Digestive System: Digestion and Absorption (Chapter 3)

Vocabulary flashcards covering key terms and concepts from the lecture notes on digestion and absorption (Chapter 3).

Digestion

The process of breaking down food into smaller components (carbs, proteins, fats) to prepare for absorption.

Absorption

substances are moved to interior parts of the body through the small intestine

Hepatic portal circulation

The blood flow from the digestive organs to the liver via the hepatic portal vein, delivering nutrients to the liver.

Small intestine

main site of digestion and absorption

Villi

Finger-like projections in the small intestine that increase surface area for nutrient absorption.

Microvilli

covers the villi of the small intestine and increases the absorptive surface area

Lacteals

Lymphatic vessels in the villi that absorb and transport lipids via the lymphatic system.

Amylase

Enzyme that digests carbohydrates (starch) into glucose; present in saliva and pancreatic juice.

Pepsinogen

inactive form of the enzyme pepsin which helps break down proteins in the stomach

Pepsin

Active protease in the stomach that digests proteins.

Parietal cells

Stomach cells that produce hydrochloric acid and intrinsic factor.

Chief cells

Stomach cells that produce pepsinogen.

Mucus cells

Cells that secrete mucus to protect the stomach lining from acid.

Gastrin

Hormone released by G cells that stimulates acid secretion and pepsinogen release in the stomach.

Pancreas

Organ that produces bicarbonate and digestive enzymes (amylase, lipase, proteases) for digestion in the small intestine.

Bile

produced in liver that absorbs fat

Gallbladder

Storage site for bile; releases bile into the small intestine as needed.

Liver

Organ that produces bile and supports digestion; has regenerative capacity.

Peristalsis

Rhythmic muscular contractions that move food through the GI tract.

Esophagus

moves food to stomach

Epiglottis

Flap that covers the airway to prevent food from entering the lungs during swallowing.

Gastroesophageal sphincter

Sphincter at the top of the stomach that opens to let the bolus in and then closes to keep contents in the stomach.

Chyme

The semi-fluid mass of partly digested food formed in the stomach.

Transit time

The time it takes for food to move through the GI tract, typically 24–72 hours in a healthy adult.

Cephalic response

Nervous system-driven preparation for digestion triggered by sight, smell, or thought of food.

Mucosa

The mucous membrane lining the GI tract; produces mucus and protective secretions.

Diffusion

Passive movement of molecules across a membrane down their concentration gradient.

Water-soluble vitamins

Vitamins absorbed into the bloodstream via the hepatic portal circulation.

Fat-soluble vitamins

Vitamins A, D, E, K absorbed with fats and transported via the lymphatic system.

Micelle

Small lipid aggregates formed during fat digestion that aid absorption of fatty acids and cholesterol.

Lymphatic system

System through which lipids are absorbed via lacteals and transported before entering the bloodstream.

capillaries

receives amino acids, sugars, and water soluble nutrients

longer stomach emptying time

large meals, solid meals, high fat meals, emotions, exercise

shorter stomach emptying time

smaller meals, liquid meals, protein meals, carbohydrate meals

factors that affect transit time

diet composition, physical activity, medication, emotions, illness

cephallic response

involves signals from the nervous system that stimulate digestive processes before food enters the stomach (sight, smell, sounds)