Comprehensive Human Digestive System and Function Quiz

Ingestion

The intake of food into the digestive system.

Propulsion

The movement of food through the digestive tract, including peristalsis and segmentation.

Peristalsis

Wavelike muscular contractions to move food along the digestive tract.

Segmentation

Rhythmic contractions mixing food with digestive juices.

Oral cavity

The area where ingestion, mechanical digestion (mastication), mixing food with saliva, taste, and limited chemical digestion occur.

Saliva

A fluid that lubricates food, begins starch/lipid digestion, cleans the mouth, and dissolves chemicals for taste.

Tooth parts

Includes enamel (hard protective coating), dentin (support and shock absorption), pulp cavity (contains nerves and blood vessels), and cementum (anchors tooth via periodontal ligament).

Dental succession

The replacement of 20 deciduous teeth with 32 permanent teeth.

Tooth decay

Bacterial acids erode enamel and dentin.

Esophagus histology

Stratified squamous epithelium resists abrasion; muscularis enables peristalsis.

Deglutition

The process of swallowing, which includes voluntary oral phase, involuntary pharyngeal phase, and involuntary esophageal phase.

Stomach anatomy

Muscular layers churn food; gastric glands secrete enzymes, HCl, and mucus.

Gastric secretory cells

Include parietal cells (HCl, intrinsic factor), chief cells (pepsinogen, gastric lipase), mucous cells (mucus), and G cells (gastrin).

HCl formation

Parietal cells pump H+ from carbonic acid breakdown; Cl- follows into lumen.

HCl functions

Kills microbes, denatures proteins, and activates pepsinogen.

Stomach protection

Provided by thick alkaline mucus and rapid epithelial turnover.

Gastric secretion regulation

Includes cephalic (CNS stimulates gastric juice before food arrives), gastric (stretch/chemoreceptors → gastrin release → increased secretion/motility), and intestinal (chyme in duodenum slows gastric activity via inhibitory hormones).

Gastroenteric reflex

Stimulates motility and secretion along the small intestine.

Gastroileal reflex

Opens the ileocecal valve.

Small intestine

The primary site for nutrient absorption, with the jejunum being the most absorptive, duodenum secreting most digestive enzymes/bicarbonate/mucus, and ileum absorbing vitamin B12 with intrinsic factor.

Pancreas exocrine secretions

Digestive enzymes (amylase, lipase, proteases) and bicarbonate.

Liver microanatomy

Includes portal triads that deliver blood, sinusoids that filter, Kupffer cells that remove debris, hepatocytes that process nutrients, and a central vein that drains.

Bile

Produced by hepatocytes, stored in the gallbladder, emulsifies fats, and is reabsorbed in the ileum and returned via enterohepatic circulation.

Duodenal hormone effects

Includes gastrin (↑ gastric acid/motility), secretin (↑ bicarbonate, ↓ gastric activity), GIP (↓ gastric activity, ↑ insulin release), CCK (↑ pancreatic enzymes, gallbladder contraction), and VIP (dilates capillaries, ↑ secretion, ↓ acid).

Large intestine

Responsible for water/electrolyte absorption, vitamin production, and feces formation.

Mass movements

Strong peristalsis that moves feces to the rectum.

Defecation reflex

Stretch → parasympathetic stimulation → internal sphincter relaxes → voluntary external sphincter control.

Microbiota

Mostly found in the large intestine; aids digestion, vitamin synthesis, and immune modulation.

Carbohydrate digestion

Involves amylase breaking down carbohydrates into disaccharidases and then monosaccharides absorbed via cotransport.

Lipid digestion

Bile emulsifies fats, lipase breaks them down into micelles, which are absorbed into lacteals.

Protein digestion

Proteases break down proteins into amino acids via active transport.

Ion absorption

Occurs through diffusion, active transport, and cotransport; major ions include Na+, K+, Ca2+, Mg2+, Cl-, phosphate, bicarbonate.

Vitamin definition

An organic compound needed in small amounts for metabolism.

Fat-soluble vitamins

Includes vitamins A, D, E, K, which are absorbed with fats.

Water-soluble vitamins

Includes vitamins B and C, which are absorbed via diffusion or active transport.

Age-related changes

Includes reduced motility, enzyme/acid secretion, taste/smell; increased constipation and malnutrition risk.