REPRODUCTIVE ANATOMY & PIISIOLOGY CH 5

Seminal fluid:

- nourishes sperm - protects sperm from acidic vaginal environment - enhances sperm motility - washes sperm out of the urethra so the maximum number are deposited in the vagina.

Penis: 2 functions

- part of the urinary tract - as a reproductive organ

The testes: 2 functions

- serve as endocrine glands - produce male gametes (or sperm/spermatozoa)

3 Glands secrete seminal fluid that carry sperm into the vagina during intercourse:

1. seminal vesicles 2. prostate 3. bulbourethral glands

Ovaries:

2 Functions: to produce sex hormones; develop ovum to maturity each reproductive cycle. Secrete estrogen & progesterone at varying levels to prepare the uterus for pregnancy. Hormone secretion gradually declines during the climacteric. At birth, the ovary contains all the ova it will ever have.

Fallopian Tubes: (also known as "Oviducts") 8-14 cm (3.2-5.6 ") Long; Narrow 2-3 mm/ 5-8 mm at widest It is the pathway for ovum between ovary and uterus; lined with cilia to propel ovum thru tubes; enters the upper uterus at the cornu, or horn, of the uterus.

4 areas of tubes are: 1. Interstitial Portions: funs into the uterine cavity & lies with in Uterine walls. 2. Isthmus: narrow part of tube adjacent to the uterus. 3. Ampulla: Wider area of tube, lateral to Isthmus; where fertilization takes place. 4. Infundibulum: Wide, funnel shape, terminal end of tube; Fimbriae are finger-like projections that surround the Infundibulum. Fallopian tubes are not directly attached to the ovaries.

Uterus:

A hollow thick walled, muscular organ that is shaped like an upside-down pear. It is the function of the uterus to house & nourish the fetus and then contract rhythmically during labor to expel the fetus. Each month it is prepared for a pregnancy whether or not conception takes place. Measures approximately: 3x2x1 inch (7.5x5x2.5 cm) Normal position is anteverted (rotated forward) and slightly anteflexed (flexed forward) The uterus is divided into 3 parts: Corpus: Body of the uterus of which the fundus is a part. Isthmus: A narrow transition zone. Cervix: tubular "neck" of the lower uterus about 2-3 cm long. The os is the opening between the uterus and the vagina. The upper part of the cervix is marked by the internal os and the lower part of the cervix is marked by the external os.

Supporting Structures: Pelvis:

Basin shaped structure at the lower end of the spine. It's posterior wall is formed by the sacrum. The side and anterior pelvic walls are composed of 3 fused bones: Ilium Ischium Pubis

Development

Breasts are inactive until puberty when increasing estrogen stimulates growth of the glandular tissues. Fat is deposited in the breasts; and it is the amount of fat that is the major determinant of breast size. The amount of glandular tissue , however, is similar for all mature females. Size is unrelated to the amount of milk a women can produce during lactation. Final maturation of the breast takes place during pregnancy. - high levels of estrogen and progesterone are produce by the placenta. - This stimulates growth of the alveoli & ductal system to prepare them for lactation. Prolactin( secreted by the ant. Pit) - stimulates milk secretion during pregnancy but this effect is inhibited by estrogen and progesterone produced by the placenta. - The Inhibiting effects of estrogen/progesterone STOP when placenta is expelled after birth, and active milk production occurs in response to the infant's nursing.

Endometrium:

Inner layer of the uterus; responsive to cyclic variations of estrogen & progesterone during the female cycle. 2 layers of endometrium: 1. Basal layer: nearest the myometrium, regenerates the functional layer of the endometrium after each menstrual cycle and childbirth. 2. Functional layer: lies above the basal layer and contains endometrial arteries, veins, glands. This layer is shed during each menstrual cycle and after childbirth (as lochia).

Muscles:

Levator ani is a collection of 3 pairs of muscles pubococcygeus; puborectal; iliococcygeus: these support internal pelvic structures & resist increases in intra-abdominal pressure. Ischiocavernosus muscle extends from the clitoris to the ischial tuberosities on each side of the lower bony pelvis. 2 transverse perineal muscles extend from fibrous tissue of perineum to the 2 ischial tuberosities to provide stabilization of the perineum

Perineum:

Most posterior part of the external female reproductive organs. It extends from the fourchette, anteriorly, to the anus , posteriorly.

Perimetrium:

Outer peritoneal layer of serous membrane that covers most of the uterus. Laterally it is continuous with the broad ligament on either side of the uterus.

Female Breast: Structure

Purpose: Secrete milk after childbirth to nourish the infant. Nipple: small, raised, at center of each breast, sl. Darker in color than surrounding skin;composed of sensitive, erectile tissue responsive to sexual stimulation, ductal openings Areola: darker area of skin, surrounding the nipple; Montgomery tubercles: sebaceous glands found in areola. Usually inactive & not obvious until pregnancy/lactation. Then, they enlarge and secrete a substance to keep the nipples soft. Within each breast are lobes of glandular tissue that secretes milk. - 15-20 of these lobes are arranged around and behind the nipple and areola. - Fibrous tissue and fat support the glandular tissue, blood vessels, lymphatics & nerves Alveoli: Small sacs that contain acini Acini: are milk secreting cells.

Mons Pubis:

Rounded, fleshy, prominence over the symphysis pubis that forms the anterior border of the external reproductive organs.

Clitoris:

Small projection of highly sensitive erectile tissue (similar to the penis) at the anterior junction of the Labia minora. The Labia majora merge to form the prepuce over the clitoris

Myometrium:

The middle layer of thick muscle; Most of the muscle fibers are concentrated in the upper uterus. 3 types of myometrium muscle fibers: 1. Longitudinal: found mostly in the fundus 2. Inter-lacing Figure 8 fibers: Middle layer, contracts after birth to compress blood vessels to limit blood loss. 3. Circular fibers: form constrictions where the fallopian tubes enter the uterus and the internal cervical os: prevents reflux of menstrual flow into the fallopian tubes, promotes normal implantation of fertilized ovum, helps retain the fetus until appropriate time of birth.

Labia Majora/ Labia Minora:

Two fleshy folds of tissue that extend from the mons pubis to the perineum. Slightly deeper in pigmentation than the surrounding tissue and are covered with pubic hair. The Labia Majora protect the more fragile tissues of the external genitalia. The labia minora runs parallel to and within, the labia majora. They have no pubic hair are highly vascular and respond to stimulation by becoming engorged with blood.

Hymen:

is a thin fold of mucosa partially separating the vagina from the vestibule.

Linea terminalis (pelvic brim):

is an imaginary line that divides the upper(false) pelvis from the lower (true) pelvis. The false pelvis provides support for internal organs & the upper part of the body. The true pelvis is important during childbirth

Testosterone

is secreted in a relatively even pattern. - small amt. of testosterone is converted into estrogen in the male and is needed for sperm formation. Seminiferous tubules: where spermatogenesis takes place. Sertoli cells: are found within the seminiferous tubules and respond to FSH secretion by nourishing and supporting sperm as they mature. Male doesn't't begin to produce sperm until puberty and continues throughout life. Production decreased with age. At ejaculation 35 - 200 million sperm are deposited in the vagina. This is directly related to fertility. - only a single sperm is needed to fertilize the ovum - Only a few sperm actually reach the fallopian tube where an ovum may be available for fertilization. From the seminiferous tubules sperm passes into the epididymis, within the scrotum, for storage and final maturation. - It is in the epididymis that the sperm develops the ability to be motile. - secretions within the epididymis inhibit actual mobility until ejaculation occurs. - The epididymis empties into the vas deferens where larger numbers of sperm are stored. - With in the pelvis the vas deferens joins the ejaculatory duct before connecting to the urethra.

Androgens:

male sex hormones and the primary secretion of the testes. - produced by the leydig cells of testes - primary male androgen is testosterone.

Vestibule:

refers to structures enclosed by the Labia minora. This includes the : urinary meatus, vaginal introits and Ducts of Skene & Bartholin. Skene (periurethral) Glands: provide lubrication fro the urethra Bartholin Glands: provide lubrication for the vaginal introitus, particularly during sexual arousal. Introitus: surrounded by erectile tissue; during sexual stimulation it is filled with blood allowing the introitus to tighten around the penis.

Ovarian Cycle

• 3 Phases • Follicular Phase • Begins the first menstrual day& ends about 14 days later • Ovum matures • Ovulatory Phase • Begins about 2 days before ovulation • LH spikes to stimulate final maturation of the follicle and cause ovulation; • Luteal Phase • LH stimulates the change • Luteal Phase • LH stimulates the change of the graafian follicle into the corpus luteum

Endometrial Cycle

• 3 Phases • Proliferative Phase • Begins with a thin, basal layer of cells • Increased amounts of estrogen cause new epithelium and endometrial gland growth • Secretory Phase • Occurs during the 2nd half of the ovarian cycle • Ongoing thickening of the endometrial layers • Progesterone from CL cause secretion of nutritional substances for fertilized ovum • Menstrual Phase • CL regresses without a fertilized ovum • Vasospasms of the endometrial blood vessels cause ischemia and necrosis • Necrotic layer then separates from the basal layer resulting in menstrual blood flow

Sexual Maturation

• Puberty • Females: thelarche, menarche • Males: testicular enlargement • Female secondary sexual characteristics