Saturday, May 29, 2010

Ovarian and Uterine Cycles

Uterine cylce: lining of ueterus builds and exits the body through the vagina(menstruation)

Ovarian Cycle: mature egg travels to the uterus

LH: aka luteinizing hormone released in the pituitary gland and causes ovulation (when follicle release and egg)

Progesterone: released by the ovaries when an egg is released from an ovary. Prepares unterine lining or endomitrium for the occurance of a fertilized egg.

FSH: aka folicle stimulating hormone from pituitary gland controls sexual maturation and reproductive system

Estrogen: Responsible for the developement of secondary sex characteristics in women. Released in larger amounts when folicles grow and then helps to thicken the uterine lining. when there is more estrogen the pituitary gland releases LH and FSH

GnRH: aka gonadotropin releasing hormone released by the hypothalamus causes FSH and LH to be released

hCG: aka human chronic hormone released when egg has been fertilized

menstruation and pregnancy: hormone levels high during pregnancy

negative feedback loop: decrease of hormones in the body

positive feedback loop: increase in hormones because the egg is released into the uterus and more hormones are needed to aid in the developement of the fetus.

first trimester: zygote divides into millions and millions of cells then officially becomes a fetus and begins to develop internal organs

second trimester: fetus develops lungs and brains

third trimester: fetus reaches full maturity and is able to function outside of the uterus

Friday, May 14, 2010

The Immune System

macrophage: a kind of white blood cells that consumes foreign invaders in the body. Help destroy bacteria and tumor cells. It also helps other cells in the immune system take action

antigen: any foreign substance that enters the body

T helper cell: white blood cell that recognizes the presence of antigens and releases cytokines that activate B and killer T cells.

B cell; lymphocyte that turns into plasma in the pressence of some antigens and releases antibodies to help fight off foreign invaders.

antibodies: protein that binds to an antigen, thus neutralizing it.

killer cells: destroy antigens that have been discovered by antibodies.

Cytotoxic T cell: type of T cell that kills cells that have been infected with viruses and other pathogens

memory cells: immune cells with long lifespans that remember attacks by certain antigens. When antigens return they can trigger a speedy immune response often before symptoms are felt.

Asthma: sensitive lungs have an allergic response to pollen and dander and the like and breathing tubes in the lungs become significantly narrower, thus restricting airflow.

eczema: also called atopic dermatitis is an uncomfortable, often reddish rash that often occurs in people with asthma.

Saturday, May 1, 2010


Though the quest for the fountain of youth is age old, it still seems to be quite elusive and seemingly inexplicable. There have been people that smoke and drink and eat fattening foods and live to 100. But, there are also people that eat healthy and exercise, have no vices, and only live to thirty.

Biological aging is believed by scientist to be cause by the breakdown of telomeres. Telomeres are pieces of DNA at the ends of chromosomes that protect the chromosomes. As cells divide over time, the telomeres get shorter, and thus less able to do their job.

There have recently been some discoveries on specific factors that may lead to increased life spans. On studies performed on some of the lucky people to live past 100, it was found that these people all contained high amounts of HDL. HDL is the good cholesterol, the kinds that helps rid the body of the bad cholesterol. A decrease in bad cholesterol leads to decreased risks of heart disease and diabetes. Such elevated levels of HDL is likely to be genetic.

Though many scientists argue that aging is an extremely complex process that involves a multitude of genes, some think that it might be much more simple. The sirtuin gene seems to do a pretty effective job on its own of impeding the aging process. When this gene is triggered, the body goes into a sort of survival mode, significantly increasing cell health. The question now seems to be how to trigger the gene. Risveritrol, the healthy chemical found in red whine, is thought to turn on the gene and lead to a healthier lifespan. Others suggest that the hunger caused by extreme dieting will throw the body into this survival mode.

There are also simple lifestyle choices (other than severe caloric restrictions) that may help slow the aging process. Avoid the following:



high cholesterol intake

drug use

sedentary lifestyle



Nova Staff. (2007, January 9). Aging. Retrieved May 1, 2010 from
Moisse, Katie. (2010, February 8). Researchers Identify Genetic Variant Linked To Faster
Biological Aging. Retrieved May 1, 2010 from
Park, Alice. (2010, February 11). How to Live 100 Years. Retrieved May 1, 2010from http://,28804,1963992_1933665,00.html

Saturday, April 24, 2010


Stress, or the reaction of the body to sudden changes in the environment, is one of those conditions that every single human being suffers from. Even the wealthiest, smartest, most successful, most popular person cannot escape stress. As stress is so unavoidable, so innate, rather than try to rid oneself of stress, the best thing seems to be to know how to handle it. A good place to start is to identify the root cause of the stress. For example right now I am stressed out because I feel like I will be spending the rest of my life working on AP English homework. Yesterday I was stressed out because I lost my cell phone. I have been mildly stressed over the long term because of my parents' increasingly frequent arguments.

Secondly, it is important to understand that stress is not always a horrible thing, it actually has a purpose. During stress the heart rate quickens, blood pressure rises, muscles tense. All these things prepare the body for a dangerous or important situation. Stress helps the body meet challenges. For example when I know I have to take a test, my body gets into a certain mode. I become solely focused and intent on that one subject. When I have a surprise assessment, no matter how prepared I may be, my body does not get the chance to get into the this "mode" and I rarely perform as well. . However, when the body does not get intermittent breaks between the stress, the adverse effects seem to be more prevalent than the positive effects.

The muscle tensing can lead to head and backaches. Stress also causes teeth grinding, poor sleep, and an increased likelihood of resorting to illegal substance to calm nerves. Heart attacks and a weakened immune system are some more severe consequences. When I stressed out my immune system becomes completely useless. I always get sick during finals time. this year it was pneumonia, last year it was streptococcus.

One has to realize that although stress is important to success, the body can not handle chronic stress. It needs breaks of relaxation. One method of helping my body to handle stress it to break larger tasks up into little pieces. If I looked at all my homework as a whole, I think I would be too overwhelmed to do anything at all. but, when I look at what I have to do for each class individually, it does not seem quite as daunting. It also helps to prevent stressful situations that you can control. I know that writing a five page paper the night before its do makes me very stressed out, so I work on it a week before its due. Furthermore (though I hate to admit it) eating right and exercising can help the body handle stress more efficiently.

Friday, April 16, 2010

Exercise Physiology

First of all, I think it is important that the athlete understand how their body produces energy. It can be broken down into two categories: aerobic and anaerobic respiration. Aerobic requires oxygen and is usually needed for long distance/endurance activities. Anaerobic does not require oxygen and is usually required for sports that consist of short bursts of intense activity. One chemical essential to energy production is adenosine triphosphate (ATP). As ATP breaks down energy is liberated. To create more energy the products of the breakdown of ATP, adenosine diphosphate and phosphate, recombine and split again. Another way of restoring ATP is the breakdown of creatine phosphate (cp) molecules. As they spilt, the energy they release re synthesizes an ATP molecule. And yet another method for ATP replenishment is a process known as glycolysis. A sugar molecule known as glycogen breaks down to produce energy for the resynthesis of ATP. Glycolysis produces a chemical called lactic acid. Lactic acid causes the pain that an athlete experiences while exercising. A good athlete will, through training, develop a high tolerance for lactic acid. Training will also help to increase an athlete's VO2 max, or the maximum amount of oxygen a person an breathe in to use during exercise. I would also consult an athlete on their diet. It should consist of 30% fat (energy stores, can be converted to glucose), 55% carbohydrates (another source of sugars) and 15% protein (replenishes, helps form tissues in the body).

Friday, April 2, 2010

Heart Surgeries

On the 5th of April 2008 64 year old John Smith begin experiencing chest pains. He is 5'7" and about 350 pounds. He is a self proclaimed couch potato and the last time he exercised was in 2001 when he was chasing an ice cream truck. He eats fast food at nearly every meal and refuses to consume anything green. As his chest pains worsened Smith reluctantly drove to the hospital. After observing Smith's weight and lifestyle habits his cardiologist decided to run a battery of tests to check for coronary heart disease. The doctor started with an electrocardiogram to check the timing and strength of the heart's beat and electrical signals. Next came a stress test where Smith ran (or attempted to run) on a treadmill while his doctors performed various tests to see how his heart handled stressed. However the very fact that he nearly vomited after five minutes of exercise seemed proof enough that the heart was not pumping properly. Lastly, he underwent an angiocardiogram where a special dye was injected into his heart so the flow of blood through the heart could be seen easily with x-ray imaging. All tests concluded that his coronary arteries were severely constricted. The fat and cholesterol from smith's daily quadruple bacon cheeseburger settled on the walls of his coronary arteries, hardening into a substance known as plaque. Though he miraculously escaped a heart attack many of his arteries were mostly if not completely constricted. Smith's cardiologist decided that the best route to go would be a quintuple bypass. Five healthy arteries were removed from his left leg and connected from his aorta to the damaged arteries. He is doing well and has since replaced chili cheese fries with apples and twelve hour America's Next Top Model marathons with bike rides.

Saturday, March 13, 2010

Artificial Organs

For the thousands of people that suffer from organ failure there may be a new hope on the horizon. Today doctors and and biomedical scientists have developed a way to actually regrow healthy tissue. Researchers at the Wake Forest Institute for Regenerative Medicine have successfully grown hearts, kidneys, parts of fingers, and ears. However the most successful organ to be generated artificially has been the bladder. Every organ has its own special stem cells specifically unique to that body part. When scientists are able to isolate the cells, the cells begin to multiply. Meanwhile, the scientists create an exact mold of the bladder. Once the scientists have grown a sufficient number of bladder cells from the stem cells they begin to layer the cells onto the mold. The mold dissolves over time as the cells continue to grow. One amazing thing about artificial organs is that because they are made from the patients own cells there is much less of a change that they body will reject the organ. Rejection can often be a major problem with transplant that often requires drugs that take a harsh toll on the body. There is a special "pixie dust" found in pigs bladders called ecm or extracellular matrix that when placed that encourage grow of healthy tissues. It has been used to regrew muscle and to ensure the sucess of hands transplants.
People die every single day waiting for an organ and this could potentially give them an organ mere weeks that they discover that they need the new organ. The biggest problem with regenerative medicine is that there is still a huge question mark next to it. There are so many trials to be done and the bladder has really been the only successful human transplant of an artificial organ. Scientists still worry about how to control growth of the new tissues within the body etc, and many still question man's right to "play god". However, in the case of regenerative medicine, the promise seems to far outweigh the problems.

Tuesday, March 2, 2010

Stem Cells

Embryonic stem cells are stem cells derived from embryos. Stem cells are usually extracted during the blastocyst stage of development. In essence, a blasotcyst is a hollow ball of cells. The out most part of the blastocyst, called the trophoblast, will eventually become the placenta. A cluster of cells inside the trophoblast, called the inner cell mass, is composed of the stem cells or the cells that will eventually become the fetus. Embryonic stem cells are undifferentiated cells that have the potential to become any cell needed in the body. In this undifferentiated state they can multiply and self renew almost indefinitely. In a lab setting, the trophoblast would be destroyed and the stem cells would placed in in small groups into petri dishes. Scientists are still trying to perfect ways of differentiating these cells, but growth factors like sonic hedgehog and activin are sometimes used to instruct the stem cells on what specific cells to differentiate into. One problem with embryonic stem cell research is that it has caused quite a moral debate. Many feel that even though embryonic stem cells have the potential to save lives, it is not humane to destroy a life to do so. However a Japanese doctor, Shinya Yamanaka, seems to have found a solution. He is able to take adult skin cells and insert four genes that reprogram the skin cells into embryonic stem cells. These cell are called IPS or induced pluripotent stem cells. Though there are still a few kinks to be worked out these cells present great promise. Another less controversial alternative to embryonic stem cells are adult stem cells. Adult stem cells are found in certain organs and tissues in the body. The cells can differentiate themselves into most parts of that particular organ or tissue. These cells however do not divide nearly as readily as embryonic stem cells.

Doctors and scientists have devised many different ways of using stem cells to treat various diseases. For instance, stem cells in bone marrow transplants help the body to produce blood and immune cells which is very helpful for people with diseases like leukemia. Stem cells taken from a patient's umbilical cord can also be used in bone marrow transplants. Scientists have also grown stem cells found in the hair follicles that can help grow skin grafts for burn victims. In horses, cells are also used to promote growth and healing in injured muscles or ligaments. The hope is that in humans stem cells can be used to regrow areas of the brain that have been damaged by degenerative neural disorders, to help patients with sickle cell anemia grow healthy blood cells, and help diabetics grows blood cells that produce more insulin.

Saturday, February 20, 2010

The developing organism

After spermocytes enter the female they are not able to fertilize the ovary right away. They must first go through a period of capacitation where uterine substances dissolve the outer proteins of the sperm cell. Then an acrosomal reaction occurs where acrosomal vesicle content is released that help the sperm to digest the membrane around the oocyte so the sperm can fuse with the oocyte. Once one sperm enters the egg cell, the membrane undergoes a process known as a cortical reaction where the membrane no longer allows any other sperm to enter. After this process, the fertilized egg or zygote undergoes cleavage where the it rapidly goes through a series of mitotic divisions where the cells get increasingly smaller. It soon becomes a ball of these smaller cells known as a morula. However the pressure of the cells on each other turns the morula into a hollow ball of cells called a blastula the cavity of which is called a blastocoel. Following the development of the blastula, cells begin to migrate into a hole in the blastula known as the blastopore. The blastula almost folds in on itself. This new folded ball of cells is called the gastrula. It contains a new cavity called the archenteron. The gastrula is composed of three layers of cells: the endoderm or the inner layer, the mesoderm or the middle layer that is composed of the migrated cells, and the ectoderm or the outer layer of cells. The three layers soon undergo organogenesis or the development of organs. The ectoderm becomes the skin, the outer layer of the eyes, and the nerves. The mesoderm becomes the organs, muscles, and skeleton. The endoderm becomes the inner lining of these organs.