The Human Heart

The human heart is an amazing organ of the human body. The heart is an organ which pumps life-giving blood throughout the body. It works together with blood and blood vessels to supply all of the needs of the cells.

The heart is located in the middle of the chest and slightly to the left. It is divided into two halves and has two hollow spaces or chambers. The blood enters the atria, which is the upper chamber and is then pumped to the ventricles, two lower chambers. Blood from the ventricles goes to the lungs and to every cell in the body. [A]

An artery is a blood vessel which carries blood away from the heart. A main artery may be as thick as a thumb. Blood is made up of red cells, white cells and platelets floating in a fluid called plasma. Plasma is a liquid and can easily pass through small blood vessels into cells and makes up over one-half of the blood. The plasma carries nutrients (food) from the stomach to be used as fuel for energy. Plasma also helps keep the body warm.

The blood then returns to the heart through blood vessels called veins. The veins on the skin, may look blue, especially on the hands and arms. The walls of a vein are much thinner than those of an artery. Two large veins bring the blood back to the heart. One comes from the brain and the chest. The other comes from the stomach and lower body. [B]

Blood doesn't flow at the same speed through all of the body. As it gets farther away from the heart, it slows down. It goes slowly when the red blood cells carrying the food and oxygen squeezethrough into the cells. [C]

The heart beats or pumps every second of the day or night. It beats or pumps 100,000 times a day, every day of a person's life. Every time a heart beats or pumps out a stream of blood, this beat, called a pulse, can be felt on the inside of the wrist. The pulse rate in an adult is between sixty and one hundred beats per minute. Children's pulse rates range from ninety to one hundred twenty beats per minute. [D]

In summary, the circulatory system which includes the heart, blood vessels and blood, work together to supply the cells with all the food and oxygen a body needs to maintain life. Blood is made up of red cells, white cells and platelets floating in a fluid called plasma. Arteries carry blood away from the heart, and veins carry the blood back to the heart. The heart beats thousands of times a day, every day. It beats much faster in children. The human heart is an amazing organ which is part of a system of many veins, arteries, and vessels which moves blood throughout the body keeping humans alive.

What is the main purpose of the heart?

According to sociologists, there are several different ways in which a person may become recognized as the leader of a social group in the United States. In the family, traditional cultural patterns confer leadership on one or both of the parents. In other cases, such as friendship groups, one or more persons may gradually emerge as leaders, although there is no formal process of selection. In larger groups, leaders are usually chosen formally through election or recruitment.

Although leaders are often thought to be people with unusual personal ability, decades of research have failed to produce consistent evidence that there is any ca gory of “natural leaders”. It seems that there is no set of personal qualities that all leaders have in common; rather, virtually any person may be recognized as a leader if the person has qualities that meet the needs of that particular group.

Furthermore, although it is commonly supposed that social groups have a single leader, research suggests that there are typically two different leadership roles that are held by different individuals. Instrumental leadership is leadership that emphasizes the completion of tasks by a social group. Group members look to instrumental leaders to “get things” done. Expressive leadership, on the other hand, is leadership that emphasizes the collectivewell-being of a social group’s member. Expressive leaders are less concerned with the overall goals of the group than with providing emotional support to group members and attempting to minimize tension and conflict among them. Group members expect expressive leaders to maintain stable relationships within the group and provide support to individual members.

Instrumental leaders are likely to have a rather secondary relationshipto other group members. They give orders and may discipline group members who inhibit attainment of the group’s goals. Expressive leaders cultivate a more personal or primary relationship to others in the group. They offer sympathy when someone experiences difficulties or is subjected to discipline, are quick to lighten a serious moment with humor, and try to resolve issues that threaten to divide the group.

As the differences in these two roles suggest, expressive leaders generally receive more personal affection from group members; instrumental leaders, if they are successful in promoting group goals, may enjoy a more distant respect.

What does the passage mainly discuss?

What is the passage mainly about?

Read the message and choose the best answer.

Antioxidants are substances - artificial or natural - that prevent and slow cell and tissue damage by attacking free radicals, which are molecules that have an unpaired electron. Free radicals are natural byproducts of our metabolism and are also generated in response to environmental stressors, such as exposure to pollution, X-rays or cigarette smoke. In high quantities, free radicals can cause oxidative stress, which is when the body has too many free radicals that start to destroy DNA, fatty tissue and proteins. [A]

Unlike free radicals, antioxidants have extra electrons. This means that they can pass their surplus electrons to free radicals, stabilizing the free radicals so they can no longer damage the body's cells and tissues. In doing so, antioxidants ward off or slow oxidative stress, preventing serious illnesses. Oxidative stress has been linked with illnesses such as cancer, heart disease and some neurodegenerative diseases, including Alzheimer's and Parkinson's disease. The best way to increase antioxidants in the body and maintain a healthy balance of free radicals is to incorporate antioxidant-rich foods into your diet. [B]

The term “antioxidant” is often used to describe different foods, but it more accurately describes chemical property. Any substance that can strip free radicals of their damaging properties is considered an antioxidant. Researchers have discovered hundreds of substances that fit the antioxidant description, and there are perhaps thousands more. Vitamin C and vitamin E are two of the most common antioxidants found in food. In addition to fighting free radicals, vitamin C supports the immune system and helps repair bones, teeth and cartilage. Vitamin E is a powerful tool in maintaining eye health, producing hormones that regulate blood pressure and repairing muscles after exercise. Carotenoids- a class of compounds found in fruits and vegetables that are red, orange and yellow - are also well-known antioxidants.

Antioxidant carotenoids include beta-carotene, lycopene, lutein and zeaxanthin. However, taking high doses of some carotenoid supplements, such as beta-carotene. Can increase health risks, such as an increased chance of lung cancer in smokers. [C]

Antioxidants are most often in fruits, vegetables and legumes, although they can be found in almost every food group. Fruits contains essential nutrients such as potassium, fibre and folate - nutrients that help maintain blood pressure, lower cholesterol and repair body tissues. Blueberries, cranberries, apples, strawberries and more are all filled with antioxidants. Dried fruits - although often high in processed sugars - have a higher antioxidant ratio than fresh fruits, since they lose mass from water. They act as quick antioxidant fuel due to their high concentration of antioxidants. Carotenoids are found in red, orange or yellow vegetables. Many green vegetables such as kale, broccoli and spinach are excellent sources of antioxidants, namely quercetin and lutein. [D]

According to the passage, which of the following is true about free radicals?

A “secondary relationship” mentioned in the last paragraph between a leader and the members of a group could be best characterized as.

How do antioxidants protect the body?

The word "fit" is closest in meaning to________.

According to paragraph 3 what can be inferred about the term “antioxidant”?

According to the passage, which antioxidant is especially good for people who do a lot of physically demanding activities?

The phrase "the wee hours" in paragraph 3 probably refers to the period of time

The word “squeeze” is closest meaning to _______.

The word “collective” in the third paragraph is closest in meaning to.

According to the passage what might HIV/AIDS and COVID-19 have in common?

Which of the following best explains how cilia works with the sense of smell?

Bones support the human body. They are the structure on which the skin hangs. Without bones the body would collapse. A person could not walk or run. Bones provide both support and protection for parts of the body.

In the front of the body the bony rib cage covers the chest. Underneath are the heart and lungs. The ribs are bones which protect the heart, lungs and stomach in case of injury. The skull protects the brain. The bones in the back (or spine) protect the nerves of the spinal column. [A]

The bones store minerals needed by other parts of the body. When the minerals are needed, they will be released into the blood. They also form new red and white blood cells each day. New bone is still made until a person reaches the age of thirty-five. When a person gets much older, the bones start to weaken. The minerals begin to disappear from the bones.

Besides storing minerals and forming blood cells, the bones work with muscles and joints. They allow movement in the body. The place where two bones come together is called a joint. The knee joint is the biggest and strongest joint in the body. Ligaments link bones together at the joints. They are very strong and can stretch. Muscles are attached to bones by tendons. The muscles and tendons together allow the bones move. [B]

The whole bone structure of the body is called the skeleton. The skull protects the brain, eyes, face, jaw and ears. Vertebrae make up the column of bones running down the back. Between each vertebra is a small cushion called a disk. The vertebrae are hollow. Nerves run down through the hollow parts to the whole body.

Knees, hands, feet and legs all have different kinds of bones. Some of these bones can move freely. Some are bound tightly together. Arm bones are connected at the top to the collarbone and shoulder bone. They are connected at the bottom to the hand. Leg bones are attached to the spine at the top by the group of bones called the pelvis. The upper part of the leg is the thigh bone. Itforms part of the knee. The lower part of the leg is made up of two bones. They are attached to the foot at the bottom. [C]

Bones are actually living cells. The bones grow and change over time. A person is born with three hundred bones. Some of these bones can join together. By the time a person becomes an adult, he will have only about two hundred and six bones.

In summary, bones are a necessary part of the body. They provide protection and support for the vital organs, like the heart, brain and lungs. The bones are strong and can handle heavy weights. They allow a person to walk. They work with muscles to help the body move and stretch. [D]

Which of the following bones protect the heart?

Which serve as the best title for the last paragraph?