Human Health: Factors, Diseases, and Defense Mechanisms
Health: A Holistic State
Health is a state of complete physical, mental, and social well-being, not merely the absence of disease.
Parameters of Health in a Population
Health, Social, and Economic Development
Poverty and ill health form a positive feedback loop: people get sick, and because they are poor, they get poorer because they are sick, and sicker because they are poorer. Health programs contribute to the economic welfare of countries. The levels of investment in health of a country influence the development of human capital, productivity, and competitiveness in the fight against poverty and economic and social progress. Developing countries have made great achievements in health, such as the reduction of polio or smallpox eradication, which increases life expectancy. The health systems of developing countries face different challenges:
- Increase spending on health for the whole population, not just the wealthy, ensuring that drugs reach everyone.
- Achieve health coverage for as many people as possible. It is recommended that the state provide family planning, birth control, and control of certain infectious and childhood diseases.
- Allocate resources efficiently, mainly aimed at prevention, information campaigns, and research into diseases that are very abundant in these countries.
Health Determinants
Environment
Global atmospheric pollution has led to certain diseases. Environmental quality is of paramount importance in health; poor environmental conditions are the cause of many illnesses and deaths. Different types of pollutants contribute to environmental deterioration:
- Physical contaminants: Include dust from deserts and volcanic eruptions, UV radiation, radioactivity, noise, and heat. They cause irritation of mucous membranes, cardiorespiratory diseases, tumors, and stress, among others.
- Chemical contaminants: Gases that are emitted in the combustion of hydrocarbons and coal, organic compounds, heavy metals, photochemical oxidants, detergents, etc.
- Biological contaminants: Viruses, protozoa, bacteria, arthropods, algae, and other parasites. They cause infectious diseases. They are found in untreated water, contaminated food, and air.
Social and Labor Relations
Several social and work factors are related to the environment around us, which are harmful to our health. These include stress, overload, exhaustion, and poor industrial relations.
Personal Lifestyle
Practicing good health habits may not always guarantee a longer life, but it enriches it and reduces the risk of disease. These habits include:
- Regular exercise
- Not smoking
- Reducing or eliminating alcohol consumption
- Avoiding drugs
- Maintaining a healthy diet
- Sexual hygiene
- Personal grooming
- Sexual protection
Biological Factors
These include aging and genetic agents. There are genes and mutations that can cause disease; their detection and knowledge can be used to diagnose, treat, and even prevent these diseases. Genetic diseases are caused by chromosomal abnormalities or defects in genes.
Health System
The health system is the means by which a country organizes and funds the protection of health and the provision of medical services to its citizens. Our health system is characterized by:
- Universal coverage (all citizens are entitled to public health care)
- Financing through taxes, according to income
- Guaranteeing equal access to resources and services
Disease
A condition in which the physical functioning, emotional, intellectual, social, or spiritual development of a person is reduced or changed compared with previous experience.
Infectious and Parasitic Diseases
These are produced by biological pathogens. Some symptoms are similar, and they generally go through three stages with different durations depending on the disease:
- Incubation: Time lag between the entry of the pathogen into the body and the first symptoms. Sometimes it is a long period, making it difficult to diagnose and promoting contagion.
- Development: Disease progression with symptoms.
- Convalescence: Time lag, overcoming the disease, until the body regains its initial state.
According to the agent, the cause may be:
- Prion diseases: Pathogens are prions, proteins with a different configuration from the original protein. This configuration can be transmitted to adjacent proteins. (e.g., Mad Cow Disease)
- Viral diseases: Pathogens are viruses, cell-free particles like prions. They consist of a nucleic acid surrounded by a protein envelope. They self-replicate using the machinery of infected cells. They are obligate intracellular parasites, so they cause disease. Treatment is complicated because the lack of metabolism means that we cannot act against it. (e.g., Hepatitis, AIDS, Herpes, Rabies, Measles)
- Bacterial diseases: They are produced by bacteria, living unicellular organisms, although with a very simple structure. They are prokaryotes (no well-defined nucleus). Most bacteria are necessary and beneficial, but a few cause disease. (e.g., Brucellosis, Plague, Syphilis, Tetanus, Pneumonia)
- Fungal diseases or mycoses: They are caused by fungi, eukaryotes, and therefore are cells that possess a well-defined nucleus. Because they have an organization like ours, it is hard to attack them, especially in deep mycoses. Surface mycoses have a better prognosis and may resolve with topical treatment.
- Diseases caused by parasitic protozoa: Protozoa are unicellular organisms, heterotrophic eukaryotes that live in liquid environments and are the cause of these diseases. The infection varies depending on the disease. It can occur by ingesting contaminated food or water, or by the bite of mosquitoes that act as vectors carrying the protozoa from the carrier to the person. (e.g., Malaria, Sleeping Sickness)
- Diseases caused by parasitic metazoa: Caused by metazoan parasites, whether helminths or arthropods. In almost all cases, life cycles are very complex, with several hosts, the adult host not coinciding with the larval host.
Non-Infectious Diseases
Cancer
Results from an abnormal proliferation of cells. It is believed that the etiology involves several factors such as environment, lifestyle, heredity, and age. When dividing, cells replicate their DNA. If it changes from the original, the p53 protein is activated, stopping cell division and giving the cell time to repair the damaged gene. If it does not, programmed cell death is triggered, preventing the proliferation of cells with abnormal DNA. Sometimes these cells remain alive, reproducing quickly and without control, which leads to tumors. In most tumor cells, the gene encoding the p53 protein is mutated. If the repressor protein is lacking, cell cycle control is lost. The cells pile up, press organs, and migrate through blood or lymph to other organs, leading to metastasis. Cancer is treated with surgery, radiotherapy, and chemotherapy. Surgery is very effective in localized cancers. Radiation destroys all rapidly dividing cells, as well as tumor cells, damaging organs such as the skin, ovaries, testes, spinal cord, and the intestinal wall. Chemotherapy involves administering antimitotics, which also affect normal cells.
Endocrine, Nutritional, and Metabolic Diseases
Endocrine diseases include diabetes and thyroid disorders. Metabolic diseases include familial hypercholesterolemia. Nutritional diseases include anorexia and bulimia.
Cardiovascular Diseases
Affect the heart and blood vessels. There are non-modifiable risk factors (male condition, age, and heredity) and modifiable risk factors (smoking, sedentary lifestyle, stress, cholesterol). The most important diseases are stroke, heart attack, arteriosclerosis, and hypertension.
Mental Illnesses
A group of disorders of various origins altering the cognitive and affective processes of the individual. They are often chronic diseases that are difficult to treat. They are grouped under:
- Psychosis
- Organic disorders
- Affective disorders
- Neurosis
- Anxiety disorders
Degenerative Diseases
Conditions in which, for no apparent reason, there is an injury to organs and tissues that impair normal functioning.
- Alzheimer’s disease: Progressive and terminal, usually affects people over 65 years. The patient loses memory and changes behavior, leading to dementia. Patients end up being dependent, especially in the later stages.
- Parkinson’s disease: Affects neurons responsible for the control and coordination of movement. The patient has tremors, muscle stiffness, slow movement, and changes in posture and gait. Although there is no curative treatment, it can be controlled, achieving symptom relief.
Epidemiology
The science that studies the frequency of disease in a population and the factors that define its expansion and severity.
Transmission of Infections
Infectious diseases can be transmitted in three ways:
- Contact transmission
- Transmission by common use
- Transmission by vectors
Endemic, Epidemic, and Pandemic Diseases
A sporadic disease is given only occasionally. Endemic diseases are those that appear in a region and persist over time, affecting a significant number of people. An epidemic occurs when there is a high incidence of a disease in a large geographic area. If it affects several continents, it is called a pandemic.
New, Emerging, and Reemerging Diseases
- New diseases: Those whose recent appearance is due to the emergence of new pathogens to humans, crossing the species barrier and passing from animals to humans.
- Emerging diseases: Although known before, they have a higher incidence in the last two decades due to new living conditions.
- Reemerging diseases: Diseases that were allegedly controlled at one time again pose a health threat and may become an epidemic.
Natural Defenses
Constitutive Defenses
Affect against any disease or pathogen. We have:
- Genetic resistance: Through it, we are immune to many diseases because we lack the specific receptors necessary for the entry of these microorganisms into our cells.
- Anatomical barriers: Prevent the passage of pathogens into the organism.
- Inflammatory response: Characterized by swelling, redness, heat, and pain around the affected area.
- Phagocytic defense: Phagocytes destroy the pathogen.
Induced or Immune Response
Specific defenses are triggered in response to the presence of an antigen. Lymphocytes, when presented with the foreign substance, respond by making a protein or antibodies that act against the antigen concerned, canceling its pathogenic effect. The immune response is complex; it involves many types of cells and molecules that complement each other. There are B and T lymphocytes. When an individual is in contact with an antigen, they acquire immune memory, which causes them, upon reencounter with the body, to manufacture a large number of antibodies that act on the antigen, preventing the pathogen from installing and the disease from developing.
Artificial Defenses
Surgery
The treatment of choice in certain diseases; it involves manually and instrumentally intervening in the affected organ of the patient.
Transplants
Methods of implementing an organ or tissue from a donor to a recipient. When the organ or tissue is from the same patient, it is called autologous. If it is from another individual of the same species, it is called allogeneic. If the donor and patient are of different species, it is called xenotransplantation.
Medications
- Vaccines: Prepared with antigenicity and without virulence, which, upon entering the individual, trigger antibody formation. This will generate immunological memory, sometimes permanent, against the antigen.
- Sera: Antibodies that are injected into the patient, made by another body that previously made contact with the pathogen. This immunity lasts only a short time.
- Antibiotics: Used to destroy bacteria or prevent their growth. They act on the metabolism of prokaryotes, affecting neither viruses nor our cells.
- Other drugs: Cytotoxic (cancer), analgesics, antipyretics, anti-inflammatories, etc.
Phagocyte: Cell capable of destroying microorganisms, foreign substances, or cells killed by phagocytosis.
Antigen: Molecule that induces the formation of antibodies.
Antibody: Proteins formed in response to an antigen and used to inactivate it.
Leukocyte: Colorless or white cell in blood and lymph that can move to various parts of the body with defensive functions.
Lymphocyte: Lymphatic cell, a variety of leukocyte actively involved in the immune response.