fallopian tubes
Transcription
fallopian tubes
1. 2. 3. 4. 5. Consists of: Ovaries or paired gonads Oviducts (Fallopian Tubes) Uterus Vagina Associated Structures (External Genitalia, Mammary Glands) Unlike the male, the human female has a reproductive system located entirely in the pelvis The external part of the female reproductive organs is called the vulva. A female's internal reproductive organs are: the vagina, uterus, fallopian tubes, and ovaries. At the upper corners of the uterus, the fallopian tubes (oviduct) connect the uterus to the ovaries. Small almond shaped bodies (3.8 cm in length) Contains clusters of cells called follicles, each which produces one egg. Other cells in the follicles nourish the growing and maturing egg cell (ovum). The cell contains little yolk. Maturation is slow, and the ovaries may contain many follicles at different stages of development. Ovaries produce, store, and release eggs into the fallopian tubes in the process called ovulation. Called oviduct, uterine tubes or ovarian tubes The passageway for the ovum between the ovary and the uterus Located on each side of the uterus, oviducts are about 10 to 12.5 cm long. As the ovum bursts from the ovary into the pelvic cavity, the oviduct catches it in structures called fimbriae Fimbriae are the fringe-like ends of the fallopian tubes Cilia on the inner surfaces of frimbrae and on the lining of the oviducts move the ovum towards the uterus Smooth muscles of the oviducts contract in peristaltic waves to propel the ovum The inner layer of the oviducts contains mucous-secreting cells that may assist in transporting the ovum and provide nutrients for the ovum Fertilization of the ovum normally occurs midway in the oviduct Implantation happens in the uterus. If implantation happens in the fallopian tubes it causes an ectopic pregnancy or tubal pregnancy Hollow, muscular, upside-down pear-shaped organ Found in the pelvic cavity above and behind the bladder Non-pregnant uterus is about 7.5 cm long and 5 cm wide and 2.5 cm thick During pregnancy the uterus increases in size about 16 times the above dimensions The fundus is the upper part of the uterus; the oviducts enter here The body is the broad central portion The cervix is the narrow end, which opens into the vagina The uterus has three layers; serous, muscular, and mucous The serous layer is called the perimetrium The muscular layer is called the myometrium; it is the smooth muscle that increases in size during pregnancy and contracts during labor and delivery The mucous layer is the endometrium, which forms the maternal portion of the placenta during pregnancy At the bottom of the uterus is the cervix. The cervix has strong, thick walls. The opening of the cervix is very small (no wider than a straw). During childbirth, the cervix can expand to allow a baby to pass. The vagina connects with the uterus at the cervix About 10 cm long Glandular secretions from mucous membrane moisten the vagina. Mucus is acidic and retards microbial growth Rugae are expandable folds within the vagina walls that accommodate insertion of the penis and passage of the fetus during childbirth Vagina’s functions are to receive sperm, provide an exit for menstrual flow and to serve as the birth canal Mons pubis – rounded part of fat in front, covered by dense skin and during puberty becomes covered with hair Labia majora – two prominent longitudinal folds of skin and underlying fat that extend backward from the mons pubis towards the anus. Skin of this contains numerous hair follicles and sweat glands Labia minor – two small folds of skin which unite just above the clitoris to form the prepuce Between labia major No hair follicles or sweat glands Clitoris – Small erectile structure that responds to sexual stimulation Similar in structure and origin to the penis Vestibule Floor – The labia minor skin folds can be spread apart to expose the vestibule floor Contains Bartholin’s glands, which lubricate the vagina Vagina and urethra open in this area Modified sweat glands Located in breasts Hormones (prolactin and oxytocin) stimulate them to produce and release milk after childbirth Each breast is divided into 15 to 20 lobes of glandular tissue covered by adipose (fat) tissue Structure of the breast include the nipple, the areola, and the areolar glands Nipple is a circular projection containing some erectile tissue Nipple if surrounded by pigment areola. Areolar glands make the areolar appear rough. Secretions prevent the nipples from drying out. Egg cells are produced in the ovaries of female organisms A diploid cell in the ovaries called the primary oocyte undergoes meiosis. In the first meiotic division, a large cell called the secondary oocyte and smaller cell called the first polar body are produced. Oogenesis – production of egg cells in females The secondary oocyte undergoes a second meiotic division, forming a large cell called an ootid and a second polar body. Sometimes, the first polar bodies divide into two second polar bodies. The ootid develops into the mature haploid egg cell, or ovum. The polar bodies do not develop into egg cells. The ovum contains more cytoplasm than the polar bodies The extra cytoplasm is used as food during early development of a new organism. Only 1 egg (ovum) gets made during meiosis Females have about 2 million oocytes in their ovaries at birth and only 400-500 are released during the reproductive years. The rest get absorbed by the body. At birth, primary oocytes have already entered meiosis l, but stay in prophase l until females enter reproductive age. When a girl begins her menstrual cycle meiosis continues and eggs are produced. When a woman hits menopause, she stops producing eggs.
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