What I Know About The Human Body

It's been several years since we last studied the human body in science class, however, I can still remember several things about the human body. The body is entirely composed of cells, which have been the basis of study for much of this year and can be read about in depth in many posts of this blog. The outside of the body is covered by many layers of skin cells, which are resistant to water and can heal themselves if damaged. Underneath our skin, we have bones connected by mussels and tendons and cushioned by cartilage. These bones have marrow inside of them, and are made of calcium. Throughout our entire body runs a vital substance called blood. In the blood there are many small cells, included red blood cells, which carry oxygen to the rest of the body, and white blood cells which fight diseases and parasites in the body. The disease-fighting agents are part of the lymphatic system. This system runs a substance called lymph through the entire body, which fights diseases and is filtered in certain places called lymph nodes. Blood can have four major types: O, A, B or AB. These types are determined by the presence or absence of certain antigens. Blood can also be RH positive or RH negative. Blood types are determined by genetics. The red blood cells receive oxygen in the lungs. In the lungs the oxygen diffuses into the cell. The blood is pumped by the heart, which has four chambers. These chambers come in two types, atrium or ventricle. Blood is brought in or out of the heart by veins or arteries. The brain controls the body, is sends signals to various body parts, telling them how to behave and complete their functions. The brain can be damaged in various ways, and yet it can also survive the most extraordinary circumstances. There is the remarkable case of Phineas Gage, who was stabbed in the brain. A metal rod went entirely through his head. His frontal lobe was destroyed, and even though his personality was changed he still lived for a remarkable twelve years before dying from seizures. The brain is a remarkable part of the human body, which is remarkably unknown.

 The brain also controls the system which allows us to feel pain. This is done by nerves, which run throughout our bodies. They send signals to our brain, which make us feel pain. I know that when we eat food it travels down our esophagus into our stomach and through our intestines, where the food is broken down and nutrients are removed. This is the majority of what I know about the human body.

Mendilian Genetics, or, Why I Can't Curl My Tongue

For the past few days in Biology we have been investigating genetic traits. These traits are determined by alleles. You receive one allele from each of your parents. These alleles can carry the genetic code for a dominant or recessive gene. If you receive two dominant alleles or one dominant and one recessive allele, you will express the dominant trait. If you receive two recessive alleles you will express the recessive trait. I tested myself and a variety of my family members for four different traits. These traits were: attached ear lobes, widow's peak, hitchhiker's (bent) thumb, and ability to curl your tongue. My findings are below.

From this chart I was able to create the following three pedigrees:

Pedigree for Attached Earlobes. 

Pedigree for Widow's Peak

Pedigree for Tongue rolling

I was quite surprised that only one member of my family had unattached earlobes, none of my family had widow's peaks, and that neither my cousin, my brother, nor myself was able to roll our tongues while our parents could. I found this odd because unattached earlobes are dominant, widows peaks are dominant, and tongue rollers are dominant. I was unable to create several pedigrees because my grandparents could have been AA and Aa or Aa and Aa. There were several such situations, in which it was impossible to find a result.

Gene Therapy

A diagram explaining Gene Therapy

Imagine the treatment of a cancer patient. It is typically a long string of doctors appointments, surgeries, and medications such as chemotherapy. But what if there was a way to treat cancer with a simple injection? It seems incredible, and yet this is the aim of a new type of medical treatment called gene therapy. Not only would gene therapy treat cancer, but it could also treat cystic fibrosis, familial hypercholesterolemia, HIV/AIDS, gaucher disease, hearing loss, and could allow patients with circulatory problems in the legs to avoid amputation.

So, how would this incredible process work? It would begin on a molecular level. All of the aforementioned diseases and complications are caused by imperfections and mutations of the DNA. These are obviously very hard to treat with medications, and are typically hereditary. They can affect almost any part of the DNA. It is clearly quite hard to change a gene that is written into each and every cell in the human body, and coming up for a cure for these diseases has always been quite daunting. This is where gene therapy comes in. Gene therapy is the use of genes as treatment or prevention for diseases.

Using genes as a treatment? As fantastical as it sounds, this is the reality of gene therapy.  A "normal" gene is put into the genome in place of an "abnormal" gene which causes a disease or disfunction. This is done with several different treatments which fall under two headings: Germ-line gene therapy and somatic gene therapy. Germ-line gene therapy is when genes are introduced into reproductive cells or into embryos, so that the child will not have genetic abnormalities. On the other hand, somatic gene therapy is when therapeutic genes are inserted into cells to replace the current DNA or to make a protein/substance that is not present or not working in the patient. Most current research is developing somatic gene therapy.

Somatic gene therapy usually works via a "vector". The vector delivers the new gene to the patients cells. These vectors are almost always a virus which has had the infectious DNA replaced with the proper gene. These are either a retrovirus (such as HIV, which works well in dividing cells), an Adenovirus (such as the common cold, which works well in non-dividing cells), an Adeno-associated virus (which inserts DNA at a specific singular site on chormosome 19) or Herpes simplex virus (typically causes cold sores). There are new ways of developing gene therapy, including introducing the DNA directly to the cells, creating an artificial lipid with a water-based core which can travel directly through a cell membrane to deliver the gene, chemically linking the DNA to a molecule that attaches to the cell receptors, or even adding a 47th chromosome, which would not affect the cell in any way other than changing the defective gene.

Like any advancement in science, there are some questions and possible complications that come up when discussing gene therapy. If we put aside the omnipresent issue of "playing god", there are still a few problems. The primary problem is the use of viruses. Many scientists and researchers fear that one of the viruses injected into the DNA will go awry. Instead of being completely removed, the original virus would still retain its own DNA and begin infecting people. Although this is a justified concern, I believe that the benefits far outweigh the risks. If the makers of the injections are thorough in their testing, the company can have a product that is both safe and infinitely helpful to the modern world.

Check out this game about gene therapy!

http://ghr.nlm.nih.gov/handbook/therapy/genetherapy

http://www.ornl.gov/sci/techresources/Human_Genome/medicine/genetherapy.shtml

http://www.encyclopedia.com/topic/gene_therapy.aspx

http://autocww.colorado.edu/~toldy2/E64ContentFiles/VirusesMoneransAndProtists/RetrovirusB1.html

A gene that can cure cancer and diabetes?

When you think of a cure for cancer and diabetes, what comes to mind? Probably scientists, hard at work in a lab. But surely not a group of Ecuadorians who are all under three and a half feet tall. According to this article, scientists have discovered a that these people are immune not only to cancer, but also to diabetes. This is because they have a disease known as Laron syndrome, and it may be the key to finding a cure for two very deadly diseases. 


The cause of this syndrome is directly tied to the cell cycle. It turns out that Laron syndrome is caused by a specific mutation of a gene which is a receptor for Human Growth Hormone. This gene is known as IGF-1, and if a person has Laron syndrome they have very little IGF-1. Therefore, the Human Growth Hormone is not accepted by the cells, and the person does not grow. This ties into the ideas of proto-oncogenes and tumor suppressors. Certain parts of the cell, called proto-oncogenes, tell the cell when to go through the cell cycle and split apart. If there are no proto-oncogenes, as with Laron syndrome, the cell will not split. 


This is a remarkable progression in the war against cancer and other deadly diseases. If scientists can find a way to change the ways our genes deal with the Human Growth Hormone to cure cancer without harming us in any other way, it would be truly remarkable. However, I highly doubt this could happen. It is always dangerous to mutate a person's genes, and without proper checks this could create even larger problems than cancer itself. Nevertheless, it seems that the secret to curing cancer could really have been hiding in a small village of Ecuador. 




Sources:
http://www.nytimes.com/2011/02/17/science/17longevity.html?_r=1

Lymphoma: HL and NHL (no, not that NHL)

For a human being to function well, it is imperative that they remain healthy. This is the role of the immune system: to keep a body functioning smoothly.  One key component of the immune system is the lymphatic system. The lymphatic system is made up of vessels that carry a substance called lymph. They lymph is cycled around the body, and remove bacteria, viruses, and rouge cells. It travels trough various areas that contain lymphatic tissue such as: the tonsils, the thymis gland, the spleen, and the bone marrow. It also travels through many small pockets of lymph tissue around the body called "lymph nodes". The purpose of the lymph nodes is to filter the lymph, which has picked up large amounts of foreign substances in the body. This is all very well and good, as long as the system works. It can be interrupted by several factors, some as  simple as infections, which make the lymph nodes swell up. One of the most serious disturbances to the lymphatic system is a type of cancer called lymphoma.  It is the seventh most common cancer in adults and the third most common cancer in children.

Lymphoma affects the lymphocytes found in the lymph. These lymphocytes identify any foreign cells, bacteria, viruses, and mutated cells. There are two different types of lymphocytes: B cells and T cells. B lymphocytes create antibodies which alert other cells, such as white blood cells, to the presence of pathogens so that the pathogens can be destroyed. T cells can kill pathogens without any outside help, and also assist in regulating the immune system. Once they have encountered a pathogen initially they will recognize it upon any further encounters. This is a key component in the way vaccines work. When a vaccine is injected into a person, the lymphocytes recognize the strain of the bacteria or virus and will attack it in the future.

A lymphoma occurs when either the B or T cells grow and multiply rapidly. The cells will continue to multiply, forming a large mass called a tumor. This tumor prevents the areas around it from having enough resources to function normally. Lymphomas are also able to metastasize and spread across the body very rapidly via the channels that make up the lymphatic system. Lymphomas are separated into two different categories: Hodgkin's Lymphoma (referred to as HL) and non-Hodgkin's Lymphoma (referred to as NHL). As of 2010, 628,415 people had lymphoma or were in remission. 153535 of these cases were HL and 474880 were NHL. 


The first known example of Hodgkins.  lymphoma was found in 1666, by Malpighi. In his paper De viscerum structuru exercitatio anatomica, he describes the disease that would later be referred to as "Hodgkin's lymphoma" or "Hodgkin's disease". Almost 200 years later, in 1832, Hodgkin publishes his own paper on the lymphoma, and thus the affliction was named after him. Research into "Hodgkin's disease" continued for many years afterwards, and in 1898 Cal Sternberg, a German researcher, discovers the Reed-Sternberg cells present in Hodgkin's lymphoma. Four years later, in 1902, Dorothy Reed, working at the Johns Hopkins Hopital in the United States, discovered the Reed-Sternberg cell on his own. From that point on scientists devoted time and energy into finding a cure of this disease

An image of a lymphoma

Hodgkin's lymphoma is given a separate classification because it occurs from one specific abnormality in the B cells alone. The tumors also contain Reed-Sternberg cells, named for the scientists who initially discovered the cell. Hodgkin's lymphoma will typically start in the area around the neck. It will then spread downward through the nodes to the rest of the body. If the cancer manages to spread below a person's diaphragm it will infect the spleen and therefore infect both the liver and the bone marrow. The cancer will also begin in the chest occasionally. From there it will spread to the areas around the heart and the lungs. There are five different types of Hodgkin's Lymphoma: Nodular Sclerosing Hodgkin Lymphoma (NSHL), Mixed Cellularity Hodgkin Lymphoma (MCHL), Lympocyte Depleted Hodgkin Lymphoma (LDHL), Lymphocyte-rich Classic Hodgkin Lymphoma (LRCHL), and Nodular Lymphocyte Predominant Hodgkin Lymphoma (NLPHL). There are four different stages of HL. Stage I is the infection of one singular lymph node region. Stage II affects two lymph node areas on the same side of the diaphragm (either waist up or waist down). Stage III has lymph nodes affected on both sides of the diaphragm (both waist up and waist down). Stage IV indicates that the cancer has spread outside of the lymph nodes. The cause of Hodgkin's lymphoma is currently unknown, but there are many risk factors that can lead the the development of a tumor. Primarily, it is believed that immune suppressive diseases increase a person's risk of developing the disease. These include: having had mononucleosis as a young adult, having suffered from human T-cell lymphoctyotropic virus (a virus that affects the lymphatic system, also called HTLV), having contracted HIV, being infected with Hepatitis B or C, having herediaty diseases that affect the immune system (severe combined immunodefience, ataxia telangiectasia), having received immune suppressive therapy, exposure to toxic chemicals, or having a family history of lymphoma. 


Non-Hodkgin lymphoma was first differentated from Hodgkin's lymphoma by Henry Rappaport in the years 1956 tp 1966, which led to the Rappaport classification, the first classification of Non-Hodgkin lymphoma. The classification "Non-Hodgkin's lymphoma" refers to any type of lymphoma without the Reed-Sternberg cells, which can affect both the B cells and the T cells and has a variety of genetic markers. There is a one in fifty chance that a person will develop non-Hodgkin's lymphoma at some point in their life, although the affliction is more common in men. There are thirty different types of non-Hodgkin's lymphoma, which fall into three different classifications. These are classifications are Indolent (slow-growing, low grade), Moderately aggressive (intermediate grade), and aggressive (high grade). These are differentiated by how quickly the cancers are spreading, with low grade as the slowest spreading and high grade as the fastest spreading. As with HL, the cause of NHL is unknown. However, scientists and researchers have linked the disease to "immune suppression". Immune suppression is when a person has had a disease which has impacted their immune system to a point at which it does not function properly. Some examples of these diseases would be HIV, HTLV, Hepatitis B or C, hereditary diseases that affect the immune system (severe combined immunodeficience, and ataxia telaniectasia) and mononucleoisis. Additionally, having contact the bacterium Heliobacter pylori can also increase the likelihood of developing a lymphoma (and has also been linked to stomach cancer). An interesting factor that can increase the chance of a person having a lymphoma is living in a faming community. Doctors believe that the use of pesticides and herbicides may be the reason, because they contain certain chemicals. These chemicals may also be found in black hair dye, the use of which has been linked to NHL. As with HL, a family history of lymphoma is also a factor. 


Both HL and NHL have very similar symptoms. The most common of these are: swelling of the lymph nodes, fever, unexplained weight loss, sweating, chills, lack of energy, itching, rashes, lower back pain, and sore lymph nodes after drinking alcohol. Unfortunately, the symptoms vary greatly between cases, and are often misdiagnosed as the common cold or the flu.


There are three different treatments used on both HL and NHL. These are radiation therapy, chemo therapy, and biological therapy (or immunotherapy). Radiation therapy employs high-energy rays (radiation) to kill the cancerous cells. This is used on specific areas of the body, rather than the entire body. Chemotherapy uses powerful drugs to kill cancer cells. These are administered intravenously, then circulate trough the bloodstream impacting the entire body. Biological therapy is a relatively new type of therapy, which essentially trains the body to remove the cancerous cells on its own. There are three different types of biological therapy used to treat cancers. The first us Monoclonal anitbodies. A monoclonal antibody is an anibody that is made in a lab instead of in the body. They are designed to attack a certain pathogen. They are used by the immune system to kill tumor cells and or can bring raditation or chemotherapy directly to an “antigen”. The second is Cytokines. They are naturally in the human body, but can also be created in a lab. They are then brought into the body to assist in the finding of cancers. The third is a cancer vaccine. These vaccines do not prevent a cancer from developing, instead they allow the immune system to recognize cancerous cells and destroy them. After Hodgkin's Lympoma has been treated, patients typically make a strong recovery. Similarly, 30-60% of patients with aggressive non-Hodgkin's Lymphoma can be cured. However, there is currently no cure for indolent NHL, although patients typically live up to twenty years after the cancer has been diagnosed. Even after being treated, people who have had HL can have complications such as infertility, liver failure, lung problems, and the development of other cancers. People who have had NHL and are in remission can become Autoimmune hemolytic anemic and develop other infections. 


In conclusion, there are a wide variety of lymphomas. They can be fatal if ignored, and are often mistaken for the common cold. However, when they are found they are usually treatable,  and if we continue to focus our efforts on innovative treatments, such as immunotherapy, this cancer could be cured. 


Sources:
http://www.emedicinehealth.com/lymphoma/article_em.htm

http://www.lymphoma.org/site/pp.asp?c=bkLTKaOQLmK8E&b=6299689

http://www.cancer.gov/cancertopics/treatment/biologicaltherapy

http://www.lls.org/all_page?item_id=7030

http://www.lymphomainfo.net/lymphoma/symptoms.html

http://health.nytimes.com/health/guides/disease/hodgkins-lymphoma/overview.html?scp=1&sq=lymphoma&st=cse

http://health.nytimes.com/health/guides/disease/hodgkins-lymphoma/in-depth-report.html

http://health.nytimes.com/health/guides/disease/non-hodgkins-lymphoma/overview.html

http://lymphoma.about.com/od/hodgkinlymphoma/p/hodgkintypes.htm

http://www.oncologychannel.com/nonhodgkins/types.shtml

http://www.lymphomainfo.net/hodgkins/timeline.html

http://www.news-medical.net/health/Non-Hodgkin-Lymphoma-History.aspx

Photosynthesis

It's a well known fact that plants need water and sunlight to make food, but how is that possible? Essentially, plants create their own food through a process called photosynthesis. Photosynthesis is made up of two different processes called the light dependent reaction (also called the light reaction) and the light independent reaction (also called the dark reaction or the Calvin cycle). Both of these reactions take place in the chloroplast (shown at the left). The light reactions specifically take place in the thylakoid. Inside each thylakoid there is a system very similar to the electron transport system. This reaction is shown in the image below labeled "Light dependent reaction". This reaction begins with energy from the sun. The plant can use this energy because they have several pigments, one of which is chlorophyll. These pigments allow the plant to absorb the sun's energy. One photon of energy enters into photosystem two (PSII) and bounces off of the walls of photosystem two. The photon then reaches the reaction center at the base of the photosystem. There, a water molecule (H2O) has broken apart into H+ and O2. When the water is broken apart, an electron is released. The photon excites the electron, giving is energy. This electron travels up to the top of photosystem two. It then descends across the system and enters photosystem one (PSI). As is descends it pumps one H+ ion from the stroma into the thylakoid lumen (the area inside the thylakoid). Once the electron is inside photosystem one, it travels upward until is reaches the electron carrier. There, it reduces NADP+ to NADPH. As this process repeats, a high concentration of H+ ions is build up in the lumen. These ions then travel through the ATP synthase one by one. As they move through, they physically rotate the synthase. This creates energy, and the energy converts ADP and P to ATP. 

As a review, the inputs of the light dependent reaction are as follows:

1 H2O

Light

and the outputs are:

1 O2 (final product)

2 ATP (used in the Calvin Cycle)

1 NADPH (used in the Calvin Cycle)

Light dependent reaction

The next component of photosynthesis is the Calvin Cycle. The calvin cycle creates G3P, or PGAL, which the plant uses to make glucose. It takes three molecules of CO2 to create one molecule of PGAL, therefore this explanation will be describing the cycle in terms of three molecules of CO2. The Calvin Cycle begins with CO2, in this instance three molecules. These molecules of CO2 combine with three molecules of RuBP to form a six carbon molecule. The enzyme rubisco assists in this joining. This is a brief transition phase, and soon these molecules split into three carbon molecules, for a total of six three carbon molecules. These molecules must be rearranged and gain phosphates. Therefore, six ATP oxidize to form ADP and six NADPH oxidize to form six NADP+ and phosphate. Next, the three carbon molecules each lose a carbon. These carbons form a PGAL, and the unused substances are rearranged. The rearranging takes energy, and three ATP oxidize to become 3 ADP. The result is three Rubisco and the cycle continues. When two PGALs are created, they combine to form glucose.

As an overview, the inputs of the Calvin cycle (when one pyruvate is created) are:
3 CO2
9 ATP
6 NADPH

And the outputs are:

9 ADP
6 NADP+
6 P
1 Pyruvate

The equation for photosynthesis is: 6CO2 + 6H2O -> C6H12O6 + 6CO2


This autotrophic system of plants is amazing. Plants take in CO2 and water, two substances that are abundant on our planet, and they convert them to food and oxygen. This phenomenon is present every plant, and even some species of bacteria. It is an essential factor to maintaining the delicate balance of life on Earth. Although we have not yet studied this in class, I believe that the amount of light will assist in photosynthesis and the amount of water. Light would increase the amount of photosynthesis because light is used to excite the electron in the light reaction and water would assist because if there is a lack of water a light reaction cannot occur and therefore there will be no energy to use in the dark reaction.


Sources:

http://en.wikipedia.org/wiki/Photosynthesis

Images:

http://dft.ba/-anQ

http://micro.magnet.fsu.edu/primer/java/photosynthesis/

http://www.daviddarling.info/images/Calvin_cycle.jpg

Cellular Respiration Video

Here is a video that Megan, Peter, and I made. It explains the process of cellular respiration using both claymation and video clips. Enjoy!