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Reproductive System

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Shreya Ganeshan

on 12 March 2014

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Transcript of Reproductive System

Reproductive System
Exploring Uncharted Territory: Period 2, Group 1
Introduction
reproductive system arguably the most important
serves human purpose to repopulate
major organs: external genitalia, internal reproductive organs
gonads - organs that produce gametes (reproductive cells)
males: testes produce sperm
females: ovaries produce eggs
Male Reproductive System
Anatomy of the Male
Tunica albuginea- white fibrous tissue surrounding testis... extends inward into testis, producing wedge shaped compartments containing seminiferous tubules
Seminerferous tubules- site of production of sperm cells
Rete testis- sperm travel into the rete testis, it is the temporary holding area before entering the epidiymis
Epididymis- hugs the exterior of testis...temporary storage area for immature sperm. Takes about 20 days for the sperm to mature
Vas defrens- runs upward from epididymis... sheathed along with blood vessels in spermatic cord
External Structures
Penis- the male organ for sexual intercourse. It has three parts: the root, the shaft, and the glans.
Scrotum- sac-like organ, houses testes, inferior to penis consists of two adjacent pouches that contain testis composed of smooth that regulates distance between testes and rest of body
Testes- male reproductive organs which are responsible for producing sperm and testosterone.
Epididymis- hugs the exterior of testis...temporary storage area for immature sperm. Takes about 20 days for the sperm to mature

Internal Structures
Seminal Fluid
Slightly alkaline in nature, have a pH of 7.2-7.6. Helps to neutralize the acid environment of the vagina (pH of 3.5-4.0)
At a pH<6.0, sperm become sluggish
Semen contains seminalplasmin, which is a natural antibiotic.
It also contains the hormone relaxin, which aids in preventing immune response and helps with motility.
3-5 mL per ejaculate
Each milliliter can contain between 50-150 million sperm
>20 million is considered infertile
Meiosis
a process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, which results in the production of sex cells
Functions:
produce, maintain and transport sperm and protective fluid (semen)
discharge sperm within the female reproductive tract
produce and secrete male sex hormones

Female Reproductive System
External Structures
Labia majora – enclose and protect external reproductive organs; contain sweat and oil-secreting glands
Labia minora –surround openings of vagina (canal that joins lower part of uterus to outside of body) and urethra (tube that carries urine from bladder to outside of body)
Bartholin’s glands – glands located beside vaginal opening; produce mucosal secretion
Clitoris – meeting point of two labia; small, sensitive protrusion; covered by a fold of skin called prepuce (similar to foreskin at end of penis); like penis, clitoris sensitive to stimulation and can become erect

Before Ovulation
Vesicular ovarian follicle – "Graafian follicle;" most mature stage of ovarian follicle (4th stage) housing primary oocyte (egg) in cumulus oophorus
follicle large size (nearly entire width of ovarian cortex),
primary oocyte (egg) almost done meiosis division one
surrounded by zona pellicuda (extracellular glycoprotein)
activated by FSH and LH from pituitary gland to begin developmental cycle leading to ovulation
Corpus luteum – mass of active follicular cells (luteal cells) in cortex of ovary; formed when vesicular follicle discharges secondary oocyte after LH pulse
secretes estrogen and progesterone
degenerates into croups albicans (dense fibrous connective tissue) at end of menstrual cycle

Ovulation
Ovulation – process by which Graafian follicles rupture and release mature oocytes
Endometrium - inner membrane of uterus
function: prevent adhesion between myometrium walls
during menstruation, endometrium thickens into a glandular tissue layer (optimal environment for implantation of egg due to estrogen and progesterone (secretory lining))
during pregnancy, grows to form placenta (supplies oxygen and nutrition to embryo and fetus
cyclical regeneration lasts 28 days; after menopause, endometrium atrophic
Myometrium – muscular wall of uterus between endometrium and perimetrium (outer membranous layer)
composed of smooth muscle but contains connective tissue and blood vessels
during pregnancy, expands for growing fetus and aids in labor (muscles push baby out of placenta)

Oogeneis
Development and maturation of oovum (meiotic)

1) Begins in the fetal period: development of oogonia (female stem cells) by mitosis
2) Meiosis division I, which produces primary oocytes (remain in meiotic prophase I)
3) at puberty, in response to increasing blood levels of FSH and LH from the anterior pituitary gland, meiosis continues in ovarian follicles every month (menstrual cycle)
4) development of vesicular follicle (Graafian follicle - most mature; stage 4)
5) ovum completes meiosis division I at the time of ovulation
6) if secondary oocyte is fertilized, nucleus undergoes second meiotic division - produces another polar body and the ovum nucleus
if not fertilized, secondary occyte deteriorates without ever completing meiosis II - forms mature egg
7) fusion of the haploid egg creates zygote
FSH and LH
Follicle stimulating hormone (FSH) stimulates small number of primary follicles to grow and mature each month

Luteinizing hormone (LH) causes release of secondary oocyte from Graafian follicle - and ultimately ovulation
Functions:
Produce sex hormones – estrogen
Produce eggs (ova or oocytes)
Provide nourishing environment in which fertilized egg can develop in to a baby

Testes- male reproductive organs. Exhibit both endocrine and exocrine functions.
Endocrine- interstitial cells located between the seminiferous tubules and produce and secrete testosterone (androgen)
Exocrine- production and transfer of the spermatazoa through a duct system
Endocrine and Exocrine Functions
Seminal vesicles- produces 60% of the semen. Rich in vitamin C, frutose, and protaglandins. Lies adjacent to duct of ampullae.
Prostate Gland- lies inferior to bladder, produces prostatic fluid which drains into urethra...nourishes sperm
Bulbourethra (cauper's) glands- inferior to prostate glands; produces a clear, mucus liquid which cleanses the urethra of urine and serves as a lubricant.

Spermatogenisis
the process by which male gametes form
FSH and LH
Follicle-stimulating hormone(FSH) and luteinizing hormone(LH) are the primary hormones involved in the functioning of the male reproductive system.

FSH and LH are produced by the pituitary gland located at the base of the brain.
FSH is necessary for sperm production and LH stimulates the production of testosterone
STD's
Ghonorrhea- caused by Neisseria gonorrhoeae, a bacteria that multiplies in the mucus membranes of the body. Symptoms include: greenish yellowish discharge from the vagina, abdominal or pelvic pain, burning when urinating, swelling. This disease is a very common infectious disease in the U.S.
Syphillis- a highly contagious disease spread by sexual activity (including oral and anal sex). This disease is caused by the bacteria Treponema pallidum. There are many possible symptoms, many of which look like symptoms from other diseases.
Chlamydia- Chlamydia is the most reported STD in the U.S. Chlamydia is spread through unprotected sex with an infected person. Sexually active young people are at a higher risk. Symptoms include: an abnormal vaginal discharge; a burning sensation when urinating; a discharge from their penis; a burning sensation when urinating; pain and swelling in one or both testicles.

Genital Herpes- an STD caused by two different types of viruses: herpes simplex type 1 and herpes simplex type 2. Fluids found in a herpes sore carry the virus, and contact with those fluids can cause infection. Herpes can also be spread through sex with an infected partner without a visible sore.
AIDS- Human immunodeficiency virus (HIV) causes HIV infection and AIDS. The virus attacks the immune system. As the immune system weakens, the body is vulnerable to life-threatening infections and cancers. Once a person has the virus, it stays inside the body for life.The virus is spread through sexual contact, through blood, and from mother to child.
Hepatitis- inflammation of the liver from the hepatitis virus. There are vaccines for prevention, but no specific treatment of it.
Genital warts- a sexually transmitted infection that causes soft growths on the skin and mucus membranes of the genitals.

Non-STD's
Uterine, ovarian, and cervical cancer- disease in which malignant (cancer) cells form in the tissues of the ovaries/cervix/uterus.
Amenorrhoea- the absence of menstruation — one or more missed menstrual periods. The most common cause is pregnancy. Other causes include problems with the reproductive organs or with the glands that help regulate hormone levels.
Dysmenorrhoea- pain with menstruation. Symptoms include aching pain in the abdomen, feeling of pressure in the abdomen and pain in the hips, lower back, and inner thighs.
Ectopic pregnancy- a pregnancy that occurs outside the womb; it is life-threatening to the mother. Anything that blocks or slows the movement of the egg through the fallopian tubes can cause an ectopic pregnancy. The pregnancy cannot continue to birth.
Endometriosis- a female health disorder that occurs when cells from the lining of the womb grow in other areas of the body. This can lead to pain, irregular bleeding, and infertility.
Fibroids- noncancerous tumors that develop in the womb. There is no known cause. Symptoms include: bleeding between periods, heavy bleeding during period, and longer periods.
Polycystic ovarian syndrome- a condition in which a woman has an imbalance of a female sex hormones. This may lead to menstrual cycle changes, cysts in the ovaries, trouble getting pregnant, and other health changes.
Anatomy of the Female
Internal Structures
Vagina – canal that joins cervix (lower part of uterus) to outside of body; birth canal
Uterus – womb; two parts (cervix and corpus)
Cervix – lower part, opens into vagina; sperm enters, menstrual blood exits
Corpus – main body of uterus; can easily expand to hold developing baby
Ovaries – small, oval-shaped glands located on both sides of uterus; progesterone activates reproductive system before and during pregnancy; ovulation – release of egg
Fallopian tubes – narrow tubes attached to upper part of uterus; allows ova to travel from ovaries to uterus; conception occurs in fallopian tubes; after fertilization zygote travels to uterus, implanted into uterine wall

Menstrual Cycle
MENSES (days 1- 5) - endometrial lining of uterus becomes detached from uterine wall
bleeding for 3 to 5 days; detached tissues and blood pass through vagina as menstrual flow
average blood loss is 50 150 ml
PROLIFERATIVE STAGE (days 6- 14) - rising estrogen levels allow ovarian follicle growth
endometrium repaired and thickens
ovulation occurs in ovary at end of this stage in response to sudden surge of LH in blood
SECRETORY STAGE (days 15- 28) - rising levels of progesterone (from corpus luteum) act on endometrium and increase its blood supply more
progesterone causes endometrial glands to swell and secrete nutrients into the uterine cavity to sustain developing embryo
if fertilization does occur, the embryo produces a hormone similar to LH
if fertilization does not occur, corpus luteum degenerates to corpus albicans
*without oxygen and nutrients, endometrial cells die and menses begin again
Mammary Glands
glands located in female breast that lactate (produce milk)
function: lactation to sustain infant
development in response to increased estrogen levels after puberty
only produce milk after childbirth
progesterone and prolactin hormonones produced during pregnancy
increased progesterone prevents lactation
pre-milk fluid "colostrum" can sustain infant for first few days
after childbirth, progesterone decreases and prolactin allows lactation
during menopause, ductile system hardens into fibrous tissue - inability to lactate
fertilization - occurs at moment the genetic material of a sperm combines with that of ovum to form a fertilized egg or zygote
dipolid set of chromosomes
first cell of offspring
embryo - eight weeks after fertilization
rudimentary major organ systems
fetus - ninth week of development
organ specialization accompanied by changes in body proportions
zygote formation - union between two gametes (egg and sperm cells); after fertilization has taken place
the two gamete cells joined by sexual reproduction

Embryonic Development
Prenatal Development
8-9 days after conception, zygote (blastocyst) that attaches to uterine wall
receives oxygen and nutrients for further development
after implantation, trophoblast part of blastocyst develops chorionic villi (form the placenta)
3 weeks after conception, placenta functioning
deliver oxygen/nutrients and remove wastes from blood through placental barrier
2 months into pregnancy, placenta becomes an endocrine organ - produced estrogen, progesterone, and other hormones to maintain the pregnancy
corpus luteum of ovary becomes inactive
Labor and Delivery
signs of labor: lightening (baby's head drops into pelvis region); bloody discharge from cervix, diarrhea; ruptured membranes ("water breaking"); contractions

Stage 1: latent, active, transition
latent - longest, least intense; contractions to dilate cervix
active - cervix dilates from 4 to 7 cm; pain in back/abdomen
transition - cervix dilates to 10 cm; painful contractions every 3 to 4 minutes lasting 1 to 1.5 minutes each
Stage 2: cervix completely open; push baby through birth canal; suction amniotic fluid, blood, mucus from nose; cut umbilical cord
Stage 3: deliver placenta

labor and deliver process about 12 to 14 hours
Diseases
Testicular and prostate cancer - development of cancer from defect of germ cells (sperm-producing cells)
2 main types of germ cell tumors (GCT's): seminomas (slower) and non-seminomas (or mixed cell tumors)
cancer can begin in prostate gland (slow) and metastasize to testicles
Epididimytis - inflammation of epididymis (posterolateral storage area for immature sperm) often caused by STI like gonorrhea or chlamydia. It is most common in males from ageas 14 - 35.
Hoypogonadism - decreased function of ovaries and testes. The gonads no longer secrete sex hormones (androgen, estrogen, progesterone, inhibin, activin, etc.) which impacts spermatogenesis and ovulation to the point of partial or total infertility.
Erectile dysfunction - inability to sustain or achieve erection for sexual intercourse; can first emerge in males around age 40; impacts nearly 18 -30 million men. ED is often accompanied by prostate cancer.
Klimefelter's syndrome - presence of an extra X-chromosome in males (XXY). KS impacts pyhsical and cognitive development: learning problems, small testes/penis, breast growth, narrow shoulders/wide hips, etc.
Prostatitis - inflammation of prostate gland due to bacterial infection or no infection. The most common symptom is bladder infection. It is most common in men ages 5 or younger. It does not increase risk of prostate cancer.
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