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The Physiology of Female Genital System

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The Physiology of Female Genital System THE PHYSIOLOGY OF FEMALE GENITAL SYSTEM 1 Susy Purnawati Learning Objectives Summarize the physiological, and hormonal aspects of the male and female reproductive cycles Discuss the physiology of sexual intercourse Two major phases of female reproductive functions: 1. Preparation of the female body to conception and pregnancy 2. The period of pregnancy itself. The female hormonal system consists of three hierarchies of hormones: 1. GnRH (Gonadotropin-Releasing Hormone, from hypothalamus) 2. FSH and LH (from anterior pituitary) 3. Estrogen and progesterone (from the gonads- ovarium) The Pituitary-Gonad Axis Feedback Pathways Trophic hormones: Follow the general pattern When circulating levels of gonadal steroids are low, the pituitary secretes FSH and LH. Once streroid secretion reaches a certain level, negative feedback usually inhibits gonadotropin release. Feedback Pathways … (cont.) In contrast, estrogen alternates between positive and negative feedback. Lower concentrations of estrogen have a negative feedback effect. However, if estrogen rises rapidly to a threshold level or above for at least 36 hours, feedback changes from negative to positive, and gonadotropin release (particularly LH) is stimulated. Ovarian and endometrial cycle The female reproductive (monthly) cycles: 1) Ovarian cycle Three phases of ovarian cycle: 1. Follicular phase 2. Ovulation 3. Lutheal phase 2) Uterine (endometrial) cycle: 1. Proliferative phase 2. Secretory phase 3. Menstruation Oogenesis & Ovarian cycle Reproduction begins with the development of ova in the ovaries About 7 million oogonia in embryonic ovary develop into half a million primary oocytes During fetal life, the outer surface of the ovary is covered by a germinal epithelium, primordial ova (a primary oocyte), with a layer of granulosa cells = primordial follicle During childhood, when almost no pituitary gonadotropic hormones are secreted, the ovaries remain inactive At the age of 9 to 12 years, the pituitary does begin to secrete progressively more FSH and LH = puberty Which then leads to onset of monthly sexual cycles beginning (= menarche) between the ages of 11 and 15 years Oöcytes (egg cells) develop within follicles 1.Stages of follicular development Primordial follicle Single layer of squamous cells around the oöcyte Primary follicle Layers of cuboidal granulosa cells around the oöcyte Granulosa cells secrete estrogens 1. The follicular phase (or the phase of follicular maturation) Rapid proliferation of the granulosa cell Several layers outside the granulosa cells develop the theca During the follicular phase, the follicle secrete hormones: estrogens (prepare the uterus to receive the embryo). 2. The ovulation phase Ovulation occurs 14 days after the onset of menstruation The protruding outer wall of the follicle swells rapidly, than the stigma rupture During ovulation, the ovum is extruded from the follicle, whose wall breaks, and is aspirated into the Fallopian tube Secondary follicle Antral cavity forms Graafian follicle Follicle mature ready to ovulate oöcyte Ovulation Follicle ruptures releasing oöcyte The ovulation phase 15 The ovulation phase 16 3. The lutheal phase (or preparation of the uterus for the potential implantation of an embryo) The follicle (the remaining granulosa and theca interna cells) is transformed into a corpus lutheum (lipid inclusion) 17 Corpus Luteum After ovulation, empty follicle becomes a corpus luteum Corpus Luteum secretes:- Progesterone – completes the preparation of uterine lining Estrogens – work with progesterone Relaxin – relaxes uterine muscles and pubic symphysis Inhibin – decreases secretion of FSH and LH Corpus albicans is a white scar tissue left after the corpus luteum dies. 2. Oogenesis: while in men spermatogenesis happens in about a month, in females oogenesis takes several years. During fetal development oocytes undergo meiosis I but do not completel it; at this point they are called primary oocytes. At ovulation the primary oocyte completes meiosis I and begins meiosis II which is completed only if fertilization occurs. At the completion of meiosis II the oocyte is called an ovum. The monthly endometrial cycle 1. Proliferative phase (estrogen phase) Occurring before ovulation The stromal cells and the epithelial cells proliferated rapidly (the endometrial glands and new blood vessels) under influence of estrogen The endometrium is 3 to 5 mm thick (at the time of ovulation) Mucus secretion 20 2. Secretory phase (progestational phase) Occuring after ovulation Progesteron and estrogen together are secreted in large quantity by the corpus lutheum Swelling and secretory development of the endometrium Endometrium is 5 to 6 mm thick (at the peak of the secretory phase) 21 3. Menstruation Estrogens and progesterons decrease to low levels of secretion Blood vessel vasoplastic release vasoconstrictors materials (prostaglandin) … necrotic of the endometrium The menstrual fluid is normally noncloting … fibrinolysin 22 Summary of Ovarian and Menstrual Cycles Female Reproductive Physiology All together Secretory proliferasi 25 Functions of estrogens Their effects on the primary and secondary female sex characteristics: 1. Uterus and external female sex organ Change (ovaries, fallop. tube, uterus and vagina) from those a child to those of an adult The ext. genitalia enlarge, with deposition of fat in the mons pubis and labia majora and with enlargement of the labia minora. 2. Fallopian tubes 26 Functions of estrogens 2. Fallopian tubes Estrogen cause the glandular tissues in this lining to proliferate, cause the number and activity of ciliated epithelial cells to increase 27 Functions of estrogens 3. Breasts (1) Development of the stromal tissues of the breasts (2) Growth of an extensive ductile system, and (3) Deposition of fat in the breasts Do not complete the job of converting the breasts into milk producing organs 28 Functions of estrogens 4. Skin Cause the skin to develop a texture that is soft and usually smooth , become more vascular (increased warmth, greater bleeding) 5. Skeleton Increase osteoblastic activity in the bones (growth in height becomes rapid for several years Cause uniting of the epiphyses with the shafts of the long bones 29 Functions of estrogens 6. Protein deposition Cause a slight increase in total body protein 7. Body metabolism and fat deposition Cause deposition of increased quantities of fat in the subcutaneous tissues (buttocks and thighs, feminine figure) 30 Functions of estrogens 8. Hair distribution Estrogen do not greatly affect hair distribution (pubic region and in the axillae after puberty). Androgens are mainly responsible for this. 9. Electrolyte balance Cause sodium and water retention by the kidney tubules 31 Functions of progesterone Their effect on: 1. Uterus Promote endometrium to increase secretion Decreases frequency and intensity of uterine contraction 2. Fallopian tubes 3. Breasts Promotes development of the lobulus and alveoli of the breast Promote breast to swell But does not cause to secrete milk 4. Electrolyte balance 32 Adrenal androgens influence female secondary sex characteristics Pubic and axillary (armpit) hair growth, and Libido (sex drive) Female sexual act Female sexual desire Is affected by estrogen levels and adrenal androgen Similar with male sexual act. Stimulation (psychic and local ) of the female sexual act Erogenous zone 34 Female sexual act Stages are comparable to those of male sexual function Arousal causes clitoral erection Vaginal surfaces are moistened Parasympathetic stimulation causes engorgement of blood vessels in the nipples Female sexual act Female erection Erectile tissue Parasimpathetic nerve (that pass through the nervi erigentes from sacral plexus to the external genitalia) 36 Female sexual act Lubrication (by Bartholin) Parasympathetic signal also pass to the bilateral Bartholin’s glands located beneath the labia minora and cause them to secrete mucus immediately inside the introitus Is responsible for much of lubrication during sexual intercourse, to avoid irritation sensation 38 Female orgasm When local sexual stimulation reaches maximum intensity, and supported by appropriate psychic conditioning (cerebrum reflex) During the orgasm, the perineal muscles contract rhytmicaly, which results from spinal cord reflexes. 39 Female orgasm The walls of vagina and uterus contract Seems to cause dilatation of cervical canal (30’), allowing easy transport of the sperm The intense sexual sensations also pass to the cerebrum and cause intense muscle tension throughout the body, than resolution 40 One case Ni Nyoman Wartini, 25 y.o., unmarried, came to emergency room a private hospital at Ubud with her family with complain of nausea and vomiting. The doctor diagnose her with “observasi vomiting and moderate dehydration”. She was hospitalized with some medication for her vomiting symptom. Thinking, raise your opinion! What is her problem??????? Fertilization Pregnancy: occurs once an egg is successfully fertilized and successfully implants. Fertilization Fertilization of an egg by sperm is the result of a chance encounter, possibly added by chemical attractants produced by the egg An egg can be fertilize for only about 12-24 hours after ovulation. Sperm in the female reproductive tract remain viable for four to six days Fertilization If fertilization occurs:- Embryo implants in endometrium Must maintain levels of progesterone to maintain the endometrium and pregnancy Since corpus
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