Niveles de Organización en el Cuerpo Humano

Levels of Organization in the Human Body

• Human beings are complex organisms, organized in levels of increasing complexity.
• Atomic level: basic elements forming living matter.
• Molecular level: atoms bonded to form molecules.
• Cellular level: first level of life, made of distinct structures.
• Tissue level: cells of similar origin working together.

Human Cells

• Cells are the basic units of life.
• Human cells are eukaryotic and heterotrophic; they obtain nutrients from outside sources.
• Eukaryotic cells contain a nucleus to house genetic material (unlike prokaryotic cells).

Organelles of a Human Cell

• Ribosomes: protein synthesis machinery.
• Mitochondria: cellular respiration occurs here (generating energy from nutrients).
• Endoplasmic Reticulum (ER): system of interconnected membranes (smooth and rough).
• Golgi Apparatus: flattened sacs involved in processing and packaging proteins and lipids.
• Vesicles: small sacs for storing, transporting, or digesting substances

Cell Differentiation and Disease

• Cells are programmed to grow, divide, and die.
• Cancer: uncontrolled cell division leading to tumors.
  • Benign tumors: grow slowly, locally.
  • Malignant tumors (cancer): invade tissues and spread (metastasis).
• Cancer causes: Various factors, including environmental exposures, radiation, obesity, infections, tobacco, sunlight, alcohol, age, poor diet, heredity.
• Cancer prevention: key through prevention and early detection.

Tissue Types

• Muscle Tissue: elongated cells (fibers) with contractile proteins.
  • Skeletal Muscle: striated, voluntary movement, attached to bones.
  • Cardiac Muscle: striated, involuntary, heart muscle.
  • Smooth Muscle: non-striated, involuntary, surrounds internal organs.
• Epithelial Tissue: layers of closely packed cells; lines surfaces and forms glands.
• Nervous Tissue: responsible for signal transmission; composed of neurons and glial cells.
  • Neurons: highly specialized cells.
  • Glial cells: support the neurons.
• Connective Tissue: diverse types (bone, cartilage, tendons, ligaments, adipose (fat) tissue, blood) providing support and connecting other tissues.

The Function of Nutrition

• Respiratory System: exchange of oxygen and carbon dioxide.
• Urinary System: elimination of waste products.
• Digestive System: obtaining nutrients from food.

Health and Illness

• Health (WHO definition): state of complete physical, mental, and social well-being.
• Health Dimensions: social, physical, and mental health.
• Health Determinants: biological factors, lifestyle choices, environment, and the health system.
• Disease: disturbance of structure or function, causing harm.
• Pathology: study of diseases.

Types of Diseases

• Non-infectious diseases: not caused by pathogens.
  • Genetic diseases
  • Tumor/Neoplastic diseases (cancer)
  • Immune disorders
  • Mental disorders
  • Degenerative diseases
  • Nutritional/behavioral diseases
  • Accidental injuries
• Infectious diseases: caused by pathogens.
  • Acute (sudden onset, short duration)
  • Chronic (slow onset, long duration).
• Pathogenic Agents:
  • Prions (abnormal proteins)
  • Viruses (require host cells to reproduce)
  • Bacteria (prokaryotic cells)
  • Fungi (eukaryotic cells)
  • Parasites (protozoa and worms)
• Reservoir and Source of Infection
• Host: organism harboring the pathogen.

Immunity

• Immunity: body's defense system.
• Innate immunity: initial defenses (primary and secondary barriers).
• Acquired immunity: developed through exposures to pathogens; adaptive, long-term protection.

Epidemics, Endemic, Pandemic

• Endemic: disease regularly present in a specific area.
• Epidemic: disease spreading rapidly in a geographic area.
• Pandemic: widespread epidemic across multiple countries or continents.