Halloran Honors Bio - 05 Ch31 Digestion

Nutrient

Any substance an organism uses for metabolism, growth, maintenance, and repair

Ingestion

The act of taking food into the digestive tract

Mechanical Digestion

The breaking of food into physically smaller pieces (does not alter the molecules)

Chemical Digestion

The chemical breakdown of the biomolecules in food from polymer to monomer

Absorption

The process of taking in and incorporating nutrients (the movement of biomolecule monomers from the digestive tract to the cells)

Elimination

The expulsion of waste from the body

Herbivore

Organism that eats plants

Carnivore

Organism that eats meat/other animals

Omnivore

Organism that eats both plant and animal based foods

Insectivore

Carnivore that eats mainly insects

Frugivore

Herbivore that eats mainly fruits

Piscivore

Carnivore that eats mainly fish

Foliovore

Herbivore that eats mainly foliage

Bulk Feeder

Organism that ingests large pieces of food; tend to eat discontinuously (had distinct periods of eating vs not eating)

Fluid Feeder

Organism that drinks its meal; can include pollinators and parasites

Suspension/Filter Feeders

Organisms that strain food particles from the water they live in

Substrate Feeders

Organisms that live on, or in, the material they eat; tend to be continuous feeders

Intracellular Digestion

Digestion that occurs entirely inside the cell (most likely within a food vacuole)

Extracellular Digestion

Digestion that occurs outside of the body's cells and then is absorbed; conducted by organisms with a gastrovascular cavity or gastrointestinal tract

Gastrovascular Cavity

Incomplete digestive tract; digestive chamber with only one opening

Alimentary Canal

Complete digestive tract; has two openings (mouth and anus) and a unidirectional flow of food; the actual pathway the food follows through the organism; also called a gastrointestinal tract

Gastrointestinal Tract

Complete digestive tract; has two openings (mouth and anus) and a unidirectional flow of food; the actual pathway the food follows through the organism; also called an alimentary canal

Paramecium

A single-celled protist that conducts intracellular digestion

Hydra

A simple, soft-bodied animal; feeds using tentacles, has a gastrovascular cavity and conducts extracellular digestion

Ruminant Herbivore

Herbivore with a rumen; eats mainly grasses and regurgitates food to remasticate

Rumen

Four-chambered organ specialized for grass digestion

Mouth

Entrance to the gastrovascular cavity or the gastrointestinal tract; performs both mechanical and chemical digestion in humans

Teeth

Accessory structures in the mouth that aid with mechanical digestion

Incisor

Teeth with a thin, sharp cutting edge that are used for cutting and biting; two central and two lateral on both upper and lower jaw in humans (8 total) (the front teeth)

Canine

A pointed tooth used to grip and tear; the cuspid teeth; 4 total in humans

Premolar

The teeth immediately behind the canines; used in chewing, grinding, and shearing food; the bicuspid teeth; 8 total in humans

Molar

The rear teeth with a flat surface used for grinding and crushing food; the sixth, seventh, and eighth teeth from the middle of the dental arch in humans; the rear most molars are referred to as the wisdom teeth; 12 total

Tongue

Muscular accessory organ in the mouth used to manipulate food during chewing and swallowing; helps mix food with saliva

Hard/Soft Palate

The roof of the mouth; hard and bony just behind the teeth, transitioning to soft and pliable toward the pharynx; ends with the uvula

Uvula

Projection hanging from the center edge of the soft palate; helps initiate gag reflex

Tonsils

Collections of lymphatic tissue located on each side of the throat

Parotid Salivary Gland

Largest of the salivary glands; lies just under the skin in front of and slightly below the external ear; its duct passes across the masseter (cheek) muscle to deliver the saliva to the mouth just to the side of second upper molars.

Sublingual Salivary Gland

Salivary gland located toward the middle front of the floor of the mouth, below the tongue; delivers saliva through 12 small ducts

Submandibular Salivary Gland

Salivary gland located just inside the mandible toward the base of the tongue; delivers saliva via the submandibular duct

Salivary Amylase

Enzyme in saliva that breaks down starch to disaccharides (amylose to maltose)

Bolus

A soft mass of chewed food mixed with saliva

Pharynx

The passageway that leads food from the mouth to the esophagus; region also known as the throat; extends from just behind the nasal cavity to the trachea

Epiglottis

cartilage that covers the opening of the trachea, routing food toward the esophagus during swallowing

Esophagus

muscular tube that leads from the pharynx to the stomach

Mucosa

The tissue layer that forms the inner epithelial (skin) lining of the digestive tract

Submucosa

The tissue layer of the human digestive system just below the mucosa that contains nerves, blood vessels, and lymph nodes

Muscularis

The tissue layer of smooth muscle in the GI tract, responsible for movement, motility and peristalsis

Peristalsis

Involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system

Stomach

A J-shaped, muscular pouch located in the abdomen that conducts mechanical and chemical digestion of food

Rugae

Ridges or folds in the stomach mucosa that allow for expansion of the organ

Cardiac Sphincter

Circular ring of muscle that permits food from the esophagus to enter the stomach and prevents the reflux of chyme back out of the stomach

Pyloric Sphincter

Circular ring of muscle that regulates the movement of chyme from the stomach into the duodenum

Gastric Pit

Small pores in the stomach mucosa, lined with three types of epithelial cells that produce the components of gastric juice

Epithelial cells

Skin cells that cover the external body surface and line the internal surface of the gastrointestinal tract; the cells that make up the mucosa

Mucous cell

Epithelial cell in the stomach that secretes mucus

Parietal cell

Epithelial cell in the stomach that secretes HCl

Chief cell

Epithelial cell in the stomach that secretes pepsinogen

Hydrochloric acid (HCl)

Secreted by the parietal cells in the gastric pits of the stomach mucosa

Pepsinogen

Secreted by the chief cells in the gastric pits of the stomach mucosa; Enzyme precursor activated by HCl to form the active enzyme pepsin

Pepsin

Enzyme in the stomach that catabolizes proteins to peptides

Chyme

Semi-fluid mass of food and gastric juice that moves from the stomach to the small intestine

Liver

Accessory organ to the digestive tract that produces bile

Gall Bladder

Pouch associated with the liver that stores bile

Bile

Substance produced by the liver and secreted to the duodenum that emulsifies fats

Emulsify/Emulsification

To break into smaller droplets

Bile Duct

Leads from the gall bladder to the duodenum

Glucose

Monosaccharide found in the bloodstream; anabolized and stored as the polysaccharide glycogen in the liver

Glycogen

Energy-storage polysaccharide found in the liver; catabolized into glucose when blood sugar levels drop

Pancreas

Accessory organ to the digestive system that produces pancreatic juice

Pancreatic Duct

Leads from the pancreas to the duodenum

Pancreatic Amylase

Enzyme that catabolizes starch to dissacharides (amylose to maltose); produced by the pancreas

Trypsin/Chymotrypsin

Enzymes that catabolize proteins to peptides; produced by the pancreas

Nuclease

Enzyme that catabolizes nucleic acids to nucleotides; produced by the pancreas

Lipase

Enzyme that catabolizes fats to monoglycerides and fatty acids; produced by the pancreas

Sodium Bicarbonate

Base produced by the pancreas that helps neutralize chyme from the stomach

Insulin

Hormone produced by the pancreas that triggers the body to take glucose from the bloodstream and store it as glycogen in the liver

Glucagon

Hormone produced by the pancreas that triggers the body to breakdown glycogen in the liver and deliver the resulting glucose to the bloodstream

Small Intestine

The part of the gastrointestinal tract following the stomach where the vast majority of digestion and absorption of food takes place

Duodenum

The first part of the small intestine; receives bile from the gallbladder and pancreatic juice from the pancreas; main purpose is further chemical digestion of food

Jejunum

Second part of the small intestine; mainly responsible for the absorption of monosaccharides and amino acids

Ileum

Third part of the small intestine; mainly responsible for the absorption of fats, water, vitamins, and minerals

Villi

Finger-like projections of the small intestinal mucosa that increase the surface area for absorption

Lacteal

Lymphatic vessel found in the center of a villus responsible for the absorption of lipids

Microvilli/Brush Border

Finger-like extensions of the cell membrane of intestinal epithelial cells; increase surface area and aid in absorption of nutrients; produced final digestive enzymes

Maltase

Enzyme that catabolizes the dissacharide maltose to monosacchrides; produced by the microvilli

Sucrase

Enzyme that catabolizes the dissacharide sucrose to monosacchrides; produced by the microvilli

Lactase

Enzyme that catabolizes the dissacharide lactose to monosacchrides; produced by the microvilli

Peptidase

Enzyme that catabolizes peptides to amino acids; produced by the microvilli

Nucleotidase

Enzyme that catabolizes nucleotides to pentose sugar, nitrogenous bases and inorganic phosphate; produced by the microvilli

Large Intestine

The part of the gastrointestinal tract following the small intestine; largely responsible for the reabsorption of water and the elimination of feces

Ileocecal Valve

Sphincter that controls movement from the ileum of the small intestine to the cecum of the large intestine

Cecum

The pouch at the entrance to the large intestine; may be quite large in herbivores to house bacteria that help ferment cellulose

Appendix

A small, finger-like extension of the cecum; contains white blood cells that contribute to immunity

Ascending Colon

Part of the large intestine that extends upward along the right side of the body from the cecum toward the transverse colon

Transverse Colon

Part of the large intestine that crosses the body from right to left, connecting ascending colon to descending colon

Descending Colon

Part of the large intestine that extends down the left side of the body, connecting transverse to sigmoid colon

Sigmoid Colon

The S-shaped portion of the large intestine between the descending colon and the rectum

Rectum

A short tube at the end of the large intestine where waste material is compressed into a solid form before being eliminated

Anus

A muscular opening at the end of the rectum through which waste material is eliminated from the body

Bacterial Flora

Live in our large intestine; help us to break down certain biomolecules that we lack the enzymes to properly digest; can sometimes release irritating gas as a byproduct of their metabolism; synthesize vitamins B and K; competitively exclude the proliferation of harmful bacteria