Human Blood Groups, Rh Factor, Nutrition, Diseases and Genetic Disorders: A Health Reference

Blood Groups and Antigens

Red blood cells carry antigens (proteins) on their surface. Depending on which antigens are present, the blood belongs to a specific group, and the plasma contains antibodies against the antigens that are absent.

• Group A: has A antigens and anti-B antibodies.
• Group B: has B antigens and anti-A antibodies.
• Group AB: has A and B antigens and no antibodies against them.
• Group O: has no A or B antigens and has both anti-A and anti-B antibodies.

The agglutination reaction occurs when an antibody meets its matching antigen, causing red blood cells to clump together.

Rh Factor

Some people have a protein called the Rh factor on their red blood cells:

• Rh positive (Rh+): the protein is present.
• Rh negative (Rh-): the protein is absent. If an Rh- person receives Rh+ blood, the immune system can produce antibodies that destroy the transfused cells, which may be fatal.

Blood Donation Compatibility

Group O-negative is the universal donor for red blood cells, while AB-positive individuals are universal recipients. Compatible donations include:

• A can donate to A and AB.
• B can donate to B and AB.
• AB can donate only to AB.
• O can donate to all groups.

Injuries

Common injuries include sprains (stretched or torn ligaments) and dislocations (bones forced out of their joint).

Heat and Body Temperature

When body temperature rises above 41 °C, it can cause brain damage. Heatstroke can be fatal if not treated quickly.

Metabolic Diseases and Nutrition

An adult should consume about 2000 calories per day. An excess or deficiency of nutrients causes disease.

Nutritional Deficiencies

• Malnutrition: a general lack of nutrients.
• Calcium deficiency: rickets, fragile bones and osteoporosis.
• Iodine deficiency: goiter and thyroid problems.
• Vitamin C deficiency: bleeding gums and loss of teeth (scurvy).
• Vitamin D deficiency: rickets.

Excess Nutrition and Obesity

Excess food is converted into fat. Excess body fat leads to:

• Hyperlipidemia: high levels of fat in the blood.
• Hypercholesterolemia: excess cholesterol.
• Type 1 diabetes: an inherited condition caused by lack of insulin activity.
• Type 2 diabetes: sugar in the blood that cannot be processed properly despite insulin.
• Hyperuricemia: excess uric acid.

Cardiovascular Diseases

• Atherosclerosis: arteries become hard and deformed.
• Aortic aneurysm: a bulge in the aorta.
• Hypertension: high blood pressure that damages vessels and can cause hemorrhage.
• Myocardial infarction: blockage of the coronary arteries.
• Embolism: a blood clot forms in one place and travels to block another blood vessel.
• Cerebral infarction (stroke): a clot blocks blood flow to the brain and destroys brain tissue.
• Cerebral hemorrhage: an artery in the brain ruptures and releases blood.

Economy class syndrome can occur when a person remains seated for long periods, such as more than 12 hours on a plane. Reduced movement can cause clots in the legs that may travel to the lungs or brain and cause a stroke.

Autoimmune Diseases

Autoimmune diseases occur when the immune system produces antibodies against the body's own substances, mistaking them for foreign ones. Examples include:

• Fibromyalgia: widespread pain.
• Psoriasis: a skin condition.
• Vitiligo: antibodies destroy melanin-producing cells, causing loss of skin pigment.
• Lupus.
• Rheumatoid arthritis.

Excessive hygiene may weaken the immune system's ability to distinguish harmful agents, contributing to these diseases.

Cancer

Skin cells are replaced approximately every 28 days. Cancer begins when cells lose control of division and multiply uncontrollably, forming a tumor. These cells can migrate to other parts of the body through metastasis.

Environmental Causes

• Skin cancer: excessive sun exposure without protection.
• Mouth cancer: tobacco use.
• Blood cancer: leukemia.

Congenital and Genetic Diseases

Some diseases are present from birth and are caused by genetic or chromosomal alterations:

• Albinism: a genetic condition in which the body cannot produce melanin, the pigment responsible for skin, hair and eye color.
• Hemophilia: a gene on the X chromosome prevents proper blood clotting, causing prolonged bleeding.
• Color blindness: caused by a defect on the X chromosome, which leads to confusion between red and green.
• Down syndrome (mongolism): a person has three copies of chromosome 21 instead of two, resulting from an extra chromosome inherited from one parent.