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