Untitled Quiz

Digestion Basics

• Digestion is the process of breaking down food into smaller components for absorption and use by the body.
• The digestive tract is a flexible muscular tube extending from mouth to anus, including the throat, esophagus, stomach, small intestine, large intestine, and rectum. Its total length is about 8 meters.
• The digestive tract's primary role is to digest food into components, absorb nutrients, and excrete waste.

Basic Tastes

• The five basic chemical tastes are: sweet, sour, bitter, salty, and umami (savory).
• Sweet, salty, and fatty foods are commonly desired, potentially leading to overconsumption.

Chewing and Swallowing

• Saliva from salivary glands adds water, minor digestive enzymes (for starch and fat), and antimicrobial components to food to form a smooth bolus.
• Teeth crush food, increasing surface area for digestion.
• The tongue pushes the food bolus towards the pharynx.
• The epiglottis seals off the trachea, preventing food from entering the respiratory system during swallowing.

Swallowing Coordination

• Swallowing coordination can be affected by diseases such as Alzheimer's, Parkinson's, stroke, or prematurity.

Mechanical Digestion

• Mechanical digestion begins in the mouth through chewing and aided by saliva.
• Peristalsis in the stomach and small intestine helps liquefy food, creating a chyme/digesta-like substance.

Muscular Stomach

• The muscular stomach stores, churns, and mixes food with gastric juices, including acid and enzymes.
• The pyloric valve controls the flow of chyme into the small intestine.

Chemical Digestion

• Digestive juices from salivary glands, stomach, pancreas, liver, and small intestine are secreted.
• Digestive juices contain enzymes that break down nutrients (e.g., starches by salivary amylase and fats by lingual lipase).
• Protein digestion begins in the stomach, where gastric juices (water, enzymes, hydrochloric acid) are required to activate the protein-digesting enzyme pepsin.
• Acid strength is determined by pH.

pH Values of Digestive Juices and Fluids

• The acidity or alkalinity of substances is measured by pH.
• Each step lower on the pH scale indicates a tenfold increase in hydrogen particle concentration, determining acidity.

Pyloric Sphincter

• The pyloric sphincter separates and controls the passage of food between the stomach and small intestine.

Nutrient Absorption Rate

• Digestion and absorption of 90% of carbohydrates, fats, and proteins typically occurs within 24 to 48 hours.
• The rate of nutrient absorption depends on the form of the nutrient, other nutrients, the body’s need for the nutrient, and the health of the gastrointestinal (GI) tract.

Small Intestine

• The small intestine is the organ responsible for digestion and absorption of nutrients and secrets fluids (including bile from liver and gall bladder and pancreatic enzymes) crucial to digestion.

Absorption and Transportation of Nutrients

• Nutrient molecules traverse intestinal lining cells.
• Cells absorb nutrients (carbohydrates, proteins, minerals, most vitamins) and deposit them into blood or lymph (fat, some vitamins).
• Intestinal cells are selective and increase the absorption of nutrients in short supply.

Large Intestine

• The large intestine (colon) absorbs water and some nutrients/metabolites generated by bacterial activity.

Digestive Tract Responses

• Eating or drinking too fast or too much can lead to digestive distress, including hiccups, choking, heartburn, or gastroesophageal reflux disease (GERD).
• Treatments with antacids or acid reducers may aggravate some digestive problems.
• Other common digestive disturbances include constipation and diarrhea.