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Questions and Answers

What are the five basic chemical tastes recognized by the human palate?

Sweet, sour, bitter, salty, and umami (correct)

Sweet, sour, bitter, salty, and spicy

Sweet, salty, bitter, sour, and aromatic

Sweet, sour, savory, salty, and tangy

How long is the digestive tract in an adult human approximately?

5 meters

12 meters

8 meters (correct)

3 meters

What is the primary role of the digestive system?

To excrete waste products only

To regulate metabolic processes

To break down food, absorb nutrients, and excrete (correct)

To enhance taste sensitivity

What process do the salivary glands contribute to during digestion?

Formation of the food bolus Signup and view all the answers

Which diseases can negatively affect swallowing coordination?

Alzheimer’s and Parkinson’s Signup and view all the answers

What essential role do villi and microvilli play in the small intestine?

They trap nutrient particles for absorption. Signup and view all the answers

Which factor does NOT influence the absorption rate of nutrients?

The color of the food. Signup and view all the answers

Which fluid is produced by the liver and stored in the gallbladder to aid digestion?

Bile Signup and view all the answers

What type of substances make up the main components absorbed into the blood from the small intestine?

Carbohydrates and proteins Signup and view all the answers

Which condition can affect the efficiency of nutrient absorption?

Health of the GI tract Signup and view all the answers

Where does mechanical digestion primarily begin?

In the mouth Signup and view all the answers

What is the role of peristalsis in the digestive system?

To liquefy food and aid in digestion Signup and view all the answers

Which digestive juice is involved in protein digestion?

Gastric juices containing pepsin Signup and view all the answers

What determines the strength of gastric acid?

The pH level Signup and view all the answers

What is the primary function of the pyloric sphincter?

To separate sections of the digestive system Signup and view all the answers

How long does it typically take for the digestive system to process and absorb most nutrients?

24 to 48 hours Signup and view all the answers

Which enzyme is responsible for breaking down starches in the mouth?

Salivary amylase Signup and view all the answers

What composition is required to activate the protein-digesting enzyme in the stomach?

Gastric juices including hydrochloric acid Signup and view all the answers

Study Notes

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.