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103 terms

The Reproductive System

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Gonads
primary sex organs
Sperm
male gametes
Ova
(eggs)-female gametes
What are the Male Reproductive System Overview?
Testes
Ducts
-epididymis
-ductus (vas) deferens
-urethra
What are the accessory organs of the reproductive system?
seminal vesicles, prostate, bulbourethral glands
What are the external genitalia of the reproductive system?
penis, scrotum
Facts about the Testes
Coverings of the testes.
-Tunica albuginea-capsule that surrounds each testis.
-Septa-extensions of the capsule that extend into the testis and divide it into lobules.
Each lobule contains one to four seminiferous tubules
-tightly coiled structures
-function as sperm-forming factories
-empty sperm into the rte testis (first part of the duct system)
Interstitial cells in the seminiferous tubules
Sperm travles through the rete testis to the epididymis***
...
What makes up the "Duct System"
Epididymis, Ductus (vas) deferens, Urethra
What is the Epididymis?
Comma-shaped, tightly coiled tube.
Found onthe "superior part of the testis and along the posterior lateral side".
Functions to "mature and store sperm cells" (at least 20 days)
"Expels sperm" with the contraction of muscles in the epididymis walls "to the vas deferens".
What are the Ductus Deferens (Vas Deferens)?
Carries sperm "from the epididymis to the ejaculatory duct".
Passes throught the inguinal canal and over the bladder.
Moves sperm by "peristalsis".
Spermatic cord-ductus deferens, blood vessels, and nerves in a connective tissue sheath.
Facts about the Ductus Deferens (Vas Deferens)
Terminates in the ejaculatory duct which unites with the urethra
Ejaculation—smooth muscle in the walls of the ductus deferens create peristaltic waves to squeeze sperm forward
Vasectomy—cutting of the ductus deferens at the level of the testes to prevent transportation of sperm (form of birth control)
Facts about the Urethra
Extends from the base of the urinary bladder to the tip of the penis
Carries "both urine and sperm"
Sperm enters from the ejaculatory duct
What are the accessory organs?
Seminal vesicles
Prostate
Bulbourethral glands
Explain the Seminal Vesicles...
Located at the base of the bladder!
Produces a thick, yellowish secretion (60 percent of semen)
Fructose (sugar)
Vitamin C
Prostaglandins
Other substances that nourish and activate sperm
Explain the Prostate...
Encircles the upper part of the urethra
Secretes a "milky fluid"
Helps to activate sperm
Enters the urethra through several small ducts
"Prostatitis"-inflammation of the prostate
"Prostate cancer-third most common cancer in males"
What are the Bulbourethral Glands?
Pea-sized gland "inferior to the prostate"
Produces a "thick, clear mucus"
"Cleanses the urethra of acidic urine prior to ejaculation"
Serves as a "lubricant during sexual intercourse"
Secreted into the penile urethra
What is Semen?
"Mixture of sperm and accessory gland secretions"
"Advantages" of accessory gland secretions
Fructose provides energy for sperm cells
Alkalinity of semen helps neutralize the acidic environment of vagina
Semen inhibits bacterial multiplication
Elements of semen enhance sperm motility
What are the external genitalia?
Scrotum,Penis
Explain the Scrotum..
Divided sac of skin outside the abdomen
Maintains testes "at 3°C lower" than normal body temperature to protect sperm viability
Explain the Penis...
Delivers sperm into the female reproductive tract
Regions of the penis
Shaft
Glans penis (enlarged tip)
Prepuce (foreskin)
Folded cuff of skin around proximal end
Often removed by circumcision
What is Spermatogenesis?
"Production of sperm cells"
Begins at puberty and continues throughout life
Occurs in the seminiferous tubules
Explain further about Spermatogenesis.
"Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty"
Follicle-stimulating hormone (FSH) modifies spermatogonia division
One cell produced is a stem cell, called a type A daughter cell
The other cell produced becomes a primary spermatocyte, called a type B daughter cell
More facts about Spematogenesis...
Primary spermatocytes undergo meiosis
"One primary spermatocyte produces four haploid spermatids"
"Spermatids—23 chromosomes" (half as much material as other body cells)
Explain the Human Life Cycle...
"Union of a sperm" (23 chromosomes) "with" an egg (23 chromosomes) creates a zygote (2n or "46 chromosomes")
What is Spermiogenesis?
Late "spermatids" are produced with distinct regions
"Head "
"Midpiece"
"Tail"
Sperm cells result after maturing of spermatids
Spermatogenesis (entire process, including spermiogenesis) takes 64 to 72 days
Explain the Anatomy of a Mature Sperm Cell
Th only hman flagellated cell.
Head
----contains DNA
----acrosome-helmet on the nucleus, similar to a large lysosome.
----breaks down and releases enzymes to help the sperm penetrate an egg.
"Midpiece"
----wrapped by mitochondria for ATP generation
Explain Testosterone Production...
The "most important hormone" of the testes
Produced in interstitial cells
During puberty, "luteinizing hormone (LH) activate the interstitial cells"
In turn, "testosterone is produced"
What are the functions of testosterone?
Stimulates "reproductive organ development"
Underlies "sex drive"
Causes "secondary sex characteristics"
Deepening of voice
Increased hair growth
Enlargement of skeletal muscles
Thickening of bones
What is the Female Reproductive System?
Ovaries
Duct System
Uterine tubes (fallopian tubes)
Uterus
Vagina
External genitalia
What are the Ovaries?
Composed of ovarian follicles (sac-like structures)
Each follicle consists of
"Oocyte" (immature egg)
"Follicular cells—surround" the oocyte
What is Ovulation?
when the egg is mature, the follicle ruptures; occurs about every 28 days
What do suspensory ligaments do?
secure ovary to lateral walls of the pelvis
What is the Duct System for females?
Uterine tubes (fallopian tubes)
Uterus
Vagina
Explain the Uterine (Fallopian) Tubes...
Receive the ovulated oocyte
Provide a "site for fertilization"
Attach to the uterus
Little or no contact between ovaries and uterine tubes
Supported and enclosed by the broad ligament
What are Fimbriae?
"Finger-like projections" at the distal end of the uterine tube
Receive the "oocyte from the ovary"
What is Cilia?
Located inside the uterine tube
Slowly move the oocyte towards the uterus (takes 3 to 4 days)
Fertilization occurs inside the uterine tube since oocyte lives about 24 hours**
...
What are the functions of the Uterus?
"Receives" a fertilized egg
"Retains" the fertilized egg
"Nourishes" the fertilized egg
What are the Regions of the Uterus?
"Body"—main portion
"Fundus"—superior rounded region above where uterine tube enters
"Cervix"—narrow outlet that protrudes into the vagina
What is the Endometrium in the walls of the uterus?
Inner layer
Allows for implantation of a fertilized egg
Sloughs off if no pregnancy occurs ("menses")
Myometrium—middle layer of smooth muscle
Perimetrium (visceral peritoneum)—outermost serous layer of the uterus
Explain the Vagina...
Extends from "cervix to exterior of body"
Located between bladder and rectum
Serves as the "birth canal"
Receives the penis during sexual intercourse
Hymen—partially closes the vagina until it is ruptured
What is the female external genitalia (vulva)?
Mons pubis
Labia
Clitoris
Urethral orifice
Vaginal orifice
Greater vestibular glands
Labia?
Skin folds.
Vestibule
Enclosed by labia majora
Contains external openings of the urethra and vagina
Greater vestibular glands
Secretes lubricant during intercourse
Clitoris
Contains "erectile tissue"
Corresponds to the male penis
The clitoris is similar to the penis in that it is
Hooded by a prepuce
Composed of "sensitive erectile tissue"
Becomes swollen with blood during sexual excitement
Diamond-shaped region
between the anterior ends of the labial folds, anus posteriorly, and ischial tuberosities laterally
Oogonia
female stem cells found in a developing fetus
Oogonia undergo mitosis "to produce primary oocytes"
...
Follicle stimulating hormone (FSH) causes some primary follicles to mature each month**
...
Follicle development to the stage of a vesicular follicle takes about 14 days
Ovulation of a secondary oocyte occurs with the release of luteinizing hormone (LH)
**
...
Oogenesis and the Ovarian Cycle
Meiosis is completed after ovulation "only if sperm penetrates"
Ovum is produced
Two additional polar bodies are produced
Once ovum is formed, the "23 chromosomes can be combined with those of the sperm to form the fertilized egg (zygote)"
If the secondary oocyte "is not penetrated by a sperm, it dies" and does not complete meiosis to form an ovum
Important Male and Female Differences
Sex cell size and structure:
----sperm are tiny, motile, and equipped with nutrients in seminal fluid.
----egg is large, non-motile, and has nutrient reserves to nourish the embryo until implantation.
Uterine (menstrual) cycle
Cyclic changes of the endometrium
"Regulated by" cyclic production of "estrogens and progesterone"
"FSH and LH regulate the production of estrogens and progesterone"
Both menstrual and ovarian cycles are about "28 days in length"
"Ovulation" typically occurs about midway through cycle on "day 14"
Uterine (Menstrual) Cycle
Stages of the menstrual cycle
Menstrual phase
Proliferative stage
Secretory stage
Menstrual Phase
Stages of the menstrual cycle
Menstrual phase
Proliferative stage
Secretory stage
Proliferative Stage
"Days 6 to 14"
Regeneration of functional layer of the endometrium
"Estrogen levels rise"
"Ovulation" occurs in the ovary at the end of this stage
Secretory Stage
Days 15 to 28
Levels of progesterone rise and increase the blood supply to the endometrium
Endometrium increases in size and readies for implantation

"If fertilization does occur"
Embryo produces a hormone that causes the corpus luteum to continue producing its hormones
"If fertilization does NOT occur"
"Corpus luteum degenerates" as LH blood levels decline
Estrogens
Produced by follicle cells
Cause "secondary sex characteristics"
Enlargement of accessory organs of the female reproductive system
Development of breasts
Appearance of axillary and pubic hair
Increase in fat beneath the skin, particularly in hips and breasts
Widening and lightening of the pelvis
Onset of menses (menstrual cycle)
Progesterone
Produced by the corpus luteum
Production continues until LH diminishes in the blood
"Does not contribute to the appearance of secondary sex characteristics"
Other major effects
Helps "maintain pregnancy"
"Prepare the breasts for milk production"
Anatomy of Mammary Glands
Areola—central pigmented area
Nipple—protruding central area of areola
Lobes—internal structures that radiate around nipple
Lobules—located within each lobe and contain clusters of alveolar glands
Alveolar glands—produce milk when a woman is lactating (producing milk)
Lactiferous ducts—connect alveolar glands to nipple
Mammography
X-ray examination that detects breast cancers too small to feel
Recommended "every 2 years" for women between "40 and 49" years old "and yearly thereafter"
Embryo
period of time from fertilization until week 8
fetus
week 9 until birth
Accomplishing Fertilization
Sperm are viable for 24 to 48 hours after ejaculation"

For "fertilization" to occur, "sexual intercourse must occur no more than 2 days before ovulation and no later than 24 hours after"
Accomplishing Fertilization
When sperm reach the oocyte, "enzymes break down the follicle cells" of the corona radiata around the oocyte
Once a path is cleared, sperm undergo an "acrosomal reaction" (acrosomal membranes break down and enzymes "digest holes" in the oocyte membrane)
"Membrane receptors on an oocyte pull in the head of the first sperm cell to make contact"
Mechanisms of Fertilization
Fertilization occurs when the genetic material of a sperm combines with that of an oocyte to form a zygote
The Zygote
First cell of a new individual
The result of the "fusion of DNA" from sperm and egg
The zygote begins rapid mitotic cell divisions
The zygote stage is in the uterine tube, moving toward the uterus
Cleavage
"Rapid series of mitotic divisions" that begins with the zygote and ends with the blastocyst
Zygote begins to "divide" 24 hours after fertilization
"Three to 4 days after ovulation, the preembryo reaches the uterus and floats freely for 2 to 3 days"
Late blastocyst stage—embryo implants in endometrium (day 7 after ovulation)
The Embryo
"The embryo enters the uterus" at the 16-cell state (called a morula) "about 3 days after ovulation"

"Uterine secretions are used for nourishment"
The Blastocyst (Chorionic Vesicle)
Secretes human chorionic gonadotropin (hCG) to induce the corpus luteum to continue producing hormones
The Blastocyst (Chorionic Vesicle)
Primary germ layers are eventually formed
Ectoderm—outside layer
Mesoderm—middle layer
Endoderm—inside layer
The late blastocyst implants in the wall of the uterus (by day 14)
Amnion
fluid filled sac that surrounds the embryo
umbilical cord
Blood vessel-containing stalk of tissue
Attaches the embryo to the placenta
Functions of the Placenta
Forms a barrier between mother and embryo (blood is not exchanged)
Delivers nutrients and oxygen
Removes waste from embryonic blood
Becomes an endocrine organ (produces hormones) and takes over for the corpus luteum (by end of second month) by producing
Estrogen
Progesterone
Other hormones that maintain pregnancy
The Fetus
"All organ" systems are formed by the end of the "eighth week"
Activities of the fetus are "growth and organ specialization"
Anatomical changes
Enlargement of the uterus
Accentuated lumbar curvature (lordosis)
Relaxation of the pelvic ligaments and pubic symphysis due to production of relaxin
Physiological changes
Gastrointestinal system
Morning sickness is common due to elevated progesterone and estrogens
Heartburn is common because of organ crowding by the fetus
Constipation is caused by declining motility of the digestive tract
Physiological changes (continue
Urinary system
Kidneys have additional burden and produce more urine
The uterus compresses the bladder, causing stress incontinence
Effects of Pregnancy on the Mother(physiological changes (continued)
Respiratory system
Nasal mucosa becomes congested and swollen
Vital capacity and respiratory rate increase
Dyspnea (difficult breathing) occurs during later stages of pregnancy
Physiological changes (continued)
Cardiovascular system
Blood volume increases by 25 to 40 percent
Blood pressure and pulse increase
Varicose veins are common
Labor
series of events that expel the infant from the uterus
Rhythmic, expulsive contractions
Operates by the positive feedback mechanism
False labor-Braxton
Hicks contractions are weak, irregular uterine contractions
Childbirth (Parturition)
Initiation of labor
:Estrogen" levels "rise"
Uterine contractions begin
The "placenta releases prostaglandins"
"Oxytocin is released" by the pituitary
Combination of these hormones oxytocin and prostaglandins produces "contractions"
Stages of Labo
"Dilation"
Cervix becomes dilated
Full dilation is "10 cm"
Uterine "contractions" begin and increase
"Cervix softens and effaces" (thins)
The "amnion ruptures" ("breaking the water")
Longest stage at 6 to 12 hours
Expulsion
Infant passes through the cervix and vagina
Can last as long as 2 hours, but typically is 50 minutes in the first birth and 20 minutes in subsequent births
"Normal" delivery is "head first (vertex position)"
"Breech" presentation is "butt"ocks-first
Placental stage
"Delivery" of the "placenta"
Usually accomplished "within 15 minutes" after birth of infant
Afterbirth—placenta and attached fetal membranes
"All placental fragments should be removed to avoid postpartum bleeding"
Gender is determined at fertilization
Males have "XY" sex chromosomes
Females have "XX" sex chromosomes

"Testosterone" determines whether male or female structures will form
Developmental aspects of the reprodutive system
reproductive system organs do not function until puberty.
Males
enlargement of testes and scrotum signals onset of puberty (often around age 13)
Females
budding breasts signal puberty (often around age 11)
Menarch
first menstrual period
Menopause
a whole "year" has passed without menstruation.
Ovaries stop functioning as endocrine organs
Childbearing ability ends
Birth control pill
most used contraceptive.

Relatively constant supply of ovarian hormones from pill is similar to pregnancy
Ovarian follicles do not mature, ovulation ceases, menstrual flow is reduced
Mornig-after pill (MAP)
Taken within 3 days of unprotected intercourse
Disrupts normal hormonal signals to the point that fertilization is prevented
Other pills for contraception are:
Minepill (tablet)
Norplant (rods placed under the skin)
Intrauterine device (IUD)
Plastic or metal device inserted into uterus
"Prevents implantation of fertilized egg"
Sterilization
"Tubal ligation (females)"—cut or cauterize uterine tubes
"Vasectomy (males)"—cut or cauterize the ductus deferens
Coitus interruptus
withdrawa of penis prior to ejaculation
rhytm
fertility awareness)—avoid intercourse during period of ovulation or fertility
Record daily basal temperature (body temperature rises after ovulation)
Record changes in pattern of salivary mucus
Barrie methods
Diaphragms
Cervical caps
Condoms
Spermicidal foams
Gels
Sponges
RU486 or "abortion pill"
induces miscarriage during first 7 weeks of pregnancy