Pathway of Sperm
Created in seminiferous tubules --> travel to lumen (opening) in center of seminiferous tubules --> move through lumen to epididymis --> Mature and stored in epididymis --> Vas Deferens --> Urethra (All Accessory Glands)
Produced in the process of meiosis, occurring in the seminiferous tubules; millions created daily
Tubes sperm travel up from the epididymis (during sexual activity) bringing the sperm to the prostate.
Small portion of urethra passing through prostate gland and emptying into the penile urethra.
Produces nutrient rich material "sack lunch," high in fructose (simple sugar), prostaglandins, and clotting proteins.
Help cause muscular contraction of: smooth muscle of urethra aiding in ejaculation & muscle contraction in female tract aiding in movement of sperm through uterus and oviduct.
Provides the "red bull"; secretes slightly acidic solution, stimulating ATP production in sperm cell mitochondria; needed to have energy to swim through reproductive tract.
Produce fluids before ejaculation; a slightly alkaline fluid "the shield," neutralizes the acid environment of penile urethra and acts as lubrication in penile urethra
Composed of millions of sperm cells with fluids from seminal vesicles, prostate, and bulbourethral (cowpers) glands.
Sex Hormone Production Beginning
Begins at puberty with hypothalamus; at puberty this part of the brain beings producing "releasing hormones" (GnRH or Gonadotropin Releasing Hormone)
Male Sex Hormone Production
GnRH travels to pituitary gland, causing the pituitary start producing FSH and LH. Once these reach testes, seminiferous tubules begin meiosis & producing sperm; also cause testes to start testosterone production.
Male sex hormone made by the testes; responsible for male secondary sex characteristics signaling growth in muscle, bone and cartilage. Also influences behavior/aggression.
the response reduces or shuts off the original stimulus; testosterone level stopping pituitary gland production of LH and FSH, while it is the pituitary glad that controls testosterone production through the testes.
Abnormal Prostate Size
After 50, it will enlarge leading to restriction on the urethra causing difficulty urinating
Used to treat enlarged prostate; resectoscope inserted into urethra --> electrical loop extended at prostatatic urethral --> this removes excess tissue, thus opening the urethral orifice
Prostate Cancer Prevalence
Far more prevalent than lung cancer, death rate is much lower--due to early detection and slow rate of growth
Stages of Prostate Cancer
[A] few cancer cells [B] More cancer cells [C] Lots of cancer cells, starting to spread [D] Huge amount of c. cells, spreading
Spread of Prostate Cancer
Localized: Discomfort, not usually fatal--Metastasizes (breaks up and spreads): life-threatening, often spreading to lymph, and bones in the spine causing severe pain
Prostate Cancer Risk Factors
Increases with age (60-79 yrs at 1 in 7 risk); family hx, heritage (black men @ higher risk), and occupation (farmers) can have effects
Early Prostate Cancer Protection
Earlier prostate tumors are found, more successful surgery will be and better chances of survival
Digital Rectal Exam
Start at age 40; MD feels for marble sized tumors. Advantages--inexpensive and available to all ; Disadvantages -- Cannot identify earliest stage (Stage A) b/c of tumor size
Prostate Specific Antigen test for protein in blood showing prostate changes, detecting only 80% of prostate cancers. MD looking for unusual changes (PSA increases with age normally). PSA increases also caused by ejaculation, hair growth meds.
Attempting to dx at stage A. Biopsy gun inserted into rectum, [6-18] needle samples taken, analysis determines if cancerous and genetic analysis to identify cell type (Gleason Scale).
Two types: Radical Prostatectomy-- the removal of entire gland OR Nerve-Sparing Prostatectomy-- leaves tissue near nerves
2 types: Beam (high dose of radiation aimed at prostate cancer) and Radioactive Seed Implants (small pellets of radioactive material inserted into gland delivering treatment from inside the body. x2 the dose of Beam)
Radiation Pros and Cons
Pro: less recovery time, less likely to get ED -- Con: may not eliminate all c. cells, if radiation fails surgery not usually possible b/c of scarring of the tissue
Drugs eliminate or block testosterone production, slowing or stopping tumor growth--side effects include feminization (menopausal SX'S), and cells are not removed or killed
Recommended to men 75-80 b/c of possible slow prostate cancer growth (10+ yrs to be fatal) and treatment may not be worth it
Gamete (egg) produced here & hormone production. Thousands of follicles (nest of ovary cells) surround immature egg & produce estrogen. Each month, egg responds to reproductive hormones, matures, and is ovulated into oviduct
Inner layer of uterus, becomes vascular to prep for implantation of blastocyst. Layer is shed monthly when pregnancy doesn't occur.
"Neck" of uterus extending into vaginal canal. Sperm swim through it to enter uterus & baby exits through cervix.
Cyclic buildup and breakdown of endometrium as uterus prepares for monthly blastocyst [Declines with time]
Female Sex Hormone Production
FSH causes cells around 1 early stage ovum (called follicle) to grow and produce estrogen causing female sex characteristics & endometrium preparation. LH causes the follicle (w/ egg inside) to rupture and egg is released. After ovulation, "old" follicle produces progesterone, causing endometirum to be maintained
unsafe sex can lead to pregnancy from the 10th day of the month to the 17th day--few women are regular so this is only estimate
A follicle after it goes through ovulation; produces progesterone which regulates the uterine lining in case of preg. Shift from follicle to corpus luteum happens during each 28 day cycle from puberty to meno.
Fertilized Egg Cycle
Implants in endometrium --> Embryo produces and sends out hormonal message (HCG) to corpus luteum signaling embryo is present --> Corpus luteum continues to produce progesterone and estrogen to maintain endometrium
Special type of mitosis; during division cell mass doesn't enlarge but # of cells increase, each being smaller than original, & continues till it takes on hollow ball form called blastocyst.
If Egg NOT Fertilized
Egg doesn't implant --> HCG not sent, thus stopping of progesterone and estrogen production --> without estrogen and progesterone, endometrium is shed --> menstrual cycle happens
In woman's 40's, estrogen production declines --> Early signs/SX's of meno and may last for 5 yrs --> Estrogen production eventually stops, mentrual cycle stops and woman enters meno (actual meno is 12 consecutive months of no mentrual flow--usually 45-55)
SX'S of Meno
Hot flashes, dry skin, brittle hair, insomnia, vaginal dryness, mood swings, and skipped periods
Hormone Level Change W/ Meno
Uneven rise and fall of hormone lvls during perimenopause may be responsible for menstrual irregularities and other problems.
Hormone Replacement Therapy Hx
1960's -- Women over 50 recommended to begin estrogen therapy to remove meno SX's
1970's -- Discovered estrogen alone increased chance of endomtrial cancer
1980's & 1990's -- Correlative studies suggested women who took estrogen post-meno less likely to have M.I. MD's recommend estrogen therapy combined with progesterone to prevent endometrial cancer
2002 -- WHI showed HRT increased risk of m.i., strokes, and clots, and breast cancer.
2010 -- Research suggest taking estrogen good for women in 50's but not older
Correlation v. Causation
Women who took HRT may have more $, better healthcare/more health conscious. HRT make women healthier, or were healthy women more likely to take HRT
Women's Health Initiative (WHI)
Study of thousands of women looking @ HRT effects in a two group experimental design (woman on HRT and placebo)
4 Estrogen Do's and Don'ts
DO - Use estrogen prn for hot flashes, night sweats, and other SX's
DON'T take it to prevent heart disease, osteoporosis, or other chronic conditions
DO use estrogen in smallest dose possible for minimum amount of time
DO take it with progesterone unless you have had a hyst.
Human Sexual Response
Men and women have very different sexual responses, the largest difference is the refractory period during which males aren't responsive to sexual stimulation.
Problems decrease with age; lowest in married women and slightly higher in women who never marry
Absence of Orgasm
Women have greater problem with reaching climax, problem decreases slightly w/ age
Male Sexual Stimulation
Includes hearing, sight, touch, psyche, and smell & is the result in nerve transmission from the brain to the penis effecting cyclic GMP levels in penis. It is INCREASED cyclic GMP levels that cause an erection to occur
Enzyme causing relaxation of muscles in walls of blood vessels in penis --> muscles relax and more blood can flow into penis --> erection
Physiology of Erection
Stimulation increases cyclic GMP in penis and relaxation of smooth muscle --> Increased blood flow into erectile tissue --> Veins carrying blood are shut off --> Blood is trapped in erectile tissue
Loss of Erection Cycle
Lack of sexual stimuli leads to breakdown of cyclic GMP by PDE5 --> Decreased blood flow into erectile tissue --> Blood no longer trapped in tissue
Inability to achieve erection, possibly caused by not enough cyclic GMP--It is the 2nd most common sexual dysfunction and is not common in younger men. 80% of men 70+ have ED.
Vacuum pumps, penile implants, gel suppositories in urethra, and shots into penis.
Inserted into the erectile tissue that could be "pumped up" when erection is desired
How ED Drugs Work
Allow stimulation to increase cyclic GMP by SUPPRESSING PDE5--> Increased blood flow into erectile tissue --> Veins carrying blood out are shut off --> Blood trapped in Erectile tissue
PDE5 Inhibitor that blocks the activity of PDE5 allowing for more cyclic GMP to ACCUMULATE. It does NOT produce more cyclic GMP
An erection that does not end when sexual stimulation ends, and may last for hours damaging the tissue contributing to ED.
ED Drug Discovery
First examined as a drug to help w/ heart problems, but it didn't work. Test subjects would not return the pills, this ED drugs discovered to be awesome.
How RU486 Works
Normally progesterone is necessary for implantation of fertilized egg, but RU486 blocks the action of preogesterone. Prostaglandins are taken to cause uterine contractions.
The "pill" (oral contraceptives)
Combo of synthetic estrogen and pregesterone hormones, stops ovulation preventing the ovaries from releasing eggs, also thickens cervical mucus making it harder for sperm to enter the uterus
The Morning After Pill
Post-Coital pill can be taken up to 72 hours after unprotected sex & scientist are not sure how it works. It may: stop ovulation, stop implantation, stop pregnancy from proceeding.
Human Development Involves
The addition of more cells through mitosis, creation of adult cells with special functions through cell differentiation creating about 210 different tissues in the body.
Mitosis of Body Cells
Prior to mitosis is replication of 46 chromosomes forms 46 replicated pairs. Splitting of replicated chromosomes forms two daughter cells with 46 chromosomes like the original cell.
Life Cycle of Humans Terms
Meiosis -- process of cutting chromosomes in half while in the body. [you have 23 chromosomes per sperm and egg]
Fertilized egg (Zygote) has 23 chromosomes from sperm AND egg, making 46.
DNA directs changes in cells from general cell type (embryonic stem cells) to specialized cell types in the adult. It's hierarchical and once a cell moves from general to specific, it cannot change paths.
Non-specialized cells that can be differentiate into other specific cell types; there are two kinds--embryonic and adult
Embryonic Stem Cells
Have the most potential for differentiation and can become nearly any type of cell in the body.
Adult Stem Cell
Usually can become only a particular type of cell because it has already started on a "specific path" in cell differentiation.
Embryonic Stem Cell Location
In the blastocyst (4-5 days after fertilization) and contains 50-150 cells
Adult Stem Cell Location
These are responsible for tissue repair and regeneration; birth = adult; found throughout the body; cells constantly die and must be replaced; these are not as flexible as embryonic
Adult Stem Cell Treatment
Bone marrow transplants (stem cells in bone marrow make new blood cells) and umbilical cord blood (banking cord blood, its almost as flexible as embryonic stem cells and could be needed in future)
Infertility in Women Causes
Hormone imbalance, blocked fallopian tube, ovarian cysts, endometriosis, uterine cysts
In Vitro Fertilization
Eggs are retrieved from the ovary and fertilized in a dish. The embryos are then introduced into the uterus.
Hundreds of thousand embryos created via IVF and stored in liquid nitrogen tanks. Couples can use, donate, discard, or allow them to be used to stem cell research.
Treatment of Spinal Injuries
253k have spinal cord injuries, w/ 11k more each yr.
Rats were partially paralyzed, then injected with human embryonic stem sells and several weeks later they could walk again.
Dr. James Thomson
University of Wisconsin who in 1998 collected surplus embryos created at fertility clinics. Stopped the cells from differentiating, and kept them alive and reproducing.
Stem Cell Controversy
Fertilized egg from IVF is: 2-3 days old, only 8 cells, one cell can be removed and cultured as stem cells LEAVING the remaining to divide and develop normally.
Reprogramming Stem Cells
We can now reprogram adult stem cells to behave like embryonic -- Discovered by Dr. Thomson who can now make stem cells out of normal skin cells
Ban on Stem Cells
2001- Bush banned use of federal funds for stem cell research, except on cell lines already cultured in labs
Federal Funding Argument
Stem cells offer hope to cure diseases, and federal funding drives the speed of research progress. Without it, the US could slip behind in the biotechnology race.
Obama has signed an executive order permitting federal funding for human embryonic stem cell research
Each person has unique DNA which causes each person to have a unique complement of proteins which contributes too each person having unique appearance and behavior.
DNA IS NOT A PROTEIN, it's the instructions for making proteins
Life Cycle of Humans
Meiosis to produce sperm/egg --> fertilization and cleavage --> a zygote --> mitosis and cell differentiation --> a baby
DNA & Chromosomes
Chromosomes are a dense mass of DNA and some associated proteins. Each has specific genes, most genes code for the production of specific proteins.
is more than simply a chain of amino acids--to function properly, different proteins take different shapes
Sickle Cell v. Normal Hemoglobin
The addition of valine, only one variation to the amino acid chain results in sickle cell anemia
Essential Amino Acids
the nine amino acids that cannot be made by the body and much be received via diet qd.
Genetics was born in 1866 this monk who published a paper defining "gene" as the unit that passes down heritable traits. Argued kids get 2 copies of each gene--one from father and mother.
3 nucleotides code for one amino acid [different codes of nucleotides code for different amino acids.
DNA & Protein
DNA in the chromosomes of the nucleus determine the protein synthesis made at ribosomes.
"The Central Dogma"
DNA uncoils and 1 strand is used to produce mRNA in nucleus --> mRNA leaves nucleus and goes to ribosomes with recipe --> amino acids linked together according to nucleotide recipe of mRNA
The "cop" which reads detects any mRNA that does not belong to the system. If it finds one, it destroys all of the mRNA containing the similar sequence and the production of that protein stops.
Human Genome Project
Defined as sum total of genes in a human, estimating 2o-25k genes in each human controlling protein production.
Human Genome Facts
a] began in late 1980's supported by 15 billion b] sequenced rought 3 billion chemical letters in DNA that comprise the genetic code for humans c] completed in 2000
-Figure out what the Junk DNA does accounting for 99% of DNA.
-Sequence of letters in DNA for the human gnome is known, but gene-protein relationship unknown
-Learning about molecular switches regulating how DNA guides protein synthesis.
These are the specific expression of each gene and every pair of chromosomes has the same GENES but the alleles on each member may be different.
Meiosis results in:
1. Gametes with half the number of chromosomes as the number in our body cells (23 instead of 46)
2. gametes with different chromosome combination
humans are unique because each have a unique set of genetic instructions (set of alleles in DNA chromosomes) due to the random assortment of chromosomes during generation of gamestes (egg/sperm) through meiosis
70 trillion possibilities
There are over 70 trillion possibilities that can occur during meiosis in a human.
Produced when the 2 cell stage splits, forming 2 separate cells. Then the cells continue to divide separately, forming 2 embryos.
Genetic Code: Identical Twins
Identical chromosomes --> Identical Proteins --> Highly similar appearances
Inner cell masses subdivide, but do not separate completely, forming conjoined twins.
Takin an ADULT (fully differentiated) cell and restarting its gentic program and protein synthesis as if it were a fertilized egg.
Cloning thought impossible...
because as genes DNA regulates protein synthesis during development, the genes turn off (zygote stage genes inactive in adulthood)--therefore to clone a mammal, the DNA would have to be turned back on and read from the start (zygote stage)
Born in Scotland in 1997, this sheep was the first mammal to be cloned and showed DNA in adult cells can be restarted.
High Failure Rate in Cloning
2-5% success rate--miscarriages frequent, developmental abnormalities can occur, and death of offspring is x10 high than normal b4 birth; x3 higher after birth
could be used to produce stem cells that could treat diseases. Cells would be perfect genetic match for person donating cells
will be used to produce embryos that will be implanted into a woman's uterus and allowed to develop into infant
Cloning a Child: The Problems
A cloned child would be genetically identical, but have a different personality from the parental clone b/c of nature & nurture effect personality.
Also lead to problems w/ parents putting unrealistic expectations upon the child.
EXCEPTION: Cloning child who died at birth.