Microbial Infectious Diseases, Cardiovascular Health, Cancer, and Healthy Living
Microbial Infectious Diseases
Infective Agents
Most microorganisms are harmless to other living beings. Only pathogenic microorganisms produce infectious diseases. There are four types:
- Viruses: These are acellular organisms. Their structure is very simple: a capsule that involves a protein molecule of nucleic acid (DNA or RNA). They are not considered alive because they do not feed or reproduce. They only relate.
- Bacteria: These are unicellular prokaryotic organisms. They are very simple, with various forms. They have no nucleus or membranous organelles. They cause damage by releasing toxins that destroy cells affected by their reproduction within the body.
- Protozoa: These are unicellular eukaryotic organisms. They are heterotrophs. Only about 20 species cause diseases.
- Fungus: These are heterotrophic eukaryotic organisms, unicellular or multicellular. Their cells are equipped with a cell wall. Their infections are called mycoses.
Transmission of Infectious Diseases
Pathogens from the infection foci are transmitted through two mechanisms:
- Direct transmission: By physical contact (hands, kissing, sex).
- Indirect transmission: By water, air, food, clothing, or contaminated utensils (syringe).
Deadly Diseases
These can be emerging or reemerging.
- AIDS: Caused by the Human Immunodeficiency Virus (HIV), which attacks a certain type of cell responsible for immune defense, T4 lymphocytes. This leads to the suppression of the immune system. HIV is in body fluids (blood, sweat, semen). It is spread by sexual contact, sharing personal objects, and from mother to child during pregnancy. It is not transmitted by breathing, saliva, or casual contact. It is a serious pandemic, with 3 million deaths each year and 40 million people infected.
- Ebola: Named after the Ebola River (Congo). It is a contagious, viral hemorrhagic fever. It is transmitted by direct contact with infected bodily fluids.
- Tuberculosis: Kills about 2 million people a year. It is transmitted through the air, by coughing or sneezing. It produces lung and bone injuries. It is cured with antibiotics (6-9 months). It affects people who are malnourished or have low defenses.
- Cholera: Produces an intestinal toxin. It affects the epithelium, producing vomiting, diarrhea, and severe dehydration. Water and food contaminated with feces are the causes of cholera epidemics.
- Malaria: Produced by protozoa transmitted by the bite of female mosquitos. It causes headaches, joint pain, diarrhea, listlessness, high fever, chills, and sweating. Prevention measures include mosquito nets, draining moisture, and fumigation.
- Pneumonia: May be due to bacteria or viruses. It is a common complication of influenza.
Body Response to Infection
Our body has natural barriers that impede the entrance of infectious agents. The skin, tears, or secretions of our digestive acid inhibit the entry of germs. These are non-specific defenses, whatever their nature.
The immune system is the set of organs, cells, and molecules whose function is to defend the body against infectious agents and the body’s own abnormal cells, such as cancerous cells. Its principal component cells are white blood cells.
- Antigens: Organisms or molecules that are recognized as foreign by the immune system and stimulate its response.
- Antibodies: Proteins made by lymphocytes. They are poured into the blood plasma, where they join the particular antigen for which they were produced and initiate their destruction.
The immune response is characterized by specificity, diversity, distinction between self and stranger, and memory.
The immune system remembers a particular germ, and upon a second meeting, reacts much faster and more intensely. In these conditions, that person is able to resist infectious disease caused by the same germ and is said to be immune.
Immunity is the ability of our body to fight infections caused by a determined infectious agent. There are two types:
- Natural immunity: Achieved after recovering from some diseases.
- Artificial immunity: Acquired by introducing pathogens into the body that have lost their ability to cause infection but maintain the ability to stimulate the immune system response. This process is called vaccination.
Drugs Against Infection
These are chemical substances that prevent or hamper the multiplication of germs in the host, as long as they are present in the blood.
- Antibiotics: Chemicals that kill bacteria or prevent their propagation.
- Resistance to Antibiotics:
- By mutation: Their genetic information can change spontaneously and randomly, and that change can provide the ability to survive the action of an antibiotic.
- By exchange of genes: Between variants or species of bacteria. If this capability allows a type of bacterium that has acquired resistance to one antibiotic, it can pass this information to other bacteria.
- Incomplete treatments: It is necessary to take the prescribed antibiotic dose.
- Unnecessary use of antibiotics.
- Antivirals: It is not easy to achieve a medicine that ends a viral infection because viruses are not cells. They are reproduced in the interior of the body’s cells.
Microbes Without Borders: Pandemics
The WHO estimates that for an infectious disease to become a pandemic, it is necessary that:
- A new virus appears.
- It is capable of producing severe cases of disease.
- It is transmitted effectively between people.
Characteristics that facilitate transmission:
- Large urban concentrations.
- Huge mobility of people.
- Intense deforestation of rainforests.
- Conditions in which livestock breeding is performed.
Reproduction of Influenza Virus
- The virus attaches to the membrane of a cell.
- The virus enters the cell by endocytosis.
- Membranes of the vesicle and virus join, releasing fragments of RNA.
- Cellular machinery can be used to process the virus’s genetic information, constructing new capsids.
- New viruses leave the cell, surrounded by a membrane envelope, and can infect new cells.
Cardiovascular Diseases
Principal Cardiovascular Diseases
- Arteriosclerosis: The thickening of the walls of the arteries due to the deposition of cholesterol and other fats that form atherosclerotic plaques. A thrombus is a blood clot that occurs in an artery or vein and leads to their partial or complete obstruction (thrombosis). The thrombus can free itself and move to another place, resulting in a stroke.
- Hypertension: Blood pressure is the pressure of blood against the walls of arteries. It is expressed by two numbers separated by a slash; the first is the systolic and the second the diastolic. It is a silent killer because it deteriorates blood vessels, favors the release of clots, and forces the heart to make an overexertion.
- Heart Attack: The myocardium is the muscular layer of the heart that receives blood through coronary arteries. A heart attack occurs as a result of total obstruction of a coronary artery, so an area of heart muscle is left without an oxygen supply and nutrients. This results in the death of that part of the myocardium. If the coronary artery is only partially blocked, it reduces the blood flow to an area of the heart, and chest pain may occur when performing physical exercise (angina).
Risk Factors
High cholesterol, high blood pressure, being older, obesity, diabetes, sedentary lifestyle, and smoking.
Cancer
Social Impact
It is the second leading cause of death in developed countries after cardiovascular diseases.
General Outline
A tumor is a disorganized cell mass. It is benign when its growth is slow, it is located in a defined area, and it does not invade other tissues. It is malignant when cells have three characteristics:
- Abnormal appearance and altered functionality.
- Multiply rapidly and invade surrounding tissues.
- Metastasis: Ability to penetrate into the blood and lymph vessels, moving through blood and lymph and depositing in any part of the body to form a tumor.
Factors
- Heredity
- Virus
- Food
Cancer Treatment
- Surgery: Includes the removal of the tumor mass by surgery.
- Radiotherapy: Use of radiation to kill cancer cells.
- Chemotherapy: Administration of drugs that kill cancer cells.
Other Diseases of Great Social Impact
Endocrine Diseases
- Diabetes: A chronic disease caused by total or partial deficiency of insulin, a hormone that controls the concentration of glucose in the blood.
- Obesity: Excess body fat that may be caused by heredity, endocrine disorders, or our lifestyle. Its complications are high cholesterol, high blood pressure, insulin resistance, risk of cancer, and depression.
Habits of Healthy Living
Diet
A balanced diet provides all types of nutrients in adequate amounts. It is important to consider that fat has twice the energy of carbohydrates or protein. Saturated fats of animal origin, and hydrogenated fats, increase LDL cholesterol concentration in the blood. Unsaturated fats reduce LDL cholesterol.
Tips for a balanced diet:
- Avoid smoked foods.
- Limit salt intake.
- Prepare your food at home.
- Practice moderation.
The Mediterranean diet:
- The base of the diet are carbohydrates produced by grains, legumes, and fruits.
- Protein is ingested from fish and legumes.
- Food is prepared cooked or grilled.
- Prevents obesity and cardiovascular diseases.
- Prevents cancer.
Physical Activity
- Reduces heart rate.
- Increases pumping capacity of the blood and breathing capacity.
- Helps to maintain body weight.
- Increases bone density.
- Powers the immune system.
- Helps combat stress.
Alcohol
Long-term damage:
- Obesity.
- Digestive problems (hepatitis, pancreatitis, or cirrhosis, and stomach and duodenal ulcers).
- Cancer (mouth, larynx, esophagus, liver, and breast cancers).
Smoking
The smoke of snuff is a mixture of nicotine, carbon monoxide, and tar (carcinogen). Effects:
- Risk of cancer (mouth, larynx, lungs, bladder, esophagus, and pancreas).
- Chronic obstructive pulmonary disease.
- Risk of myocardial infarction.
- Appearance of gastric and duodenal ulcers.
- Intrauterine smoking (low weight of infants of smoking mothers, problems in the reproductive system).