HUBS Mod6 Notes - Reproduction PDF

Lecture 34: Pelvis and Perineum (Part A) Male reproductive system (Part B) Reproductive System Pelvis, perineum Male reproductive system Spermatogenesis Female reproductive system Ovarian / menstrual cycles Coitus, fertilization and contraception Differs greatly betwee...

Lecture 34: Pelvis and Perineum (Part A) Male reproductive system (Part B) Reproductive System Pelvis, perineum Male reproductive system Spermatogenesis Female reproductive system Ovarian / menstrual cycles Coitus, fertilization and contraception Differs greatly between males and females Gonads – organs where gametes (sex cells) are produced ○ Testes – spermatozoa (male) ○ Ovary – oocytes (female) Genitalia allow for coitus - so that gametes can fuse to form an embryo (fertilisation) ○ For transport of gametes to appropriate site of fertilization Define the regions of the pelvis and the differences between male and female Pelvis Bony basin/bowl between trunk and the lower limbs Hip bones (– ileum, ischium and pubis) + sacrum + coccyx Pelvic INlet is open ○ Bounded by pelvic rim Pelvic OUTlet is closed by muscles ○ Diamond shaped ○ Closed off my pelvic floor muscles INlet is ALWAYS bigger than outlet There are two pelvic subdivisions: False/greater pelvis ○ Superior region ○ Above pelvic inlet ○ Contains parts of GI tract ○ Completely encircled by the pelvis bones between the inlet and outlet ○ Occupied by the pelvic organs: rectum, anus, bladder, prostate (males) and uterus/ovaries(females). True/lesser pelvis ○ Inferior region ○ Between inlet and outlet ○ Contains internal reproductive organs  ←Difference is to allow childbirth Pelvic Floor/ diaphragm Closes over the pelvic OUTlet Made up of two muscles ○ Levator Ani- openings through this muscle allows organs (urethra, anal canal and vagina) ○ to pass through ○ Coccygeus Openings in pelvic floor: ○ Urethra ○ Anal canal ○ Vagina (females only) 2 vs 3 opening in males and females Define the perineum and its subdivisions Male Perineum Region inferior to the pelvic floor and between upper region of the thighs Includes external genitalia and anus Two triangular divisions: ○ Anterior: Urogenital triangle Urethral opening; external genitalia ○ Posterior: Anal triangle Anal canal and fat Describe the anatomy of the male reproductive tract including the testis, epididymis, ductus deferens, ejaculatory ducts and urethra Male Reproductive System Function: ○ To produce spermatozoa (sperm / male gamete) ○ Transport spermatozoa into the female reproductive tract (humans have internal fertilization) Made up of: ○ Testes (male gonad) ○ Reproductive tract/duct ○ Accessory structures and glands Sperm Travel Path Testes to (sperm production) Epididymis (sperm maturation), continuous with Ductus (vas) deferens, which widens into ampulla, which joins with the Ejaculatory duct Urethra, starts with prostatic urethra, membranous then penile/spongy Seminiferous tubule →rete testis→ efferent ductules→ epididymis→ ductus deferens→ ejaculatory ducts→ urethra The Scrotum Contains X2 Testes (testis for singular) X2 epididymis (epididymis for singular) X2 spermatic cord (with parts of ductus deferens) Testes Produce sperm (100 million per day), testosterone and inhibin Lie in scrotum – outside the body Surrounded by dense fibrous capsule: the tunica albuginea ○ Separates the testes into lobules (240 lobes, 1-3 seminiferous tubules within each lobe) like mandarin Testes have lobules containing seminiferous tubules ○ Interstitial endocrine (Leydig) cells produce testosterone ○ (Sertoli) cells produce inhibin ○ Spermatogenic cells: spermatogonia and spermatozoa at various stages of development Tubulus join to form rete testis Which join to form efferent ductules leading to the head of the epididymis Epididymis Separated into three broad (not fully distinguished) regions: head, body, tail Sperm enter from seminiferous tubules, through rete testis and efferent ductules into the epididymis and exits via ductus deferens Site of sperm maturation  ○ Sperm have no motility until they completely go through the epididymis and interact with seminal fluid ○ Epididymis is long convoluted tube, 7m long Ductus/ Vas deferens Continues from epididymis Starts in spermatic cord Covered by smooth muscle Runs posterior to the urinary bladder through inguinal canal Dilates to form the ampulla For storage and transport of sperm ○ If no ejaculation, los via urination Ejaculatory ducts Formed by the union of the duct from the seminal vesicle and the ampulla Opens in the prostatic urethra Male urethra Two functions: urination and ejaculation Epithelium changes (transitional→columnar→stratified squamous) down length of urethra Three sections: ○ Prostatic urethra ○ Membranous urethra ○ Spongy/penile urethra stretch Urinary/urethral sphincters Associated with bladder External: skeletal muscle, voluntary control of urination Internal: detrusor muscle, closes bladder ensuring sperm ejaculated through the urethra to prevent too much urine in semen and prevent retrograde ejaculation Retrograde ejaculation: sphincter doesn’t close; therefore, sperm ends up in bladder Lecture 35: Male reproductive system Pt2 Describe the anatomy of the supporting structures –penis, scrotum (including spermatic cords) Accessory Structures include the penis and scrotum ○ Scrotum Contains ○ X2 Testes (sing testis) ○ X2 epididymis ○ X2 spermatic cord (with part of ductus deferens) Houses testes away from body to maintain temperature at 34 degrees Scrotum lined by dartos muscle ○ Wrinkles the skin of scrotum to allow heat conservation Cremaster muscle contracts for heat conservation (brings testes closer to body) Spermatic Cord X2 spermatic cords Surrounded by cremaster muscle Runs between abdomen and testis Contains ○ Ductus deferens ○ Blood vessels - testicular arteries and veins ○ Venous plexus/ pampiniform plexus The pampiniform plexus acts as a heat exchanger. When arterial blood comes down from the heart, is is warmed by the core temperature. However, this temperature is too warm for the testes. This plexus of veins, transfers the warm blood from artery to vein, cooling the blood. ○ Nerves ○ Lymphatics vessels that supply the testes forms a web around artery- increase SA for thermal exchange between arteries and veins Penis Dual function: ○ Urination ○ Copulation (delivers spermatozoa into female rep tract) Adheres to body wall via urogenital triangle region Cylindrical organ: ○ Root (bulb) ○ Body (more mobile) ○ Glans covered by prepuce/foreskin The penis contains three cylindrical erectile tissues: X2 corpora CAVERNOSA (corpus cavernosum) ○ Main erectile tissue ○ DORSAL aspect X1 corpus SPONGIOSUM ○ Contains urethra ○ Forms bulb and glans ○ VENTRAL aspect Describe the accessory reproductive glands – seminal vesicles, prostate gland, bulbourethral glands Accessory glands Spermatozoa carried to female reproductive tract in seminal fluid (together called semen) Seminal fluid is mostly produced by three types of accessory glands: Seminal vesicles Prostate gland Bulbourethral glands Location Two glands located Inferior to bladder Two glands located Posterior to bladder Wraps around prostatic urethra In the urogenital diaphragm Lateral to ampulla Open into spongy/penile urethra Function Produce viscous secretion of Slightly acidic, milky fluid Secretions lubricate and neutralise ductus deferens acidity in urethra prior to Contains PSA: prostate-specific ejaculation antigen Alkaline pH protects sperm against acidic environment in Contributes to sperm activation, urethra and vagina viability and motility % of 60% of semen ~30% of semen ~5% (released during arousal) semen SPERMATOZOA MAKES UP THE LAST 5% of SEMEN Vasectomy Surgical method of sterilization in males Cut the ductus deferens (cut ends tied or cauterised) to prevent sperm making its way up ductus deferens NO effect on volume of seminal fluid because glands unaffected, but semen volume decreases by 5% Describe spermatogenesis, including its hormonal control Gametogenesis Formation of the gametes (sex cells) ○ Spermatogenesis in males ○ Oogenesis in females Under hormonal control tight control Occurs via mitosis and meiosis Cells need to be haploid (23 chromosomes) Spermatogenesis Formation of the male gamete The process by which spermatogonia are transformed to mature spermatozoa (sperm) Occurs continuously from PUBERTY onwards Occurs in the seminiferous tubules of testes Process of Spermatogenesis 1. Spermatogonia divide by mitosis into 2 daughter cells (DIPLOID - 46 chromosomes) 2. One spermatogonium (type A) stays at the basement membrane of the seminiferous tubule 3. The second spermatogonia (type B) differentiates into a primary spermatocyte (DIPLOID), which diploid undergoes meiosis I 4. Forms 2 SECONDARY spermatocytes (HAPLOID - 23 chromosomes) 5. These undergo meiosis II to form spermatids (HAPLOID) 6. Spermatids differentiate into spermatozoa with a head, body and tail via spermiogenesis 7. Spermatozoa released into lumen Reproductive Hormones GnRH- Gonadotropin releasing hormone produced by the hypothalamus LH- Luteinizing hormone (a gonadotropin) produced by the anterior pituitary FSH Follicle stimulating hormone (a gonadotropin) produced by the anterior pituitary *Gonadotropin = hormone that acts on the gonads Hormones in males Interstitial endocrine cells Inhibin- produce by nurse (Sertoli) cells in seminiferous tubules in testes Testosterone ○ Produced by interstitial endocrine (Leydig) cells in testes ○ Type of androgen Group of steroid hormones function found OUTSIDE of seminiferous tubules Responsible for male characteristics (maturation of sex organs, spermatogenesis, secondary sex characteristics, libido) Synthetic androgens (steroids) - therapeutic purposes Negative feedback Loop 1. Hypothalamus produces GnRH which travels to Anterior Pituitary 2. Ant Pituitary releases LH and FSH 3. LH stimulates production of testosterone from interstitial endocrine [Leydig] cells 4. FSH and testosterone control spermatogenesis 5. FSH stimulates Inhibin production from nurse [Sertoli] cells Negative feedback: 6. Inhibin suppresses FSH secretion 7. Testosterone suppresses LH & GnRH Lecture 36: Female reproductive system Pt 1 Functions of the Female Reproductive System To produce oocytes (female gamete) Transport ova and spermatozoa to the appropriate site for fertilization Provides a site for the developing embryo and fetus to grow – protection, nourishment Delivery of fetus Describe the female perineum and the constituents of the vulva. Female Perineum Region inferior to the pelvic floor and between upper region of the thighs ○ Urogenital triangle: external genitalia = vulva. ○ Anal triangle: anus Vulva/ Pudendum (External genitalia) Mons pubis- in front of the pubic symphysis Pubic mountain- layer of adipose or fat that sits over pubic symphysis (where pubic hair grows) Labia (means lips) - 2 lip-like structures: (labia= plural; labium=singular} ○ Major (labia majora) - larger and more lateral pubic hair also grow here ○ Minor (labia minora) smaller and more medial surround the vestibule Labia minora spreads around the vagina and the urethral (meatus) openings ○ Vestibule- space between (associated with vagina) DEEP to the labia are vestibular glands which lubricate the vaginal orifice. Clitoris Clitoris Complex erectile organ: ○ Glans ○ Body ○ Crura (x2) ○ Bulbs (x2)  Developmentally homologous to the penis BUT with corpus cavernosum (male penis) the urethra does NOT pass through the clitoris /clitoris Urethra has separate opening Describe the anatomy of the uterus and the associated tract - uterine tube; uterine cavity; cervix and vagina. The Female Reproductive Tract Structures: Ovary ○ Paired structure in female ○ Site of production of oocytes Uterine tubes/ Fallopian tubes ○ Three regions: ○ Infundibulum Most lateral portion Funnel shaped with finger like projections called fimbriae ○ Ampulla Mid-portion Dilated area where fertilization occurs (normally) ○ Isthmus Most medial portion Means “narrow passage” Uterus (womb) Consists of the body( with fundus) and the cervix Perimetrium - OUTER layer (connective tissue) Myometrium - middle layer (smooth muscle) ○ Thickest layer uterus imp for birthing Endometrium - INNER layer (columnar epithelium, uterine glands and arteries) ○ FUNCTIONALIS Layer that grows and sheds during menstrual cycle  Cervix ○ Part of uterus ○ Leans over urinary bladder ○ Cervical canal provides passage between uterine cavity and vagina External os Cervical canal Internal os (TOP) ○ Produces cervical mucus for for protection and to minimize risk of infection ○ Regulates sperm transport at appropriate time of menstrual cycle Vagina Fibromuscular, distensible female copulatory (engage in sexual intercourse) organ Also functions as part of the the birth canal Lies between the urinary bladder & rectum Extends from the perineum to the cervix Complex Blood Supply Blood supply consists of direct branches of the abdominal aorta and internal iliac arteries (often anastomose/connect) ○ Ovaries: ovarian arteries transported via suspensory ligament to ovary (branch of abdominal aorta) ○ Uterus: uterine artery (branches into spiral arteries into myometrium and endometrium) (branch of internal iliac artery) ○ Vagina: vaginal artery (brnchh of uterine artery) Uterine Blood Supply Describe the location and structure of the female gonad (the ovary) Ovary /female gonad Bilateral structures ○ Lateral and posterior to the uterus ○ Lateral portion of the TRUEEEEEEEEEEEE pelvic cavity Outer cortex (follicles) and inner medulla (connective tissue, blood/lymphatic vessels, nerves) Site of oogenesis and hormone production (e.g. oestradiol) ○ Oocytes develop within follicles Describe the structural arrangement of the female reproductive ligaments Ligaments of the Female Reproductive System Female reproductive structures are held in place by a complicated network of ligaments that: ○ Anchor and support ○ Have vasculature and nerves running through them ○ Form important anatomical boundaries (i.e. pouches) Broad ligament- continuation of peritoneum "sheet" draped over the uterus, double-layered fold of peritoneum with its own divisions: Peritoneum folds and presses over structures to create other ligaments ○ Mesometrium (“of the womb/mother”) ○ Mesosalpinx (“of the tube”) ○ Mesovarium (“of the ovary”) Ovarian ligament Suspensory ligament- from lateral surface ovary to lateral surface of abdominal wall Round ligament Describe the structure of the breasts. Breasts (mammary glands) Function to nourish infants. Located superficially to pectoralis major muscles. Mammary glands within breast are under control of Estradiol and progesterone which stimulate development and milk production Mammary gland has Lobes that divide into → lobules→ alveoli further divide into → lactiferous duct→ lactiferous sinuses that open at nipple pores. Suspensory ligaments support the glands. Lecture 37: Female reproductive system Pt2 Describe oogenesis. Oogenesis Formation and development of the oocyte (female gamete) from oogonia. Requires mitosis AND meiosis. LIFETIME supply of gametes produced BEFORE birth Oogenesis Initiated BEFORE birth. Continues between puberty and menopause. ○ Cyclic - 1 ovulation every 28 days (on average) Oocytes develop within ovarian follicles (1 oocyte per follicle). BEFORE BIRTH Oogonium (DIPLOID, 2n=46) in gonad 1. Population of oogonia increase by mitosis (stops before birth) 2. Oogonia differentiate to form PRIMARY oocytes (DIPLOID, 2n=46) Encased in PRIMORDIAL follicle Many primary oocytes undergo atresia (cell death) 3. Primary oocytes start MEIosis. 4. Meiosis halts at PROPHASE I until puberty begins From MENARCHE till MENOPAUSE At puberty, females have ~300,000 oocytes 5. Under GnRH influence, small number of follicles recruited each ovarian/menstrual cycle. 6. Only one oocyte will complete development and ovulate (within DOMINANT follicle). 7. Primary oocyte completes MEIosis I.  ○ Forms a secondary oocyte and 1st polar body (both HAPLOID, n=23). 8. Secondary oocyte starts meiosisTWO and halts at METAPHASE II until fertilisation. 9. Meiosis II resumes when the sperm penetrates the plasma membrane of the ovum at fertilisation. 10. If not fertilised, will degenerate (called atresia) and therefore never complete meiosis. Oogenesis occurs within developing follicle Oocyte develops within developing follicle Follicles are MULTILAYERED ○ Granulosa cells- produce ESTRADIOL ○ Theca cells Ovulation: oocyte and corona radiata released into peritoneal cavity Describe the major female reproductive hormones. Female Reproductive Hormones Hormone Location Function GnRH Hypothalamus Promotes release of FSH and LH Gonadotropin Releasing Hormone FSH Anterior Pituitary Stimulates growth of ovarian follicles LH Anterior PItuitary LH Surge involved in ovulation Formation of corpus luteum Estradiol Developing follicles Assists follicle growth (with FSH) Bone and muscle growth Endometrial growth Secondary sex characteristics Feedback to anterior pituitary.  Inhibin Granulosa cells Negative feedback to anterior pituitary to suppress FSH Progesterone Corpus Luteum Negatively feedback to suppress GnRH (therefore LH and FSH) Endometrial maturation Maintains a pregnant state. Describe the ovarian/menstrual (endometrial) cycles. Ovarian/ Menstrual Cycles The regular cyclic changes in the ovary and uterus that prepare an oocyte/ova for fertilization and the endometrium for embryo implantation Ovarian Cycle EARLY Follicular/ Preovulatory/ LATE Follicular phase Luteal/ Postovulatory phase (Day 15-28) MENSTRUATION phase (Day 1-7) (Day 8-14) Starts a menstruation and Ovulated follicle collapses & forms corpus ends at LH surge/ovulation Dominant follicle secretes luteum large amounts of estradiol Corpus luteum secretes progesterone, estradiol & inhibin. ↑ FSH from the anterior ↑ as granulosa cells pituitary stimulates proliferate These negatively feedback to HPA to ↓ FSH, follicular/oocyte growth High estradiol past LH and GnRH secretion. (1°→2°→3°) threshold= positive Growing follicles secrete feedback= stimulates LH If fertilisation and implantation do not occur, estradiol and inhibin surge the corpus luteum involutes (luteolysis) =causes follicle ruptures ↓ Progesterone & estradiol. AT LOW levels of estradiol, it and ovulation of Thus removes negative feedback on FSH retains negative feedback=, ↓ secondary oocyte and and LH…. FSH from anterior pituitary associated corona radiata Cycle starts again… (negative feedback) from the dominant follicle All growing follicles undergo Oocytes enter peritoneal space/collected into  atresia, except dominant uterine tube follicle. Menstrual and Proliferative Phase Secretory Phase (Day 15 – 28) Low progesterone levels= Rising Estradiol Progesterone promotes endometrial Endometrium breaks down and stimulates maturation preparing endometrium for bleeds during menstruation (from endometrial possibility of pregnancy spiral arterioles down via cervix and growth from approx ○ Glands become secretory vagina) days 6-14 ○ Spiral arterioles grow and coil Rapid tissue growth, including growth of IF FERTILISATION + IMPLANTATION OCCURS: glands and Developing ovum/embryo produces hormones vasculature (bHCG) that prevents degeneration of the corpus luteum This maintains progesterone production and prevents further menstruation. Eventually the developing placenta takes over this role of the corpus luteum (~8w) IF FERTILISATION + IMPLANTATION DON’T OCCUR: Corpus luteum atrophies thus Progesterone levels ↓ Spiral arteries contract Endometrial tissue breaks down and bleeding occurs= MENSTRUATION Shed tissue and blood removed via cervix and vagina (menstruation / menses) The lack of progesterone also disinhibits the negative feedback loop ○ GnRH production resumes in hypothalamus ○ FSH + LH production ↑ Restarts the early follicular phase. Define menarche and menopause. Menarche and Menopause Menstrual cycles occur on an approximately monthly basis (average 28 days) between menarche and menopause. Menarche: first menstrual period Occurs at age 12-13 y on average Part of puberty – orchestrated by increase in sex steroid production (estrogens) by the gonads  Menopause: cessation of menstruation Typically occurs in early 50s Reduction of estradiol and progesterone due to absence of or lack of response by follicles Anterior pituitary feedback NO longer active ∴ FSH/LH HIGH Lecture 38: Coitus, Fertilisation, Contraception Coitus/ Sexual Union/ Copulation/ Sexual intercourse Erect penis introduced into vagina (intromission) Semen released into upper part of vagina (insemination) so that sperm can travel to appropriate site for fertilization (ampulla of uterine tube) Stages of Male Sexual Act 1. Erection of penis (parasympathetic) 2. Mucus secretion into urethra 3. Ejaculation (sympathetic) ○ Emission- sperm and semen transported to urethra ○ Expulsion- urethra contracts to allow semen to leave the body 4. Resolution Describe the anatomy of the penis. Penis Anatomy Trabeculae - smooth muscle fibers that surround the lacunae Lacunae- fill with blood from deep arteries (cavernosal arteries) during erection) Penis Fascia Layers Tunica albuginea Associated with two corpora cavernosa and spongiosum Deep (Buck’s) Fascia Superficial Fascia Describe the comparative anatomy of the clitoris and the penis. Comparative anatomy of the clitoris and the penis. Structure of the clitorus and penis share developemental origins Tissues of the clitoris are erectile as in the penis Urethra runs the length of male penis, urethra is a separate structure in females Describe the vascular and nerve supply of the penis. Vascular supply Abdominal aorta→ Common iliac artery→ internal iliac artery→ internal pudendal artery (feeds into perineum and external genitalia including penis) Branches to the penis include: ○ Artery to bulb ○ Urethral artery ○ Dorsal artery ○ Deep (cavernosal) artery Gonad artery ○ Females= ovarian ○ Males= Testicular ○ High up because during development, gonads developed near abdominal artery then descending into pelvic cavity (F) and scrotum (M) Blood supply to the penis increases during erection ○ Deep artery dilates, lacunae fill with blood, corpus cavernosa expands, pressure against veins and fascia to allow erection of the penis for the sexual act Nerve supply Penis richly innervated by sensory (includes sensory fibres responsive to touch, pressure, temperature) and motor nerves Pudendal nerve supplies sensory and somatic motor innervation to perineum and external genitalia, including penis ( via DORSALl nerve) Autonomic innervation to penis is from pelvic plexus (parasympathetic & sympathetic)  ○ Parasympathetic= sacral= ERECTION Stimulates production of nitric oxide (NO, vasodilator) by deep arteries of penis. Deep arteries dilate and fill lacunae with blood in corpora cavernosa ○ Sympathetic= thoracic= EJACULATION Stimulates contraction of smooth muscle (of ducts to release seminal fluids from glands) Reproductive ducts Accessory glands ○ Somatic motor= EJACULATION ○ Stimulates contraction of skeletal muscles around bulb of penis Describe the neural control of the sexual act - erection and ejaculation. Neural Control of Sexual Act 1. Erection 2. Emission 3. Expulsion 4. Resolution Visual, mental etc stimuli + SYMPATHETIC signals Presence of seme in urethra To reduce blood flow to penis, physical stimulation of genital activates SOMATIC and SYMPATHETIC signals: region via pudendal creates DUCTUS DEFERENS: SYMPATHETHETIC reflexes: efferent PARASYMPATHETIC Peristaltic contractions INTERNAL PUDENDAL signals: of smooth muscle to SYMPATHETIC in ARTERY move sperm to ACCESSORY GLANDS: Constricts PENIS: ampulla Deep artery dilates Smooth muscle of Additional secretion TRABECULAR MUSCLES Trabecular muscle of ampulla, seminal from prostate gland Contracts to squeeze erectile tissue relaxes vesicles and prostate and seminal vesicles blood from erectile Erectile tissues fill with gland contract to Internal urethral tissues blood move sperm and sphincter (smooth Engorgement of erectie seminal fluid into muscle PENIS tissues urethra contracts/closes Becomes flaccid Penis= erect and can be Sperm + Seminal fluid (deturgescence) inserted into vagina combined= activated SOMATIC in (intromission) sperm= motility BULBOSPONGIOSUS MUSCLE: BULBOURETHRAL GLAND Contracts and Secretes bulbourethral rhythmically fluid to lubricate and compresses roo/bulb remove residual urine of penis to compress urethra Pelvic floor muscles contract Semen expelled from urethra and penis Female Sexual Response Similar sequence of reflex responses as in the male 1. Engorgement of clitoris, labia and vagina in response to autonomic stimulation 2. Lubricating fluid secreted through vaginal wall; secretion of mucus into vestibule (greater vestibular glands) 3. Increased width and length of vagina. 4. Uterus elevates UPWARDS 5. Rhythmic contraction of vaginal, uterine and perineal (pelvic floor) muscles. Semen released into the UPPER part of vagina (insemination). Sperm travel to the uterine tube for fertilization (ampulla). through cervical canal Sperm fuses with secondary oocyte Oocyte completes meiosis II. Fertilized oocyte/ovum known as a zygote. Zygote initiates cleavage (takes about 7 days) and travels towards the uterus for implantation. Describe contraception in its various forms. Contraception Any method used to prevent pregnancy Regulates when and how many pregnancies Natural Methods Rely on timing of coitus or behavior during coitus High failure rate ○ Rhythm method (periodic abstinence) ○ Withdrawal method (coitus interruptus) ○ Lactational infertility (nature’s way of preventing pregnancy soon after birth, pause in menstruating while breastfeeding) Artificial Methods Barrier Methods ○ Caps, diaphragms ○ Imperfect barrier so should be used in conjunction with spermicidal foams / jellies / creams / sponges. ○ Needs to remain at least 6 hours after intercourse. ○ Not commonly used anymore; preference for more effective and convenient methods. ○ Condoms ○ Cheap ○ Readily available ○ Easy to use ○ Only contraception that reduces risk of sexually transmitted infections (STIs) Non-hormonal Intrauterine device (IUD)- Copper IUD Causes low grade inflammation Reduces sperm transport Toxic to oocyte and zygote Impairs implantation Steroid/ Hormonal contraceptives Variable depending on type, concentration and mode of delivery of hormones Deliver a progestin with/without an estrogen Key mechanisms: ○ Suppress ovulation (affect feedback loops to hypothalamus and pituitary) ○ Affect mucus produced by cervix (prevent sperm penetration) TYPES Features Mechanism of Action Combined oral contraceptive pills Contain estrogen and Suppress ovulation (affect feedback loops to progestin hypothalamus and pituitary) Affect cervical mucus (prevent sperm penetration) Progesterone-only pill Low doses of progestin Affects cervical mucus Subdermal implant / Injectable Progestin Act primarily by disrupting follicular growth progestins and ovulation Hormonal Intrauterine device (IUD) Progestin Affects cervical mucus, (reducing sperm eg Mirena transport) Local effects on endometrium May prevent ovulation Sterilisation Tubal ligation or salpingectomy – cut/cauterise or remove uterine tubes to prevent fertilisation Vasectomy – cut ductus (vas) deferens