8 cm long going from the cervix to the outside of the body.Receives sperms during mating. Pathway through a womans body for the baby to take during childbirth. Provides the route for the menstrual blood (menses) from the uterus, to leave the body. May hold forms of birth control, such as an IUD, diaphragm, neva ring, or female condom.
VulvaSurround entrance to the reproductive tract.(encompasses all external genitalia)
EndometriumThe innermost layer of uterine wall.Contains glands that secrete fluids that bathe the utrine lining.
MyometriumSmooth muscle in uterine wall.Contracts to help expel the baby.



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