The Digestive System

Front 1

Digestion

Back 1

from ingestion to minute particles; small enough to enter body cells

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Absorption

Back 2

from gastrointestinal tract lumen into blood stream at capillaries

Front 3

gastroenterology

Back 3

sturdy of the stomach and intestines

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Proctolog

Back 4

study of the rectum and anus (diagnosis and treatment)

Front 5

Digestive System

Back 5

consists of the gastrointestinal tract, associated digestive glands, and accessory structures

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Gastrointestinal Tract (Alimentary Canal)

Back 6

includes the mouth, pharynx, esophagus, stomach, small and large intestine, rectum, and anus

Front 7

Accessory Structures to the GI Tract

Back 7

include teeth, tongue, salivary glands, liver, gall bladder, and pancreas

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Ingestion

Back 8

taking food into the mouth

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Secretion

Back 9

done by the walls of the GI tract and accessory organs (water, acid, buffers, enzymes)

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Mixing and Propulsion

Back 10

done by the smooth muscle in the GI walls (moving food ultimately toward the anus)

Front 11

Mechanical Digestion

Back 11

done by the teeth (mastication) and by smooth muscle churning

Front 12

Chemical Digestion

Back 12

catabolic reactions; enzymes aid; for carbohydrates, proteins, lipids and nucleic acids

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Absorption

Back 13

minute end products of digestion and ions enter epithelial cells of GI tract lining then move into blood and lymph through this process

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Defacation

Back 14

elimination of indigestible substances and bacteria from the anus

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Mucosa

Back 15

deep portion of the GI tract; made of epithelium, areolar connective tissue and a thin smooth muscle layer (causes folds in the inner wall to increase surface area)

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Submucosa

Back 16

areolar-like tissue of the GI tract; holds tissue in place; contains vessels, nerves and glands

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Muscularis

Back 17

layer of the GI tract made mostly of smooth muscle; there are two layers (skeletal muscle in the mouth, pharynx, upper esophagus and in external anal sphincter, the rest is smooth muscle tissue)

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Serosa

Back 18

layer of the GI tract that is made of simple squamous epithelium; minimizes friction on the outside of the GI tract

Front 19

Visceral Peritoneum

Back 19

inferior to the diaphragm; covers all abdominal organs within the peritoneum

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Parietal Peritoneum

Back 20

lines the wall of the peritoneal cavity

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Peritoneal Cavity

Back 21

within the parietal peritoneal lining; almost synonymous with the abdominal cavity (kidneys, pancreas, and duodenum are retroperitoneal)

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Retroperitoneal

Back 22

in the abdominal cavity but outside of the peritoneal cavity

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Greater Omentum

Back 23

drapes anteriorly over the transverse colon and small intestine; contains a lot of adipose tissue and lymph nodes; it is attached to the greater curvature of the stomach

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Lesser Omentum

Back 24

suspends the stomach and the duodenum from the liver; it is attached to the lesser curvature of the stomach

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Mesentary

Back 25

extension of the visceral peritoneum of the small intestine; highly vascularized; binds the small intestine to the posterior abdominal wall

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Mesocolon

Back 26

similar to the mesentery except that it binds the transverse colon and sigmoid colon to the posterior abdominal wall; vascularlized

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Falciform Ligament

Back 27

fold of connective tissue that attaches the liver to the anterior abdominal wall and to the diaphragm

Front 28

Enteric Nervous System

Back 28

controls GI tract motility; secretion of mucosal epithelium; local, intrinsic control; activated by means of chemoreceptors and stretch receptors

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Autonomic Nervous System

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regulates the enteric nervous system; sympathetic - inhibits ENS nerves and decreases GI secretion/motility; parasympathetic - increases secretion/motility

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Parotid Gland

Back 30

gland that lies between the skin and the masseter

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Submandibular Gland

Back 31

gland beneath the base of the tongue

Front 32

Sublingual Gland

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gland that is superior to the submandibular gland

Front 33

Functions of Saliva

Back 33

lubricate, dissolve and begin some chemical digestion

Front 34

Water

Back 34

99.5% of saliva; dissolves food, therefore is for taste and begins digestive reactions

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Mucus

Back 35

part of saliva that lubricates food and helps form the bolus

Front 36

Amylase (ptylin)

Back 36

part of saliva that is from the parotid glands mostly; for starch digestion

Front 37

Lysozyme

Back 37

Part of saliva that is responsible for destroying bacteria

Front 38

Tongue

Back 38

skeletal muscle; attached to hyoid, styloid process of the temporal bone and mandible

Front 39

Peiodontal Ligament

Back 39

anchors the tooth in the socket

Front 40

Crown

Back 40

visible portion of the tooth

Front 41

Root

Back 41

portion of the tooth embedded in the socket

Front 42

Neck (cervix)

Back 42

constriction of the tooth between the crown and root

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Dentin

Back 43

calcified connective tissue; gives the tooth its shape; encloses the cavity

Front 44

Pulp

Back 44

the cavity in the crown of a tooth is filled with this; connective tissue with blood vessels, nerves and lymph vessels

Front 45

Root Canals

Back 45

narrow extensions of pulp cavity into the root

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Enamel

Back 46

CaPO4 and CaCO3 covers dentin on the crown; hardest substance in the body; for protection

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Cementum

Back 47

covers dentin on the root

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Dentitions (teeth)

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primary organ for mechanical digestion (two sets)

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Decidious/Primary Teeth (milk or baby teeth)

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begin to erupt at about 6 months old; lost between 6 and 12 years of age

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Permanent/Secondary Dentition

Back 50

Incisors (8)
Canines (cuspids) (4)
Premolars (Bicuspids) (8)
Molars (12)

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Bolus

Back 51

soft mass of chewed and mixed food

Front 52

Physiology of Digestion in the Mouth

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Mechanical digestion (mastication) creates bolus, chemical digestion - salivary amylase digests starch (polysaccharide); digestion continues in stomach for about an hour; lingual lipase is to digest triglycerides into fatty acids and monoglycerides

Front 53

Pharynx

Back 53

"throat"; from the internal nares to the esophagus and larynx, there are three sections

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Esophagus

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muscular; collapsible; posterior to the trachea

Front 55

Esophageal Hiatus

Back 55

opening through the diaphragm for the esophagus to descend

Front 56

Hiatal Hernia

Back 56

a potion of the abdominal viscera protrudes into the thoracic cavity through the esophageal hiatus

Front 57

Upper Esophageal Sphincter

Back 57

muscularis layer forms a spherical sphincter muscle; skeletal muscle tissue; regulates movement of food from the pharynx into the esophagus

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Lower esophageal sphincter

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muscularis forms sphincter at the inferior end of the esophagus; smooth muscle tissue; regulates movement of food from the esophagus into the stomach

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Physiology of Deglutition (swallowing)

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to the oropharynx, through the pharynx, through the eophagus; involves the medulla oblongata and pons; to the oropharynx is the only voluntary movement

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Functions of the stomach

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reservoir for discontinous feeding; some digestion initiated; mixing of ingested contents; small amount of absorption

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Cardia

Back 61

superior portion of the stomach; closest to the heart; sphincter at the beginning of the cardia is a one-way reflex for entrance

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Fundus

Back 62

portion of the stomach that is superior to the entrance; rounded; superior and left of the cardia

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body

Back 63

portion of the stomach that is centrally located

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Pylorus

Back 64

last portion of the stomach; tapered; at the terminal aspect is the pyloric sphincter

Front 65

Pyloric Sphincter (valve)

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relaxes enough for liquids only to pass; when stomach is empty, indigestible remnants (e.g. seeds) will pass through

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Rugae

Back 66

inner folds of the stomach when empty; allow distension; increase surface area

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Gastric Pits and Gastric Glands

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secretions for the stomach are made here

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Mucous Neck and Surface Cells

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these cells make mucus (mucin) which protects own cells from digestion

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Chief Cells

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these cells make pepsinogen and gastric lipace (gastric juice)

Front 70

Parietal Cells

Back 70

these cells make HCl (low pH activates enzyme)

Front 71

Mixing Waves (peristalsis)

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from one end of the stomach to the other and back again

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Chyme

Back 72

fluid produced from the breakdown process of peristalsis

Front 73

Pepsinogen

Back 73

inactive form of pepsin; secreted and low pH changes it to pepsin; otherwise pepsin would digest the glands that produce it

Front 74

Pepsin

Back 74

causes proteins to become peptides

Front 75

HCl

Back 75

kills microbes, partially denatures proteins, stimulates hormone secretion to increase bile and pacreatic juice; activates pepsinogen

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Gastric Lipase

Back 76

triglycerides (especially in milk fat) to fatty acid and monoglyceride (limited role in adults)

Front 77

Mucus (mucin)

Back 77

protects our cells from digestion; helps bolus form (alkaline)

Front 78

Regulation of Gastric Emptying

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rate depends on contents; 2-4 hours; carbohydrates first, then protein, and last fat

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Gastric Absorption

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water, ions, short fatty acids, some drugs (especially aspirin), and alcohol

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Pancreas

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has endocrine and digestive exocrine functions

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Pancreatic duct

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from pancreas to join common bile duct then all empty into the duodenum

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Accessory Duct

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pancreas empties into the first part of the small intestine (duodenum)

Front 83

Pancreatic Juice

Back 83

mostly water secreted; also pancreatic amylase, trypsin, chymotrypsin, carboxypeptidase, pancreatic lipase, ribuluclease, deoxyribonuclease, and bicarbonate

Front 84

Pancreatic Amylase

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for carbohydrates (same as salivary); glycogen and stages to disaccharides

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Trypsin, Chymotrypsin and carboxypeptidase

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for proteins; these are proteases

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Pancreatic Lipase

Back 86

for lipids (same as gastric lipase)

Front 87

Ribonuclease and Deoxyribonuclease

Back 87

for RNA and DNA digestion

Front 88

Bicarbonate

Back 88

buffers gastric juice; creates correct pH for enzyme action in small intestine

Front 89

Endocrine function of Pancreas

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Insulin and Glucagon production (insulin - decrease blood sugar levels; glucagon - increase)

Front 90

Falciform ligament

Back 90

extension of membrane from the abdominal wall; holds liver in place and lobes together

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Gallbladder

Back 91

reservoir for bile

Front 92

Bile

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stored in the gall bladder; made by the liver; function is to emulsify fats

Front 93

Emusification of fats

Back 93

breaks big fat droplets into smaller

Front 94

Bilirubin

Back 94

continuously produces; browning-yellow' from breakdown of hemoglobin; is the principle bile pigment

Front 95

Sinusoids

Back 95

inside the liver; cavities act like capillaries; blood accumulates for adjustments (absorption and secretion)

Front 96

Bile Canaliculi - bile ducts - common hepatic duct

Back 96

travel of bile through the liver

Front 97

Cystic Bile Duct

Back 97

two-way tube; stores and releases bile from the gall bladder; runs between the gall bladder and the common hepatic duct

Front 98

Common Bile Duct

Back 98

common hepatic duct and cystic duct join to make this, which ultimately leads to the duodenum to empty blood supply

Front 99

Hepatic Artery

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supplies 20% of the total blood that is delivered to the liver

Front 100

Hepatic Vein

Back 100

drains blood from the liver and leads to the inferior vena cava

Front 101

Portal Vein

Back 101

80% of the blood that goes to the liver comes from this; capillaries of digestion and the spleen send blood via this to the capillaries of the liver (adjustments) to the hepatic vein

Front 102

Functions of the liver

Back 102

synthetic/anabolic reactions, catabolic reactions, processing of drugs and hormones/detoxification, production and excretion of bile, storage, erythrocyte/leukocyte/microbial phagocytosis, activation of vitamin D, blood cell formation (as a fetus)

Front 103

Synthetic/Anabolic Reactions

Back 103

enzymes to manufacture just about anything needed

Front 104

Catabolic Reactions

Back 104

destruction of just about anything by the liver

Front 105

Processing of drugs and hormones/detoxification

Back 105

removes chemicals from the blood that don't belong; e.g. alcohol, bilirubin, DDT, PCBs

Front 106

Storage by the liver

Back 106

generally about 24 hour supply of nutrients; except glycogen (4-6 hours); fat-soluble vitamins (2-3 months...e.g. ADEK); also Fe, Cu

Front 107

Functions of the Small Intestine

Back 107

completion of digestion and almost all absorption (most of digestion/absorption)

Front 108

Parts of the Small Intestine

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Duodenum, jejunum, ileum

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Duodenum

Back 109

first 10" (25 cm) of small intestine; pyloric valve to the first curve; large amounts of digestive enzymes added

Front 110

Jejunum

Back 110

middle 3 ft (1 m) of small intestine; digestive secretions added; much digestion and absorption begins

Front 111

Ileum

Back 111

Last 6 ft (2 m) of small intestine; primarily absorption

Front 112

Ileocecal Valve

Back 112

separates ileum and cecum; one way valve; keeps microbes out of the small intestine

Front 113

Microvilli

Back 113

finger-like projections of the simple columnar epithelial cells of the small intestine; into the lumen

Front 114

Brush Border Enzymes

Back 114

made by and inserted into the absorptive cells of intestinal lining; thus digestive action at the lining as well as in the lumen

Front 115

Villi

Back 115

finger-like projections of the mucosa; give intestines a velvety appearance

Front 116

Intestinal Glands (Crypts of Lieberkuhn)

Back 116

at the base of each villus; a cluster of cells; rapid cell division; completely replace lining every 24 hours

Front 117

Capillary Plexus/Lacteals

Back 117

for end products of digestion

Front 118

Circular Folds (Plicae Circulares)

Back 118

on the inside of the small intestine; increase surface area for secretion and absorption; deeper invaginations than villi

Front 119

Segmentation

Back 119

mechanical digestion of small intestine; forward and backward short distances and constrictions; circular muscles

Front 120

Peristalsis

Back 120

mechanical digestion of small intestine; forward a distance (not back)

Front 121

Mucus Glands (Brunner's)

Back 121

chemical digestion of small intestine; prevent digestion of small intestine lining

Front 122

Intestinal Glands and Brush Border Enzymes

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chemical digestion of small intestine; produce digestive secretions

Front 123

Intestinal Juice

Back 123

produced by intestinal glands; water mostly, some mucus, some enzymes (disaccharides to monosaccharides); also proteins

Front 124

Maltase

Back 124

maltose or matotriose to 2 or 3 glucose

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Sucrase

Back 125

sucrose to glucose and fructose

Front 126

Lactase

Back 126

lactose to glucose and galactose

Front 127

Enterokinase

Back 127

activates trypsinogen into trypsin for use in protein digestion

Front 128

Peptidases

Back 128

complete protein digestion

Front 129

Nucleosidases and Phosphatases

Back 129

Nucleotide digestion to bases, pentoses and phosphates

Front 130

Carbohydrates

Back 130

monosaccharides (glucose, galactose and fructose) are formed by these

Front 131

Proteins

Back 131

Amino acids are formed by these

Front 132

Lipids

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Fatty Acids and monoglycerides are formed by these

Front 133

Lipoproteins

Back 133

carrier molecules for transport; lacteals

Front 134

Electrolytes

Back 134

Conserved in the process of absorption by the small intestine

Front 135

Vitamins

Back 135

conserved in the process of absorption by the small intestine; are organic compounds; most we can't make; for regulation of metabolic reactions

Front 136

Water

Back 136

about 90% absorbed by small intestine

Front 137

Portal-Hepatic Vein

Back 137

end products of digestion by the small intestine are absorbed and sent to the liver by this