Chapter 16 Human Bio

Testes

-produce sperm

-outside of males because it needs to be cooler

-can descend and ascend depending on the temperature

Scrotum

sac of skin and smooth muscle that holds the testes

-maintains testes at a slightly lower temperature

seminiferous tubules

-in the testes

-produce sperm

Ductus deferens

transports sperm to where it becomes the ejaculatory duct

Route of sperm through male reproductive structures

• seminiferous tubules

• epididymis

• ductus deferens

• ejaculatory duct

• penis

Semen

mixture of sperm and secretion of accessory glands

Sperm

• just the cells carrying DNA

• 60-70% is sugar and alkaline fluid and lubricant

• can last 5-7 days in the female

seminal vesicles

secrete fructose (provides source of energy for sperm) and produce/secrete most of the seminal fluid

Prostate gland

secretes watery alkaline fluid to raise vaginal pH

Bulbourethral gland

-secretes lubricating mucus

-cleanses urethra

when does sperm production start

at puberty and never stops

Epididymis

site of sperm maturation and storage

ductus deferens

duct for sperm maturation, storage, and transport

Ejaculatory duct

duct for transporting sperm and glandular secretions

leydig

produce testosterone in the testicles (interstitial cells)

several cell divisions (mitosis and meiosis) in….

seminiferous tubules produce sperm

Sperm and eggs are referred to as…

gametes and are haploid

Sequence of cell types leading to sperm

spermatogonia (2n), primary spermatocyte (2n), secondary spermatocyte (n), spermatids (n), sperm(n)

sertoli cells

provide support, nourishment

cell divisions

produce a large number of sperm with half the number of chromosomes of somatic cells (haploid)

Testostrone

-steroid hormone produced by interstitial cells in testes (between seminiferous tubules)

Function of testosterone

• controls growth and function of male reproductive tissues

• stimulates aggression and sexual behavior

• controls development of secondary sexual characteristics

• determines rate of sperm formation

Gonadotropin releasing hormone (GnRH)

from hypothalamus stimulates release of LH and FSH

LH

from anterior pituitary, stimulates production of testosterone

FSH

from anterior pituitary, may enhance sperm formation with sertoli cells

Inhibin

produced by sertoli cells, inhibits secreation of FSH

Ovaries

• release oocytes (immature eggs) and secrete the hormone estrogen and progesterone

Oviduct (fallopian tube)

• Leads from the ovary to the uterus

• Fertilization occurs in the upper third of the oviduct

• Three to four day trip through oviduct to uterus

Uterus

hollow, pear-shaped organ where fertilized eggs grows and develops

Layers of uterus

• Endometrium

• myometrium

• cervix

Endometrium

supports fertilized egg, part of it sloughs off during menstrual flow

myometrium

smooth muscle, expands during pregnancy, constricts during labor

cervix

the narrow opening in the lower part of the uterus that permits sperm to enter the uterus and allows the fetus to exit during birth

vagina

organ of sexual intercourse and birth canal

external genitalia

• labia majora and minora (provide physical support, protection, lube

• clitoris

breasts contain what glands

mammary glands

mammary glands

modified sweat glands that are part of the integumentary system

-specialized for lactation (production of milk)

• prolactin stimulates milk production

• oxytocin stimulates contractions that eject milk

menstural cycle

• ovarian and uterine cycles

• pattern of changes, which cyles every 28 days (14-56)

• controlled by hormones of pituitary gland and ovaries

• Begins at puberty and contiues until menopause, except during pregnancy

ovarian cycle

• series of changes in ovaries associated with oocyte maturation

• controlled by fsh and LH

Uterine cycle

• changes in the endometrial lining of the uterus

• controlled by steroid based hormone estrogen and progesterone

Granulosa cells…

divide and produce zona pellucida around oocyte

Antrum…

develops within the follicle; some estrogen and progesterone are secreted

Secondary oocyte and polar body are produced…

follicle matures (Graafian follicle)

Corpus luteum

when eggs are released, remanent of this is the corpus luteum, large amounts of estrogen and progesterone are secreted

-prevents eggs from degrading

If fertilization and pregnancy occurs

• chorion (embryonic tissue) secretes human chorionic gonadotropin (hCG) only released by females

what is detected by pregnancy tests

hCG

hCG causes…

corpus luteum to continue to produce estrogen and progesterone for another 9-10 weeks, after the placenta takes over estrogen and progesterone production

what prevents ovulation during pregnacy

high levels of estrogen and progesterone

Fertilization is…

when sperm and egg meet the end product is called a zygote

Menstrual phase

• days 1-5

• Estrogen and progesterone decrease decrease

• endometrial lining degenerates

• Menstruation occurs

proliferative phase

• Days 6-14

• estrogen and progesterone increase

• endometrial lining proliferates

ovulation

• day 14

• release of LH triggers ovulation (midway point)

secretory phase

• days 15-28

• corpus luteum produces progesterone and estrogen

• endometrium continues to proliferate

• uterine glands mature

• uterus is prepared to accept and nourish a fertilized egg

positive feedback is in which phase

proliferative phase, increasing estrogen causes surges in LH which in turn causes ovulation

Negative feedback is in which phase

in secretory phase, steady levels of estrogen and progesterone inhibit LH and FSH

human sexual response

• excitement: increased sexual awareness and arousal

• plateau: intense and continuing arousal

• orgasm: peak of sexual sensations

• Resolution: abatement of arousal

• Male sexual response: orgasm, marked by ejaculation, refractory period

• Female sexual response: orgasm, marked by rhythmic muscular contractions

Fertilization

• Ejaculate: may contain several hundred million sperm

• sperm may reach egg within hours to a day or more (hours to days)

• one sperm penetrates egg within the oviduct

• sperm may be viable for up to 5 days within the reproductive tract

• end product is a zygote

Abstinence

• not having intercourse

• 100% effective

vasectomy in males

cut and tie off both ductus deferens

Tubal ligation in females

cut and tie off both oviducts

hysteroscopy in females

cauterize the oviducts to seal them off

Birth control pills (oral contraceptives)

• combination of synthetic progesterone and estrogen

• inhibit release of FSH and LH

Hormone injections

-depo-provera (lasts 3 months)

hormone patch

ortho evera

vaginal ring

NuvaRing

implant

implanon and nexplanon; progestrone-containing rod under skin

Advantages of birth control methods

• may reduce cramps and menstrual flow

• some protection against ovarian and uterine cancers

disadvantages of birth control methods

-side effects include acne, headaches, fluid retention, high blood pressure, blood clots

-do not protect against STDs

IUDs (Intrauterine devices)

-Small plastic or metal piece inserted into uterus

-create mild chronic inflammation that prevents fertiliztion or implantation

-Mirena: includes progesterone-like drug

Diaphragms and cervical caps

-prevent sperm from entering the cervix

-effectiveness improved when used with spermicides

Chemical spermicides

kill sperm cells

Elective Abortion methods

• mifiprex can be used up to seven weeks after pregnancy onset

• vacuum suctioning of uterus

• surgical scraping of uterine lining

• infusion of strong saline solution

The Future in Birth Control

• male birth control; reduces sperm production

• vaccines for women

  • vaccine against hCG

  • vaccine against sperm

infertility

Inability to achieve pregnancy after a year of trying

Causes of infertility

• number and quality of sperm

  • less than 60 million/ejaculation is considered indertile

• pelvic inflammatory disease (PID)

  • scarred, blocked oviducts

• Abnormal production of FSH and/or LH

• irregular menstrual cycles

• endometriosis (inflammation of the endometrium

• strongly acidic vaginal secretions

• decreased reproductive capacity with age

• miscarriage (spontaneous abortion) almost every female has at least one they just may not notice

In virto fertilization (IVF)

• fertilization in test tube outside of the body

• after several cell divisions, embryo is inserted into the uterus via the vagina

GIFT (gamete intrafallopian transfer)

unfertilized eggs and sperm placed directly in oviduct

ZIFT (zygote intrafallopian transfer)

fertilized egg is placed in oviduct

STDs

• can be transmitted by genital, oral genital, anal genital

• can be very damaging or deadly

• may affect organs outside the reproductive system

• some are not treatable

• infectious agents include viruses, bacteria, protozoa, fungi, and arthropods

Syphylis

• causes by bacteria Treponema pallidum

• Three phases

  • primary: lesion in genital area

  • secondary: rash

    • bacteria invades blood, lymph nodes, nervous system, bones

  • Tertiary: widespread damage to nervous system and the cardiovascular system

• Congenital syphilis: transmitted by infected mother to fetus

• Treatment:penicilliin

Gonnorrhea

• caused by bacteria Neisseria gonorrhoeae

• Male symptoms: penile discharge, painful urination

• Female symptoms: vaginal discharge, burning sensation when urinating

  • Females are often asymptomatic, have worse outcome

• can be passed to newborn during birth, causing serious eye infection

• if untreated can lead to inflammation, scarring, and infertiltliy

• usually can be treated with antibiotics

Chlamydia

• The most common STD, can get gonorrhea infection from it

• caused by bacteria Chlamydia trachomatis

• often goes undiagnosed due to mildness of symptoms

• if untreated my lead to pelvic inflammatiory disease in women

• can infect newborn during birth

• Treatment: antibiotics

HIV

• one of the most dangerous STDs (HIV in secondary condition, AIDs is what kills you

• slowly destroys the immune system, causing AIDs

• Treatment may achieve remission, but no cure

Hepatitis B virus

• more contagious than HIV but not as deadly

• affects liver

• vaccine is available for prevention

Genital herpes: Herpes simplex virus

• painful blisters may recur periodically

• drugs will suppress outbreaks and contagious phase, but no cure

• may infect infants during birth

human papillomavirus (HPV)

• number 1 cause of cervical cancer

• many strains can cause warts in genital area

• two types cause cervical cancer

  • CDC recommends that all children (girls and boys) be vaccinated at age 11 or 12 (before first sexual contact)

Candida albicans (yeast)

• normally present but may overgrow (more common in females

• pain, inflammation, discharge

• can be passed sexually

• may follow antibiotic treatment for bacterial infections

• Treatment: topical or oral antifungal medication

Trichomoniasis

• caused by protozoan Trichomonas vaginalis

• women:

  • vaginitis-inflammation of vagina

  • frothy foul smelling discharge

• men:

  • inflammation of penis, discharge

• treatment: flagyl (metranidazole)

Pubic lice

-tiny arthropod related to spiders

-crabs

-prefer to live on pubic hair

-cause intense itching and skin irritation

-treatment: anti lice medication

-clothes and bedding should be throughly washed in hot water