Reproductive System Powerpoint Lecture

7/30/2019 Reproductive System Powerpoint Lecture

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The gonads are the primary sex organs. Gonads produce gametes, or sex cells, and

sex hormones.

In males, the testes are the gonads and sperm arethe gametes.


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The hormones required to stimulate andmaintain spermatogenesis are not fullyproduced until puberty.

Testosterone

Follicle-Stimulating Hormone (FSH) Spermatogenesis is also highly sensitive to

temperature changes. Optimal temperature is 2C below body

temperature.

Testes are kept in an external scrotum to maintain

this temperature.


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A sperm stem cell,located in the

seminiferous tubules,undergoes mitosis,producing two exactcopies

One copy remains theseminiferous tubule.

One copy begins to migrate

towards the epididymis.


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The sperm stem cellcopy undergoes

meiosis, whichresults in theproduction offourgenetically differentcells with only halfthe normal numberof chromosomes.


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As the sperm cellsmature, they

develop threebody regions,including a head,body, and tail.


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The vas deferens is a ductthat transports maturedsperm from the epididymis

to the ejaculatory duct. Sperm move by peristalsis,

the same rhythmiccontraction of smoothmuscles seen in theesophagus and intestines.

Sperm can also be stored in

the vas deferens.


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UrinaryBladder

Symphysis

Pubis (Pelvis)Seminal Vesicle

Ejaculatory Duct

Rectum

Bulbourethral

Gland

Epididymis

Testicle

Scrotum

Urethra

Erectile

Tissue

Vas Deferens

Prostate


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Three accessory glands secrete different substancesinto the sperm cells. This is called semen.

The seminal vesicles produce the majority (60%) of

semen. Their secretion contains: Fructose Provides nourishment for sperm cells. Prostaglandins stimulate smooth muscle contractions

along the male and female reproductive tract. Fibrinogen- Causes semen to temporarily clot inside the

vagina (so it doesnt leak back out). Alkaline Secretions Neutralizes acids produced by the

prostate gland and vagina. The is the beginning ofcapacitation (activation of

sperm cells)


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The prostate gland secretes a milky fluid thatcontinues capacitation. (20-30% of semen)

This secretion adds fluid to the semen and containsnutrients to aid the sperm.

The bulbourethral gland adds a thick alkalinemucus (pre-ejaculate) to the semen.

This makes for easier transport through the urethra

and into the female and also neutralizes the acidity

of the urethra and vagina.


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Made up of 3 major components

1. Spermatozoa- 20 million to 100 million sperm

per milliliter of semen 2. Seminal Fluid- fluid components produced by

the accessory glands.

3. Enzymes- important enzymes that dissolve

mucous secretions in the vagina, kill bacteria, andcause semen to clot.


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The penis is the external male reproductiveorgan.

The erectile tissue of the penis is made oftwo large tubular structures that, when filledwith blood, produce an erection.

The urethra carries both urine and semen outthe penis.


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Ejaculation of sperm and semen, which occurs aftera period of sexual stimulation, occurs in thefollowing order:

1. Sperm is released from the epididymis.2. Fluid is added from the seminal vesicles. Semen enters

the ejaculatory duct.Point of no return.

3. The prostate and bulbourethral glands add theirsecretions and sperm is expelled from the body.

During this time, the entrance from the bladder tothe urethra is closed, preventing sperm from

moving into the urinary tract.


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In humans, adult men whochoose to be surgically

sterilized can have avasectomy, which severs thevas deferens above eachtesticle.

The male will still maketestosterone and semen as usual,

but sperm cells will not leave the

epididymis.


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The gonads of the femalereproductive system are the

ovaries. The gametes are the ova, or

egg cells.


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The female reproductive system is responsible forproducing an ovum on a regular cycle, providing aplace for fertilization, implantation of the embryo,

and nourishing the fetus until it is ready for birth.


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Ovary Fallopian Tube

Sacrum Ligament

ndometrium Myometrium

Bladder

Symphysis Pubis

Clitoris

VaginaAnus

Rectum

Urethra

Cervix


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Ovary

Fallopian Tube

Myometrium

Endometrium

Cervix

Vagina


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Each ovary is composed of hundreds of sac-like structures called follicles.

Each follicle consists of: An oocyte, or an immature egg cell.

Follicular cells, which produce the female

reproductive hormones.


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Before birth, mitosis occurs inside the ovaries.

This produces all the oocytes the woman willneed in her lifetime.

These oocytes will not be released until puberty,when the brain releases follicle stimulating

hormone (FSH).


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Every 28 days, one oocyte inside a follicle in one of the ovaries

begins to grow and mature. Meiosis begins, just like with sperm cells, but occurs in two separate

stages.

When Meiosis I occurs, one daughter cell receives most of thecytoplasm. This will be the oocyte. The other daughter cell receiveslittle, and is called the polar body.

The polar body degenerates, while the oocyte matures.


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When the oocyte is mature, the follicleruptures, and it is released. This is ovulation.

The mature egg cell, called an ovum, beginstravelling down the fallopian tubes, headingtowards the uterus.


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The ovum is gradually moved towards theuterus by the movement ofcilia.

The ovum lives for about 24 hours, sofertilization must occur here.


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The ovum eventually reachesthe uterus, located betweenthe bladder and the rectum.

The uterus is a small muscular

pear shaped organ roughly 3inches long.

It is held in place by variousligaments.

The uterus is composed of 3layers of tissue. Endometrium (inner),

myometrium (middle),perimetrium (outer)


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The uterus has four main functions, alldirectly related to a fertilized ovum.

Receiving the egg. Attaching to and holding the egg.

Nourishing the egg as it grows into a fetus.

Ejecting the fetus at birth

If the ovum is not fertilized, it is expelled outthe vagina along with the lining of the uterus.This is menstruation.


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The cervix is a narrow canal that leads from theuterus into the vagina.

The vagina then leads to the exterior of the body.

Functions of the vagina include: The birth canal for a full-term fetus. Receiving the penis during sexual intercourse.

The vagina normally contains resident bacteria

in the cervical mucus. The metabolic activity of these bacteria create an

acidic environment which restricts the growth ofother, harmful pathogens.


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The female reproductive system undergoes twomajor changes every 28 days:

A new oocyte matures into an ovum and is released. The wall of the uterus thickens with blood vessels, in

anticipation of a fertilized embryo.

All of the changes that occur during this 28 day

time period (on average) are called themenstrual cycle.

Can extend up to 35 days in healthy individuals


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The Menstrual Phase ( Days 1-5 )

The thickened outer layer of the endometrium sheds,causing a blood-like secretion.

During this time, follicles in the ovary start growing andproducing estrogen.

The Proliferative Phase ( Days 6-14)

The follicles in the ovary continue growing. Estrogen levels will peak.

Whichever follicle produces a mature ovum first will ovulate.

The walls of the endometrium are repaired by multiplication

of epithelial cells.


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The Secretory Stage ( Days 15-28 )

Once the ovum is released, the remaining folliculartissue begins producing a hormone called

progesterone. Progesterone stimulates the outer lining of the

endometrium to thicken and uterine glands increasetheir rates of secretion. This peaks around 12 days after ovulation

If fertilization occurs, the embryo will produce ahormone that stimulates the continued production ofprogesterone. The pregnancy hormone


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If fertilization does not occur, thefollicular tissue degenerates, theuterine lining breaks down, andthe cycle repeats.

The most fertile point in thewomans cycle is the days

immediately following ovulation. This timing is not consistent,

however, and can vary by severaldays with each cycle.

The Woman ofWilldendorf22,000-21,000 BCE.

Fertility statue.


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The birth control pill is taken daily,and comes in 4-week packs.

21 of the pills contain a combination ofprogesterone and estrogen.

7 of the pills are placebos, given tomaintain the daily habit of taking the pill.

The two hormones inhibit the brainfrom producing FSH, preventing afollicle (and ovum) from developing.


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Humans have a surgery called tubal ligation,where the fallopian tubes are cut and tied off,preventing ova from reaching the uterus.

Complications from this surgery are more likely thanfrom a vasectomy.

In domesticated animals, spaying removes theovaries.


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Sperm cells have three distinct regions:

The head contains the DNA and a specialized

organelle called the acrosome. The acrosome is a large, specialized lysosome that

contains enzymes to help the sperm penetrate the outerlayer of the egg cell.

The midpiece is wrapped by mitochondria togenerate ATP for movement.

The tail is a flagella used for movement.


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Sperm swim up through the cervix, uterus, andinto the oviducts.

When one sperm fertilizes the egg, it begins the

second phase of meiosis. Its cell membrane alsochanges, preventing any other sperm cells fromentering.

The ovum again gets most of the cytoplasm,leaving a polar body behind to degenerate.

The 23 chromosomes of the sperm and egg cellcombine into one nucleus, forming a zygote.


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The zygote will begin undergoing mitosis within 24hours of fertilization.

The cell keeps dividing for about 7 days until it finallyimplants into the uterus.


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When the embryo implants into the uterus, itis a ball of about 100 cells called a blastocyst.

The blastocyst secretes a hormone thatstimulates the ovaries to continue producingprogesterone.


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The uterus will generate theplacenta, the amniotic fluid,and the umbilical cord at this

time. The placenta forms a blood

barrier between the motherand embryo.

Nutrients, oxygen, and waste areexchanged, but blood is not. The placenta also takes over the

role of producing progesterone forthe remainder of the pregnancy.


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Third Trimester

Eyes open.

Arms and legs are at the finalproportions.

Skin and hair develop.

Subcutaneous fat develops.


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Multiple anatomical changes occurin the mother during pregnancy.

The uterus enlarges to accommodatethe fetus.

The ligaments of the pelvis relax.

Curvature of the lumbar vertebrae

increases.


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Digestive System

Morning sickness caused by increased

hormones. Heartburn due to the fetus crowding

the stomach.

Constipation due to progesterone

relaxing smooth muscles throughoutthe body.

(Decreases peristalsis)


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Urinary System

Kidneys process more

blood and produce moreurine.

Fetus crowds the bladder.


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Respiratory System

Lung capacity and respiratory rate increase.

Cardiovascular System Blood volume increases.

Blood pressure and pulse rate increase.


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As birth initiates, estrogen levels rise and theuterus begins contracting.

The cervix dilates up to 10cm in diameter. The amniotic sac ruptures.

Breaking the water.


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Once the cervix issufficiently dilated,

expulsion can begin. Infant exits the body

through the cervixand vagina.

Normal delivery ishead first.


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The last stage is the placental stage, wherethe placenta, umbilical cord, and afterbirth

are expelled.


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The entire design of both the male and femalereproductive system, hormones, organs, fluids,and feelings of pleasure are all intended tomaximize the possibility ofproducing ahealthy, fertile offspring.

Reproductive System Powerpoint Lecture

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