The Reproductive System; Alyssa Najarro P.1
Functions of the Reproductive System
The Reproductive System system doesn't function like the other organ systems because it isn't active until puberty.
Male and females reproductive organs quite different but share the same four functions.
I. Form specialized cells for sexual reproduction call Gametes;
Sperm-gametes in females
Ova (eggs)-gametes in females
II. Bring gametes from male and female together through sexual intercourse
III. Combine genetic information contained within gametes through fertilization
Zygote is formed when a sperm and an egg fuse
A zygote is the first cell of new individual and all body cells form from it
IV. Support development of a fetus and birth of a baby
Gonads and Accessory Reproductive Organs
Male and female reproductive structures are homologous structures sharing a common origin during development.
Reproductive Hormone Secretion
Hypothalamus, Pituitary, and Gonadal Axis
Hormones involved;
Primary Sex Organs (gonads)- testes (males) and ovaries (females) produce two products;
1) Gametes; sperm (males) and ova (females)
Gametes are formed by cell division called meiosis
2) Sex Hormones (steroid hormones); Testosterone (males) and Estrogens and Progesterones (females)
These hormones are vital in development and functions of the reproductive organs and other organs/tissues, sexual behavior and sexual drives
Accessory reproductive organs include ducts, glands, and external genetalia
Sex Hormones; Testosterone (males) and Estrogens and Progesterones (females)- acting at target tissues in the body. Exerting negative feedback on hypothalamus and anterior pituitary
Follicle-stimulatory hormone (FSH) and Luteinizing hormone- gonadotropins release from the anterior pituitary
Inhibin- are released from gonads of both males and females exerting negative feedback on FSH release from the anterior pituitary
Gonadotropin- the cleansing hormone (GnRH)
-Released from the hypothalamus then reaches pituitary cells via hypophyseal portal system
Male Reproductive System
Anatomy
Scrotum
Sperm is delivered to the body through the system of ducts;
Testes are sperm producing male gonads that lie within the scrotum
I. Epididymis- a duct behind the testis, where sperm passes to the vas deferens and is made up of the head, the body, and the tail.
II. Ductus Deferens- are 45 cm long and passes through the inguinal canal to the pelvic cavity. Joining the duct of seminal vesicle to form Ejaculatory Ducts
III. Ejaculatory Duct- a smooth muscle in the walls and propels sperm from the epididymis to the urethra
IV. Urethra- Conveys both urine and semen at different times
The Testes
Contains paired testes and is 3C lower than the core body temperature. A lower temperature is necessary for sperm production otherwise the scrotum is affected by temperature changes
The sac of skin and superficial fascia which hangs outside abdominopelvic cavity at root of penis
The midline septum divides the scrotum into two compartments, one for each testes.
Male Duct System
Accessory ducts- carry sperm from testes to the body exterior.
Epididymis, ductus deferens, ejaculatory duct, and urethra
The septa divided the testes into 250 lobules, each containing one-four Seminiferous tubules
Each testis is surrounded by two tunics;
Tunica Vaginalis- the outermost layer derived from peritoneum
Tunica albuginea- the inner layer forms fibrous capsule
The site for sperm production and sperm is conveyed from the seminiferous tubules to straight tubule -> Rete Testis -> efferent ductules -> epididymis
The Epididymis is made up of the head, the body, and the tail where sperm is held in the tail until ejaculation
Spermatic Cord encloses nerve fibers, blood vessels, and lymphatic that supply testes
Sperm mature in the epididymis and is highly coiled. Passing slowly through at a rate that usually takes 20 days which is when they finally gain the ability to swim and can be stored for several months. During ejaculation, epididymis contracts, expelling sperm into the ductus deferens
Penis
Vasectomy is cutting and ligating the ductus deferens and is a nearly 100% effective form of birth control
Ductus Deferens (vas deferens) is 45 cm long passing through inguinal canal to the pelvic cavity. It then joins the duct of seminal vesicle to form the ejaculatory duct. The smooth muscle in the walls propels sperm from the epididymis to the urethra.
Urethra conveys both urine and semen at different times*
Male Accessory Glands
Prepuce or foreskin- is the cuff of loose skin covering the glans
Circumcision is a surgical removal of the foreskin
It consists of the root and shaft that ends in Glans Penis
Internally the penis is made up of connective tissue and smooth muscle with vascular spaces;
Corpus sponglosum- surrounds the urethra and expands to form glans and bulbs of penis
Corpora Cavernosa are paired dorsal erectile bodies
Erection is erectile tissue filling with blood causing the penis to enlarge and become rigid
The Penis is the male copulatory organ and one of the two External genitalia, the other being the scrotum
Semen is a milky white mixture of sperm and accessory gland secretions.
2-5 ml of semen are ejaculated containing 20-150 million sperm. It contains fructose for ATP production protecting and activating sperm and sperm movements.
Alkaline fluid neutralizes acidity of the male urethra and female vagina enhancing motility
Prostate encircles the urethra inferior to the bladder. Consisting of a smooth muscle that contracts during ejaculation.
Secreting milky, slightly acidic fluid also containing citrate, enzymes, and prostate-specific antigens.
It contributes in the role of sperm activation and enters prostatic urethra during ejaculation making up 1/3 of the semen volume
Ducts of the seminal glands joins ductus deferens to form ejaculatory duct
Bulbo-urethral glands producing thick, clear mucus during sexual arousal lubricating glans penis. Also neutralizing traces of acidic urine in the urethra
Seminal Glands contain smooth muscles that contracts during ejaculation producing viscous alkaline seminal fluid. Fructose, citric acid, congulating enzymez, and prostaglandins comprising 70% volume of semen
Spermatogenesis is the process of forming male gametes and occurs in the seminiferous tubules beginning at puberty around 14 years old
Adults males make about 90 million sperm daily
Takes 64-72 days if the conditions are stable
Mechanism and Effects of testosterone activity
Summary of events in the Seminiferous Tubules
Major regions of the sperm
Head- genetic region that includes nucleus and helmetlike Acrosome containing hydrolytic enzymes that enable sperm to penetrate the egg
Midpiece- metabolic region containing a mitochondria that produces ATP to move the tail
Tail- locometer region that includes flagellum
Male Secondary Sex Characteristics features induced in non-reproductive organs by male sex hormones; mainly testosterone
Deficiency leads to atrophy of accessory organs, semen volume declines, and erection and ejaculation are impaired. treatments include replacement of testosterone.
Testosterone synthesizes from cholesterol is transformed at some target cells prompting spermatogenesis and target all accessory organs. It has multiple anabolic effects throughout the body
Bones grow, increase in density
Skin thickens and becomes oily
Skeletal muscles increase in size and mass
Larynx enlarge causing your voice to deepen
Boosts basal metabolic rate
Enhanced growth of hair on the chest or other areas
Basils of sex drive in males
Appearance of pubic, axillary, and facial hair
Disorders associated with the reproductive system (including STI’s)
Female Reproductive System
The reproductive role of female more complex because of pregnancy
Testicular Cancer is a rare but the most common cancer in men ages 15-33 having mumps that lead to orchitis which is the inflammation of testis which could be a risk factor
Cryptor Chidism is the most common risk factor which is the non descent of the testes
*Symptoms are painless and solid mass in the testis
90% curable by surgical removal of testis and often radiation or chemotherapy
Prostatitis is the swelling and inflammation of the prostate gland. Prostatitis often causes painful or difficult urination.
Prostate Cancer is the 3rd most common cause of cancer death in males that affects one in six men in the U.S.
Digital exam screening, PSA levels can be checked by having a high rate of false positives.
Treated with surgery and sometimes radiation.
Metastatic prostate cancer is treated with drugs that block testosterone synthesis or action.
Cervical Cancer affects 450k women worldwide each year killing half of them. It is most common in women ages 30-50.
Risks are frequent cervical inflammation, STI's, including HPV, or multiple pregnancies
Gardasil is a three dose vaccine that protects against HPV recommended for young girls ages 11-12 years old.
Pap smear for detection recommended every 3 years for ages 21-30. Every 5 years for ages 30-65 but include HPV testing discontinuing at 65, after a hysterectomy, or with sexual inactivity
Breast Cancer
Invasive breast cancer is the most common malignancy and second most common cause of cancer death in US women.
13% of women will develop the condition usually arising from epithelial cells of smallest ducts that eventually metastasize
STIs and reproductive disorders
STIs are also called Sexually transmitted diseases or Venereal discases
Contraceptives help prevent the spread
STIs are single most important cause of reproductive disorders
Treatments Depending on the characteristics of the lesion, radiation, chemotherapy, or surgery, with more radiation and chemotherapy to destroy stray cells
Drugs for estrogen responsive cancers
Diagnosis can be an early detection via self-examination and *mammography which is a type of x-ray
Lumpectomy is a less invasive and excises only cancerous lumps
Risk factors
-early onset of menstration and late menopause
-no pregnancies or first pregnancy late in life
-No or short periods of breast feeding
-Family history of breast cancer
70% of women with breast cancer have no known risk factors
Bacterial and Parasitic sexually transmitted infections
Newborns picking bacteria up from birth canal can develop;
Conjunctivitis which is a painful eye infection that can lead to corneal scarring if untreated along with inflammation with the respiratory tract including pneumonia
Treatment includes antibiotics
Responsible for 25-50% of all diagnosed cases of pelvic inflammatory disease
Symptoms are Urethritis which is penile and vaginal discharges, abnormal, rectal, or testicular pain, painful intercourse, irregular menses.
Only 20% of women and 10% of men have symptoms if its left untreated which can lead to sterility.
Chlamydia is the most common bacterial STI in the US caused by Chlamydia Trachomatis and can be contracted from the birth canal by newborns
Trichomoniasis is a parasitic infection that is common in women than men and is easily and inexpensively treated.
Symptoms; 70% of women have no symptoms, 30% have yellow-green vaginal discharge with a strong odor
Gonorrhea is a bacterial infection of mucosae of reproductive and urinary tracts caused by Neisseria gonorrhoea
Syphilis is a bacterial infection transmitted sexually or congenitally caused by *Treponema Pallidum. Infected fetuses can be stillborn or die shortly after birth.
In females, symptoms can include abdominal discomfort, vaginal discharge, or abnormal uterine bleeding and possible urethral symptoms.
If untreated, it can result in the pelvic inflammatory disease and sterility
Treatments are antibiotics
Most infections are asymptomatic. In males, symptoms ran include urethritis, painful urination, discharge of pus from the penis (penile "drip")
If untreated it can cause urethral constriction and inflammation of duct system
Viral Sexually Transmitted Infections
The disease can enter latent period which may or may not progress to tertiary syphilis is characterized by gummas* lesions developed in CNS, blood vessels, bones, and skins
Treatment includes penicillin
If its untreated, secondary signs appear weeks later such as pink skin rash, fevers, and joint pain can develop then appear for 3-12 weeks then disappear again
Bacteria invades muscosae or even broken skin, infections are asymptomatic for 2-3 weeks and then painless Chancre appears at the site of infection. It goes away within a few weeks
Genital Herpes are caused by herpes simplex virus which is one of the most difficult human pathogens to control because most do not know they aren't infected. Only 15% display signs of infection.
Characterized by latent periods and flare-ups with vesicle formation that can be passed on to the fetus. Congenital herpes can cause malformations
Treatments are antiviral drugs can reduce duration and intensity of flare-ups
80% of cases of invasive cervical cancer are linked to some strains of HPV and can also cause some penile, anal, and or pharyngeal cancers. It is recommended for boys and girls before becoming sexually active
Group of 40 or more viruses is most common STI in the US, over 50% of adults are infected during their lifetime causing genital warts
Anatomy
Female duct system
The Uterine tube system doesn't have direct contact with ovaries. Ovulated oocytes are released into peritoneal cavity where some oocytes never make it to the tube system. The tube system includes, Uterine Tubes , Uterus, and the Vagina
Ovaries- paired structures flank the uterus, are almond shaped and about twice as large
Each ovary is held in place by several ligaments
Ovarian Ligaments- anchors ovary medially to uterus
Suspensory Ligaments- anchors ovary laterally to pelvic wall
Suspensory ligaments and mesovarium are a part of broad ligaments that supports uterine tubes, uterus, and vagina.
Internal Genitalia is located in the pelvic cavity including Ovaries and Duct System (Uterine tubes, uterus, and vagina)
Ovarian Follicles are tiny sac like structures embedded in the cortex containing immature egg encased by one or more layers of very different cells
Each month a ripened follicle ejects oocyte in an event called Ovulation
Ovaries are female gonads. They produce female gamates and secrete female sex hormones Estrogens and Progesterone
Uterine Tubes are also called fallopian tubes or oviducts receiving the ovulation cycle and is the normal site for fertilization.
The Uterus is a hollow thick walled and muscular organ. Its function is to receive, retain, and nourish fertilized ovums
Regions of the Uterine Tube
Infundi bulumn is a funnel shaped opening into the peritoneal cavity. The margins contain ciliated projections called fimbriae that drape over the overy and is the site where fertilization usually occurs
Each tube is 10 cm long and extends from the area of ovary to the superior region of the uterus
During ovulation, the uterine tube captures ooocytes and it is then carried along towards the uterus by smooth muscle peristalisis and ciliary action
The Vagina is a thick walled tube 8-10 cm in length and functions as a birth canal and passageway for menstrual flow and organ of copulation
Vaginal secretions are acidic in adult females
Mucosa near the vaginal orifice forms incomplete partition called Hymen that ruptures with intercourse
Uterine Wall has three layers
Regions of the Uterus
Body is the main portion
Fundus is the rounded superior region
Isthmus is the narrowed inferior region
Cervix is the narrowed neck, or outlet that projects into the vagina
Cervical Canal communicates with the vagina via external os and the uterine body via internal os
Perimetrium is the outermost serous layer (visceral peritoneum)
Myometrium is the bulky layer consisting of interlacing layers of smooth muscle and contracts rhythmically during childbirth
Endometrium is the mucosal lining. A simple columnar epithelium on top of a thick lamina propia where the fertilized egg burrow into the endometrium and resides there during development
External Genitalia Females external genitalia also called vulva include;
The female Perineum is a diamond shaped region between the pubic arch and the coccyx
Clitoris is anterior to the vestibule, the counterpart of the penis, the body of the clitoris has erectile tissue
Vestibule is a recess within the labia majora
Labia Majora is a hair covered fatty skin folds, the counterparts of the male scrotum
Mons Pubis is the fatty area overlying the pubic symphysis
Mammary Glands are present in both males and females but normally function only in females.
Their main function is milk production to nourish newborns. Modified sweat glands consist of 12-25 lobes.
Areola is pigmented skin surrounding the nipple. Lobules within the lobes contain glandular alveoli that produce milk.
Breast size is due to the amount of fat deposits.
Oogenesis is the production of female gametes and begins in the fetal period
Relationship between oocytes and follicles
Oogonia is divided by mitosis to produce;
Primary oocytes that undergo meiosis I to produce;
Secondary Oocytes that undergo meiosis II to produce Ova
Ovarian Follicles are the functional unit of the ovary that encloses a single oocyte
Secondary Follicles: have multiple layers of granulosa cells surrounding primary oocytes
Primodial Follicle: single layer of squamous pre-granulosa cells surrounding primary oocytes
Vesicular (antral) follicles: have a fluid-filled cavity called an Antrum
Before ovulation primary oocyte inside vesicular follicle resumes meiosis and becomes secondary oocyte
Oogenesis begins during fetal period and takes a year to complete where primordial follicles are the first to develop in the fetus.
Ovulation: each month after puberty, a select few primary oocytes are activated meaning the release of an egg. It is caused by high hormonal levels, especially FSH. One from this group is selected each month to become a Dominant follicle
Stages of follicle development
Follicles and oocytes may take nearly a year to mature before ovulation
The Ovarian Cycle is a montly 28 day series of events associated with maturation of an egg.
Phase Two- Intra-phase stimulated by FSH and LH.
A dominant follicle is selected and a primary oocyte resumes meiosis I
Phase One- gonadotropin independent pre-antral phase involves intra follicular paracrines
A Primordial follicle becomes a Primary Follicle. Oocytes then secrete glycoprotein-rich substances that forms Zona pellucida that encapsulates oocytes.
Maturation processes occurs in two phases
Secondary follicle becomes vesicular follicle
Follicular phase of the Ovarian Cycle during the follicular phase, several vesicular follicles become sensitive to FSH and are stimulated to grow.
One Dominant follicle becomes especially sensitive to FSH and FSH levels drop around the middle of follicular phase.
Dominant follicles outcompetes other follicles and is only one to continue on. Other non-dominant follicles will undergo atresia.
Primary oocyte of dominant follicle completes meiosis I to dorm a secondary oocyte and first polar body
Follicular phase varies but luteal phase is always 14 days from ovulation to the end of the cycle
There are two consecutive phases with ovulation occurring mid-cyle between phases.
Follicular Phase- a period of vesicular follicle growth (days 1-14)
Luteal Phase- period of corpus luteum activity (days 14-28)
Only 10-15% women have 28-day cycles
Ovulation- in between follicular and luteal phase, the ballooning ovary wall ruptures, expelling secondary oocytes with its corona radiata into a peritoneal cavity
Luteal Phase of the Ovarian Cycle
1-2% of ovulations release more than one secondary oocyte, which if fertilized results in fraternal twins
Identical twins result from fertilization of one oocyte then separates of daughter cells
Hormonal Regulation of the Ovarian Cycle
If no pregnancy occurs, corpus luteum degenerates into Corpus albieans in 10 days
It lasts 2-3 days of luteal phase, when endometrium begins to erode.
If pregnancy does occur, corpus luteum produces hormones that sustain pregnancy until the placenta takes over at about 3 months.
After ovulation, ruptured follicle collapses and atrum fills with clotted blood, remaining cells form Corpus Luteum. Corpus secretes progesterone and some estrogen.
Effects of Estrogen and Progesterones
Maintains low cholesterol and high HDC levels, facilates calcium uptakes
-Growth of breasts
-Increased deposit of subcutaneous fat such as hips and breasts
-widening and lightening of pelvis
-Estrogen also has metabolic effects
Estrogens promote oogenesis and follicle growth in the ovary. Exerting anabolic effect on female reproductive tract. It induces secondary sex characteristics and support rapid short lived growth spurt at puberty
Progesterone
Promotes changes in cervical mucus
Works with estrogen to establish and regulate uterine cycle
Effects of placental progesterone luring pregnancy
Inhibits uterine motility and help prepare breasts for lactation
1) GnRH stimulates FSH and LH secretion
2) FSH and LH stimulate follicles to grow ,mature, and secrete sex hormones.
FSH stimulates cells to release estrogen, and LH prods other cells to produce androgens, which converts to estrogens
Hormonal interaction during ovarian cycle
3) Negative feedback inhibits gonadotropin release
5) LH surge triggers ovulation and formation of the corpus luteum.
Shortly after ovulation:
– Estrogen levels decline
– LH transforms ruptured follicle into corpus luteum
– LH stimulates corpus luteum to secrete progesterone and some estrogen almost immediately
-Progesterone helps maintain stratum functionalis
-Maintains pregnancy, if it occurs
4) Positive feedback stimulates gonadotropin release.
Estrogen levels continue to rise as a result of continued release by dominant
follicle
-Triggers LH surge
6) Negative feedback inhibits LH and FSH release
If no fertilization occurs:
-Corpus luteum degenerates when LH levels start to fall
-Causes a sharp decrease in estrogen and progesterone, which in turn ends
blockage of FSH and LH secretion, causing cycle to start all over again
Oocyte is actually activated 12 months prior to ovulation but matures 14 days before
ovulation
The Uterine (Menstrual) Cycle
Days 1–5: menstrual phase
-Ovarian hormones are at lowest levels
-Gonadotropin levels are beginning to rise
-Stratum functionalis detaches from uterine wall and is shed
-Menstrual flow of blood and tissue lasts 3–5 days
-By day 5, growing ovarian follicles start to produce more estrogen
Days 6–14: proliferative (preovulatory) phase
-Rising estrogen levels prompt generation of new stratum functionalis layer
-As layer thickens, glands enlarge, and spiral arteries increase in
number
-Estrogen also increases synthesis of progesterone receptors in endometrium
-Thins out normally thick, sticky cervical mucus to facilitate sperm passage
-Ovulation occurs at end of proliferative phase on day 14