Ovarian and Uterine Cycles

Key Terms –

Ovarian cycle: the normal cycle of reproductive function and development in the female ovary, which includes development of an ovarian follicle, rupture of the follicle, discharge of the egg, and formation and regression of a corpus luteum (yellow tissue formed in the ovary after the release of the egg).

Uterine cycle: also known as the menstrual cycle, in which the endometrial lining of the uterus prepares for pregnancy. If pregnancy does not occur, the lining is shed at menstruation.  The average menstrual cycle is 28 days.

GnRH: a hormone which is produced by the hypothalamus in the brain. It stimulates the pituitary gland to produce and release both LH and FSH.

LH: a hormone produced during the menstrual cycle. The luteinizing hormone causes an egg to be released from the ovaries.

FSH: (follicle-stimulating hormone) promotes follicle development within the ovary, thus allowing certain eggs to mature and the follicle cells surrounding each egg to produce estrogen in preparation for fertilization.

Estrogen: female steroid sex hormones. They are secreted by the ovary and responsible for typical female sexual characteristics.

Progesterone: a steroid hormone produced in the ovary, which prepares and maintains the uterus for pregnancy.

hCG: (human chorionic gonadotropin) hormone produced early in pregnancy by the placenta. Detection of the hormone in the urine is the basis for one type of pregnancy test.

Positive feedback loops: hormone levels increase after the release of an egg into the ovary because more hormones are needed to ensure proper development of the egg to a fetus.

Negative feedback loops: a decrease in the hormone levels within the body leads to a decrease of the production of GnRH.

Menstruation vs. Pregnancy: hormone levels are much lower during menstruation than during pregnancy because there is no egg for fertilization.

Fetal Development: is the process in which an embryo or fetus gestates during pregnancy, from fertilization until birth.

1^st Trimester – the first twelve weeks of pregnancy: the zygote is turning into a fetus and the embryo is made up of three layers, ectoderm, endoderm and mesoderm. These are the first stages of organ development.

2^nd Trimester – the second twelve weeks of pregnancy: fetus continues to grow and organs are developing. The ectoderm forms skin tissue, the endoderm forms the digestive and respiratory systems, and the mesoderm forms muscles, cartilage, bone and blood.

3^rd Trimester – the third and final twelve weeks of pregnancy: the fetus is growing rapidly. It will fully develop during this period of time.

Immune System

Key Terms –

Pathogens: an infectious agent, or more commonly germ, is a biological agent that causes disease to its host.

Macrophage: a type of phagocyte or white blood cell that digests foreign invaders and damaged tissues.

Antigen: any substance (as a toxin or enzyme) that stimulates an immune response in the body (especially the production of antibodies).

Helper T cell: are a sub-group of lymphocytes (a type of white blood cell or leukocyte) that play an important role in establishing and maximizing the capabilities of the immune system.

B cell: a lymphocyte derived from bone marrow that provides immunity; it recognizes free antigen molecules in solution and matures into plasma cells that secrete immunoglobulin (antibodies) that inactivate the antigens.

Antibody: any of a large variety of proteins normally present in the body or produced in response to an antigen which it neutralizes, thus producing an immune response.

Killer cell: a white blood cell that attacks and kills “foreign” cells, including tumor cells and cells infected with bacteria or viruses.

Cytotoxic T cell: a type of white blood cell that can directly destroy specific cells.

Memory cell: a subset of T-cells and B-cells that have been exposed to specific antigens and can then proliferate (recognize the antigen and divide) more readily when the immune system re-encounters the same antigens.

Problems of the Immune System –

Severe combined immunodeficiency (SCID): is also known as the "bubble boy disease" after a Texas boy, David Vetter, with SCID who lived in a germ-free plastic bubble. SCID is a serious immune system disorder that occurs because of a lack of both B and T lymphocytes, which makes it almost impossible to fight off pathogens in the body. Its victims are extremely susceptible to infectious diseases and some of them, including David who became known as “the bubble boy”, become famous for living in a completely sterile environment. SCID is the effect of a highly compromised immune system.

HIV (human immunodeficiency virus) infection/AIDS (acquired immunodeficiency syndrome): is a disease that slowly and steadily destroys the immune system. AIDS is caused by HIV, a virus that wipes out a specific lymphocyte, helper T cells. Without these cells, the immune system is unable to defend the body against normally harmless organisms. By damaging your immune system, HIV interferes with your body's ability to fight off life-threatening infections and diseases. Newborns can get HIV infection from their mothers while in the uterus, during the birth process, or during breastfeeding. People can get HIV infection by having unprotected sexual intercourse with an infected person or from sharing contaminated needles for drugs, steroids, or tattoos.

Aging

Aging is unavoidable – it is a natural, physiological process that, although can be slowed down or covered up with cosmetic procedures, will happen to everyone. Aging is caused by a combination of genetics and lifestyle.

Genetics account for aging because of our cells dividing, resulting in our telomeres becoming shorter and shorter with each division. “Biological age…is related to the length of telomeres – stretches of DNA at the ends of chromosomes, which protect these precious packages of genes from daily wear and tear. We’re born with telomeres of certain length, and these get shorter as our cells divide, resulting in aging, scientists think” (Moisse, 2010). Aging occurs on a cellular level – eventually cells lose their ability to divide and repair themselves. This loss of capability to divide and repair is known as senescence. As the telomeres become increasingly shorter in the division process, there is the possibility that essential parts of DNA can be damaged with each new divide.

Lifestyle also accounts for aging. “…good habits, such as a healthy diet, regular physical activity and mental exercises that might keep the elderly vibrant through their golden years. The New England Centenarian Study, which includes 850 people entering their 100s, for example, has identified several behavioral and personality traits that seem to be critical to longevity, including not smoking, being extroverted and easygoing and staying lean” (Park, 2010). Taking care of your body can help maintain your youth, while engaging in risky lifestyle choices can speed up the aging process. Lack of exercise increases the risk of cardiovascular disease and diabetes, while smoking not only damages your lungs but also speeds up the rate at which telomeres decay and in turn age your body faster.

Another factor of aging is the relationship between good cholesterol – high-density lipoprotein (HDL) – and health. “HDL plasma concentrations decline with age in prospective studies. Decline in HDL concentration and function may occur secondary because of…specific aging processes [that] may be involved. Replicative aging, the telomere-driven loss of divisional capacity, is a species-specific aging mechanism that may decrease HDL concentration and function. Cross-sectionally, by contrast, HDL levels do not change much or even slightly increase with age, suggesting that only people with still high HDL concentrations survive” (Walter, 2009). People with higher levels of HDL tend to live longer because HDL removes the bad cholesterol – low-density lipoprotein (LDL) – from the body and helps decrease the risk of heart disease.

Works Cited

Moisse, K. (2010). Researchers identify genetic variant linked to faster biological

aging. Scientific American. Retrieved April 11, 2011 from http://www.scientificamerican.com/article.cfm?id=aging-telomere

Park, A. (2010). How to live 100 years. Time. Retrieved April 11, 2011 from

http://www.time.com/time/specials/packages/article/0,28804,1963392_1963365,00.html

Walter, M. (2009). Interrelationships among HDL metabolism, aging, and

atherosclerosis. American Heart Association. Retrieved April 11, 2011 from http://www.atvb.ahajournals.org/cgi/content/full/29/9/1244

Stress

Causes of Stress:

A stressor is a situation that causes stress. Stressors can be classified into three categories –

1.       Accidental hassles: temporary but can cause significant stress

Ex. Losing a house key, having a flat tire, missing the bus or getting a traffic ticket

2.      Major life changes

Ex. Marriage, graduation, having a baby, starting a business, surgery, death in the family, losing a job, or divorce

3.      Ongoing problems

Ex. An unhappy marriage, unstable job, a poor relationship with a family member, coworker or peer, or accumulating debt

Ways to Reduce Stress:

Prevent –

1.       Avoid controllable stressors

2.      Plan major lifestyle changes

3.      Realize your limitations and learn how to say no to things that stress you out and responsibilities you know you cannot take on

4.      Prioritize

5.      Improve communication

6.      Share your thoughts and get advice to avoid/get out of a stressful situation

7.      Develop a positive attitude

8.     Reward yourself with relaxation as you successfully overcome challenges

9.      Exercise

10.  Eat and sleep well

Manage –

1.       Plan by visualizing expected events

2.      Think positively

3.      Imagine potential negative big events and think about what you can do to make them positive

4.      Relax with deep breathing

5.      Relax by clearing your mind

6.      Relax your muscles

7.      Relax with stretching and exercise

8.     Relax with massage therapy

9.      Ask for help

10.  Find professional help from doctors if needed

Effects of Stress: