Human Digestion and Absorption - Chapter 4 Review

Vocabulary flashcards covering key terms related to human digestion and absorption, including anatomy, physiology, nutrient processing, and common gastrointestinal disorders.

Filiform Papillae

Structures on the human tongue that help sense food and texture.

Chemical level

Atoms combine to form molecules such as protein, carbohydrate, lipid, DNA, or RNA.

Cell level

Molecules form organelles, such as the nucleus and mitochondria, which make up cells.

Tissue level

Similar cells and surrounding materials make up tissues.

Organ level

Different tissues combine to form organs, such as the stomach and small intestine.

Organ system level

Organs such as the stomach and intestines make up an organ system, for example, the gastrointestinal system.

Organism level

Organ systems make up an organism.

Cell

The smallest functional unit of the body, capable of growth, absorbing nutrients, using energy, conducting metabolic functions, and excreting waste.

Adenosine triphosphate (ATP)

The energy currency that carbohydrates, proteins, and lipids are transformed into for the body to use.

Epithelial tissue

A type of human tissue that covers surfaces inside and outside the body.

Connective tissue

A type of human tissue that provides support and protection, such as tendons, cartilage, and bone.

Muscle tissue

A type of human tissue that contracts and relaxes for movement.

Nervous tissue

A type of human tissue found in the brain and spinal cord that transmits nerve impulses.

Major Organs of Digestion

Mouth, Esophagus, Stomach, Small intestine, Large intestine, Anus.

Accessory Organs of Digestion

Liver, Pancreas, Gallbladder.

GI Tract (Alimentary Canal)

A long, hollow, muscular tube, about 15 ft from mouth to anus, where nutrients pass through its wall to be absorbed.

Mucosa

The innermost layer of the GI tract, consisting of epithelial cells and glands, with a hollow area called the lumen.

Submucosa

A layer of the GI tract wall containing blood vessels that carry nutrients.

Muscle layer (GI tract)

A layer of the GI tract wall arranged in double layers that moves food forward.

Serosa

The outside layer of the GI tract wall that protects the tract.

Sphincters

Ring-like muscles that open and close to control the flow of contents in the GI tract.

Peristalsis

Food mixing with digestive secretions and being propelled down the GI tract through waves of contraction and relaxation.

Segmentation

A back and forth movement, primarily in the Small Intestine, that breaks apart contents and mixes them with digestive juices.

Mass movements

Peristalsis occurring over a widespread area, typically in the large intestine.

Digestive Enzymes

Proteins that speed up or catalyze hydrolysis reactions, breaking down large molecules into smaller forms for absorption.

Hydrolysis reactions

Reactions catalyzed by enzymes where water is used to break apart large molecules.

Saliva

A secretion produced in the mouth containing lysozyme, mucus, amylase, and lipase, contributing to starch and fat digestion, lubrication, and swallowing.

Lysozyme

An enzyme in saliva that destroys bacteria.

Amylase (salivary)

An enzyme in saliva that begins starch digestion, breaking it down into simple sugars.

Lipase (salivary)

An enzyme in saliva that begins fat digestion.

Bolus

Food mixed with saliva, formed in the mouth for swallowing.

Epiglottis

A flap that prevents food from entering the trachea (windpipe) by covering the larynx during swallowing.

Lower Esophageal Sphincter (LES)

The sphincter controlling food entry from the esophagus into the stomach; malfunction can cause heartburn.

Heartburn

Occurs when stomach acid backflows into the esophagus.

GERD (Gastroesophageal Reflux Disease)

A chronic condition where heartburn occurs 2 or more times per week, potentially leading to serious complications.

Gastric Juice

Secretions from the stomach, containing hydrochloric acid (HCl), intrinsic factor, pepsinogen, gastric lipase, and gastrin.

Hydrochloric Acid (HCl)

Secreted by parietal cells in the stomach; inactivates proteins, destroys bacteria, dissolves minerals, and converts pepsinogen into active pepsin.

Intrinsic Factor

A protein secreted by parietal cells in the stomach, required for the absorption of Vitamin B12 in the small intestine.

Pepsinogen

An inactive protein-digesting enzyme (proenzyme) secreted by chief cells in the stomach, activated by HCl to become pepsin.

Gastric Lipase

An enzyme secreted by chief cells in the stomach that aids in fat digestion.

Gastrin

A hormone made in the stomach that controls the release of HCl and pepsinogen and stimulates motility.

Pepsin

An active protease enzyme, formed from pepsinogen, that breaks down protein into peptides.

Mucus (stomach)

Secreted by mucous cells in the stomach to lubricate and protect the stomach lining from digestion by HCl and pepsin.

Prostaglandins

Substances that help maintain mucus production in the stomach; inhibited by NSAIDs and aspirin, potentially leading to stomach damage.

Ghrelin

A hormone produced by the stomach that increases appetite, involved in short-term regulation of food intake.

Chyme

The semi-fluid mass of partly digested food mixed with stomach secretions, which passes from the stomach to the small intestine.

Pyloric Sphincter

The sphincter that controls the release of chyme from the stomach into the small intestine.

Glucose-dependent insulinotropic peptide (GIP)

A hormone that slows the release of chyme into the small intestine.

Small Intestine

The major site of digestion and absorption, divided into the duodenum, jejunum, and ileum.

Duodenum

The first 10-inch section of the small intestine.

Jejunum

The middle 4-foot section of the small intestine.

Ileum

The final 5-foot section of the small intestine.

Villi

Finger-like projections in the small intestine that, along with circular folds and microvilli, increase surface area for absorption and mix chyme.

Enterocytes

Cells lining the villi that secrete enzymes and absorb nutrients.

Microvilli

Tiny, hair-like projections on enterocytes, forming the 'brush border' and covered with digestive enzyme-containing glycocalyx.

Gastrointestinal Microbiota

The population of microorganisms (bacteria) housed in the large intestine that keeps the GI tract healthy, synthesizes vitamins, and aids digestion.

Bile

A fluid produced by the liver, stored in the gallbladder, that aids in fat digestion (emulsifies fats) and absorption.

Emulsification

The process by which bile breaks down large fat globules into tiny fat droplets called micelles.

Enterohepatic circulation

The recycling process where bile is reabsorbed in the ileum and returned to the liver.

Pancreatic Juices

Secretions from the pancreas containing sodium bicarbonate, pancreatic amylase, pancreatic lipase, and proteases.

Sodium bicarbonate (pancreatic)

Component of pancreatic juice that neutralizes acidic chyme entering the small intestine.

Pancreatic amylase

An enzyme in pancreatic juice that digests starch.

Pancreatic lipase

An enzyme in pancreatic juice that digests fats.

Proteases (pancreatic)

Enzymes in pancreatic juice that digest proteins.

Sphincter of Oddi

A sphincter where the bile and pancreatic ducts meet, emptying into the duodenum.

Cholecystokinin (CCK)

A hormone released by the small intestine in response to fat in chyme, stimulating the release of pancreatic enzymes and bile from the gallbladder.

Secretin

A hormone released by the small intestine in response to acidic chyme, stimulating the release of pancreatic bicarbonate.

Motilin

A hormone signaled by gastric distention and fat, stimulating motility and signaling the stomach to slow the release of juices.

Peptide YY (PYY)

A hormone from the ileum and large intestine, released in response to fat, that inhibits gastric and pancreatic secretions.

Somatostatin

A hormone produced in the stomach, small intestine, and pancreas, that inhibits the release of digestive hormones and slows gastric emptying, motility, and blood flow.

Passive Diffusion

A process of nutrient absorption where substances move from a higher to a lower concentration, used for fats, water, and some minerals.

Facilitated Diffusion

A process of nutrient absorption where substances move from a higher to a lower concentration with the help of a carrier protein, used for fructose.

Active Transport

A process of nutrient absorption where substances move from a lower to a greater concentration, requiring energy, used for amino acids and glucose.

Endocytosis

A process of nutrient absorption involving the engulfment of substances by the cell membrane to form a vesicle.

Cardiovascular System

The system including the heart, blood vessels, and blood, which transports water-soluble nutrients via the portal vein to the liver.

Hepatic Portal Vein System

The network of veins that transports water-soluble nutrients from the villi of the small intestine directly to the liver.

Lymphatic System

An alternative route to the bloodstream for large or hydrophobic molecules, transporting fat-soluble nutrients and large particles via lymph vessels to the thoracic duct.

Lacteals

Lymphatic capillaries located within the villi of the small intestine that transport most fats and fat-soluble vitamins.

Ileocecal valve

The valve connecting the small intestine to the large intestine.

Large Intestine

Organ divided into the colon, rectum, and anus, responsible for housing microbiota, forming and expelling feces, and absorbing water and electrolytes.

Probiotics

Live bacteria found in food and supplements that colonize the large intestine and provide health benefits.

Prebiotics

Non-digestible carbohydrates (food ingredients) that promote the growth of beneficial bacteria in the large intestine.

Peptic Ulcer

Small erosions of the top layer of cells in the stomach or duodenum, commonly caused by heavy NSAID use or Helicobacter pylori infection.

Helicobacter pylori

A bacterium that is a main cause of peptic ulcers.

Gallstones

Crystal-like particles formed from cholesterol and bile pigments in the gallbladder, often related to slow gallbladder motility and bile composition.

Food Intolerance

Inability to digest certain food components, often due to deficiencies in digestive enzymes, sensitivities, contaminants, or chemical residues.

Intestinal Gas (Flatulence)

A mixture of gases, often with an unpleasant odor due to sulfur, caused by the fermentation of undigested carbohydrates by bacteria in the large intestine.

Constipation

Difficult or infrequent bowel movements, characterized by slow movement of fluid absorption, with various causes including diet, medications, and medical conditions.

Diarrhea

Loose, watery stools occurring more than three times a day, caused by bacterial/viral infections, parasites, food intolerance, or intestinal diseases, leading to fluid secretion instead of absorption.

Irritable Bowel Syndrome (IBS)

A common digestive disorder characterized by irregular bowel function, abdominal pain, and distension, linked to abnormal intestinal motility, psychosocial distress, altered gut immunity, and intestinal dysbiosis.

Inflammatory Bowel Disease (IBD)

A chronic intestinal disease with recurring inflammation and ulceration, including Ulcerative Colitis and Crohn's disease, linked to an overactive inflammatory response and strong genetic association.

Ulcerative Colitis

A type of IBD involving inflammation and ulceration of the innermost layer of the large intestine.

Crohn's Disease

A type of IBD involving inflammation and ulceration in all layers and any part of the GI tract.

Hemorrhoids

Swollen veins in the anus and lower rectum, often associated with constipation and straining during bowel movements.