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

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