A&p 23

Front 1

Alimentary Canal

Back 1

Gastrointestinal/GI Tract; Digests and absorbs food; Mouth, pharynx esophagus, stomach, small intestine, large instestine

Front 2

Accessory Digestive Organs

Back 2

Teeth, tongue, gallbladder; Digestive glands - Salivary glands, liver, pancreas

Front 3

Digestive Processes

Back 3

Ingestion; Propulsion (peristalsis and segmentation); Mechanical digestion (mastication/liquification); Chemical Digestion (breakup macromolecules via hydrolytic enzymes); Absorption (active transport, facilitated diffusion, pinocytosis); Defecation

Front 4

Mechanoreceptors and Chemoreceptors

Back 4

Respond to stretch, changes in osmolarity and pH, and presence of substrate and end products of digestion; Initiate reflexes that activate/inhibit digestive glands, stimulate smooth muscle to mix and move lumen contents

Front 5

Enteric Nerve Plexuses

Back 5

Gut brain; Initiate short reflexes in response to stimuli in GI tract

Front 6

Long Reflexes

Back 6

In response to stimuli in or outside the GI tract; Involve NCS centers (esp. medulla oblongata) and autonomic nerves (parasympathetic division)

Front 7

Gastrin

Back 7

Hormone in stomach that stimulates target cells in same or different organs

Front 8

Secretin and CCK

Back 8

Hormones in small intestine that stimulate target cells in same or different organs

Front 9

Peritoneum

Back 9

serous membrane of abdominal cavity; Visceral Peritoneum on external surface of most digestive organs; Parietal peritoneum lines body wall

Front 10

Peritoneal Cavity

Back 10

Between the two peritoneums; Fluid lubricates mobile organs

Front 11

Arteries (Splanchnic Circulation)

Back 11

Hepatic, splenic, left gastric; Inferior and superior mesenteric

Front 12

Hepatic Portal Circulation

Back 12

Drains nutrient rich blood from digestive organs; Delivers it to liver for processing

Front 13

Alimentary Canal Histology

Back 13

Basic Layers - Mucosa, submucosa, muscularis externa, serosa

Front 14

Mucosa

Back 14

Lines lumen; Secretes mucus, digestive enzymes, and hormones, absorbs end products of digestion, protects against infectious disease; Three sublayers are epithelium, lamina propria, and muscularis mucosae

Front 15

Epithelium

Back 15

Simple columnar and mucus secreting cells; Mucus protects digestive organs from enzymes and eases food passage; May secrete enzymes and hormones

Front 16

Lamina Propria

Back 16

Loose areolar connective tissue; Capillaries for nourishment and absorption; Lymphoid follicles (part of MALT)

Front 17

Muscularis Mucosae

Back 17

Smooth muscle that produces local movements of mucosa

Front 18

Submucosa

Back 18

Dense connective tissue; Blood and lymphatic vessels, lymphoid follicles, and submucosal nerve plexus

Front 19

Muscularis Externa

Back 19

Responsible for segmentation and peristalsis; Inner circular and outer longitudinal layers; Myenteric nerve plexus; Sphincters in some regions

Front 20

Visceral Peritoneum

Back 20

Replaced by fibrous adventitia in esophagus; Retroperitoneal organs have both an adventiita and serosa

Front 21

Enteric Nervous System

Back 21

Intrinsic nerve supply of alimentary canal; Linked to CNS via afferent visceral fibers

Front 22

Submucosal Nerve Plexus

Back 22

Regulates glands and smooth muscle in mucosa

Front 23

Myenteric Nerve Plexus

Back 23

Controls GI tract motility

Front 24

Long ANS Fibers

Back 24

Synapse with enteric plexuses; Sympathetic impulses inhibit secretion and motility; Parasympathetic impulses stimulate

Front 25

Oral (buccal) Cavity

Back 25

Bounded by lips, cheeks, palate, tongue; Oral orifice is anterior opening; Lined with stratified squamous epithelium; Salivary glands release secretions here

Front 26

Salivary Glands

Back 26

Intrinsic (buccal) salivary glands are scattered in oral mucosa

Front 27

Saliva (Secretion)

Back 27

Cleanses mouth; Moistens and dissolves food chemicals; Aids in bolus formation; Contains enzymes that begin breakdown of starch

Front 28

Parotid Gland (Salivary)

Back 28

Anterior to ear external to the masseter muscle; Parotid duct opens into vestibule next to second upper molar

Front 29

Submandibular Gland (Salivary)

Back 29

Medial to body of mandible; Duct opens at base of lingual frenulum

Front 30

Sublingual Gland (Salivary)

Back 30

Anterior to submandibular gland under tongue; Opens via 10 - 12 ducts into floor of mouth

Front 31

Composition of Saliva

Back 31

Secreted by serous and mucous cells; 97 - 99.5 % water, slightly acidic solution containing electrolytes, salivary amylase and lingual lipase, mucin, metabolic wastes - urea and uric acid, and lysozyme, lgA, defensins, and a cyanide compound protect against microorganisms

Front 32

Intrinsic Salivary Glands

Back 32

Keep mouth moist

Front 33

Extrinsic Salivary Glands

Back 33

Ingested food stimulates chemoreceptors and mechanoreceptors in mouth; Salivatory nuclei in brain stem sends impulses along parasympathetic fibers in cranial nerves VII and IX

Front 34

Strong Sympathetic Stimulation

Back 34

Inhibits salivation and results in dry mouth (xerostomia)

Front 35

Oropharynx and Laryngopharynx

Back 35

Allow passage of food, fluids, air; Stratified squamous epithelium lining; Skeletal muscle layers - inner longitudinal, outer pharyngeal constrictors

Front 36

Esophagus

Back 36

Flat muscular tube from laryngopharynx to stomach; Pierces diaphragm at esophageal hiatus; Joins stomach at cardiac orifice; Adventitia instead of serosa

Front 37

Esophageal Mucosa

Back 37

Contains stratified squamous epithelium; Changes to simple columnar at stomach

Front 38

Esophageal Glands

Back 38

In submucosa; Secrete mucus to aid in bolus movement

Front 39

Muscularis (Esophagus)

Back 39

Skeletal superiorly; smooth inferiorly

Front 40

Mouth Digestive Processes

Back 40

Ingestion; Mechanical digestion - mastication is partly voluntary, partly reflexive; Chemical digestion (salivary amylase and lingual lipase); Propulsion - deglutition (swallowing)

Front 41

Deglutition

Back 41

Involves tongue, soft palate, pharynx, esophagus, and 22 muscle groups; Buccal phase - voluntary contraction of tongue; Pharyngeal-esophageal phase - involuntary, control center in medulla and lower pons

Front 42

Buccal Phase (Deglutition)

Back 42

Upper esophageal sphincter is contracted; Tongue presses against hard palate, forcing food bolus into oropharynx where the involuntary phase beings

Front 43

Pharyngeal Phase (Deglutition)

Back 43

Uvula and larynx rise to prevent food from entering respiratory passageways; Tongue blocks off mouth; Upper esophageal sphincter relaxes, allowing food to enter esophagus

Front 44

Esophageal Phase (Deglutition)

Back 44

Constrictor musces of pharynx contract, forcing food into esophagus inferiorly; Upper esophageal sphincter contracts (closes) after entry; Food moves to stomach by peristalsis; Gastroesophageal sphinctor opens and food enters stomach

Front 45

Cardiac Region (Cardia)

Back 45

Surrounds the cardiac orifice

Front 46

Fundus

Back 46

Dome shaped region beneath diaphragm

Front 47

Pyloric Region

Back 47

Antrum, pyloric canal, and pylorus; Pylorus is continuous with duodenum through the pyloric valve (sphincter)

Front 48

Greater Curvature

Back 48

Convex lateral suface

Front 49

Lesser Curvature

Back 49

Concave medial surface

Front 50

Lesser Omentum

Back 50

From liver to lesser curvature

Front 51

Greater Omentum

Back 51

Drapes from greater curvature; Anterior to small intestine

Front 52

ANS Nerve Supply

Back 52

Sympathetic via splanchnic nerves and celiac plexus; Parasympathetic via vagus nerve

Front 53

Blood Supply

Back 53

Celiac trunk; Veins of hepatic portal system

Front 54

Mucularis Externa

Back 54

Three layers of smooth muscle; Inner oblique layer allows stomach to churn, mix, move, and physically break down food

Front 55

Mucosa

Back 55

Simple columnar epithelium composed of mucous cells; Layer of mus traps bicarbonate rich fluid beneath; Gastric pits lead into gastric glands

Front 56

Gastric Gland Cell Types

Back 56

Mucous neck cells (secrete thin, acidic mucus); Parietal cells; Chief cells; Enteroendocrine cells

Front 57

Body and Fundus Glands

Back 57

Produce most of the gastric juice

Front 58

Parietal Cell Secretions

Back 58

HCl - pH is 1.5 to 3.5, denatures protein in food, activates pepsin and kills bacteria; Intrinsic factor - glycoprotein required for absorption of vitatim B12 in small intestine

Front 59

Chief Cell Secretions

Back 59

Inactive enzyme pepsinogen; Activated to pepsin by HCl and by pepsin itself (positive feedback mechanism)

Front 60

Enteroendocrine Cells

Back 60

Secrete chemical messengers into lamina propria; Paracrines - serotonin and histamine; Hormones - somatostatin and gastrin

Front 61

Mucosal Barrier

Back 61

Layer of bicarbonate rich mucus; Tight junctions between epithelial cells; Damaged epithelial cells are quickly replaced by division of stem cells

Front 62

Gastritis

Back 62

Inflammation caused by anything that breaches mucosal barrier

Front 63

Peptic or Gastric Ulcers

Back 63

Erosion of stomach wall; Most are caused by Helicobacter pylori bacteria

Front 64

Digestive Processes in Stomach

Back 64

Physical digestion; Denaturation of proteins; Enzymatic digestion of proteins by pepsin (rennin in infants); Secretes intrinsic factor required for B12 absorption (lack of intrinsic factor - pernicious anemia); Delivers chyme to small intestine

Front 65

Gastric Secretion Regulation

Back 65

Neural and hormonal mechanisms; Stimulatory and inhibitory events occur in 3 phases - cephalic, gastric, and intestinal

Front 66

Cephalic (Reflex) Phase

Back 66

Few minutes prior to food entry

Front 67

Gastric Phase

Back 67

3 - 4 hours after food enters stomach

Front 68

Intestinal Phase

Back 68

Brief stimulatory effect as partially digested food enters duodenum, followed by inhibitory effects (enterogastric reflex and enterogastrones)

Front 69

HCl Secretion Regulation and Mechanism

Back 69

ACh, histamine, and gastrin stimulate parietal cells through second messenger systems; All 3 necessary for max HCl secretion; Antihistamines block H2 receptors and decrease HCl release

Front 70

Stomach Filling Response

Back 70

Stretches to accommodate incoming food

Front 71

Reflex-mediated Receptive Relaxation

Back 71

Coordinated by swallowing center of brain stem

Front 72

Gastric Accommodation

Back 72

Plasticity (stretch-relax response) of smooth muscle

Front 73

Gastric Contractile Activity

Back 73

Peristaltic waves move toward pylorus at rate of 3 per minute; Basic electrical rhythm (BER) initiated by pacemaker cells (cells of Cajal); Distension and gastrin increase force of contraction; Most vigorous near pylus

Front 74

Chyme

Back 74

Delivered in 3 ml spurts to duodenum or forced backward into stomach

Front 75

Propulsion

Back 75

Peristaltic waves move from fundus toward pylorus

Front 76

Grinding

Back 76

Most vigorous peristalsis and mixing action occur close to pylorus

Front 77

Retropulsion

Back 77

Pyloric end of stomach acts as a pump that delivers small amounts of chyme into duodenum, simultaneously forcing most of its contained material backward into stomach

Front 78

Gastric Emptying Regulation

Back 78

As chyme enter duodenum receptors respond to stretch and chemical signals, enterogastric reflex and enterogastrones inhibit gastric secretion and duodenal filling; Carb-rich chyme moves quickly though duodenum; Fatty chyme remains in duodenum for 6 hours or more

Front 79

Small Intestine

Back 79

Major organ of digestion and absorption; 2 to 4 m long - from pyloric sphincter to ileocecal valve; Subdivions are Duodenum, Jejunum, and Ileum

Front 80

Duodenum (Retroperitoneal)

Back 80

Bile duct and main pancreatic duct; Join at hepatopancreatic ampulla; Enter duodenum at major duodenal papilla; Are controlled by hepatopancreatic sphincter

Front 81

Jejunum

Back 81

Attached posteriorly by mesentery;

Front 82

Ileum

Back 82

Attached posteriorly by mesentery;

Front 83

Structural Modification of Small Intestine

Back 83

Increase surface area of proximal part for nutrient absorption; Circular folds (plicae circulares), Villi, Microvilli

Front 84

Circular Folds

Back 84

Permanent - 1 cm deep; Force chyme to slowly spiral through lumen

Front 85

Villi

Back 85

Motile fingerlike extensions of mucosa - 1mm high; Villus epithelium - simple columnar absorptive cells (enterocytes), goblet cells

Front 86

Microvilli

Back 86

Projections (brush border) of absorptive cells; Bear brush border enzymes

Front 87

Intestinal Crypts

Back 87

Epithelium; Secretory cell produce intestinal juice; Enteroendocrine cells; Intraepithelial lymphocytes (IELs); Paneth cells; Stem cells

Front 88

Intraepithelial lymphocytes (IELs)

Back 88

Release cytokines that kill infected cells

Front 89

Paneth Cells

Back 89

Secrete antimicrobial agents (defensins and lysozyme)

Front 90

Submucosa of Small Intestine

Back 90

Peyer's patches protect distal part against bacteria; Duodenal (Brunner's) glands of duodenum secrete alkaline mucus

Front 91

Intestinal Juice

Back 91

Secreted in response to distension or irritation of mucosa; Slightly alkaline and isotonic with blood plasma; Largely water, enzyme poor, but contains mucus; Facilitates transport and absorption of nutrients

Front 92

Liver

Back 92

Largest gland in body; Four lobes - right, left, caudate, and quadrate

Front 93

Falciform Ligament

Back 93

Separates the larger right and smaller left lobes; Suspends liver from diaphragm and anterior abdominal wall

Front 94

Round Ligament (Ligamentum Teres)

Back 94

Remnant of fetal umbilical vein along free edge of falciform ligament

Front 95

Associated Structures of Liver

Back 95

Lesser omentum anchors liver to stomach; Hepatic artery and vein at porta hepatis; Bile ducts

Front 96

Bile Ducts of Liver

Back 96

Formed by union of the common hepatic duct, which leaves the liver, and the cystic duct, which connects to the gallbladder

Front 97

Liver Lobules

Back 97

Hexagonal structural and functional units; Filter and process nutrient rich blood; Composed of plates of hepatocytes (liver cells); Longitudinal central vein

Front 98

Portal Triad (Corner of Lobules)

Back 98

Bile duct receives bile from bile canaliculi; Portal arteriole is branch of hepatic artery; Hepatic venule is branch of hepatic portal vein

Front 99

Liver Sinusoids

Back 99

Leaky capillaries between hepatic plates

Front 100

Kupffer Cells

Back 100

Hepatic macrophages in liver sinusoids

Front 101

Hepatocyte Functions

Back 101

Process bloodborne nutrients; Store fat-soluble vitamins; Perform detoxification; Produce 900 ml of bile per day

Front 102

Bile

Back 102

Yellow green; alkaline solution containing bile salts, bilirubin, and cholesterol, nuetral fats, phospholipids, electrolytes

Front 103

Bile Salts

Back 103

Cholesterol derivatives that function in fat emulsification and absorption

Front 104

Bilirubin

Back 104

Pigment formed from heme

Front 105

Enterohepatic Circulation

Back 105

Recycles bile salts; Bile salts to duodenum to reabsorption from ileum to hepatic portal blood to liver to being secreted in bile

Front 106

Gallbladder

Back 106

Thin walled muscular sac on ventral surface of liver; Stores and concentrates bile by absorbing it water and ions; Releases bile via cystic duct, which flows into bile duct