Amazing Eyes

 

http://www.google.com/search?hl=en&q=major+eye+structures&biw=1020&bih=580&bav=on.2,or.r_gc.r_pw.&wrapid=tlif130636625289010&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi

The major eye structures include:

Cornea is a clear, thin tissue that covers the surface of the eye. It is extremely sensitive and contains numerous nerve cells.

Lens of the eye allow the refraction of light to occur. These clear tissues are usually bent, so that when the rays of light can be focused to one specific point on the retina.

Retina is a tissue found towards the back of the eye that is layered with multiple sensory tissues. Millions of photoreceptors that are found in the retina capture light rays and convert them into electrical impulses.

Optic nerve is a pathway for the electrical impulses to travel through to the brain from the retina. The electrical impulses by the rays of light are sent to the brain through the optic nerve and are portrayed by the brain as images.  

Lasik surgery begins with the removal of the top layer of the cornea. Afterwards, the doctor uses laser to steepen or flatten the tissue of the eyes. This process in done in order to make sure that the eye is adjusted so that the lenses of the eye bend to focus on a point on the retina. After reforming the eye tissue, the removed layer of cornea is placed back to heal by itself.

Usually, when a person has a 20/20 vision, the refraction of the light through the lenses is focused exactly on the retina of his/her eyes. However, the refractive defect causes nearsightedness, or farsightedness to occur.  Myopia is when the refraction of the light does not quite reach the retina of the eye. Because of this, one cannot see distant objects clearly. On the other hand, hyperopia is the exact opposite of myopia. When a person has a refractive defect of hyperopia, the refraction of the light focuses on a point far beyond the retina. Therefore, he/she cannot see close objects clearly.   

Sleep

Neurotransmitters are chemicals that signal the nerves in the brain in order to control our sleeping cycle. It acts on many different groups of nerve cells, or neurons in the brain. For an example, the neurons located near the brainstem produce neurotransmitters such as serotonin and norepinephrine. These neurotransmitters function to keep the brain active.

Circadian clock is also known as biological clock. It describes the physical, mental and behavioral changes that follow a daily (24-hour) cycle, responding primarily to light and darkness in the environment. Hence, our bodies are prone to feel tiredness without sunlight.

REM, also known as the Rapid Eye Movement, is a stage in our sleep cycle when our eyes move around. Although uncertain, there are many theories that conclude that the movements in the eyes are initiated by different phases of dreaming. REM can further be broken down to tonic and phasic. During this phase, REM sleep-on cells are active, and its activity might be an explanation to why such movements occur in the eyes. The researchers found activity in areas of the brain that control sight, hearing, smell, touch, arousal, sleep-wake transitions, balance and body movement, but some parts of the brain were completely shut down. Although some neurons are very active during this phase, some neurotransmitters, such as norepinephrine, serotonin, and histamine, stop functioning during REM.

nREM, also known as non-Rapid Eye Movement, is found to be a dreamless sleep. 80% of the sleep consists of nREM. This phase is when the breathing and the heart rate of the sleeper is slow and regular. The blood pressure is low, and the sleeper is relatively still.

Insomnia is a sleep disorder when the sleeper has trouble falling asleep. It can be caused by many different causes, but some of the main factors that trigger such disorder are alcohol, coffee, anxiety, and/or stress.

Sleep Apnea is a sleep disorder commonly found in overweight people, or children with enlarged tonsil tissues. This is due to the airway that collapse or is blocked during sleep.  This leads to shallow breathing, breathing pauses, snoring, or even gasping in the middle of the sleep. When the airway is blocked, the oxygen flow rapidly decreases. The body signals the brain to stop sleep, which leads to the sleeper to wake up in the middle of the night, gasping for more air.

Restless leg syndrome is caused by the disturbance in sleep due to a sudden urge/ need to move one’s legs. The sleeper feels uncomfortable creeping, crawling, aching, pulling, searing, tingling, bubbling, or crawling sensation that can only be relieved by moving his/her legs. Although it can be considered very minor, it can be very uncomfortable for the sleeper and impact one’s sleep cycle by disrupting the sleep pattern.  

Narcolepsy is caused by reduced amounts of a protein called hypocretin. The disorder is characterized by the numerous sleep attacks throughout the day, and/or excessive sleepiness. Some of the symptoms of this disorder include: dream-like hallucinations involving different senses that occur during the stage in between sleep and wakefulness; sleep paralysis that prevents the body from being able to move around as soon as one wakes up; a sudden loss of muscle tone, also known as cataplexy.

Researches have shown that teenagers need at least 8-9 hours of sleep daily. Without sufficient amount of sleep, our bodies tend to become more vulnerable to sickness and stress. Even from personal experiences, I’ve noticed that whenever I got less than 6.5 hours of sleep, I was dysfunctional. The tiredness was overwhelming, and I was incapable of controlling my brain. I’ve noticed that my lack of sleep plus stress guarantees a sick day.

 

Ovarian and Uterine Cycle

Uterine Cycle is more commonly known as the menstrual cycle, which occurs every 4 weeks or so. A woman’s body prepares for pregnancy, but when pregnancy does not occur, blood is released as the woman’s endometrial lining of the uterus sheds. Ovarian Cycle is starts with a development of an oocyte. As it begins to mature, it erupts and travels down the oviduct to the uterus. This cycle is called the ovarian cycle.  GnRH is a hormone that stimulates the brain to produce LH and FSH. LH is also known as the luteinizing hormone, and FSH is also known as the follicle stimulating hormone. These two hormones help control how the body produces a specific sex hormone, called Estrogen. Estrogen is a type of hormone found in women, as well as in men. However, it has a stronger role in women’s bodies as it is the main sex hormone and is vital to the menstrual cycle.  It is known to regulate the menstrual cycle and enriches and thickens the endometrium, ultimately preparing the uterus for pregnancy. Progesterone is a type of hormone that is naturally produced in the ovaries of menstruating women. When a woman is pregnant, this substance is produced by the placenta. Progesterone has numerous roles in a woman’s body. It is often ingested by women in birth control pills, menopausal hormone replacement therapy, or just sometimes to induce a menstrual period or regulate abnormal bleeding problems.hCG comes to play when a blastocyst is embedded in the walls of the uterus. It is during this period when a hormone called hCG comes to play. hCG stands for human chorionic gonadotropin, and is released by the cells around the blastocyst. Its main function is to maintain the corpus luteum in the ovary, preventing the pregnant woman from ovulating.

Positive feedback loops occur when there is an increase in the level of the hormones because of the need of hormones to develop the zygote. Negative Feedback Loops occurs because there is no need for hormones any longer, hence decreasing the GnRH level to limit the release of LH and FSH. An easy way to differentiate between menstruation and pregnancy is the fact that hormone levels are much higher during pregnancy because of the need of hormones to reproduce and develop the fetus.

Fetal Development during the Three Trimesters of Pregnancy:

1^st trimester: Various hormonal changes are taking place in the body. The body begins to prepare itself to nurture the fetus. It is within this period when the baby’s heart starts to beat, and its facial features as well as digestive system are beginning to form.

2^nd trimester: The maximum development of the baby takes place during this period. Most of the major organs are completely formed and start to function in the second trimester of pregnancy.

3^rd trimester: By this time the baby would have fully descended into the pelvis from the abdominal region.

Immune System

The four types of pathogens include Bacteria, viruses, fungi, and parasites.

Macrophage- A type of white blood that absorbs material that our bodies are not accustomed to. Macrophages play a vital role by responding immediately t microorganisms that are possibly infectious.

Antigen- foreign microorganisms that the body is not used to, that stimulates an immune response through activating the body’s infection-fighting white blood cells

T cell- a type of lymphocytes that protect the body through identifying, directly attacking and destroying the infectious substances found in the body. These cells activate the B cells and killer T cells.

B cell- these cells are produced in the bone marrow. They develop into plasma cells that become the source of antibodies.

Antibody- the protein that is produced by the body’s immune system whose function is to detect and respond to antigen.

Killer cell- type of cell that is able to kill off cancerous cells or virus-infected cells.

cytotoxic T cell- The cytotoxic T-cells fit as a sub-category of the t-cells. However, it is distinguished from the other t-cells because of its CD8 receptor. These cells are able to detect antigens on the surface of a virus-infected cell. As soon as it spots an infectious cell, the T-cells bind itself to the infected cell and kill it.

Memory cell- These cells are capable of remembering specific intruders. Therefore, as soon as an intruder tries to invade the body for the second time, B and T memory cells help the immune system to activate much faster. The invaders are wiped out before the infected human feels any symptoms.

We are born with Passive immunity. The mother’s immunity is passed down to the newborn in order to protect the baby from infection. The passive immunity stays as the time needed for the body to develop its own immune response. Another form of immunity that we are born with, is called innate immunity. It protects and prevents all of the external diseases from entering into our bodies. However, the adaptive immunity is the immunity where the memory cells kick in. As our bodies are exposed to various different antigen, our adaptive immunity is continuously built.

Selective IgA Deficiency : Selective IgA Deficiency is the most common of the primary Immunodeficiencies. People with this condition have total absence or severe deficiency of IgA because B-lymphocytes  are unable to mature into IgA-producing plasma cells. IgA deficient people have B cells that are stopped at an immature stage. The IgA class of immunoglobulins has the specific function of protecting the body's mucosal surfaces (eyes, mouth, throat, lungs, gastrointestinal, and genitourinary tract) from infection. Therefore, the lack IgA at these places typically causes infection, allergies, chronic diarrhea, or autoimmune diseases. In autoimmune diseases, the immune system mistakenly attacks the body's own tissues.

Hay Fever: is also known as allergic rhinitis.  The body’s  immune system thinks that the allergen (pollen, mold, dander, etc.) as an "foreign invader" and responds by releasing a chemical called histamine into the bloodstream. This chemical, Histamine,  causes inflammation (swelling and redness) of the sinuses, nose, and mucus membranes of the eyes and triggers sneezing. The swelling reaction is designed to block the allergen from entering the body and sneezing is a method to expel it out of the body. Histamine also allows fluids to enter the nasal tissue, resulting in congestion and an itchy, runny nose.

Aging

Is aging caused by genetics, lifestyle, or both?
As scientific studies have proven, aging is a continuous process that all animals as well as us, humans, have dealt with. 

No matter what their individual lifestyles were, all of the people who were living over their life expectancy, had large amounts of High Density Lipoprotein. When the word ‘cholesterol’ is thrown at us, we think of it as a harmful substance that clogs our arteries and causes all sorts of problems in our bodies. While that may be true to some extent, there are also ‘good cholesterols’ present. The ‘bad cholesterol’ as we know it, is called Low Density Lipoprotein (LDL).  However, the ‘good cholesterols’ help the body by pushing LDL and fatty substances towards the liver, where they are broken down.  

A specific gene that is directly related to the longevity of an organism had not yet been discovered. However, the discovery of sirtuin proteins proved that we weren’t too far from extending the lives of people by a couple of years. Throughout Dr. Sinclair’s experimentations, Sirtuin proteins had a significant role in the longevity of numerous organisms. Sirtuin proved to be the gene that is very closely related to energy utilization, recombination, and control of gene expression, heavily influencing the lifespan of the organism.

Aging is caused by genetics because although it has been proven through animals, scientist haven’t yet discovered a gene in human bodies that allows them to

"Cholesterol"  World Encyclopedia. Philip's, 2008. Oxford Reference Online. Oxford University Press.  Deerfield High School.  31 March  2011  <http://www.oxfordreference.com/views/ENTRY.html?subview=Main&entry=t142.e2396>

Campisi, Judith. "Genetics: Gene Expression." Encyclopedia of Aging. Ed. David J. Ekerdt. Vol. 2. New York: Macmillan Reference USA, 2002. 545-549. Gale Virtual Reference Library. Web. 31 Mar. 2011.

Exercise Physiology

Exercise Physiologist is a health care professional that has completed a degree in exercise physiology, and has been certified by the American Society of Exercise Physiologists. As their occupation, exercise physiologist analyses the improvement and the maintenance of health and fitness. They also oversee the rehabilitation of heart disease and other chronic diseases, and the professionally guide athletes and others in sports training.  The exercise physiologist helps athletes to improve their performance level by guiding them in a specific way fit for the individual sport. Through testing, he/she is able to find the VO2 max, which is the maximum amount of oxygen a person can use in one minute per kilogram of body weight.  The level of lactic acid is determined by taking a sample of the athlete’s blood which shows how much the athlete has pushed his/her body beyond its natural limit, which is called the anaerobic threshold. When an athlete pushes his/her body to maintain and produce energy in a level of exercise that exceed the aerobic capacity, can only be met through anaerobically.

Energy comes in many different pathways, including adenosine triphosphate, CP and glycolysis. Depending on what area the athlete needs attention in, the exercise physiologist can help train the athletes specifically. If an athlete needs attention in short term energy release, the exercise physiologist would focus on exercises that would improve the breaking down and replenishment of ATP and CP, and if an athlete needs to improve on long term exercises, glycolysis would be focused more extensively than other areas.

Depending on what condition the athlete is in, the exercise physiologist can also recommend the athlete to consume a certain percentage of his/her diet in carbohydrates, fats, or proteins. Ideally, 55% of carbohydrates, 30% fats, and 15% proteins should be included in his/her diet.

Heart Surgeries

Name: Mr. Ronny Evans

Age: 58

Weight: 289 lbs.

Family History: Weakened heart conditions caused by high blood cholesterol have been present for three generations.

Symptoms: For a couple of months now, Mr. Evans feels pain and pressure near the chest area, as well as nausea, indigestion, and heart burn occurring more frequently than before. For a healthier lifestyle, Mr. Evans attempted to exercise regularly but was unable to do so due to shortness of breath and fatigue.

History:  Mr. Evans is not married. Without a wife to cook for him at home, he likes to dine at a fast food restaurant. With the new opening of a fast food chain in the vicinity of his office, all of his meals have been in a form of unhealthy food for the last couple of weeks. Although he is fully aware of his family history, Mr. Evans does little to control his consumption of cholesterol. He also likes to snack on chips and cookies throughout his work time. While Mr. Evans does not smoke, he works with heavy smokers.

Test: When Mr. Evans decided to get his heart checked for any irregularities, his EKG found his heart rhythm detrimentally irregular. On top of the irregularities of his heart, he also had a fast heartbeat compared to men his age. He was asked by the doctor to wear a Holter monitor for a couple of days to see the heart’s continuous electrical activity. To see if there were any other abnormalities with his heart, chest X-ray was also taken. The X-ray showed an enlarged mass of the heart.

Mr. Evans was diagnosed with cardiomyopathy because of his heart’s inability to pump blood effectively, which led to changes in his heart muscle. His heart could not produce enough blood to meet the body’s needs. Just like any other muscle, his heart enlarged itself to hold more blood, and started to beat faster to pump out what his body needed.

http://www.google.com/imgres?imgurl=http://drmiri.com/molcardiology/images/stories/dilated_cardiopathy_anatomy.jpg&imgrefurl=http://drmiri.com/molcardiology/defenitions/114-dilated-cardiomyopathy&usg=__9npWBX_6IOe92NKs0K6r1xD_BKs=&h=391&w=547&sz=119&hl=ko&start=0&sig2=ye5JIjxf4TqVB0Aoshs5PA&zoom=1&tbnid=ofjHL5tsfx2DpM:&tbnh=128&tbnw=183&ei=vX-ATcGdOeyP0QG9r5SLCQ&prev=/images%3Fq%3Dcardiomyopathy%26um%3D1%26hl%3Dko%26sa%3DN%26rls%3Dcom.microsoft:ko-KR:IE-SearchBox%26rlz%3D1I7ADSA_ko%26biw%3D1259%26bih%3D843%26tbs%3Disch:10%2C126&um=1&itbs=1&iact=hc&vpx=133&vpy=392&dur=1297&hovh=190&hovw=266&tx=92&ty=113&oei=vX-ATcGdOeyP0QG9r5SLCQ&page=1&ndsp=32&ved=1t:429,r:20,s:0&biw=1259&bih=843

Treatment: In order to relieve his heart muscle from straining work, a surgery was performed through cardiac resynchronization therapy (more commonly known as the pacemaker). The pacemaker was implanted in the upper chest to help Mr. Evans’s heart pump blood more effectively. Because it allows both of the ventricles to pump blood at the same time, the heart can gradually decrease its size and obtain its regular heartbeat.