Ch. 27: The Reproductive System (A&P)
Uterine Wall
Perimetrium Myometrium Endometrium
Ovaries
Primary sex organ of females producing ova and hormones Female gonads Produce female gametes (ova) Secrete female sex hormones- estrogen and progesterone
Meiosis I
Primary spermatocyte (2n), secondary spermatocytes
Several stages of follicle development
Primordial follicle (mature follicles) Vesicular follicle Ovulation Corpus luteum
Ovarian cycle stages
Primordial follicle - primary follicle Primary follicle - Secondary follicle Secondary follicle - late secondary follicle - vesicular follicle (bulges from ovary) Ovulation - Expelling secondary oocyte
Spermatogenesis
Process of sperm cell formation from spermatogonia Occurs in seminferous tubules Before puberty: Spermatogonia (stem cells) undergo rapid mitosis At puberty: FSH modifies cell division, 2 cells produced (stem cell and primary spermatocyte)
Ovaries
Produce and release female gametes and sex hormones like estrogen and progesterone
Effects of Estrogens
Promote oogenesis and follicle growth in ovary Exert anabolic effects on female reproductive tract Rapid, short-lived growth spurt at puberty Induce secondary sex characteristics (breasts, hips, pelvis widening) Blood cholesterol levels, calcium uptake *Simulate growth and maturation of reproductive organs and breasts at puberty and maintain their adult size and function. Promote the proliferative phase of the uterine cycle. Stimulate production of watery cervical mucus and activity of fimbriae and uterine tube cilia. *Promote oogenesis and ovulation by stimulating formation of FSH and LH receptors on follicle cells. Stimulate capacitation of sperm in the female reproductive tract *During pregnancy stimulate growth of the uterus and enlargement of the external genitalia and mammary glands
Effects of testosterone activity
Prompts spermatogenesis Targets accessory organs Multiple anabolic effects throughout the body Deficiency problems- How to treat?
Breast cancer treatment depends on the cancer (how severe it is)
Radiation, chemotherapy, surgery Specific drugs and immune therapy
Uterine tubes
Receives ovulated oocyte, usual site of fertilization Problems: 1) Ectopic Pregnancy: The fertilized egg grows in the wrong place, outside the uterus, usually in the fallopian tubes 2) Pelvic inflammatory disease: spread of infection to peritoneal cavity
Females are born with essentially all of these early versions of eggs in all of the primordial follicles they will ever have (around 1 million at the time of birth)
Right after birth, the oocytes stop developing- they get stuck in the first stage of meiosis
Proliferative phase (Days 6-14)
Rising estrogen levels: new stratum funtionalis layer Cervical mucus thins allowing sperm passage Ovulation occurs at end of this stage
Problem- Cervical Cancer
Risks: STIs, multiple pregnancies Pap smear, vaccine, HPV (human papilloma virus)
*3 parts of the penis
Root, body, glans penis
Luteal Phase of the Ovarian cycle
Ruptured follicle collapses Formation of corpus luteum which secretes progesterone and some estrogen If no pregnancy, corpus luteum into corpus albicans in 10 days Pregnancy - hormones start producing
Seminal glands (vesicles)
Saclike organ Secretes alkaline fluid Makes up 70% of semen, released prior to ejaculation
Male external genitalia
Scrotum Testes Seminiferous tubules Penis Urethra Glans penis Prepuce
Accessory Structures of male genitalia
Seminal Vesicles Prostate Gland Bulbourethral Gland
Epididymus of Penis
Sit on top of testes Highly coiled tube Receive spermatids formed in seminiferous tubules for maturation
Comparison of Oogenesis and Spermatogenesis
Spermatogenesis- 4 viable sperm Oogenesis- 1 viable gamete, 3 polar bodies Unequal divisions ensure oocyte has nutrients for journey to uterus Polar bodies degenerate and die
Internal structures of Penis
Spongy urethra and 3 bodies of erectile tissue Erection- erectile tissue fills with blood
Prostate Gland
Surrounds proximal portion of urethra Disorders: BPH, Prostatitis, Prostate Cancer
Primary sex organs (gonads)
Testes and Ovaries *Only 23 chromosomes
Testes: how it regulates secretion
Testosterone to male characteristics
The follicle-stimulating hormone lives up to its name by stimulating the growth of a follicle- but only one: the one that happens to be furthest along in development at the time
The FSH drives that one lucky follicle to keep growing, by triggering the follicle itself to secrete its own estrogen hormones, which locally signal the follicle to mature even more.
That surge of follicle-secreted estrogen then ends up stimulating the pituitary to secrete another pulse of luteinizing hormone to finish the job
The LH gets to work on the oocyte that's been dormant inside the follicle, and triggers it to finally start dividing again- getting it to complete meiosis I and move on to metaphase II. This whole process takes about 14 days, at the end of which, the follicle- which is now mature- pushes up against the ovary wall, ruptures, and, with the help of enzymes, breaches the wall and ejects a single, now mature, oocyte. (ovulation).
Oogenesis
The actual process of egg creation. Delayed until puberty, when the rest of the body is physically ready to reproduce.
Oogenesis
The actual process of egg creation. Delayed until puberty, when the rest of the body is physically ready to reproduce. Production of female gametes takes years to complete Begins in fetal life- oogonia- primary oocytes- primordial follicles After puberty- "one" selected each month to resume meiosis I, get secondary oocyte, first polar body, to ovum, secondary polar body *(cause of periods)
Primary, internal sex organs
The gonads (testes and ovaries)
Ovarian cycle
The maturation of the follicle and egg Structural changes in the ovarian follicles during the ovarian cycle are correlated with (d) changes in the endometrium of the uterus during the uterine cycle.
Ovarian cycle
The maturation of the follicle and egg. Drives the menstrual cycle.
*Both the menstrual and proliferative phases occur before ovulation, and together they correspond to the follicular phase of the ovarian cycle.
The secretory phase corresponds in time to the luteal phase of the ovarian cycle.
Every day, even before birth, a bunch of follicles will begin a process of maturation, very slowly morphing from primordial follicles into what's known as the late-tertiary follicles, which are the ones that will support a fully developed egg.
This process takes 375 days but out of that bunch of follicles- usually about 20 or so- only one follicle will end up supporting a single, mature egg. The rest won't get the hormonal boost they need to bring the egg to completion. This is what happens to the ones that start maturing before puberty for example, so they undergo atresia.
Ovarian follicles
Tiny-sac-like structures that each hold a single primary oocyte- a sort of incomplete proto-egg, along with a bunch of supporting follicle cells around it
Ductus deferens of Penis
Tube connected to each epididymis Carry sperm to urethra Vasectomy -If you want to make yourself infertile, they cut a little hole into the ductus deferens and then overtime he'll become infertile as the tube dies off (?). Still produces testosterone, just not sperm
Ductus (vas) deferens
Tube connected to each epididymis, carry sperm to urethra, cut and tied during vasectomy
Development Aspects
Two months before birth, testosterone stimulates migration of testes toward scrotum Ovaries also descend, but stopped by broad ligament at pelvic brim Reproductive organs grow to adult size, functional at puberty
Sexually Transmitted Infections (STIs)
U.S. -- Highest rates for developed countries Many diseases are in epidemic numbers Most important cause of reproductive disorders (including infertility) How to prevent????? Safe sex.
Vagina- Birth Canal and Organ of Copulation (sex)
Urethra parallels course anteriorly (urethra in front of vagina) Acidic environment, dendritic cells Vaginal fornix ("arch" of vagina. Refers to any one of the deepest sections of the vagina that extends into the vaginal region of the cervix)
Accessory ducts include
Uterine tubes, Uterus, Vagina
Menstrual Cycle
What happens in the uterus to prepare for a fertilized egg
Starting around puberty, the hypothalamus and pituitary set up 2 concurrent cycles- the ovarian cycle in the ovaries, which ripens eggs and secretes sex hormones, and the menstrual, or uterine cycle, which prepares the uterus to capture and nourish any mature, fertilized eggs
When puberty begins, the hypothalamus starts up the ovarian cycle by secreting gonadotropin-releasing hormone about once a month. This is a sex hormone that stimulates the anterior pituitary to release 2 more hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
Postovulatory phase
When the ruptured follicle forms in the corpus luteum. And if fertilization didn't happen, the corpus will stop producing progesterone, and the endometrium will start to shed its functional layer. And it starts all over again. BUT, if by this time, the egg has met a nice sperm and gotten fertilized, then the pulse of progesterone from the corpus triggers even more thickening of the functional layer of the endometrium, and a secretion of nutrients that will tide an embryo over until it has implanted itself in the blood-rich lining
Effects of progesterone
Works with estrogen to establish and regulate uterine cycle Promotes changes in cervical mucus Effects of placental progesterone during pregnancy *Cooperates with estrogen in stimulating growth of breasts. Promotes the secretory phase of the uterine cycle. Stimulates production of viscous cervical mucus. Progesterone surge after ovulation enhances beating of cilia in the uterine tube, promoting meeting of sperm and oocyte. *During pregnancy, quiets the myometrium and acts with estrogen to cause mammary glands to achieve their mature milk-producing state.
The 3 phases of the uterine cycle
• Menstrual: The functional layer of the endometrium is shed. • Proliferative: The functional layer of the endometrium is rebuilt. • Secretory: Begins immediately after ovulation. Enrichment of the blood supply and glandular secretion of nutrients prepare the endometrium to receive an embryo.
Meiosis cont.
# of divisions: 2, each consisting of prophase, metaphase, anaphase, and telophase. DNA replication does not occur between the 2 nuclear divisions. Synapsis of homologous chromosomes: Occurs during prophase I; tetrads form, allowing crossovers Daughter cell # and genetic composition: 4. Each haploid (n) cell contains half as many chromosomes as the mother cell and is generally different from the mother cell Roles in the body: Produces cells for reproduction (gametes). Introduces genetic variability in the gametes and reduces chromosomal number by half so that when fertilization occurs, the normal diploid chromosomal # is restored (in humans, 2n=46).
Gametes
(sperm and eggs) Haploid cells, meaning that they only have one set of chromosomes and are formed by meiosis
*Seminiferous tubule: sperm making factory
*Generated constantly
Testosterone effects on reproductive organs
*Stimulates formation of male reproductive ducts, glands, and external genitalia. Promotes descent of the testes. Stimulates growth and maturation of the internal and external genitalia at puberty; maintains their adult size and function. *Required for normal spermatogenesis via effects promoted by ABP, which keeps its concentration high near spermatogenic cells. Suppresses mammary gland development.
*Testes have to be below normal body temp. or else you don't have production of working sperm- become infertile
*Testes do 2 things: produce sperm and testosterone
Male Reproductive System
-Functions together with female reproductive system to produce offspring -Consists of internal and external structures -Produces horomones (androgens) -Gamete (sperm) production
Testes
-Primary organs of male system (located in scrotum) -Produce sex cells (sperm) -Produces testosterone (interstitial cells) -Fibrous capsule divided into lobules -Surrounded by 2 tunics -Seminiferous Tubules -Interstitial endocrine cells: what do they produce? -Blood supply
The scrotum
-Sac of skin and superficial fascia -Lower than core temperature- why? -Temp. kept constant by 2 sets of muscles
Testicular Cancer
-Younger men -Sign: painless, solid mass -Risk factors: family history, undescended testicle (can cause cancer- need surgery to remove testicles, as a result you need to bank your sperm because you'll become infertile) (90% survival if early detection; get a monthly check) -Cancer is forming in germ cells (aka forming in the sperm itself) -As it spreads it becomes more painful in the abdominal area
Sex hormones play roles in:
1. Development and function of reproductive organs 2. Sexual behavior and drives 3. Growth and development of other organs and tissues
Prostate Disorder
1. Prostatitis (Inflammatory Disorder) 2. Benign Prostatic Hyperplasia (Growth of prostate, distorts urethra) -Problem w/ this: the urethra gets squeezed and makes it difficult for you to urinate. If the urine goes backward into the bladder bc it's squeezed back then you can get a urinary infection. 3. Prostate Cancer (2nd common cause of cancer deaths of men, detection, treatment) -Screening issue
Developmental Aspects: Determination of Genetic Sex
2 sex chromosomes: -X chromosome (large) -Y chromosome (small) Females are XX, Males are XY *The SRY gene on the Y chromosome initiates testes development and maleness *Sexually indifferent stage: fifth week *X is larger than Y because it has an extra line (way to remember)
Atresia
A kind of programmed self-detruction
Hormonal Interactions During Ovarian Cycle
Anterior pituitary releases FSH stimulates ovarian follicle to mature Mature follicle secretes estrogen which causes uterine lining to thicken Anterior pituitary releases LH which triggers ovulation Following ovulation, follicular cells become a corpus luteum which secretes progesterone Progesterone causes uterine lining to become more vascular and glandular If release oocyte not fertilized, corpus luteum degenerates and hormone levels fall
Gonorrhea
Bacterial infection Signs and symptoms -Males: discharge (yellowish), painful urination -Females: 20% no signs/symptoms, vaginal discharge, uterine bleeding, PID Treatment: antibiotics, resistant strains
Syphillis
Bacterial infection, sexually or congenitally Asymptomatic (no symptoms) for 2 - 3 weeks, if untreated then to secondary stage (rash, fever, joint pain) Tertiary stage (latent) - CNS, blood vessels, bones, skin Painless chancre (ulcer- sore that develops) at site of infection, disappears Treatment - penicillin, some strains resistant
Spermatogenesis cont.
Blood-testis barrier (so that sperm cells aren't destroyed at the child is developing?) Supporting cells: Sertoli cells -Provide nutrients, secrete testicular fluid Infertility: What can be done? -Causes: environmental toxins, lead exposure (flint water), fever, hot tubs usage (affects temp.)
Only if an when an egg fuses with a sperm does it actually complete meiosis II and officially become an ovum
But, whether its fertilized or not, the egg works its way down the tube until it enters the uterus, a hollow, thick-walled, and very stretchable muscular organ that sits anterior to the rectum and posterosuperior to the bladder, and ends with the cervix.
Urethra of Penis
Carries both urine and semen (at different time) Three regions: 1. Prostatic Urethra 2. Membranous urethra 3. Spongy urethra
The Uterine (menstrual) Cycle
Cyclic changes in endometrium in response to ovarian hormone level changes 3 phases: -Menstrual phase -Proliferative (preovulatory) phase -Secretory (postovulatory) phase
The male perineum
Diamond shaped region between pubic symphysis, coccyx, and ischial tuberosities Suspends scrotum
When a sperm fuses with an egg, they make a diploid cell, which has all the genetic instructions required to make a baby. And pretty much everything about how our reproductive systems work is designed to make that happen
Each ovary lives in a fibrous sac that consists of a layer of connective tissue called the tunica albuginea, and another layer of cuboidal epithelial cells called the germinal epithelium, which is actually part of the peritoneum that lines the abdominal cavity.
Meiosis II
Each secondary spermatocyte (n), 2 spermatids (n)
Internal Structures of male genitalia
Epididymis Ductus (vas) deferens
Male sexual response
Erection vs. Ejaculation Nervous system: parasympathetic spinal reflex
The vulva
External female genital organs. Includes the mons pubis over the pubic bone, and labia major and labia minor- the elongated skin folds that surround the vestibule, which contains both the urethral and vaginal openings
Parts of female reproductive system
Female Duct System (ducts have no contact with ovary) Uterine (fallopian) tubes or oviducts Uterus Vagina
Fluctuation of ovarian hormone levels
Fluctuating levels of ovarian hormones (estrogens and progesterone) cause the endometrial changes of the uterine cycle. The high estrogen levels are also responsible for the LH/FSH surge in gonadotropins
Fluctuation of gonadotropin levels
Fluctuating levels of pituitary gonadotropins (follicle-stimulating hormone and luteinizing hormone) in the blood regulate the events of the ovarian cycle.
Pituitary Gland: how it regulates secretion
Follicle stimulating hormone to sperm production, luteinizing hormone to testosterone production
Female Reproductive system
Functions together with male reproductive system to produce offspring- gamete production Consists of internal and external structures Produces hormones Has accessory organs Nurture and develop offspring (breast milk)
Meiosis
Gamete formation involves meiosis Differs from mitosis Two consecutive cell divisions: meiosis I and meiosis II Produces 4 daughter cells Functions: Number of chromosomes halved -Genetic diversity
Functions
Gamete production Hormone Secretion
Hypothalamus: how it regulates secretion
Gonadotropin-releasing hormone stimulates anterior pituitary
Genital warts
HPV, second most common STI in US and causes increased risk of cancers in infected body areas
3 parts
Head: holds the nucleus with the 23 chromosomes; covered with acrosome Mid-piece: position between head and tail, filled with mitochondria to fuel movement of flagella Tail: Flagellum, propels sperm *Mitochondria produces ATP which allows the flagella to propel and move the body of sperm (?)
Ovaries cont.
Held in place by ligaments Two regions- cortex and medulla Embedded in cortex: ovarian follicles Ovulation: ejection of oocyte
Penis
High vascularized cylindrical organ Passageway (urethra) for both urine and semen Contains specialized erectile tissue Prepuce covers glans penis (removed through circumcision: ~70% of men; reduces risk of HIV and STD infections)
Epididymis
Highly coiled tube, sits on top of testes, received spermatids for maturation
Uterus
Hollow, thick-walled, muscular organ which receives, retains, and nourishes ovum
Hormonal Regulation of Ovarian Cycle
Hormone interaction produces cyclic events in the ovaries Gonadotropin - releasing hormone (GnRH) Pituitary gonadotropins Ovarian estrogen Ovarian progesterone
Male secretion regulated by
Hypothalamus, anterior pituitary gland, and testes
The uterine wall is composed of 3 layers: the perimetrium on the outside, the bulky, smooth muscle myometrium that contracts during labor, and the inner mucosal lining, the endometrium, which consists of a thin, deep basal layer, and an outer functional layer
If fertilization does happen, then the new embryo snuggles into the endometrium for gestation- but the uterus is only receptive to implantation for a short time, about a week after ovulation. If the egg isn't fertilized, that outer, functional layer sloughs off. And that's the first phase of the uterine, or menstrual cycle- the series of changes that the endometrium goes through every 28 days or so, in response to changing hormone levels, and in coordination with the ovarian cycle.
Erectile Dysfunction
Impotence Causes: alcohol, drugs, NS problems, blood vessel problems Treatments including lifestyle changes
Bulbourethral Glands (Cowper's Gland) of Penis
Inferior to prostate gland Mucus like fluid cleanses urethra before ejaculation and acts as lubricant during intercourse
Genital herpes
Latent periods and flare-ups Treatment with antiviral drugs
The fallopian tubes
Made of sheets of smooth muscle and a highly folded mucosa layer. About 10 cm long and aren't actually connected to the ovaries. This means that when the egg pushes though ovary, it has to float a short way through the peritoneal cavity before it's caught be a fallopian tube
Male life span
Males retain reproductive capabilities until very late in life Mid 50s: -Decline in testosterone -Decrease muscle strength -Fewer viable sperm -Decreased sex drive
The shedding of the functional layer is triggered when the progesterone and estrogens that were being produced by the corpus luteum start to drop, about 10 days after ovulation. This phase lasts about 5 days.
Meanwhile, the FSH and LH released from the anterior pituitary start to rise again, stimulating the next round of follicles, which begin to make estrogen. This heralds the start of phase 2 of the menstrual cycle, the proliferative, or pre-ovulatory phase, which typically lasts from days 6-14 of the cycle. The rising estrogen levels in the follicles stimulate the regeneration of the endometrium, building a busy, well-vascularized habitat for another potential fertilized egg to call home
Menopause
Menses have ceased for an entire year Declining estrogen levels -Atrophy of reproductive organs and breasts, hot flashes, irritability, depression, gradual thinning of skin and bone loss, increased cholesterol levels *Atropy: Gradual decline; waste away; Due to degeneration of cells
Semen
Mixture of sperm cells and fluids from seminal vesicles, prostate gland and bulbourethral glands Alkaline to counteract acidic environment of vagina Contains nutrients to nuture sperm Contains 15-250 million sperm per ml
Mammary Glands
Modified Sweat glands made up of lobes Lobules within lobes contain glandular alveoli that produce milk Milk- lactiferous ducts- lactiferous sinuses- nipple
External Genitalia
Mons pubis, labia majora, labia minora, clitoris, vaginal orifice, Bartholin's glands, perineum
External Genitalia (Vulva)
Mons pubis: overlying pubic symphysis Labia majora: skin folds Labia minora: skin folds within labia majora Clitoris: counterpart of penis Perineum: region between pubic arch and coccyx
Ovarian Cycle
Monthly events associated with maturation of egg Follicular phase: Period of follicle growth Ovulation (midcycle); best time to get pregnant Luteal phase: period of corpus luteum (only 10-15% of women have 28 day cycle)
Chlamydia
Most common bacterial STI in US Signs/symptoms: discharges, urethritis, pain, irregular menses Can cause UTI in men, sterility in women, babies (trachoma- a bacterial infection that affects the eyes) Treatment: tetracycline (form of antibiotics)
Trichomoniasis
Most common curable STI in sexually active young women Parasitic infection, can treat Signs/Symptoms: vaginal discharge, some symptomless
Breast cancer
Most common malignancy in women (Harmful; not benign) Second most common cause of cancer death in American women How many will develop this condition? 1 in 8 women (12%) Risk factors: Genetics, no pregnancies or late in life, early onset of menstruation, late menopause, 70% no known risk factors Detection: Self exam, mammography, screening guidelines and issues
Cervix
Narrow neck projects into vagina
Menstrual Phase (Days 1-5)
Ovarian hormones at lowest level Estrogen/ progesterone begin to rise Menstrual flow - 3 to 5 days By day 5 growing ovarian follicles produce more estrogen
Internal genitalia in pelvic cavity of females
Ovaries Uterine tubes Uterus Vagina