Digestion, Absorption, and Metabolism

Flashcards covering key concepts from the 'Digestion, Absorption, and Metabolism' lecture notes, formatted as questions and answers to aid exam preparation.

What is the primary function of the digestive system?

Responsible for processing foods and relies on nutrient intake for its maintenance.

Which organs are part of the gastrointestinal (GI) tract?

Mouth, Esophagus, Stomach, Duodenum, Jejunum, Ileum, Colon, Rectum, Anus

What are the accessory digestive organs?

Salivary glands, Liver, Pancreas, Gallbladder

What are the three types of salivary glands and their primary secretions?

Parotid Gland (watery saliva and enzymes), Submandibular Glands (mucus and enzymes), Sublingual Glands (mucus)

What are the functions of saliva in the mouth?

Moisten food and break down starch via amylase (chemical digestion).

What is the role of teeth and the tongue in digestion?

Teeth perform mechanical digestion, while the tongue aids in bolus formation, movement, and initiates the pharyngeal phase of swallowing.

During which phase of swallowing is the bolus moved to the back of the mouth and the nasopharynx closes?

Pharyngeal phase

What is peristalsis?

A muscular action of the GI tract that moves the bolus through the esophagus (and other parts of the GI tract) via wave-like contractions.

What is segmentation in the GI tract?

A back-and-forth muscular movement of the tract that mixes food.

What is the function of the Esophageal/Cardiac Sphincter?

A muscular band that opens and closes to the stomach, triggered by swallowing, and prevents GERD/heartburn.

What are the key functions of the stomach?

Holding food for partial digestion, producing gastric juices, providing muscular action for mixing and tearing food, secreting intrinsic factor for Vitamin B12 absorption, releasing Gastrin, and assisting in the destruction of pathogenic bacteria.

Which specific substance secreted by the stomach is essential for Vitamin B12 absorption?

Intrinsic factor

What are the three phases of gastric secretion?

Cephalic (Psychic Phase), Gastric, and Intestinal

What are the main components of the small intestine?

Duodenum, Jejunum, and Ileum

Why is the small intestine considered the major organ of digestion and most absorption?

It contains villi and microvilli, which greatly increase its surface area for efficient nutrient absorption.

What is the primary role of the duodenum?

To mix food from the stomach with enzymes from the pancreas and bile from the gallbladder to further break down food. Water, iron, and some minerals are also absorbed here.

Which part of the small intestine is largely responsible for absorbing the food's nutrients, due to its many circular folds?

Jejunum

What does the ileum primarily absorb?

Bile acids and Vitamin B12

What is the function of Secretin?

It signals the pancreas to send bicarbonate to the duodenum.

What is the role of Bile in digestion?

It acts as an emulsifier of fats, coating them to allow pancreatic lipase to work effectively.

What is Cholecystokinin (CCK)?

A hormone that signals for pancreatic secretions.

What is absorption?

The process by which substances pass through the intestinal mucosa into the blood or lymph.

Describe passive diffusion/osmosis in the context of absorption.

When pressure is greater on one side of the membrane, a substance moves from an area of greater pressure to less pressure through capillaries without requiring energy.

What are some factors that can affect nutrient absorption?

Bioavailability (e.g., fiber and other binders can hasten transit time) and the relationship between food and drug absorption.

Which organ is considered the 'powerhouse' organ, where all nutrients pass by first after absorption?

The liver

Which system transports lipids and fat-soluble vitamins after absorption?

The lymphatic system

What are the main components of the large intestine?

Cecum, Colon, Rectum, and Appendix.

What are the primary functions of the large intestine?

Site of final absorption of water and some minerals, production of several vitamins by bacteria, formation of feces, and excretion from the colon through the anus.

What is defecation?

The expulsion of feces or body waste products.

What is the approximate total duration from ingestion to elimination?

16-27 hours

What is metabolism?

A set of processes through which absorbed nutrients are used by the body for energy and to form and maintain body structures and functions.

What is Catabolism?

The metabolic process of breaking down substances, such as gluconeogenesis (creation of glucose by breaking down protein or fat) and glycogenolysis (breakdown of glycogen).

What is Anabolism?

The metabolic process of building substances, such as lipogenesis (fatty acid/triglyceride synthesis), growth, and repair.

How are metabolism waste products generally excreted?

Through the lungs, kidneys, or large intestine.