Transcript Chapter 16 & Chapter 17 - Los Angeles City College

Chapter 16 & Chapter 17
Biology 25: Human Biology
Prof. Gonsalves
Los Angeles City College
Based on Mader’s Human
Biology,7th edition and Fox’s 8th ed
Powerpoints
Sexual Reproduction
Sexual Reproduction:
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Only organ system that is not essential for
individual survival.
Continuation of species.
Gamete formation (eggs and sperm) cells.
Homeostatic Role:

Maintains secondary sexual characteristics.
Sexual Reproduction:



The most common type of animal reproduction.
Occurs through the fusion of gametes (sperm and egg).
 Male: Produces sperm cells. Small and motile, propels
itself by whiplike flagellum.
 Female: Produces eggs (ova). Large and nonmotile.
Zygote: Egg cell fertilized by a sperm cell.
Fertilization: Creation of zygotes by fusion of ova and sperm
cells. Two types:

Internal Fertilization: Gametes fuse inside the female’s
body.
 Usually requires copulation (intercourse) in which male
delivers sperm directly into body of female.
 Practiced by most terrestrial animals, aquatic reptiles,
birds, and mammals.
Sexual Reproduction

External Fertilization: Gametes fuse outside the
female’s body.
 Mating partners release eggs and sperm
simultaneously into the water.
 Practiced by most aquatic animals: fish, amphibians.
 Many eggs are lost and eaten by predators.
Therefore, many must be made and released for a
few to survive.
Hermaphroditism:
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A single individual produces both sperm and eggs.
Some such as the tapeworm are capable of selffertilization.
Others (e.g.: earthworm) must mate with other animals.
In some species self-fertilization is prevented by
development of testis and ovaries at different times.
Used by “solitary” animals.
Reproductive System of Humans
Reproductive Functions of Male:


Produces sperm
Delivers sperm to female reproductive tract
All of these processes are regulated and coordinated by hormones
secreted by:
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Hypothalamus
Pituitary gland (anterior portion)
Testes (Sing. Testis)
Front View of Male Reproductive System
Major Organs of Male Reproductive System:
 Testes: Paired male gonads.
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Produce sperm through spermatogenesis, which
produces four sperm cells of equal size.
Spermatogenesis occurs in a vast system of hollow
tubes called seminiferous tubules.
Each mature sperm has a head, a midpiece, and a
flagellum.
Sperm head has an acrosome, which produces enzymes
that help it penetrate the egg.
Human sperm cannot develop at body temperature.
Testicles descend from abdominal cavity into scrotum,
a skin covered sac, about two months before birth.
Undescended testicles (cryptorchidism) may cause
infertility.
Spermatogenesis Occurs in Seminiferous
Tubules of Testes
Reproductive System of Humans
Major Organs of Male Reproductive System:
 Epididymus:
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Large coiled tube (23 ft long) that surrounds testes.
Stores sperm while they develop fertilizing ability
and motility (about 20 days).
During ejaculation, sperm cells are propelled from
epididymus.
Vas Deferens:
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Long muscular ducts from scrotum to back of
bladder.
During ejaculation, the sperm pass from epididymus
into these two ducts.
Vasectomy: Each vas deferens is cut to prevent
sperm from entering urethra.
Reproductive System of Humans
Major Organs of Male Reproductive System:
 Ejaculatory Duct:
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Short duct after two vas deferens ducts unite.
Urethra:
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Deliver sperm to the exterior.
In males, urine and sperm pass through the urethra.
Females have a separate urethra from the reproductive system.
Reproductive System of Humans
Major Organs of Male Reproductive System:
Accessory Glands: Produce semen.
 Functions of semen:
 Activate sperm cells
 Provide nutrients for motility
 Counteract acidity of vagina and male urethra
 Stimulate contractions of female reproductive tract
 Antimicrobial action
 Ejaculation volume 4 to 5 ml.
 One ejaculation has 50-500 million sperm cells
 Sperm cells account for less than 5% of semen volume.
 Secretions from 3 different accessory glands make up the rest
of the volume: Seminal vesicles (2), prostate, and
bulbourethral glands (2).
Major Organs of Male Reproductive System:
Accessory Glands:
A. Seminal vesicles (2): Secrete fluid that nourishes sperm.
Contribute about 60% of semen volume.
 Thick, clear, alkaline fluid.
 Contains:
 Fructose: Provides energy for sperm
motility.
 Prostaglandins: Stimulate smooth muscle
contractions of female and male
reproductive tracts.
 Fibrinogen: Forms temporary clot in
vagina.
 Sperm cells become highly motile when mixed
with this fluid.

Accessory Glands:
B. Prostate gland: Produces a thin milky secretion.

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Largest of semen secreting glands.
Contributes 30% of semen volume.
Produces an antibiotic that may prevent urinary tract
infections in men.
Benign (noncancerous) prostate enlargement is common among
older men.
 50% of men over 40.
 Almost all men over 70.
Prostate cancer is the second leading cause of cancer and
cancer deaths in men.
 Over 330,000 new cases/year and 40,000 deaths.
 Average age at diagnosis: 72
 Detected by blood test or digital rectal exam.
 Treated surgically or with drugs to reduce prostate size or
activity.
Benign Prostate Enlargement Usually
Procedes Prostate Cancer
Normal prostate is 2 to 3 cm in diameter
Major Organs of Male Reproductive System:
Accesory Glands:
C. Bulbourethral glands (2): Release a mucous secretion that
lubricates penis and facilitates its entry into vagina.
Pair of small glands below the prostate.
 Contribute 5-10% of semen volume.
 Before ejaculation secrete a clear mucus that
neutralizes acid from remaining urine in
urethra.
 Bulbourethral fluid also carries some sperm
that is released before ejaculation. One cause
of high failure rate of withdrawal method.

Major Organs of Male Reproductive System:
 Penis: Copulatory organ that delivers sperm to female
body.
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Composed of three cylinders of erectile tissue.
During sexual arousal, the penis fills with blood from the
arteries.
Erection is essential for penetration.
Impotence is the inability to maintain an erection.
 May be caused by alcohol, drugs, illness, and/or emotional
problems.
 Viagra acts by relaxing smooth muscle of penis blood
vessels, allowing blood to enter erectile tissue.
Penis structure:
 Shaft: Long cylinder with thick skin.
 Glans: Enlarged tip of penis. Thin skin, covered by
prepuce or foreskin.
Reproductive System of Humans
Reproductive Functions of Female:
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Produces eggs (ova)
Receives sperm
Incubates and nourishes the embryo and fetus
Gives birth
Produces milk for young
All of these processes are regulated and coordinated by hormones
secreted by:
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Hypothalamus
Pituitary gland (anterior portion)
Ovaries
Reproductive System of Humans
Major Organs of Female Reproductive System:
 Ovaries: Produce ova (oogenesis) and sex hormones.
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Size and shape of large almonds.
Located close to lateral walls of pelvic cavity
and held in place by connective tissue.
Mainly connective tissue containing scattered
eggs (ova) in different stages of development.
Follicles: A single egg with surrounding cells
that nourish and protect it.
 Women are born with all of their follicles
(40,000 to 400,000).
 Only a fraction of follicles release eggs
during a woman’s reproductive life.
Female Reproductive System:

Ovulation & Oogenesis: After puberty, each month one
immature egg (oocyte), is released from ovary.
 Each follicle contains a primary oocyte, arrested in
prophase I of meiosis.
 Pituitary hormones FSH (follicle stimulating hormone)
and LH (luteinizing hormone) cause a follicle to enlarge
and complete meiosis I.
 One large cell (secondary oocyte) and a tiny cell (polar
body) are produced.
 LH (luteinizing hormone) causes the secondary oocyte to
be released by the ovary during ovulation.
 Oocyte will not finish meiotic division, until fertilized.
 In the end, one large ovum (egg) and 3 small polar bodies
are made from oogenesis.
Oogenesis and Ovary Structure
Major Organs of Female Reproductive System:
 Oviducts (Fallopian Tubes): Transport the egg from the ovary to
the uterus.
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Peristalsis of smooth muscle in oviduct and beating
of cilia, help the egg move along.
Fertilization occurs in the first third of oviduct.
Scarring of oviducts is a common consequence of
sexually transmitted diseases: chlamydia and
gonorrhea.
Ectopic Pregnancy: Fertilized egg does not reach the
uterus. Usually starts to develop in oviduct.
 Usually due to a blocked oviduct.
 Occurs in 1% of all pregnancies in the U.S.
 Must be surgically removed.
 May cause death and severe hemorrhage.
Ectopic Pregnancy of Twins
Ectopic pregnancies occur in about 1% of pregnancies in U.S.
and usually require surgical removal of embryos.
Reproductive System of Humans
Major Organs of Female Reproductive System:
 Uterus: Incubates the embryo/fetus.
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Size of a fist, in center of pelvic cavity.
Oviducts open into upper corners of uterus.
Has thick walls of smooth muscle (myometrium)
responsible for uterine contractions and cramps.
Endometrium: Inner mucous lining, which thickens
each month in preparation for pregnancy.
If fertilization does not occur, endometrium breaks
down and is discharged during menstruation.
If fertilization occurs, the egg implants in the
endometrium which supports its growth until the
placenta develops.
The Uterus Incubates and Nourishes the Fetus
Reproductive System of Humans
Major Organs of Female Reproductive System:

Cervix: Lower portion of the uterus, which projects into the
vagina.
Pap smear: Examination of cervical tissue to detect
abnormalities. Recommended yearly.
 Cervical cancer: Most cases caused by a viral
infection with human papillomavirus.
 Women are infected through intercourse with
asymptomatic male.
 Takes about 20 to 30 years to develop.
 Men don’t appear to be affected.

Reproductive System of Humans
Major Organs of Female Reproductive System:
 Vagina: Thin walled, muscular chamber.
 Receives the sperm and penis
 Acid pH kills bacteria and sperm cells
 Part of birth canal
 Vulva: External structures.
 Clitoris: Equivalent to male penis.
 Labia minora: Skin folds that border vaginal opening.
 Labia majora: Protect entire genital region.
 Hymen: Ring of tissue that forms a border around vaginal
entrance. No known function.
 Bartholin’s gland: Secrete lubricating fluid during sexual
arousal.
 Breasts: Lactation
Female Hormones Controlling Reproduction
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Follicle Stimulating Hormone (FSH)
 Secreted by pituitary gland
 Stimulates growth of ovarian follicle
Luteinizing Hormone (LH)
 Secreted by pituitary gland
 Stimulates growth of follicle and completion of meiosis I
 Induces ovulation
 Promotes development of corpus luteum and hormone secretion.
Estrogen
 Secreted by ovarian follicle
 Low levels inhibit FSH and LH secretion
 High levels stimulate FSH and LH secretion
 Promotes growth of endometrium
Progesterone and Estrogen
 Secreted by corpus luteum
 Maintain endometrium, sharp drop causes menstruation
 High levels inhibit inhibit FSH and LH secretion
Female Menstrual Cycle: Approximately 28 days.
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Menstruation: Day 1 of cycle.
 Walls of endometrium break down.
 Caused by falling levels of progesterone and estrogen.
 Lasts 3 to 7 days.
Pre-Ovulatory phase: Starts around day 5 of cycle.
 Rising estrogen levels cause the endometrium to start thickening.
Ovulation: Occurs around day 14 of cycle.
 FSH stimulates growth of ovarian follicle.
 LH causes follicle to finish meiosis I (secondary oocyte) and to be
released by ovary.
 Corpus luteum: Starts to secrete estrogen and progesterone.
Post-ovulatory Phase: Starts around day 15.
 Endometrium continues to grow in response to rising estrogen and
progesterone.
 If no fertilization occurs, corpus luteum degenerates and menstruation
occurs.
 If fertilization occurs, embryo maintains corpus luteum.
Stages of Female Reproductive Cycle
Different Contraceptive Methods
1. Prevent Release of Gametes:
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Birth control pill (combination): Prevents ovulation
2. Prevent Fertilization
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Vasectomy: Male sterilization
Tubal ligation: Female sterilization
Minipill: Progestin only, blocks cervical opening
Norplant implant: Releases progestin for 5 years
Rhythm (calendar): Avoid intercourse around ovulation
Withdrawal: Remove penis before ejaculation
Condom: Latex or sheepskin barrier
Diaphragm, cervical cap: Block cervical opening
Spermicide: Kill sperm cells
3. Prevent Implantion
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Intrauterine device (IUD)
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Morning after pills
Effectiveness of Methods of Contraception
Effectiveness of Methods of Contraception
Characteristics of all viruses
Acellular infectious agents
 Obligate intracellular parasites
 Possess either DNA or RNA, never both
 Replication is directed by viral nucleic
acid within a cell
 Do not divide by binary fission or
mitosis
 Lack genes and enzymes necessary for
energy production
 Depend on host cell ribosomes, enzymes,
and nutrients for protein production

Unique Characteristics of HIV
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Retrovirus: Unique enzyme reverse
transcriptase, converts viral RNA into DNA.
Genetic material: 2 strands of RNA.
Integrase: Inserts viral DNA into host DNA.
Protease: Processes viral proteins. Essential for
maturation.
Envelope with glycoproteins: Viral capsid is
covered by envelope derived from host cell
membrane.
Envelope contains a glycoprotein (gp120) which
attaches to CD4 receptor on host cell membrane.
Coreceptors: Required for HIV infection.
CXCR4 and CCR5.
Structure of the Human Immunodeficiency Virus HIV
is a Retrovirus
Life Cycle of HIV
1. Attachment: Virus binds to surface molecule
(CD4) of T cells and macrophages.
 Coreceptors: Required for HIV infection.
 CXCR4 and CCR5 mutants are resistant to
infection.
2. Fusion: Viral envelope fuses with cell membrane,
releasing contents into the cell.
3. Reverse Transcription: Viral RNA is converted
into DNA by unique enzyme reverse transcriptase.
Reverse transcriptase
RNA ---------------------> DNA
Reverse transcriptase is the target of several HIV
drugs: AZT, ddI, and ddC.
HIV Life Cycle: Reverse Transcriptase
Converts RNA into DNA
Life Cycle of HIV
4. Integration: Viral DNA is inserted into host cell
chromosome by unique enzyme integrase.
Integrated viral DNA may remain latent for years
and is called a provirus.
5. Replication: Viral DNA is transcribed and RNA
is translated, making viral proteins.
Viral genome is replicated.
6. Assembly: New viruses are made.
7. Release: New viruses bud through the cell
membrane.
Course of HIV Infection
Definition of AIDS
AIDS is a syndrome: A collection of several diseases and symptoms
that differ from one individual to another, but point to severe
immunosuppression.
HIV Antibody positive and one of the following (partial list):
Kaposi’s sarcoma
 Pneumocystis carinii pneumonia
 HIV dementia
 non-Hodgkin’s B cell lymphoma
 Yeast infection of esophagus, trachea, or lung
 Multiple bacterial infections in children <13 years
 Tuberculosis of the lung*
 Recurrent pneumonia*
 Invasive cervical carcinoma*
 All HIV+ persons with <200 CD4+ cells/ul*
*Added January 1, 1993.

AIDS Associated Disease Categories
1. Gastrointestinal: Cause most of illness and
death of late AIDS.
Symptoms:
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Diarrhea
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Wasting (extreme weight loss)
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Abdominal pain
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Infections of the mouth and esophagus.
Pathogens: Candida albicans, cytomegalovirus,
Microsporidia, and Cryptosporidia.
African AIDS patient with slim disease
Source: Tropical Medicine and Parasitology, 1997
Opportunistic Oral Yeast Infection by
Candida albicans in an AIDS Patient
Source: Atlas of Clinical Oral Pathology, 1999
AIDS Associated Disease Categories
2. Respiratory: 70% of AIDS patients develop
serious respiratory problems.
Partial list of respiratory problems associated
with AIDS:

Bronchitis

Pneumonia

Tuberculosis

Lung cancer

Sinusitis

Pneumonitis
Chest X-Ray of AIDS Patient with Tuberculosis
AIDS Associated Disease Categories
3. Neurological: Opportunistic diseases
and tumors of central nervous system.
Symptoms many include: Headaches,
peripheral nerve problems, and AIDS
dementia complex (Memory loss, motor
problems, difficulty concentration, and
paralysis).
AIDS Associated Disease Categories
4. Skin Disorders: 90% of AIDS patients develop skin or mucous
membrane disorders.
 Kaposi’s sarcoma
• 1/3 male AIDS patients develop KS
• Most common type of cancer in AIDS patients
 Herpes zoster (shingles)
 Herpes simplex
 Thrush
 Invasive cervical carcinoma
5. Eye Infections: 50-75% patients develop eye conditions.
 CMV retinitis
 Conjunctivitis
 Dry eye syndrome
Extensive tumor lesions of Kaposis’s sarcoma in AIDS patient.
Source: AIDS, 1997
Chronic Herpes Simplex infection with lesions on tongue and lips.
Source: Atlas of Clinical Oral Pathology, 1999.
Non-Hodgkin’s Lymphoma & ascites in AIDS patient
Source: Tropical Medicine and Parasitology, 1997
Drugs Against HIV
Reverse Transcriptase Inhibitors: Competitive
enzyme inhibitors. Example: AZT, ddI, ddC.
 Protease Inhibitors: Inhibit the viral proteases.
Prevent viral maturation.
 Problem with individual drug treatments:
Resistance.
 Drug Cocktails: A combination of:
 One or two reverse transcriptase inhibitors
 One or two protease inhibitors.
 Drug cocktails have been very effective in
suppressing HIV replication and prolonging the
life of HIV infected individuals, but long term
effectiveness is not clear.

Herpes Simplex 1 & 2
Characteristics:

Herpes Simplex 1 (Oral Herpes): Recurring painful
blister lesions that form mainly on lips, but may be found
in other areas of body. In immunocompromised patients
may have extensive lesions on tongue and inside mouth.

Herpes Simplex 2 (Genital Herpes): Recurring painful
blister lesions in genital and/or rectal areas.

Pathogens:

Human Herpes Virus 1: Oral Herpes.

Human Herpes Virus 2: Genital Herpes.

Reservoir: Humans.

Transmission: Kissing, touching lesions, sexual contact.
Oral Herpes: Recurrent Herpes Labialis
Less than 1 day with
erythema and burning
Same patient 24 h later with multiple
fluid filled vesicles and erythema
Source: Atlas of Clinical Oral Pathology, 1999.
Oral Herpes: Recurrent Herpes Labialis
Recurrent Herpes Labialis: Bilateral vesicles on upper and lower lips.
Source: Atlas of Clinical Oral Pathology, 1999.
Oral Herpes: Chronic Atypical Lesions
Chronic Herpes Simplex infection with lesions on tongue and lips.
Source: Atlas of Clinical Oral Pathology, 1999.
Genital Herpes
Herpes simplex 2 infection with fluid filled vesicles on penis.
Source: Mike Remington, University of Washington Viral Disease Clinic
Genital Herpes
Acyclovir resistant peri-rectal HSV2 infection in HIV infected male.
Source: AIDS, 1997
Herpes Simplex 1 & 2
 Incubation period: Several days to weeks. May be
asymptomatic.
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Epidemiology : Millions cases/year in U.S.

Oral Herpes: Up to 70% of population is infected.
Many have no symptoms.

Genital Herpes: Up to 20% of population is infected.
Many have no symptoms. Others have recurring
lesions several times a year.
Treatment and Prevention: No cure. Infection is for life.
Antiviral medications (acyclovir) decrease frequency and
severity of outbreaks.
Women with genital herpes should deliver by cesarean
section to avoid infecting newborn. Neonatal herpes is
very serious and can be deadly.
Chlamydia
 Characteristics: Painful urination, watery discharge,
salpingitis, and pelvic inflammation in women.
Symptoms may be mild or absent, especially in women.
Common cause of sterility in both men and women.
Newborns may develop eye infections and pneumonia.
 Pathogens: Chlamydia trachomatis.
 Reservoir: Humans.
 Transmission: Direct sexual contact or mother to infant
transmission during childbirth.
 Incubation period: 2 to 3 weeks. May be asymptomatic.
 Epidemiology : Up to 1 million new cases/year in U.S.
 Control: Use of condoms, avoid sexual contact with infected
individuals. Prophylactic treatment of contacts and pregnant
women.
 Treatment: Antibiotics.
Both Chlamydia and Neisseria gonorrhea
Cause Salpingitis
Chlamydia Infections: Inflammation of eyelid
Source: Microbiology Perspectives, 1999
Gonorrhea
 Characteristics: Acute infection of urethra, anus, vagina,
cervix, and fallopian tubes.
Yellow foul discharge (more common in men).
Causes pelvic inflammatory disease (PID) in women.
Major cause of infertility in both men and women.
May also result in throat and eye infections.
In a large percentage of cases, symptoms are mild or
absent.
 Pathogens: Neisseria gonnorrhoea (bacterium).
 Transmission: Direct sexual or mucous membrane
contact.
Mother to infant transmission during childbirth.
 Incubation period: 2 to 7 days.
Gonorrhea: Acute Urethral Infection
Typical discharge in male with gonorrhea.
Source: Tropical Medicine and Parasitology, 1995
Gonorrhea: Eye Infection in Newborn
Ophtalmia neonatorum caused by Neisseria gonorrheae
Source: Microbiology Perspectives, 1999
Gonorrhea (Continued)

Epidemiology : Up to 500,000 new cases/year in
U.S.

Control: Use of condoms, avoid sexual contact
with infected individuals.
Vaginal and cervical cultures of pregnant
women.

Treatment: Antibiotics. Erythromycin for
pregnant women.
Syphilis
Characteristics: Disease occurs in three stages:
1. Primary stage: Painless lesion (chancre),
which disappears after several days.
2. Secondary stage: Skin rash with fever and
mucous membrane lesions.
Typically followed by a long latent period.
3. Tertiary stage: Extensive damage to central
nervous system, cardiovascular system, bones,
sense organs, visceral organs, and other sites.

Pathogens: Treponema pallidum (bacterium).
Syphilis: Primary and Secondary Stage Lesions
Primary syphilitic chancre and secondary rash.
Source: Tropical Medicine and Parasitology, 1997
Syphilis: Secondary Stage Rash
Secondary syphilitic rash.
Source: Tropical Medicine and Parasitology, 1997
Syphilis: Tertiary Stage Lesions
Syphilis, Gumma: Large rubbery ulceration of anterior tongue
in a patient with tertiary syphilis.
Source: A textbook of oral pathology, 1983.
Syphilis: Advanced Tertiary Stage Lesions
Severe gumma lesions in tertiary syphilis.
Source: Tropical Medicine and Parasitology, 1997
Syphilis (Continued)
 Transmission: Direct contact with lesions, body
secretions, blood, semen, saliva, vaginal
discharges; usually during sexual contact.
Mother to infant transplacental transmission
(congenital syphilis).
Blood transfusions.
 Incubation period: 10 days to several weeks.
 Epidemiology : Over 80,000 new cases/year in
U.S.
 Control: Use of condoms, avoid sexual contact
with infected individuals. Blood tests (VDRL)
for high risk individuals.
 Treatment: Antibiotics, long acting penicillin G,
tetracycline, etc.
Congenital Syphilis Causes Teeth and Bone Defects
Congenital Syphilis with Hutchinson incisors.
Source: Physical evaluation of the dental patient, 1982.
Candidiasis (Yeast Infection)
 Characteristics: Painful irritation and inflammation of
vagina and vulva in women. Redness and intense itching.
White vaginal discharge.
May cause infections of mouth, throat, and rectum in
immunocompromised patients.

Pathogen: Candida albicans (yeast), part of normal flora
of mucous membranes.

Reservoir: Humans.

Transmission: Opportunistic pathogen.

Antibiotic treatment

Weakened host: stress, diet, or illness.

Incubation period: 2 to 3 weeks. May be asymptomatic.

Epidemiology : Millions cases/year in U.S.

Treatment: Antifungal medication.
Genital Warts
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Caused by Human Papillomaviruses (HPVs)
Over 1 million a year get it. Most common STD in the US.
Teenagers with multiple sex partners at risk
Often assymptomatic
Newborn can become infected during vaginal delivery
Associated with:
 cancer of the cervix (90-95% of all cases)
 Tumors of the vulva, vagina, anus, and mouth
NO CURE but can be treated with:
 Surgery
 Freezing
 Application of an acid
 Laser burning
Can still be transmitted AFTER treatment!!