Reproductive system and pregnancy

body

middle region, major part of the organ and is composed of thick wall of smooth muscle.

hymen

mucosal folds project into the lumen to form a vascularized membranous barrier.

isthmus

narrow constricted inferior region of the body that is superior to cervix.

cervix

narrow inferiormost portion of uterus that projects into vagina.

polar body

nonfunctional cell that later regresses. as the secondary follicle matures into a vesicular follicle, its primary oocyte finishes meiosis I, and two cells form. one of these cells receives a minimal amount of cytoplasm and forms polar body. the other cell receives the bulk of the cytoplasm and becomes the secondary oocyte, which continues to develop and reaches metaphase II of meiosis before it is arrested again. this secondary oocyte does not complete meiosis unless it is fertilized by sperm. if oocyte is not fertilized, it breaks down and regress 24 hrs later.

fimbriae

numerous fingerlike folds. enclose ovary only at time of ovulation.

luteal phase

occurs during days 15-28 of ovarian cycle, when the remaining follicle cells in the ruptured vesicular follicle become the corpus luteum. the corpus luteum is essentially a temporary endocrine gland. it secretes progesterone and estrogen that stabilize and build up the uterine lining and prepare for possible implantation of fertilized oocyte. corpus luteum has a life span of about 10-13 days if the secondary oocyte is not fertilized.

Gametogenesis

Process of forming human sex cells, called gametes. female gametes are secondary oocytes (commonly referred to as eggs), whereas male gametes are sperm. the process of gametogenesis begins with a specific type of cell division called meiosis. the events of meiosis generally are similar in both females and males, with few differences. here we describe the basics of heredity and meiosis; sex specific differences are described later in this chapter.

meiosis

a type of sex cell division that starts off with a diploid parent cell and produces haploid daughter cells called gametes. (sex cell division) - mitosis produces two daughter cells that are genetically identical to the parent cell. in contrast, meiosis produces four daughter cells that are genetically different to the parent cell. - mitosis produces daughter cells that are diploid, whereas meiosis produces daughter cells that are haploid. - meiosis includes a process called crossing over, whereby genetic material is exchanged between homologus chromosomes.

menstruation

after this time, corpus luteum regresses and becomes a corpus albicans. as corpus luteum regresses, its level of secreted progesterone and estrogen drop, causing uterine lining to be a shed in a process.

uterine tubes

also called fallopian tubes or oviducts, extend laterally from both sides of uterus toward ovaries.

gonads

both female and male have primary reproductive organs. (ovaries and testes)produce sex cells.

diploid

cell that contains 23 pairs of chromosomes and to have 2 n chromosomes, where n is the unpaired chromosome #.

medulla

composed of areolar connective tissue and contains branches of ovarian blood vessels, lymph vessels, and nerves.

sex chromosomes

conisists of either 2 x or an x and y chromosome. these chromosomes primarily determine whether an individual is a female ( 2 x) or male ( 1 x 1 y) although they also contain genes that code for cellular functions.

haploid

contain 23 chromosomes and not 23 pairs. chromosome # is 1n or just n.

autosomes

contain genes that code for cellular functions. these genes also help determine most human characteristics, such as eye color, hair color, height, and skin pigmentation.

accessory reproductive organs

ducts to carry gametes away from gonads toward site of fertilization (in females) or to the outside of the body ( in males).

puberty

external sex characteristics become more prominent, such as breast enlargement in females, pubic hair growth in both sexes, and fully functional reproductive organs in both sexes. gametes begin to mature, and the gonads start to secrete sex hormones.

menarche

females first menstrual cycle, indicates culmination of femal puberty and typically occurs around age 11-12.

infundibulum

free, funnel shaped, lateral margin of uterine tube.

crossing over

genetic material is exchanged between homologus chromosomes.

human chrionic gonadotropin (hCG)

hormone that enters mothers blood and acts on corpus luteum. if secondary oocyte is fertilized and if it successfully implants in uterine lining, this fertilized structure, now called pre-embryo starts secreting hCG. essentially, hCG mimics effects of LH and continues to stimulate corpus luteum. as a result, corpus luteum continues producing progesterone and estrogen, which maintains and continues building uterine lining. after 3 months, placenta of developing fetus starts producing its own progesterone and estrogen. thus, typically by the end of the third month corpus luteum has usually regressed and formed corpus albicans.

vaginal orifice

inferior region of vaginal mucosa contains numerous transverse folds, or rugae. near external opening of vagina.

oogenesis

maturation of a primary oocyte to a secondary oocyte. we describe this process as it relates to the life stages of a female.

ovulation

occurs on day 14 of a 28 day ovarian cycle and is defined as the release of the secondary oocyte from a vesicular follicle. typically, only one ovary ovulates each month that is typically the left ovary ovulates one month and the right ovary ovulates next. ovulation is induced only when there is a peak in LH secretion. as the time of ovulation approaches, the follicle cells in the vesicular follicle increases their rate of fluid secretion, forming a larger antrum and causing further swelling within the follicle. the edge of the follicle that continues to expand at the ovarian surface becomes quite thin and eventually ruptures, expelling the secondary oocyte.

cortex

ovarian follicles

homologus chromosomes

pair of matching chromosomes.

ovaries

paired, oval organs located within the pelvic cavitiy lateral to the uterus. in adult, ovaries are slightly larger than an almond 2-3 cm long, 2 cm wide, and 1 to 1.5 cm thick. their size varies during each menstrual cycle as well as during pregnancy.

sex hormones

produced by gonads, affect maturation, development, and changes in activity of reproductive system organs.

gametes

produced by gonads, unite at fertilization to initiate the formation of a new indv.

copulation, coitus, sexual intercourse

sexual union between male and female. If fertilization occurs, then the support, protection, and nourishment, of developing human occurs within the female reproductive tract.

menses

shed lining or a period. mark ends lutueal phase.

homologues

some mature reproductive system structures in both sexes are derived from common developmental structures called primordial and serve common function in adults.

vagina

thick walled, fibromuscular tube that forms the inferiormost region of female reproductive tract and measures 10 cm in length in adult female. vagina connects uterus with outside of body and functions birth canal. also, the copulatory organ of female, as it receives the penis during intercourse, serves as passageway for menstruation.

ovarian cycle

when a female reaches puberty, the hypothalamus releases gonadotropin releasing horomone (GnRH) in a pulsatile manner. GnRH stimulates the anterior pituitary to release Follicle stimulating hormone (FSH) and luteinizing hormone (LH). the levels of fsh and lh vary in cylical pattern and produce a monthly sequence of events in follicle development . 3 phases follicular phase, ovulation, and luteal.

menopause

when a woman stops having monthly menstrual cycles for 1 year and is not pregnant, or has medical condition that leads to a cessation of menstruation such as extremely low body fat or in cases of anorexia nervosa.