Rabu, 31 Juli 2013

Summary about Circulatory System at English text, in Biologi/ Ringkasan tentang Sistem Peredaran Darah pada teks bahasa Inggris, di Biologi

Summary about Circulatory System at English text, in Biologi

(Source: Maharani.2011. Circulation System. Ponorogo: Junior High School 1 Ponorogo.)

Circulation system, cir-from Greek word circe meaning “circle”. All the cells of our bodies need oxygen, food, and other nutrients. Cells also produce waste products that need to be removed. How do substances get to and from cells? All these substances are transported by the blood in the circulatory system. The circulatory system is the system that contains the heart and blood vessels and transports blood throughout the body. The circulation system consist of 3 Major Parts there are:

Ø  Blood vessels; routes blood travels.

Ø  Heart; pumps or pushes blood through body

Ø  Blood: carries important “stuff” through body (stuff-includes oxygen, food, and waste).

I) Blood Vessels

Your body resembles a large roadmap, there are routes or “arteries” that take you downtown to the “heart” of the city. Blood travels to and from the heart in vessels. The vessels of the circulatory system are like the roads of a city. A city has large interstates, smaller highways, and even smaller neighborhood streets. Similarly,  the circulatory system has large blood vessels that are connected to smaller vessels. Arteries are vessels that cary blood away from the heart to organs in the body. Arteries branch into smaller vessels, and then even smaller vessels called capillaries. Capillaries are the blood vessels that deliver oxygen and nutrients to the organs. Jus as oxygenated blood flows away from the heart, deoxygenated blood carrying carbon dioxide must return to the heart. The capillaries take up carbon dioxide and other wastes before joining with large vessels that carry the blood on its return path. These vessels connect to larger vessles called veins that carry blood to the heart.

2) Heart

The heart is the organ of the circulatory system that pumps blood. It is hollow, muscular, about the size of your fist, and located in the middle of the chest between the lungs. How the heart is divided into four chambers. The two upper chambers of the heart that receive blood area called atria (singular, atrium). The ventricles area the two lower chambers that pump blood out of the heart. Deoxygenated blood enters the right atrium of the heart. The heart pumps this blood through the righ ventricle and into the lungs. Then the blood flows back to the left atrium of the heart where it is pumped through of left ventricle and to the body.

Heart Facts

Ø  Hold out your hand and make a fist. If you’re a kid, your heart is about the same size as your fist, and if you’re an adult. It’s about the same size two fists.

Ø  Your heart beats about 100,000 times in one day and about 35 million times in a year. During an average lifetime, the human heart will beat more than 2,5 billion times.

Ø  Give a tennis ball a good, hard squeeze. You’re using about the same amout of force your heart uses to pump blood out to the body. Even at rest, the muscles of the heart work hard—twice as hard as the leg muscles of a person sprinting.

3)Blood
If you have seen your body, you know that it is a dark red liquid. Blood is a tissue that contains many different substances-even cells. Blood is about 55 percent plasma, which is 90 percent water. The remaining 10 percent is composed of ions, proteins, and other substances of body produces or requires.

I) Plasma

Ø  Liquid part of blod

Ø  Blood is about 55 percent plasma, which is 90 percent water. The remaining 10 percent is composed of ions, proteins, and

Ø  Other substances the body produces or requires.

II) Red Blood Cells

Ø  Your body contains about 25 trillions red blood cells
Ø  Red blood cells are normally shaped like a disc that is flattened on both sides.
Ø   Red blood cells have iron-containing proteins called hemoglobin that carry oxygen.

III) Platelets and White Blood Cells

Ø  Platelets are fragments of cells contained in your body. After an injury, proteins in the blood cause platelets to form a plug which stops the bleeding. Without platelets, even a small cut would continue bleeding because a scab would not form.
Ø  White blood cells are part of the immune system, which fights infection. White blood cells figh and kill germs that may enter your bloodstream.

Blood cells
Function
Red blood cells
Transport oxygen, help transport carbon dioxide
White blood cells
Defense and immunity
platelets
Clotting

Problems in the Circulatory System

Problems in the circulatory system prevent oxyven from reaching the cells and can lead to serious health problems and death. Diseases of the heart and blood vessels are called cardiovascular diseases. Cardiovascular disease cause more than half the deaths in the United States. Risk factors for cardiovascular disease include being overweight, eating a diet high in saturated fat and hole sterol, smoking, having high sugar in the blood, being physically inactive, and consuming too much alcohol. Older men are more likely to show symptoms of cardiovascular disease than anyone else. Although test are available to screen for heart disease, it is instead recommended that people who dno not show symptoms, such as heart and stroke, identify and eliminate risk factor in their lives.

1) Heart attack

The arteries that supply the heart muscle with blood and oxygen are the coronary arteries. A heart attack occurs if the coronary arteries cannot supply enough blood to the heart. This happens when the coronary arteries clog. The heart muscle may die and the heart may stop working if the muscle does not receive enough oxygen. Symptoms of a heart attack include chest pain, pain in the arms and back, shortness of breath, and dizziness.

2) Stroke


Without oxygen, brain tissue will die within 4-5 minutes. A stroke is the death of brain tissue. A stroke can happen if a blood vessel to the brain is blocked or if one of these blood vessels breaks. A ruptured blood vessel, or a blocked vessel. Prevents blood flow to the brain. Once brain tissue dies. It is not replaced. A stroke may result in memory loss, loss of muscle control, or other loss of nerve function, depending on where in the brain the stroke occurs, stoke is the third leading cause of death in adults. When the blood vessels in the brain have degenerated enough in one place to have a stroke, the overall condition is usually not healthy.