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132 Cards in this Set
- Front
- Back
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where are the testes located and what is their anatomy?
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testes located in scrotum: sac of skin + superficial fascia outside abdominopelvic cavity at root of penis. sparse hairs, more heavily pigmented
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what does the midline septum of the testes provide? exterior position of the testes provides what?
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• midline septum provides one compartment/testis
• exterior position provides essential (why?) temp 30 C lower than core |
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What are the roles of the dartos & cremaster muscles in testicular temperature regulation?
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two fibromuscular sacs that make up the scrotum called -dartos muscle -cremaster muscle
the dartos muscle made from? -smooth muscle and is -woven into the scrotum the cremaster muscle made from -skeletal muscle the cremaster muscle is found -surrounding each testicle These muscles contract and relax allowing for it to remain a constant 3 degrees below normal body temperature |
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2 tunics of the testes
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Tunica vaginalis: outer, 2-layered (derived from the processus vaginalis of the peritoneum, which in the fetus preceded the descent of the testis from the abdomen into the scrotum.)
Tunica albuginea: fibrous capsule of testis (white coat); septal extensions divide each testis into 250-300 wedge-shaped lobules |
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each lobule of the testes contains how many tubules?
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each lobule = 1 to 4 coiled seminiferous tubules
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innermost to outermost layer in the testes
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seminiferous tubules (1)
tubulus rectus (2) rete testes (3) efferent ductules (4) epididymis (5) |
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Leydig Cells of the testes produce what
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interstitial cells that produce androgens (testosterone)
What are interstitial cells |
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Blood Supply
testicular arteries and veins and spermatic cord: |
• testicular arteries (branch from abdominal aorta)
• testicular veins form pampiniform plexus (role?) • spermatic cord: blood & lymph vessels, nerves, vas deferens |
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describe in detail the pathway followed by sperm from the epididymis to the exterior of the body
part 1 epididymis |
head caps superior part of testis (Spermatozoa formed in the testis enter the caput epididymis)
• body & tail contain highly coiled duct of epididymis ;(uncoiled = ~6 m!) • sperm that enter epididymis are immature, nonmotile • ~20 days to traverse epididymis > gain ability to swim |
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describe in detail the pathway followed by sperm from the epididymis to the exterior of the body
part 2 ducus (vas deferens) |
Ductus (Vas) Deferens (1/testis)
• ~45 cm long • describe the pathway taken by the vas deferens to the point where it becomes the ejaculatory duct • ejaculatory duct passes into prostate gland, then into urethra • each vas deferens propels sperm out during ejaculation |
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describe in detail the pathway followed by sperm from the epididymis to the exterior of the body
part three the urethra |
The Urethra
• terminal portion, serves both urinary & reproductive functions |
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What happens to the epididymis during ejaculation?
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During ejaculation, the epididymis and vas deferens muscles contract to propel the sperm into the ejaculatory duct. Here the sperm is joined with the secretions of the seminal vesicles and prostate gland (which contribute the bulk of the seminal fluid) to form the semen.
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What happens to sperm that do not get ejaculated for a long period of time?
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The male reproductive system constantly generates sperm and at any given time there are millions in multiple stages of development. Mature sperm survive between 7 to14 days, at the end of which they degenerate. Seminal fluid volume is maintained based on frequency of use and over all body fluid/hydration status. Once adequate amounts are made and stored the system is stimulated to rest and the cells do not produce more until needed.
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How long can sperm be stored in the epididymis?
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They may then be stored in the epididymis for up to a month. If they are not ejaculated during that time, they degenerate and are reabsorbed by the body.
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What is a vasectomy? Are there any risks associated with this procedure?
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The surgical cutting and sealing of part of each vas deferens, typically as a means of sterilization.
The complications that may occur are related to bleeding or infection at the site of the procedure. Occasionally prolonged pain occurs that is a result of inflammation around the vas deferens that is due to sperm leakage or from congestion of sperm at the epididymis. The usual treatment for these complications is rest and the use of an anti-inflammatory medication. |
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what is the prostatic urethra?
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The prostatic urethra, the widest and most dilatable part of the urethra canal, is about 3 cm. long
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what is the membranous urethra?
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The intermediate part of male urethra (membranous portion) is the shortest, least dilatable, and, with the exception of the external orifice, the narrowest part of the canal
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what is the spongy (penile) urethra
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The spongy urethra (cavernous portion of urethra, penile urethra) is the longest part of the male urethra, and is contained in the corpus spongiosum urethraeæ.
It is about 15 cm long, and extends from the termination of the membranous portion to the external urethral orifice. |
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Localize & describe the structure of the male reproductive accessory glands
1) seminal vesicles |
. Seminal Vesicles (2)
• posterior wall of bladder; about size & shape of little finger • contribute ~60% of semen volume (yellow, viscous, alkaline; fructose, ascorbic acid, coagulating enzyme, prostaglandins) • sperm + seminal fluid in ejaculatory duct |
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Localize & describe the structure of the male reproductive accessory glands
Prostate Gland (1) |
single gland, size & shape of chestnut; encircles urethra inferior to bladder
milky secretion (~1/3 semen volume; contains enzymes; role in activating sperm) secretion to prostatic urethra via several ducts during ejaculation |
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Localize & describe the structure of the male reproductive accessory glands
Bulbourethral Glands |
Bulbourethral Glands (2)
pea-sized, inferior to prostate thick, clear mucus to spongy urethra before ejaculation (purpose: During sexual arousal each gland produces a clear, viscous secretion known as pre-ejaculate. This fluid helps to lubricate the urethra for spermatozoa to pass through, and to help flush out any residual urine or foreign matter. It is possible for this fluid to pick up sperm, remaining in the urethral bulb from previous ejaculations, and carry them out prior to the next ejaculation. |
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describe the structural organization of the penis as a copulatory organ
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penis = attached root + delivers sperm into ♀ reprod tract
external genitalia = penis free shaft or body; enlarged tip = glans penis foreskin or prepuce = cuff of skin around glans (circumcision) |
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internall the penis contains:
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internally, penis contains:
(i) spongy urethra (ii) 3 corpora of erectile tissue 2 corpora cavernosa 1 midventral corpus spongiosum (expands distally > glans; proximally, expands > bulb of penis) |
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describe the composition of semen
secretions provide: |
(i) transport medium
(ii) nutrients (eg: fructose) (iii) chemicals (eg: PGs) -protect/activate sperm • pH 7.2-7.6 neutralizes pH 3.5-4 of vagina SEMEN: 2-5 ml/ejaculation; [sperm] = 50-100 million/ml |
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regulation of the male reproductive system
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normal rate of sperm production is 2x108 sperm/day
• testis is a source of both germ cells & hormones |
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testis is composed of:
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(i) seminiferous tubules: = Sertoli cells + spermatogenesis
intermediates; 80% of testicular mass (ii) Leydig cells: synthesize androgens (testosterone) |
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levels leading up to testosterone
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Cholesterol
Progesterone Androstenedione Testosterone |
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Actions of testosterone:
gonadal |
: (i) growth/maturation of gonads & accessory organs (puberty)
(ii)essential for spermatogenesis |
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Actions of testosterone:
somatic |
somatic: (i)adolescent growth spurts (start & stop - how???)
(ii) growth of larynx & vocal cords (iii) secretion of sweat (iv) hair (face, chest, armpits, groin) |
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actions of testosterone
metabolic and CNS |
metabolic: (i) anabolic: hematopoiesis, BMR
CNS: (i) maintenance of libido (ii) aggression |
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what hormones are released to create testosterone
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Gonadotropin-Releasing Hormone (GnRH)
Luteinizing Hormone (LH) Testosterone |
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describe the hypothalamic & pituitary regulation of steroidogenesis in the male
Anterior Pituitary Hormones: |
• gonadotropins are glycoproteins
• water-soluble – significance? cell surface receptors; 2nd messengers > regulate activity of enzymes |
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Follicle Stimulating Hormone (FSH)
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stimulates Sertoli cells to support spermatogenesis (T required)
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Luteinizing Hormone (LH)
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stimulates Leydig cells to secrete testosterone
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GnRH: Gonadotropin Releasing Hormone
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Gonadotropin Releasing Hormone
pulsatile secretion by hypothalamic neurons stimulates secretion of FSH & of LH |
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Inhibin:
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released by Sertoli cells
inhibits secretion of ONLY FSH |
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outline the main steps in spermatogenesis
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• starting point is spermatogonium [diploid]
• at puberty, 6 x 106 spermatogonia per testis; self-perpetuating |
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From Spermatogonium to Spermatozoan
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(i) Spermatogonium: (2N)
• starting point; supply constantly maintained • first step: spermatogonium B undergoes 2 mitotic divisions 4 10 spermatocytes (ii) Primary Spermatocyte (2N) • starting point of meiotic divisions • first round yields 2 secondary spermatocytes/primary spermatocyte (iii) Secondary Spermatocyte: • N x 2: 2 copies of each of 23 chromatids (eg: if ♂, would have 2 Y chromatids) • 2nd division 2 haploid (N) spermatids iv) Spermatid: • 22 autosomal chromatids + X or Y - still a round cell (v) Spermatozoan: conversion of spermatid to spermatozoan requires structural reorganization (i) reorganization of nucleus & cytoplasm (ii) development of a flagellum • spermatozoa then released into lumen; still not completely mature • in epididymis will acquire ability: (i) ………………………………… (ii) …………………………………………. |
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from 10 spermatocyte to spermatozoan takes how many days
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70 days
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Role of Sertoli Cells
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spermatids & spermatocytes at various stages embedded in Sertoli cells
Sertoli cells sit on basement membrane; tight junctions create 2 compartments: >basal compartment: >adluminal compartment: tight junctions create blood-testis barrier; all stages after initiation of meiosis occur in avascular environment |
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main functions of sertoli cells
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(i) nourish developing spermatozoa
(ii) secrete fluid into seminiferous tubule lumen (iii) digest cytoplasm discarded by spermatozoa (iv) bind FSH and testosterone (v) produce inhibin |
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B. Role of Leydig Cells
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located between seminiferous tubules
• vascularized - why important? • receptors for LH - stimulated by LH to secrete testosterone to: > support spermatogenesis |
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describe the functional contributions of the epididymis & the accessory organs to the production of semen
1. epididymis |
Epididymis
sperm spend ~20days here further maturation – membrane & enzyme changes to permit: > sustained motility > binding to egg |
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2.seminal vesicles
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B. Seminal Vesicles
• secrete viscous, yellow fluid rich in fructose • Why fructose? • also contains PGs > What do they do? |
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3. prostate gland
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. Prostate Gland
• secrete thin, milky fluid to neutralize acidity of male urethra & female vagina |
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4. Bulbourethral Glands
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thick, clear mucus
neutralizes traces of acidic urine in urethra |
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female reproductive system more complex > must:
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(i) produce gametes
(ii) prepare to nurture developing embryo > internal genitalia: ovaries > accessory ducts: uterine tubes (oviducts), uterus, vagina > external genitalia: vulva |
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Ovaries
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anchored by ligaments
ovarian suspensory mesovarium NB: suspensory/mesovarium ligaments are part of broad ligament that supports uterine tubes, uterus, vagina • ovarian arteries (branches of ???) & ovarian branch of uterine arteries |
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anatomy of ovaries
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ext surface covered by tunica albuginea
final outer covering is germinal epithelium ovarian cortex contains follicles at all stages of development oocyte granulosa cells theca cells corpus luteum formed from ovulated follicle each month |
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describe the gross and microscopic anatomy of the oviducts
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receive egg & provide site for fertilization; ~ 10 cm long
• ampulla, infundibulum, fimbriae: oocyte released into peritoneal cavity fimbriae direct it into ampulla of oviduct • structure of wall of oviduct also helps oocyte move toward uterus: 1) ……………………………………………………………….. 2) ……………………………………………………………….. • ext covering = visceral peritoneum; supported by mesosalpinx |
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describe the gross & microscopic anatomy of the uterus
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• anterior to rectum & postero-superior to bladder
• receives, retains, nourishes embryo • inverted pear in nulliparous women internal os: uterus to cervix external os: cervix to vagina cervical glands: mucus fills cervical canal & covers ext os prevents infection; less viscous at midcycle |
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layers of the uterus
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fundus
body isthmus cervix vagina |
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Supports of Uterus:
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mesometrium: laterally (broad ligament)
lateral cervical ligaments: inferiorly; from cervix & upper vagina to lat walls of pelvis uterosacral ligaments: to sacrum posteriorly round ligaments: to anterior body wall • supports allow mobility (eg: during ???) • principal support by muscles of pelvic floor (urogenital & pelvic diaphragms) |
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Uterine Wall:
• 3 layers: |
perimetrium: = visceral peritoneum
myometrium: middle, interlacing bundles of smooth muscle endometrium: simple columnar epithelium + thick lamina propria |
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what do the stratum functionalis and stratum basalis do
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look up :)
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vascular supply of female reproductive system
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uterine arteries (from internal iliacs)
branches into uterine wall arcuate arteries within myometrium straight arteries (stratum basalis and stratum functionalis) |
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describe the anatomy of the vagina & the external genitalia
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thin-walled tube, 8-10 cm long
urethra embedded in anterior wall passageway for: entry of sperm exit of menstrual flow delivery of infant |
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3 layers of vagina:
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adventitia: outer, fibroelastic
muscularis: smooth muscle mucosa: inner, transverse rugae; stratified squamuous epithelium (why??) • no glands; lubrication provided by cervical glands • epithelial cells store glycogen metabolized to lactic acid by resident bacteria acidic pH deters infection, but is hostile to sperm hymen: incomplete vascular partition of mucosa near vaginal orifice in virgins |
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External Genitalia
(5) plus explanation |
vulva: mons pubis, labia, clitoris, structures associated with vestibule
mons pubis: fatty, rounded area overlying pubic symphysis; covered with hair labia majora: elongated, hair-covered fatty skin folds (homologue of scrotum) labia minora: thin, hair-free skin folds enclosed by labia majora vestibule: recess between labia minora - contains external opening of urethra & vaginal opening; greater vestibular glands clitoris: erectile tissue (homologous to penis); hooded by skin fold; richly innervated; corpora cavernosa but no corpus spongiosum |
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describe ovarian steroidogenesis as a compartmentalized process
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General Information
• ovaries have two key functions: (i) produce oocytes (ii) produce reproductive hormones (eg: estradiol, progesterone) Remember: • the hormones a cell can produce depends on the enzymes it has • steroids are lipids – can easily traverse PMs |
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starting from cholesterol levels that lead to estradiol
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CHOLESTEROL
progesterone androstenedione testosterone estradiol |
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there are 3 types of steroid hormones produced in the ovarian follicle
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progestins
androgens estrogens |
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progestins
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Progestins (eg: progesterone - all have 21 carbons)
• produced by all major ovarian cell types: follicular granulosa cells, theca cells, corpus luteum • most important as a product of the corpus luteum - during luteal phase of menstrual cycle & for maintenance of pregnancy |
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androgens
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Androgens (eg: testosterone - all have 19 carbons)
• most important as a precursor for synthesis of estradiol in developing follicle • synthesized by follicular theca cells and by corpus luteum • too much testosterone is associated with follicular atresia |
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estrogens
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Estrogens (eg: estradiol - all have 18 carbons)
• synthesized by follicular granulosa cells and corpus luteum • essential for stimulation of follicular development, onset of puberty, etc. |
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Hypothalamic-Pituitary Axis:
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both FSH and LH are stimulated by GnRH
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Anterior Pituitary Hormones:
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(i) FSH
• stimulates ovarian follicles to grow & produce estradiol (ii) LH • stimulates testosterone production by theca cells • stimulates ovulation, secretion of steroid hormones by corpus luteum |
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Primordial follicle:
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starting point - oocyte surrounded by single layer of flattened granulosa cells
• oocyte (primary oocyte) arrested at prophase of meiosis I • by 6 mo postpartum, ovary has full complement of primordial follicles • ~2 million at birth; gradual loss (degeneration); ~400,000 remain by puberty |
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anatomy of primordial follicle
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oocyte + single layer of flattened granulosa cells
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what does development of primordial follicles not need?
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initiation of development of primordial follicles does NOT require gonadotropic stimulation - some follicles can and do begin developing at any time
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meiosis 1 in females
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during fetal development, meiosis 1 begins, but stops at prophase.
after puberty, primary oocytes complete meiosis 1 which produces a secondary oocyte and a polar body. |
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meiosis II in females
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the secondary oocyte begins meiosis 11 but stops at metaphase
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2 pathways of meiosis II
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1. ovulation- a secondary oocyte and first polar body are ovulated
2. fertilization- meiosis II resumes The oocyte splits and creates an ovum and a second polar body. |
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fertilization
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an ovum and the sperm cell unite and create a diploid zygote.
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From Primordial to Primary Follicle:
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gonadotropin-independent
(i) oocyte increases in size & acquires a zona pellucida (ii) granulosa cells start to divide & form several layers outside oocyte (iii) outside bm ovarian interstitial cells closest to growing follicle differentiate to form theca cells • now called a primary follicle |
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Secondary (Antral) Follicle:
antrum |
In stage 5, the fluid between the granulosa cells coalesces to form a large fluid-filled cavity called the antrum, an event that distinguishes the cesivular follicle from the late secondary follicle.
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basement membrane divides follicle into 2 compartments:
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(i) inner granulosa cell compartment
> nonvascularized > FSH-responsive: granulosa cell proliferation (E) granulosa cell E production more FSH receptors (ii) outer theca cell compartment > vascularized > LH-responsive: T production for use by granulosa cells |
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what two things need to happen in order to avoid atresia
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if development coincides with rising FSH levels at beginning of cycle development will be supported - otherwise: atresia!!
• for one follicle to become dominant, must convert potentially androgenic environment to estrogenic environment - otherwise: atresia!! |
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LH surge does what? (in the ovarian cycle)
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E levels continue to rise - FSH switches to inducing receptors for LH > LH stimulates further E & P production
stage is set for LH surge to trigger ovulation |
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Emerging dominant follicle becomes what?
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Emerging dominant follicle becomes the preovulatory follicle
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LH stimulates:
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resumption of meiosis - extrusion of PB#1
P production by granulosa cells increase in antral fluid volume release of hydrolytic enzymes |
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minor FSH surge stimulates
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ensures sufficient LH receptors for luteal phase
stimulates synthesis of hyaluronic acid - important in cumulus expansion |
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describe the corpus luteum as a transient endocrine structure
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corpus luteum = yellow body
capillaries bring cholesterol to follicle |
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anatomy of corpus luteum
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corpus luteum = luteinized granulosa + theca cells + capillaries
unless a pregnancy intervenes, lifespan of CL is <14 days – what is required to maintain CL?? |
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ovary has what two phases that lead to the uterus with what other two phases
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Ovary
Follicular phase Luteal phase to: Uterus Menstruation & Proliferative phase Secretory phase |
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Proliferative Phase of the uterus
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esurfacing of epithelium
cell proliferation in response to ovarian E development of spiral arteries & uterine glands |
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Secretory Phase of the uterus
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thickening of whole layer due to cell growth & fluid retention
When is endometrium maximally receptive to embryo implantation? Why is this called the secretory phase? as LH levels decline, CL begins to degenerate (~D24) in absence of P secretion, uterine endometrium is shed & cycle begins again |
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If oocyte is fertilized (in the uterus)
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hCG is produced in increasing amounts beginning D9-13 after ovulation; hCG rescues CL until placental P can maintain pregnancy
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Three phases of the uterine cycle
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Menstrual-shedding of the functional layer of the endometrium
Proliferative-Rebuilding of the functional layer of the endometrium Secretory- Begins immediately after ovulation. Enrichment of the blood supply and glandular secretion of nutrients prepare the endometrium to receive an embryo. |
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which phases correspond with the luteal phase of the ovarian cycle and which phases correspond with the follicular phase?
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follicular- Both menstrual and proliferative phases are before ovulation and correspond with follicular.
luteal- the secretory phase |
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Outline briefly the hormonal regulation of puberty
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initial hormonal events are the same in males & females
• FSH stimulates E secretion by ………...……….. cells (LH stimulation provides T precursor from ……………. cells) |
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estradiol responsible for:
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growth & maturation of breasts, reprod. organs
√ fat redistribution √ bone maturation (growth > closure of epiphyseal plates) |
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Puberty
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cycles of proliferation & regression until sufficient growth occurs that withdrawal of steroid support (atresia of what??) results in first menstruation = menarche
• first ovulatory cycle often may not occur until several months later • concept of a critical weight to reach before menarche: • specifically, a critical ratio of fat to lean – Why? |
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define menopause & summarize its effects on female physiology
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DEFINITION: cessation of menses for at least 12 months
• in North America, occurs at mean age of 51.4 years • primary cause is depletion of ovarian follicles |
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Perimenopause:
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extends from early 40s onward - « transitional years »
• ovarian function begins to wane - deprivation of estrogen (and its effects on FSH/LH secretion) can result in: hot flushes, insomnia, irritability, fatigue, headaches, depression/mood changes, loss of libido, poor mental performance/ nervousness, loss of skin elasticity |
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Menopause
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median age of 51.4 years; can live 1/3 of life after ovaries have ceased functioning
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loss of ovarian E affects all tissues that have E receptors (what 5 are they?)
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genital tissues: atrophy, vaginal dryness, high incidence of vaginal infections)
(ii) urinary tract: linings of bladder & urethra have E receptors urinary frequency, urgency, even incontinence (iii) breasts: some atrophy (iv) CV system: atherosclerosis, stroke (v) skeleton: osteoporosis |
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after capacitation, sperm:
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(I) have increased rate of flagellar beat & accelerated motility pattern > ?
(ii) plasma membranes are more fragile > facilitates acrosome reaction |
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IVF:
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can induce capacitation by washing sperm or running them through a Percoll gradient
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define sperm capacitation & indicate its relevance to fertility
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a further maturation sperm must undergo to be capable of fertilizing an egg
• occurs following ejaculation once sperm in ♀ tract • seminal fluid contains capacitation inhibiting factors |
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For how long after ovulation is an egg capable of being fertilized?
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12 to 48 hours
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How long do sperm remain viable in the ♀ reproductive tract?
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72 hours
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zona pellucida- what does it do?
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zona pellucida can bind many sperm but only 1 sperm fertilizes the egg
• of ~300 M sperm in ejaculate, only few hundred get close to oocyte |
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describe the acrosome reaction
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During fertilization, a sperm must first fuse with the plasma membrane and then penetrate the female egg in order to fertilize it. Fusing to the egg usually causes little problem, whereas penetrating through the egg's hard shell can present more of a problem to the sperm. Therefore sperm cells go through a process known as the acrosome reaction which is the reaction that occurs in the acrosome of the sperm as it approaches the egg. The acrosome is a cap-like structure over the anterior half of the sperm's head.
As the sperm approaches the zona pellucida of the egg, which is necessary for initiating the acrosome reaction, the membrane surrounding the acrosome fuses with the plasma membrane of the sperm, exposing the contents of the acrosome. The contents include surface antigens and numerous enzymes which are responsible for breaking through the egg's tough coating and allowing fertilization to occur. |
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fast block polyspermy
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n the egg, Na+ channels open in the plasma membrane (BELOW the jelly coat/vitelline layer.) Normally, Na+ concentration is higher outside the cell than inside. So Na+ ions flow down their gradient into the egg and the plasma membrane depolarizes (positive charges neutralize the more negative charge inside the egg cytoplasm.) This depolarization causes the FAST BLOCK TO POLYSPERMY
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slow block polyspermy
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The Ca2+ moves in a wave across the cell. This Ca++ results in the fusion of cortical vesicles with the egg plasma membrane, releasing their contents into the space surrounding the egg, called the perivitelline space. This raises the vitelline membrane, and inactivates bindin receptors on the vitelline membrane. Thus, any additional sperm are released from the vitelline membrane and no more bind. This is known as the SLOW BLOCK TO POLYSPERMY.
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as soon as first sperm penetrates perivitelline membrane:
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fast block to polyspermy:
slow block to polyspermy: resumption of meiosis, extrusion of 2nd PB, formation of ♀ pronucleus sperm nuclear material forms ♂ pronucleus; ♂ and ♀ pronuclei fuse to form 2N nucleus of zygote |
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fertilization when does it occur?
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implantation begins on ~6th day following fertilization:
• blastocyst burrows into endometrium • trophoblast cells grow out toward mat blood vessels |
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name the three different periods of growth of an embryo
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Conception to 2 weeks --- Germinal Period
3 to 8 weeks --- Embryonic Period 9 weeks to term --- Fetal Period |
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Placentation
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maternal and fetal blood supplies NOT in direct contact; nutrients, gases, wastes diffuse
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maternal and fetal blood supplies NOT in direct contact; nutrients, gases, wastes diffuse through:
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(i) trophoblast
(ii) mesenchyme (iii) fetal capillary endothelium |
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normal term placenta and umbilical cord are how large?
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normal term placenta is ~500g, measures 15-20 cm diam, 2-3 cm thick
umbilical cord usu 50-70 cm in length; contains 2 umbilical arteries, 1 umbilical vein |
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Human Chorionic Gonadotropin (hCG)
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present in maternal serum by 8th day after fertilization; levels peak by ~60-80 days, then begin to decrease
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what is the purpose of hCG?
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uman chorionic gonadotropin interacts with the LHCG receptor and promotes the maintenance of the corpus luteum during the beginning of pregnancy, causing it to secrete the hormone progesterone. Progesterone enriches the uterus with a thick lining of blood vessels and capillaries so that it can sustain the growing fetus.
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Human placental lactogen (hPL)
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structurally similar to GH & prolactin (also = human chorionic somatomammotropin)
• placenta begins to secrete hPL during 1st trimester; levels increase until delivery (i) stimulates breast development in preparation for postnatal lactation (ii) supports fetal bone growth (iii) makes glucose available to fetus = diabetogenic or anti-insulin effect |
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Estrogens
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initially come from ; function gradually assumed by placenta
• placenta converts circulating androgens (fetal & maternal adrenal glands) to estrogen • initially estrone & estradiol-17-, then estriol (i) maintains uterine endometrium (ii) contributes to breast development |
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Progesterone
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initially from ; function gradually assumed by placenta
• levels gradually increase over the course of the pregnancy • a relaxing effect on smooth muscle: (i) uterus: (ii) blood vessel walls: (iii) ureters: (iv) GE sphincter: (v) intestines: |
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where does progesterone come from?
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The second half of the cycle is where progesterone is released from the corpus luteum, the rupture that was formed on the ovary from the egg being released at ovulation. The corpus luteum is stimulated by a hormone from the pituitary gland, and large quantities of progesterone are released.
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where does estrogen come from?
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Estrogen is produced in the sex organs of the testicles in men and ovaries in women. The liver and adrenal gland produce small amounts of estrogen in women and men, and in women, breast tissue produces very tiny amounts of estrogen, too.
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outline briefly the influences of pregnancy on the CV
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Cardiovascular:
bp decreases slowly to nadir @ 24 wks; then slowly back up to NP values pulse slowly increases to max of 15-20 beats/min above NP in 3rd trimester myocardial hypertrophy, increased contractility • overall increase in blood volume (~40%): plasma by ~45% & RBCs by 20-30% decrease |
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influences of pregnancy on the GI tract
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GI tract:
• nausea: increased progesterone, hCG, both??? • when severe: hyperemesis gravidarum; if untreated can lead to dehydration, ketosis, electrolyte derangements, liver and kidney damage |
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influences of pregnancy on the urinary tract
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Urinary tract
kidneys increase in length by 1-1.5 cm (increased renal blood flow) bladder tone decreases; bladder capacity nearly doubles glomerular filtration rate (GFR) increases by 30-50% in first trimester high progesterone promotes renal Na (& water) loss; but increased aldosterone & estrogen promote salt & water retention increased risk of urinary tract infections |
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influences of pregnancy on the vagina and cervix
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Cervix:
softening & increased vascularity from early in 1st trimester increased production of mucus by endocervical glands Vagina: cervical secretions increase in quantity; decrease in pH (hi estrogen) increased susceptibility to vaginal candidiasis (fungal infection; hi estrogen, hi glycogen) |
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influences of pregnancy on the uterus
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enlarges by hypertrophy from 50-70 g (NP) to ~1000 g at term (effects of & )
• during 2nd trimester, uterus moves out of pelvis & begins to displace intestines up • by 36th week, intestines pushed up to just beneath diaphragm discomforts experienced by mother include & • blood flow to uterus at term ~500-750 ml/min (10x NP level); = 10-20% total CO • contracts every 5-20 min during pregnancy; irregular contractions that are not coordinated = Braxton Hicks contractions |
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list the 3 stages of parturition
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DILATATION: uterine contractions dilate cervix up to 10 cm; variable in duration
EXPULSION: complete cervical dilation to birth (minutes to few hours) 3) PLACENTAL: delivery of placenta;15 min after birth |
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two hormones important during labour and delivery:
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oxytocin
prostaglandins estrogen levels highest toward time of parturition: (1) lots of oxytocin receptors on myometrial cells (2) antagonizes relaxing effect of progesterone |
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summarize the neuroendocrine regulation of the onset & completion of parturition
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Baby moves into birth canal; pressure of head on cervix neuroendocrine reflex – result??
Oxytocin stimulates uterus to synthesize prostaglandins effects? |
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summarize the neuroendocrine regulation of the onset & completion of parturition (step III)
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Oxytocin levels are high during latter part of pregnancy, but labour not initiated because:
√ progesterone levels also high √ insufficient oxytocin receptors |
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escribe pregnancy-associated preparation for lactation & the roles of prolactin & oxytocin in supporting milk production & milk let-down
Hormonal Regulation of Breast Development: During pregnancy: |
alveolus: glandular structure involved in milk production; lined by a single layer of milk-secreting epithelial cells
• each mammary gland divided into 15-20 lobes; subdivided into lobules; basic component of each lobule is the alveolus |
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describe pregnancy-associated preparation for lactation & the roles of prolactin & oxytocin in supporting milk production & milk let-down
Hormonal Regulation of Breast Development During pregnancy (part II) |
estradiol & progesterone levels increased during pregnancy > stimulate further growth & development of alveoli & ducts
also permissive actions of glucocorticoids, prolactin, human placental lactogen • prolactin stimulates milk production; actual secretion during pregnancy inhibited by high levels of and |
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Postpartum:
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levels of estradiol and progesterone >, allowing full expression of ????
now can have both production and secretion |
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Classical Milk Let-down Reflex & Hormonal maintenance of Lactation 2 important hormones
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prolactin secretion of casein, lactose, fatty acids
(ii) oxytocin contraction of myoepithelial cells • both of these hormones required for continued lactation |
