Fundamentals of Human Biology: Cells, Tissues, Nutrition & Health

Cellular Foundations and Body Tissues

Understanding Cell Components

• Cell Membrane: The thin layer that wraps the cell and separates it from the external environment.
• Cytoplasm: The contents of the cell, excluding the nucleus.
• Nucleus: A structure bounded by a double membrane, traversed by pores that allow substance exchange between the nucleus and the cytoplasm. Contains DNA.

Metabolic Processes

• Catabolism: A set of reactions that break down complex molecules to provide energy for cellular activities.
• Anabolism: A set of reactions that build complex molecules from simpler ones, requiring energy.
• Diffusion: Small molecules like oxygen and carbon dioxide freely pass through the plasma membrane.

Cell Specialization and Organization

• Cell Specialization: A cell performs a specific job, develops in a characteristic way, and undergoes changes in its cytoplasm.
• Tissue: Composed of cells united among themselves, leaving no gaps between them. It covers and protects the outside of the body, organs, and internal and external surfaces.

Types of Tissues

• Connective Tissue: Distributed throughout the body, it surrounds and supports organs like intestines, muscles, and tendons, connecting bones or storing fat.
• Cartilaginous Tissue: Provides skeletal and protective functions.
• Bone: The main component of the skeleton. Stores minerals like calcium.
• Blood: Its function is to transport nutrients and waste products.

Muscle Tissue Types

• Smooth Muscle: Contracts involuntarily. Formed by elongated cells that have the ability to contract under the orders of the nervous system.
• Striated Muscle: A muscle responsible for voluntary movement and contraction.
• Cardiac Muscle: Similar to striated muscle, but its contraction is involuntary. Only located in the heart.

Body Organization Levels

• Organs: Parts of the body with a particular form, specialized in a specific function.
• System: A set of organs working together, often composed of various tissues.
• Apparatus: Distinct sets of organs and tissues working together for various functions.

Essential Nutrients and Digestive Processes

Key Nutrients for the Body

• Water: The most abundant substance in our body, forming part of all body tissues.
• Minerals: Chlorides, carbonates, phosphates, etc. Dissolved in body fluids like blood and tears, or forming solid structures in hard tissues like bones and teeth. Found in foods like fruits and vegetables.
• Carbohydrates (Glucids): Provide energy.
• Simple Carbohydrates (Sugars): Have a sweet taste and dissolve in water.
• Complex Carbohydrates: Formed by the union of simple sugars, do not dissolve in water, and have no sweet taste (e.g., starch).
• Lipids: Two types: Animal fats (solid at room temperature, e.g., butter) and Vegetable fats (liquid at room temperature, e.g., olive oil).
• Proteins: Contribute building material to our body and can provide energy.
• Vitamins: Regulate processes taking place inside the body.

The Digestive System

• Gastrointestinal Tract: A muscular tube, approximately 10 meters long.
• Digestive Glands: Organs that produce digestive juices to break down food.

Stages of Digestion

• Mechanical Digestion: Reduces food into smaller pieces without changing its chemical composition.
• Mastication (Crushing): Occurs in the mouth, thanks to the teeth.
• Swallowing: The process of moving chewed food from the mouth to the esophagus through the pharynx.
• Chemical Digestion: Breakdown of nutrients in food into smaller molecules capable of crossing the intestinal walls and passing into the bloodstream.

Respiration, Excretion and Health

Cellular Respiration and Gas Exchange

• Cellular Respiration: Takes place inside the mitochondria.
• Oxygen Consumption: Essential for the oxidation of nutrients.
• Energy Release: Used by the cell to perform its functions.
• Production of Carbon Dioxide and Water: Water is necessary for the body, but carbon dioxide is a waste product to be expelled into the external environment.

Breathing Mechanics

• Inspiration (Inhalation): The ribcage expands, drawing the lungs, which increases their volume and facilitates the entry of air.
• Expiration (Exhalation): Occurs when the thorax presses on the lungs, causing the expulsion of air.

Common Health Concerns

• Infectious Diseases: Viral (e.g., common cold, causing runny nose; influenza, causing muscle and bone pain and high fever).
• Smoking Addiction: Linked to lung cancer and other respiratory and coronary diseases.

Waste Elimination

• Excretion: Elimination of waste substances resulting from cellular activity.