Organic Substances, Nutrients, and Digestion
Organic and Inorganic Substances
Organic substances are mostly composed of carbon and hydrogen. Inorganic substances are not exclusive to living matter.
Types of Food
- Simple foods: Consist of a single type of nutrient, such as oil.
- Compound foods: Are composed of different nutrients.
Water is the most abundant compound. Mineral salts are dissolved in all body fluids.
Organic Constituents
- Carbohydrates: Such as glucose (which tastes sweet), starch, and cellulose.
- Lipids: Fats are substances that do not dissolve in water. Unsaturated fats are liquid and are called oils. Saturated fats, like butter, are solid.
- Proteins: Such as hemoglobin or gluten, are macromolecules formed by the union of hundreds or thousands of simpler molecules called amino acids.
- Vitamins: Organic substances that are needed in very small quantities.
The Digestive System
Nutrients are transformed into simpler substances within the digestive system. The digestive system consists of the gastrointestinal tract and digestive glands.
Parts of the Digestive System
- Mouth: Contains teeth and tongue. Dentin is covered by enamel.
- Esophagus: The tube that moves food from the pharynx to the stomach.
- Stomach: A widening of the digestive tract. The cardia marks the entry of food, and the pylorus marks the passage into the intestine.
- Pharynx: A cavity common to both the digestive and respiratory systems.
- Small intestine: A long tube, folded repeatedly.
- Large intestine: Thicker than the small intestine. The colon is the main part. At the junction of the colon with the small intestine is the cecum. The appendix is a pouch with a thin extension. Communication with the outside of the colon is done through the anus.
Digestive Glands and Enzymes
Digestive enzymes are a class of proteins that accelerate the breakdown of complex substances in food. Digestive glands are presented:
- Scattered along the walls outside the gastrointestinal or digestive tract.
- Salivary glands: Produce saliva.
- Pancreas: Produces pancreatic juice and pours it into the duodenum.
- Liver: Produces bile, which is stored in the gallbladder.
Digestion Process
Digestion is the process of transformation experienced by food as it passes through the digestive tract. It can be mechanical or chemical.
Mechanical Digestion
- Crushing: Performed by the teeth.
- Swallowing: The passage of food from the mouth to the esophagus.
- Movements: Caused by contractions of the muscles (mixing and peristalsis).
Chemical Digestion
- In the mouth: Saliva contains amylase, an enzyme that begins the digestion of carbohydrates.
- In the stomach: Food is stored and mixed with gastric juice. This juice contains hydrochloric acid and pepsin, an enzyme that initiates protein digestion.
- In the small intestine: The digestive process is completed. Intestinal juices contain lipase, which breaks down fats.
Intestinal Absorption and Flora
Intestinal Absorption: The passage of nutrients from the digestive tract into the blood.
Intestinal Flora: Manufactures vitamins, which are then processed in the colon.
Clarification: The remains that could not be digested or absorbed.
Nutrition and Diet
Balanced Diet
A balanced diet provides all types of nutrients in adequate amounts.
- Plastic Function: Used to build our own tissues, such as foods rich in protein or minerals.
- Energy Function: Releasing energy, such as carbohydrates or lipids.
- Regulatory Function: Ensuring all processes are met normally, such as minerals and vitamins.
Mediterranean Diet
The Mediterranean diet is followed in countries like Spain, Portugal, and Italy. It includes carbohydrates (cereals, legumes), fruits, vegetables, proteins, fats, vitamins, and minerals.
Food Labeling
Food labeling includes: name, quality and origin, instructions for use, instructions for maintenance, best-before date, expiration date, quantity, list of ingredients, nutritional information, company identification, and alcohol content (for drinks).
Food Additives
Food additives are substances added to food for preservation or to change their characteristics.
Dental Caries
Caries (tooth decay) is a disease caused by bacteria that live in the mouth and form plaque on the tooth surface.
Preventing Cavities
- Clean your teeth regularly.
- Limit sugary foods and drinks.
- Visit the dentist regularly.