BiO Exam 3 wk. 1

Ovaries

Contain follicles, single eggs surrounded by nourishing protective cells

Produce hormones: estrogen and progesterone

Oviduct

(fallopian tube) connects ovaries to uterus

where fertilization usually happens

ectopic pregnancy: when a fertilized egg stops in the oviduct

Uterus

An elastic and muscular organ that can support a fetus, lined with endometrium; a layer enriched with flood vessel to support pregnancy

Cervix

The passageway that connects uterus to the vagina

Papsmear: scraping of cervical cells to check for cancer

Testes

Paired gland, produce hormone testosterone contained in the scrotum

Kept outside of the body to lower temp; low temp means better sperm development

Seminiferous Tubules

Tightly coiled tubes, where sperm develop, sperm mature in the epididymis, travel through the vas deferans and leave the body through the urethra

Prostate

Adds fluids to sperm to make semen

Semen

Ejaculated sperm and fluids

Penis

Delivers sperm to vagina

Fluid from the seminal vesicle

Contains fructose, a sugar used as an energy source

Fluid from the prostate gland

Thin, milky white, nutrient-rich fluid (goes into urethra)

Fluid is basic to help neutralize vaginal acidity

Pre-ejaculatory fluid from the bulbourethral gland

Cleans urine out oof urethra (major function)

If fertilization occurs

Fused egg and sperm = zygote

becomes an embryo after several cell divisions, several days after fertilization, and implants in the uterus

hCG (human chorionic gonadotropin) is released by the embryo. Progesterone is released from the corpus lutea (empty egg follicle) to thicken endometriums and the placenta begins to form.

If the egg does not fertilize within 24 hours of ovulation

The corpus luteum degenerates, which causes the progesterone to drop and that causes the endometrium to slough off (menstruation)

Menopause

Ovaries stop responding to the LH and FSH hormones from brain that control the ovarian cycle

FSH

Follicle-stimulating hormone tells the egg to mature and the sperm to be made

Ovulation and menstration

Stop estrogen, progesterone production declines

Male testosterone

Stimulates sperm to develop (FHS)

Female estrogen and progesterone

Drive reproductive cycles (FHS and LH)

Ovarian and menstrual cycle

Ovarian cycle: controls the maturation and release of eggs

Menstrual cycle: prepared uterus for possible embryo implantation

Hormonal messages synchronize the two cycles

Contraception

Sterilization: prevents eggs/sperm development

Barriers: prevent sperm from accessing eggs

Hormonal: interfere with normal female hormone cycle to prevent ovulation

Causes for infertility in men

Obstructions or blockages in the vas defrens

Hormone imbalances and physical damage could lower fertility

Age decline in sperm production as men get older

Causes for infertility in women

A blocked or damaged oviduct prevents the egg from reaching the uterus

Hormone imbalances could limit ovulation or interfere with normal cycles

Menopause ovaries don’t respond to hormones, no eggs are released

If infertility can’t be corrected

In vitro fertilization (IVF) or intrauterine insemination (IUI)

Sperm are injected directly into the uterus, usually in combination with fertility drugs (FSH and LH)

Gametogenesis

Production of gametes

Gametes

Specialized male and female reproductive cells (sperm and egg)

Sperm cells add a tail and increase mitochondria

Egg cells increase in size and nutrient concentration

Meiosis

Specialized form of cell division to produce gametes

Occurs only in gonads (sex organs)

Testes in males, ovaries in females

Meiosis reduces number of chromosomes by half

Somatic (body) cells have 46 chromosomes

Gametes have 23 chromosomes

Homologous pairs of chromosomes

Found in somatic cells

One member from the mother and one from the father

same size and shape, carry the same genes

May have different alleles

Gamete receives one of each pair

Human Chromosomes

22 pairs of autosomes: nonsex chromosomes

1 pair of sex chromosomes

XX for females

XY for males

Haploid cells

contain one member of each homologous par

23 chromosomes

eggs and sperm

Diploid cells

Contain two sets of chromosomes

46 chromosomes

Zygote: fertilized egg

Somatic cells

Meiosis 1

Separates the homologous pairs into two separate cells

Meiosis 2

Separates the sister chromatids in each cell to produce four haploid cells

Nondisjunction

Chromosomes fail to separate during meiosis

sperm or eggs will have too many or too few chromosomes

may lead to lowered fertility

Mismatched chromosomes cannot pair properly at meiosis

Turner syndrom

Females with only one X chromosome

affects 1 in 2,500 females

Klinefelter syndrome

Males with two X chromosomes and one Y chromosome

Affects 1 in 800 males

Low gamete production

Major cause of infertility

Commonly caused by aging

Male fertility begins to decline in mid-thirties

Female conception declines at an earlier age and faster rate than men

Fertility rates

Can be measured by length of time needed to become pregnant compared to age

Female Differences in Meiosis

In mother uterus: ovaries begin meiosis

Birth: all potential eggs are present

At puberty: paused meiosis finishes during each menstrual cycle

Reproductive years: Number and quality of potential eggs declines until menstruation stops at 50

Meiosis interphase

Preceding meiosis, centrioles are present

3 phases

G1: cell growth

S: DNA replication

G2: cell growth and preparation for division

Meiosis 1 - Prophase 1

Nuclear envelope breaks down

Microtubules begin to assemble

Chromosomes condense

Possible crossing over: exchange of genetic info between homogous chromosome

May produce new combinations of genetic info

Meiosis 1 - Metaphase 1

Homologous pairs line up at the equator

random alignment: members of homologous pairs are arbitrarily arranged to face a pole

results in genetically diverse gametes

over 8 million possible alignments from 23 pairs of chromosomes

Meiosis 1 - Anaphase 1

Microtubules shorten

Homologous pairs separate

Meiosis 1 - telophase 1

Nuclear envelope reforms around chromosomes

Meiosis Cytokinesis

DNA is partitioned into each daughter cell

Haploid cells

Meiosis 2

Virtually identical to mitosis

Meiosis 2 - Prophase 2

Microtubules lengthen again

Meiosis 2 - Metaphase 2

Chromosomes align at equator

Meiosis 2 - Anaphase 2

Sister chromatids separate and move to opposite poles

Meiosis 2 - Telophase 2

nuclei enclose each set of separated chromosomes

Turner Supressor Genes

Inspect newly replicated DNA; if errors in new DNA are found, they pause cell division to allow DNA repair or initiate cell death.

Can be mutated to become inactivated, which now allows a cell division even if the DNA is not copied correctly. This can lead to tumor formation

Mutated Cell-cycle control genes

A few are inherited, most occur with exposures to environmental risk factors: smoking, lack of exercise, poor eating habits, and infection with viruses. HPV infection increases the likelihood of cervical, vaginal, penile, anal, and oral cancers. UV exposure.

Cancer Development

It takes more than a single mutation to cause cancer. Individuals who have inherited a high-risk mutation may require one (or a few) new mutations to develop cancer…so often develop at an earlier age.

Tumor

Solid mass of cells without no obvious function

Benign Tumor

Noncancerous, doesn’t affect the surrounding area

Malignant Tumor

Cancerous, invading surrounding tissues

Metastasis

Some cancerous cells break away from the malignant tumor and spread to a new location in the body

Cancer cells differ from normal cells

replicate when they shouldn’t, invade nearby tissue

Move to other areas of the body (metastasis)

Circulatory system

Travel through blood

Lymphatic system

Lymph fluid that’s lost from the blood

Lymph nodes

Filter lymph fluid, often we analyze lymph nodes to see if there are metastatic cancer cells there

Early Cancer detection

Can halt progression, increase survival odds

Biopsy

Surgical removal of cells for microscopic analysis