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The Human Heart

Your heart is a muscular organ that pumps blood to your body. Your heart is at the center of your circulatory system. This system consists of a network of blood vessels, such as arteries, veins, and capillaries. These blood vessels carry blood to and from all areas of your body.

An electrical system controls your heart and uses electrical signals to contract the heart's walls. When the walls contract, blood is pumped into your circulatory system. Your heart is vital to your health and nearly everything that goes on in your body. Without the heart's pumping action, blood can't move throughout your body.

Your blood carries the oxygen and nutrients that your organs need to work well. Blood also carries carbon dioxide (a waste product) to your lungs so you can breathe it out.

A healthy heart supplies your body with the right amount of blood at the rate needed to work well. If disease or injury weakens your heart, your body's organs won't receive enough blood to work normally.

The heart is one of the most important organs in the entire human body. It is really nothing more than a pump, composed of muscle which pumps blood throughout the body, beating approximately 72 times per minute of our lives. The heart pumps the blood, which carries all the vital materials which help our bodies function and removes the waste products that we do not need. For example, the brain requires oxygen and glucose, which, if not received continuously, will cause it to loose consciousness.

The heart is essentially a muscle(a little larger than the fist). Like any other muscle in the human body, it contracts and expands. Unlike skeletal muscles, however, the heart works on the "All -or-Nothing Law". That is, each time the heart contracts it does so with all its force. In skeletal muscles, the principle of "gradation" is present. The pumping of the heart is called the Cardiac Cycle, which occurs about 72 times per minute. This means that each cycle lasts about eight-tenths of a second. During this cycle the entire heart actually rests for about four-tenths of a second.

The walls of the heart are made up of three layers, while the cavity is divided into four parts. There are two upper chambers, called the right and left atria, and two lower chambers, called the right and left ventricles. The Right Atrium, as it is called, receives blood from the upper and lower body through the superior vena cava and the inferior vena cava, respectively, and from the heart muscle itself through the coronary sinus. The right atrium is the larger of the two atria, having very thin walls. The right atrium opens into the right ventricle through the right atrioventicular valve(tricuspid), which only allows the blood to flow from the atria into the ventricle, but not in the reverse direction. The right ventricle pumps the blood to the lungs to be reoxygenated. The left atrium receives blood from the lungs via the four pulmonary veins. It is smaller than the right atrium, but has thicker walls. The valve between the left atrium and the left ventricle, the left atrioventicular valve(bicuspid), is smaller than the tricuspid. It opens into the left ventricle and again is a one way valve. The left ventricle pumps the blood throughout the body. It is the Aorta, the largest artery in the body, which originates from the left ventricle.

The Heart works as a pump moving blood around in our bodies to nourish every cell. Used blood, that is blood that has already been to the cells and has given up its nutrients to them, is drawn from the body by the right half of the heart, and then sent to the lungs to be reoxygenated. Blood that has been reoxygenated by the lungs is drawn into the left side of the heart and then pumped into the blood stream. It is the atria that draw the blood from the lungs and body, and the ventricles that pump it to the lungs and body. The output of each ventricle per beat is about 70 ml, or about 2 tablespoons. In a trained athlete this amount is about double. With the average heart rate of 72 beats per minute the heart will pump about 5 litres per ventricle, or about 10 litres total per minute. This is called the cardiac output. In a trained athlete the total cardiac output is about 20 litres. If we multiply the normal, non-athlete output by the average age of 70 years, we see that the cardiac output of the average human heart over a life time would be about 1 million litres, or about 250,000 gallons(US).

Causes

Most heart attacks are caused by a blood clot that blocks one of the coronary arteries. The coronary arteries bring blood and oxygen to the heart. If the blood flow is blocked, the heart is starved of oxygen and heart cells die. A plaque can build up in the walls of your coronary arteries. This plaque is made up of cholesterol and other cells. A heart attack can occur as a result of plaque buildup. The plaque can develop cracks or tears. Blood platelets stick to these tears and form a blood clot. A heart attack can occur if this blood clot completely blocks oxygen-rich blood from flowing to the heart. This is the most common cause of heart attacks. The slow buildup of plaque may almost block one of your coronary arteries. A heart attack may occur if not enough oxygen-rich blood can flow through this blockage. This is more likely to happen when your body is stressed (for example, by a serious illness). The cause of heart attacks is not always known.

Heart attacks may occur:

 When you are resting or asleep

When you are active outside in cold weather

After sudden, severe emotional or physical stress, including an illness

Symptoms

The pain can be severe or mild. It can feel like:

A tight band around the chest

Bad indigestion

Something heavy sitting on your chest

Squeezing or heavy pressure

The pain usually lasts longer than 20 minutes. Rest and a medicine called nitroglycerin may not completely relieve the pain of a heart attack. Symptoms may also go away and come back.

Other symptoms of a heart attack include:

 Anxiety

Cough

Fainting

Light-headedness, dizziness

Nausea or vomiting

Shortness of breath

Sweating

Some people (the elderly, people with diabetes, and women) may have little or no chest pain. Or, they may have unusual symptoms (shortness of breath, fatigue, and weakness). A "silent heart attack" is a heart attack with no symptoms.

Citations:

http://www.webmd.com/heart-disease/guide/heart-disease-symptoms

http://www.medicalnewstoday.com/articles/151444.php

• Doing/ being what you want.
• to make any choice.
• Ability to do, have, be with out consequences.
• A right that everyone should have.
• Pursuing goals.
• expressing yourself with out being judged.
• Form of rebellion.
  
• A type in Liberation.
  

One thing that I can say that I truly understand is you have to go through a struggle in order to succeed. In March, we were assigned to read a book by a Haitian author named Edwidge Danticat. The book was called Create Dangerously. This book was a collection of essays about her life and Haitian issues. There was one essay in particular that really grasped my opinion. This essay was called “I Speak Out.” It was about another Haitian lady named Alérte Bélance that was mutilated by the Macout (the Haitian army), but surprisingly survived. People found her story so interesting that they flew her to the United States so she was able to share her story to other people. In my forum post responding to this I wrote “While reading “Speak Out” I was appalled by the actual reality of the things that were taking place in Haiti.” You can view my forum at this link.

In Mr. Block’s class we also did a very interesting project with garage band. We had to do a podcast interviewing someone about the boundaries they had crossed in their life. I interviewed my uncle who is a recovering addict. He has had a rough past with crack cocaine. He was on crack cocaine for about 22 years of his whole life and miraculously is clean today and has been clean for more that four years. During the podcast I expressed that this addiction has had negatively and positively affected his life. In the podcast I said, “Using crack cocaine was definitely his valley. Laughter family, and crossing the boundary of not using drugs was his peak.” You can view my podcast at this link.

Throughout the school year, I have learned that art can be interpreted in many ways; you just have to be creative enough to understand it. As the end of the school year was approaching, Mr. Block introduced us to a new unit in English class. He introduced us to the poetry unit. As soon as I heard poetry I started to have a sissy fit because I always thought that my mind was not physically able to think like a poet. My exact words in one of my English journal entries were, “I am not no Maya Angelou.”  I was definitely not looking forward to the couple of weeks we were going to be in this unit. However, when I started to write my first poem “My Baby Love” I was surprised that I could be as creative as I appeared to be. When I wrote my introduction to my wiki space account, I wrote something that reflected my whole experience in the beginning. I said, “I stepped into this whole poetry unit blinded by the complexity I thought poetry had.” You can view my poetry page at this link.

 I was assigned a book to read in about February called Passing by Nella Larsen. This book was about an African American woman named Clare Kendry who is passing for a white woman back in the 1960s. She is living a dangerous life because her husband who she has many ties to doesn’t know she is African American. By the end of the book, Clare ends up falling out of a window and there was a mystery to how she fell out. Mr. Block assigned us to create an artistic project about the book. My friend and I decided to work together on this project and decided to do an iMovie. In my forum post about the project described my entire process while doing the project. I said in my forum post, “We did two skits on our interpretation of how it would look on the news when Clare died.” This is the link to see my video

 This year has definitely been a great one. I don’t regret anything I have done this school year because all of the mistakes I have made I have learned from them. I am so very grateful to have had a teacher like Mr. Block for History and English class. This school year would not have been the same without him. I hope the rest of my years in high school will be as self learning as this year was.