Boys and girls between the ages of 9 and 13 should get 9 mg of iron every day. Girls between the ages of 14 and 18 should get 15 mg of iron every day. Boys between the ages of 14 and 18 should get 11 mg of iron every day. Pregnant women need the most iron — 27 mg daily.
Good sources of iron include shellfish such as clams and oysters. Red meat such as beef is also a good source of iron. Non-animal sources of iron include seeds, nuts, and legumes. Breakfast cereals often have iron added to them in a process called fortification. Some good sources of iron are listed in Table (below). Eating vitamin C along with the iron-containing food increases the amount of iron that the body can absorb.
Sources of Iron Food Milligrams (mg) of Iron
Canned clams, drained, 3 oz 23.8
Fortified dry cereals, about 1 oz 1.8 to 21.1
Roasted pumpkin and squash seeds, 1 oz 4.2
Cooked lentils, ½ cup 3.3
Cooked fresh spinach, ½ cup 3.2
Cooked ground beef, 3 oz 2.2
Cooked sirloin beef, 3 oz 2.0
(Created by: Niamh Gray-Wilson. Information Source: Centers of Disease Control and Prevention http://www.cdc.gov/nccdphp/dnpa/nutrition/nutrition_for_everyone/iron_deficiency/#Iron%20Sources)
Leukemia
Leukemia is a cancer of the blood or bone marrow. It is characterized by an abnormal production of blood cells, usually white blood cells. Lymphoma is a type of cancer in white blood cells called lymphocytes. There are many types of lymphoma.
Hemophilia
Hemophilia is the name of a group of sex-linked (X-linked) hereditary diseases that affect the body's ability to control blood clotting (see the Genetics chapter). Hemophilia is caused by a lack of clotting factors in the blood. Clotting factors are needed for the normal clotting of blood. A person who has hemophilia is initially able to make a clot to stop the bleeding, but because fibrin is not produced, the body is unable to keep a clot at an injury site. The risk of internal bleeding is also increased in hemophilia, especially into muscles, joints, or bleeding into closed spaces.
Lesson Summary
Blood is a colloidal solution that contains red blood cells, white blood cells, and platelets. The cells are suspended in plasma. The red blood cells give blood its red color. Blood carries oxygen and nutrients to body cells and carries wastes away. It also helps to maintain body temperature and to carry chemical messengers called hormones around the body.
Hemoglobin is the oxygen-carrying protein that is found in red blood cells. White blood cells defend the body against infection by bacteria, viruses and other pathogens. Some WBCs swallow pathogens, and others produce antibodies that attack and destroy pathogens.
Blood type is determined by the presence or absence of certain molecules, called antigens, on the surface of red blood cells (RBCs). There are four blood types; A, B, AB, and O.
If a person receives the wrong blood type, antibodies in the recipient’s blood would attack the antigens on the RBCs in the donor blood. The antibodies would cause the RBCs to clump together, and the clumps could block a blood vessel.
Sickle cell disease is a blood disease that is caused by abnormally-shaped blood protein hemoglobin.
Anemia is a disorder in which there is not enough hemoglobin in the blood to carry oxygen to body cells.
Review Questions
What types of cells are found in blood?
What is the liquid part of blood called?
What is the function of platelets?
Identify two functions of blood other than bringing oxygen to body cells.
What is the oxygen-carrying protein found in red blood cells?
Identify two ways that white blood cells defend the body from infection.
How are the red blood cells of the different blood groups different?
They have different antigens on the surface of the cells.
Why are people with type O blood called universal donors?
Why are people with type AB blood called universal recipients?
Problem | question=Identify three blood disorders or diseases. |difficulty=Beginning | solution= Problem | question=How can the shape of the hemoglobin protein in a person with sickle-cell disease affect other body systems? |difficulty=Challenging | solution=
What is a common cause of anemia in young people?
Identify two good sources of iron in the diet.
Further Reading / Supplemental Links
http://en.wikipedia.org/wiki
Vocabulary
ABO blood type system
Blood group system that is determined by the presence or absence of certain molecules, called antigens, on the surface of red blood cells (RBCs); there are four blood types in the ABO system: A, B, AB, and O.
anemia
The condition of not having enough hemoglobin in the blood to carry oxygen to body cells.
antibodies
Proteins that identify pathogens or other substances as being harmful; flow in blood; can destroy pathogens by attaching to the cell membrane of the pathogen.
blood clotting
The complex process by which blood forms solid clots.
blood transfusion
The process of putting blood or blood products from one person into the circulatory system of another person.
fibrin
A tough protein that forms strands during the blood clotting process.
hemophilia
A group of hereditary diseases that affect the body's ability to control blood clotting.
iron-deficiency anemia
Occurs when the dietary intake or absorption of iron is less than what is needed by the body. As a result, hemoglobin, which contains iron, cannot be made.
leukemia
Cancer of the blood or bone marrow; characterized by an abnormal production of blood cells, usually white blood cells.
lymphoma
Cancer of white blood cells called lymphocytes.
plasma
The golden-yellow liquid part of the blood.
platelets
Fragments of larger cells that are important in blood clotting.
red blood cells (RBCs)
Flattened disk-shaped cells that carry oxygen, the most common blood cell in the blood. Mature red blood cells do not have a nucleus.
rhesus (Rh) system
The second most important blood group system in human blood transfusion. A person either has, or does not have the Rh(D) antigen on the surface of their RBCs; written as Rh(D) positive (does have the RhD antigen) or Rh(D) negative (does not have the antigen).
sickle cell disease
A blood disease that is caused by abnormally-shaped blood protein hemoglobin.
universal donor
A person with type O positive blood; type O RBC do not have any antigens on their membranes and so would not cause an immune reaction in the body of a recipient.
universal recipient
A person with type AB positive blood; the blood plasma of AB blood does not contain any anti-A or anti-B antibodies. People with type AB blood can receive any ABO blood type.
white blood cells
Nucleated blood cells that are usually larger than red blood cells; defend the body against infection by bacteria, viruses, and other pathogens.
Points to Consider
Why is the blood in veins not under pressure?
How can your diet affect the cardiovascular system?
Lesson 18.4: Health of the Cardiovascular System
Lesson Objectives
Outline the cause of blood pressure in arteries.
Identify the healthy range for blood pressure.
Describe three types of cardiovascular disease.
Identify things you can do to avoid cardiovascular disease.
Check Your Understanding
What is the role of the cardiovascular system?
Introduction
The health of your whole body depends on the good health of your cardiovascular system. The health of the car
diovascular system (CV system) can be overlooked because damage to the CV system often does not have any symptoms. In this lesson you will learn about common health problems with the CV system, and how you can work toward having a healthy CV system.
Blood Vessels and Blood Pressure
Blood pressure is the force exerted by circulating blood on the walls of blood vessels. The contracting ventricles push blood out of the heart under force. The force of the contractions put the blood under pressure. The pressure causes the walls of the arteries to move in a rhythmic fashion. Blood in arteries is under the greatest amount of pressure. A person's pulse is the throbbing of their arteries that results from the heart beat.
The pressure of the circulating blood gradually decreases as blood moves from the arteries, and into the smaller blood vessels. Blood that is in veins is not under pressure. The term blood pressure generally refers to the pressure in the larger arteries that take blood away from the heart. Arterial pressure results from the force that is applied to blood by the contracting heart, where the blood “presses” against the walls of the arteries.
The systolic arterial pressure is the highest pressure in the arteries. The diastolic arterial pressure is the lowest pressure. Arterial pressure is most commonly measured by an instrument called a sphygmomanometer, shown in Figure below. The height of a column of mercury indicates the pressure of the circulating blood. Many modern blood pressure devices no longer use mercury, but values are still reported in millimeters of mercury (mm Hg).
Figure 18.21
A digital sphygmomanometer is made of an inflatable cuff and a pressure meter to measure blood pressure.
Healthy Blood Pressure Ranges
In the United States, the healthy ranges for arterial pressure are:
Systolic: less than 120 mm Hg
Diastolic: less than 80 mm Hg
Blood pressure is usually written as systolic/diastolic mm Hg. For example, a reading of 120/80 mm Hg, is said as "one twenty over eighty." These measures of arterial pressure are not static, they change with each heartbeat and during the day. Factors such as age, gender and race also influence blood pressure values. Pressure also varies with exercise, emotions, sleep, stress, nutrition, drugs, or disease.
Studies have shown that people whose systolic pressure is around 115 mm Hg rather than 120 mm Hg have fewer health problems. Clinical trials have shown that people who have arterial pressures at the low end of these ranges have much better long term cardiovascular health.
Hypertension which is also called high blood pressure, is a condition in which a person’s blood pressure is always high. Hypertension is said to be present when a person's systolic blood pressure is always 140 mm Hg or higher, and/or their diastolic blood pressure is always 90 mm Hg or higher. Having hypertension increases a person’s chance for developing heart disease, having a stroke, and other serious cardiovascular diseases.
Hypertension often does not have any symptoms, so a person may not know they have high blood pressure. For this reason hypertension is often called the silent killer. However, hypertension can be easily diagnosed and is usually treatable. Treatments for hypertension include diet changes, exercise, and medication.
Atherosclerosis and Other Cardiovascular Diseases
A cardiovascular disease (CVD) is any disease that affects the cardiovascular system. But, the term is usually used to describe diseases that are linked to atherosclerosis. Atherosclerosis is a chronic inflammation of the walls of arteries that causes swelling and a buildup of material called plaque. Plaque is made of cell pieces, fatty substances, calcium, and connective tissue that build up around the area of inflammation. As a plaque grows it stiffens and narrows the artery, which reduces the flow of blood through the artery, shown in Figure below.
Figure 18.22
Atherosclerosis is sometimes referred to as of the arteries; plaque build-up reduces the blood flow through the artery.
Atherosclerosis
Atherosclerosis normally begins in later childhood, and is usually found in most major arteries. It does not usually have any early symptoms. Causes of atherosclerosis include a high-fat diet, high cholesterol, smoking, obesity, and diabetes. Atherosclerosis becomes a threat to health when the plaque buildup interferes with the blood circulation in the heart or the brain. A blockage in the blood vessels of the heart can cause a heart attack. Blockage of the circulation in the brain can cause a stroke. According to the American Heart Association, atherosclerosis is a leading cause of CVD.
Coronary Heart Disease
Cardiac muscle cells are fed by the coronary arteries. Blocked flow in a coronary artery can result in a lack of oxygen and the death of heart muscle. Coronary heart disease is the end result of the buildup of plaques within the walls of the coronary arteries. Coronary heart disease often does not have any symptoms. A symptom of coronary heart disease is chest pain. Occasional chest pain, called angina can happen during times of stress or physical activity. The pain of angina means the heart muscle fibers need more oxygen than they are getting.
Most people with coronary heart disease often have no symptoms for many years until they have a heart attack. A heart attack happens when the blood supply to a part of the heart is blocked. The cardiac muscle that depends on the blood supply from the blocked artery does not get any oxygen. Cardiac muscle fibers that is starved of oxygen for more than about five minutes will die. Cardiac muscle does not divide, so dead cardiac muscle cells are not replaced. Coronary heart disease is the leading causes of death of adults in the United States. How a blocked coronary artery can cause a heart attack, and cause part of the heart muscle to die is shown in Figure below. Injured cardiac muscle does not contract as well as healthy tissue, so the heart will not work as well as it used to.
Figure 18.23
A blockage in a coronary artery stops oxygen getting to part of the heart muscle; areas of the heart that depend on the blood flow from the blocked artery are starved of oxygen.
Stroke
Atherosclerosis in the arteries of the brain can lead to a stroke. A stroke is a loss of brain function due to a blockage of the blood supply to the brain. It can be caused by a blood clot, a free-floating object that gets caught in a blood vessel, or by a bleeding blood vessel.
Risk factors for stroke include advanced age, high blood pressure, having a previous stroke, diabetes, high cholesterol, and cigarette smoking. Reducing blood pressure is the most important controllable risk factor of stroke. However, many other risk factors, such as avoiding tobacco or quitting tobacco smoking are also important.
Keeping Your Cardiovascular System Healthy
There are many risk factors that can cause a person to develop CVD. A risk factor is anything that is linked to an increased chance of developing a disease or an infection. Some of the risk factors for CVD you cannot control, but there are many risk factors you can control.
Risk factors you cannot control include:
Genetics Family history of cardiovascular disease increases a person’s chance of developing heart disease.
Gender Men under age 64 are much more likely to die of coronary heart disease than women, although the gender difference declines with age.
Age The older a person is, the greater their chance of developing a cardiovascular disease.
Risk factors you can control include:
Poor Eating Habits Eating mostly foods that are nutrient poor (do not have many nutrients other than fat or carbohydrate) leads to high cholesterol levels and overweight, among other things.
Lack of Physical Activity Aerobic activities, such as the one shown in Figure below, help keep your heart healthy To reduce the risk of disease, you should be active for at least 60 minutes a day, five days a week (or most days of the week).
High Blood Pressure Hypertension can cause atherosclerosis
Obesity Being obese, especially if the fat is deposited mostly in the torso, rather than the hips and thighs, increases risk significantly
High Cholesterol Le
vels High amounts of low density lipids in the blood, also called bad cholesterol, are a significant risk factor
Diabetes Having diabetes can cause changes (such as high cholesterol levels) which in themselves are risk factors.
Tobacco Smoking Giving up smoking or never starting to smoke is the single most effective way of reducing the risk of heart disease.
Figure 18.24
Thirty minutes a day of vigorous aerobic activity, such as basketball, is enough to help keep your cardiovascular system healthy.
Although there are uncontrollable risk factors, a person whose family has a history of CVD does not have to develop heart disease. There are many things a person can do to help prevent CVD, even if CVD is in their family. A person who is physically active every day, eats healthfully, and avoids tobacco can lower their chances of developing a CVD.
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