A&p Ii Lecture Exam 3 Ch 21

Front 1

Primary digestive organs

Back 1

1. mouth
2. oral cavity, teeth, tongue
3. pharynx
4. esophagus
5. stomach
6. small intestine
7. anus

Front 2

Accessory digestive organs

Back 2

1. salivary glands
2. liver
3. gallbladder
4. pancreas

Front 3

Primary function of hollow organs

Back 3

breaking down and absorption of nutrients

Front 4

Function of the digestive SYSTEM

Back 4

- breaking down and absorption of nutrients
- accessory organs produce secretions containing water, enzymes, buffers and other components that assist in preparing nutrients for absorption

Front 5

Functions of the digestive TRACT (6)

Back 5

- Ingestion: occurs in oral cavity, foods and liquids enter the digestive tract
-Mechanical processing: occurs in oral cavity and stomach
- Digestion: occurs through out GI tract, chemical and enzymatic breakdown of food into small organic molecules that can be absorbed by the digestive epithelium
- Secretion: occurs throughout GI tract, although it occurs throughout most acids, enzymes and buffers required for digestion provided by the accessory digestive organs
- Absorption: occurs primarily in the small intestine some absorption occurs in the large intestine. Movement of organic molecules, electrolytes, vitamins and water across the digestive epithelium and into the interstitial fluid
- Compaction: occurs in large intestine, progressive dehydration of indigestible materials and organic wastes prior to elimination from the body

Front 6

Function of oral cavity, teeth, tongue

Back 6

mechanical processing, moistening, mixing with salivary secretions

Front 7

Function of pharynx

Back 7

muscular propulsion of materials into the esophagus, common passageway for food and air

Front 8

Function of the esophagus

Back 8

transport of materials to the stomach

Front 9

Function of the stomach

Back 9

chemical breakdown of materials via acid and enzymes; mechanical processing through muscular contractions

Front 10

Function of the small and large intestine

Back 10

enzymatic digestion and absorption of water, organic substrates, vitamins and ions

Front 11

4 layers of the gastro intestinal tract

Back 11

-Mucosa
-Submucosa
-Muscularis Externa
-Serosa

Front 12

What is: Mucosa

Back 12

inner lining of digestive tract is a mucus membrane consisting of cuboidal and columnar epithelium

Front 13

What is: Submucosa

Back 13

layer of dense irregular connective tissue. Contains blood vessels, nerves and glands

Front 14

What is: Muscularis Externa

Back 14

smooth muscle in 2 layers for movement along tract and mechanical processing (circular muscle=twisting, longitudinal muscle=shortening)

Front 15

What is: Serosa

Back 15

visceral peritoneum in most segments. Replaced by adventitia on oral cavity, pharynx, esophagus and anus

Front 16

Mesentary

Back 16

- Double sheet of peritoneal membrane with areolar tissue between
- Provides access route for blood vessels, nerves, and lymphatic vessels
- Stabilizes position of attached digestive organs

Front 17

Mucosa Components - Epithelium

Back 17

- Tract begins and ends with stratified squamous epithelium
- Stomach, small intestine and large intestine are simple columnar

Front 18

Mucosa Components - Villi

Back 18

Small mucosal projections that increase surface area

Front 19

Mucosa Components - Lamina Propria

Back 19

areolar tissue containing: blood vessels, sensory nerve endings, lymphatic vessels, smooth muscle cells, lymphoid tissue, and some mucus glands

Front 20

Mucosa Components - Muscularis mucosae

Back 20

- two layers of smooth muscle (inner circular, outer longitudinal)
- Alter the shape of the lumen and move plicae circularis and villi

Front 21

Plicae Circularis

Back 21

permanent transverse folds in intestinal lining

Front 22

Submucosa Components

Back 22

- Submucosal glands: secretions carried to lumen by ducts
- Submucosal plexus: nerve network innervating mucosa and submucosa. Contains: sensory neurons, autonomic nerve fibers

Front 23

Muscularis Externa Components

Back 23

- 2 muscle layers: inner circular, outer longitudinal
- Myenteric Plexus: network of sensory neurons and autonomic neurons (between two muscle layers). Works with submucosal plexus to coordinate local control of digestive activity

Front 24

Smooth muscle

Back 24

- Found in most organs of the body
- Forms sheets, bundles or sheaths around other tissue
- Lacks myofibrils and sarcomeres (no striations=smooth appearance)
- Contraction produces shortening=corkscrew movement

Front 25

What does smooth muscle do in the digestive tract?

Back 25

Regulates movement along digestive tract (circular and longitudinal layers)

Front 26

Smooth muscle characteristics - Plasticity

Back 26

can adapt to various lengths and can still contract, important for digestive tract and other organs that change size and shape

Front 27

Smooth muscle characteristics - smooth muscle tone

Back 27

normal background activity and tension due to various stimulations

Front 28

Type of digestive movement - Peristalsis

Back 28

waves of muscle contraction that propel bolus (moist compact mass of food) through digestive tract
- circular muscle contracts behind bolus
- not for digestion/breakdown, mainly for movement

Front 29

Type of digestive movement - Segmentation

Back 29

- cycles of contraction that churn and fragment bolus
- occurs in many areas of the small intestine and some areas of the large intestine
-"breaking down" of food

Front 30

Control of digestive system - local factors

Back 30

primary stimulus for digestive activities
- Ex. pH, physical distortion, presence of chemicals

Front 31

Control of digestive system - neural control mechanisms

Back 31

-short reflexes: myenteric plexus neuron response to local factors
long reflexes: interneurons and motor neurons of CNS generally controlling movement from one digestive tract region to another (Synapse with neurons in myenteric plexus)

Front 32

Control of digestive system - hormonal control mechanisms

Back 32

- peptides produced by enteroendocrine cells within epithelium of digestive tract
- at least 18 hormones

Front 33

Oral Cavity

Back 33

- Lined by oral mucosa (stratified squamous)
- Keratinized in areas exposed to severe abrasion
- Nutrients NOT absorbed here
- Digestion of lipids and carbs start here

Front 34

Oral Cavity Boundaries - Superior

Back 34

- Hard Palate
- Soft Palate

Front 35

Oral Cavity Boundaries - Anterior and Lateral

Back 35

- Cheeks (mucosa lined, adipose and buccinator muscle within)
- Labia (lips), vestibule (space between teeth and lips), labial frenulum (attachment to gums)
- Body of tongue

Front 36

Oral Cavity Boundaries - Posterior

Back 36

- uvula (prevents food from entering the pharynx)
- palatine tonsils (oropharynx)
- root of tongue (marked by circumvallate papillae)
- lingual tonsil (base of tongue)

Front 37

Oral Cavity Boundaries - Inferior

Back 37

- tongue: lingual frenulum (floor of mouth), secretes: water, mucins, enzyme (lingual lipase=lipid digestion)
- Geniohyoid and mylohyoid muscle (support)

Front 38

Oral cavity structures and organs

Back 38

- pharyngeal arches: sides of uvula
- fauces: connection between oral cavity and oropharynx
- gingivae: gums, border each tooth
- salivary glands
- teeth

Front 39

Tooth regions

Back 39

- crown: projects into oral cavity
- neck: boundary between crown and root
- root: fits into bony cavity or alveolus

Front 40

Tooth components

Back 40

- enamel: hard surface layer (calcium phosphate)
- dentin: bulk of tooth matrix below enamel
- periodontal ligament: create gomphosis articulation between tooth dentin and alveolar bone

Front 41

Tooth types

Back 41

- Incisors
- cuspids
- bicuspids
- molars

Front 42

Tooth type: incisors

Back 42

- blade shaped with single root
- clipping and cutting

Front 43

Tooth type: cuspids

Back 43

- canines, conical with single root
- tearing and slashing

Front 44

Tooth type: bicuspids

Back 44

- premolars, flat crowns, 1-2 roots
- crushing, grinding or mashing

Front 45

Tooth type: molars

Back 45

- large flat crowns, 3+ roots
- crushing or grinding

Front 46

Pharynx - segments

Back 46

- nasopharynx
- oropharynx
- laryngopharynx

Front 47

Esophagus - Location

Back 47

- posterior to cricoid cartilage
- descends posterior to trachea
- passes through esophageal hiatus in diaphragm to reach stomach

Front 48

Esophagus - sphincters

Back 48

- upper esophageal sphincter (prevents air entering)
- lower esophageal sphincter (prevents backflow of stomach contents

Front 49

Esophagus - structural characteristics

Back 49

- mucosa and submucosa form large folds that keep lumen closed unless swallowing is occurring (non keratinized stratified squamous)
- muscularis externa: superior 1/3 is skeletal muscle, middle 1/3 is mix of skeletal and smooth, inferior 1/3 is smooth muscle
- no serosa: adventia anchors esophagus to posterior body wall

Front 50

Deglutition

Back 50

- Swallowing
- initiated voluntarily, proceeds automatically

Front 51

Phases of deglutition

Back 51

- Buccal phase
- Pharyngeal phase
- Esophageal phase

Front 52

Phases of deglutition - buccal phase

Back 52

- voluntary
- formation of bolus and movement to oropharynx

Front 53

Phases of deglutition - pharyngeal phase

Back 53

- mainly involuntary
- coordinated movement by medulla oblongata to move bolus down to esophagus

Front 54

Phases of deglutition - esophageal phase

Back 54

- mainly involuntary
- pushed to stomach by peristalic waves
- Dry bolus may require secondary peristalic waves

Front 55

Peritoneal cavity

Back 55

- encloses stomach and most of intestine
- lined with serous peritoneum (parietal and visceral peritoneum, secretes peritoneal fluid to lubricate organs)

Front 56

Accumulation of peritoneal fluid

Back 56

ascites - abdominal swelling

Front 57

Dorsal and Ventral Mesenteries

Back 57

- connective tissue
- function: provide support and carry vessels and nerves
- during development two mesenteries exist and develop into other adult connections

Front 58

Dorsal mesentery becomes:

Back 58

- Greater omentum: connects stomach to intestines
- mesentery proper: small intestine with body wall
- mesocolon: large intestine to body wall

Front 59

Ventral mesentery becomes:

Back 59

- lesser omentum: connects stomach to liver
- falciform ligament: liver to anterior body wall

Front 60

Stomach - appearance

Back 60

shape is highly variable depending on contents

Front 61

Stomach - regions

Back 61

- fundus: superior to esophageal connection
- cardia: within 3 cm of gastroesophageal junction (secretes mucus to protect esophagus from acid/enzymes)
- body: largest region
- pyloris: sharp curve of "J" leading to small intestine

Front 62

Stomach structural characteristics - lesser curvature

Back 62

medial surface

Front 63

Stomach structural characteristics - greater curvature

Back 63

lateral and inferior surface

Front 64

Stomach structural characteristics - rugae

Back 64

mucosal wrinkles that flatten when stomach fills

Front 65

Stomach structural characteristics - additional muscle

Back 65

- Oblique muscle layer - in addition to circular and longitudinal in muscularis externa
- assists in mixing and churning

Front 66

Pyloric (Stomach) structures

Back 66

- pyloric antrum: portion connected to stomach body
- pyloric canal: empties into small intestine
- pyloric sphincter: smooth muscle band regulating release of chyme into duodenum

Front 67

Chyme

Back 67

food, saliva and gastric gland secretions

Front 68

Stomach wall layers

Back 68

- mucosa: simple columnar, produces alkaline mucus to protect epithelial cells from acids and enzymes (typical cell lives 3-7 days)
- submucosa
- muscularis externa: oblique, circular, longitudinal
- serosa

Front 69

Gastric glands

Back 69

- secrete most of the acids and enzymes enabling gastric digestion
- open to stomach lumen through gastric pits

Front 70

Gastric gland cell types

Back 70

- parietal cells
- chief cells
- G Cells (enteroendocrine cells)

Front 71

Parietal cells secrete:

Back 71

- intrinsic factor: aids B12 absorption
- HCL: activates pepsinogen

Front 72

Chief cells secrete:

Back 72

- Pepsinogin: activates in acid (HCL) to become pepsin
-Pepsin=active proteolytic enzyme (protein digesting)

Front 73

G Cells (enteroendocrine cells)

Back 73

produce a variety of hormones (Gastrin)

Front 74

Intestinal structures that add surface area to increase absorption

Back 74

- plicae circularis: permanent transverse folds, mostly in jejunum
- intestinal villi: finger like projections of mucosa
- microvili (brush border): cell membrane extensions on simple columnar cells lining villi surfaces

Front 75

Where are intestinal glands located?

Back 75

base of villi

Front 76

Villi - internal structures

Back 76

- extensive capillary bed to absorb nutrients
- lymphatic capillary (lacteal) to transport materials to big for blood capillaries
- smooth muscle that squeezes lacteal and moves villi
- brush border increases surface area and contains enzymes to digest nutrients

Front 77

Small intestine characteristics

Back 77

- plays key roll in digestion and absorption
- 90% of nutrient absorption
- 3 regions: duodenum, jejunum, ileum

Front 78

Duodenum

Back 78

- receives chyme from stomach and digestive secretions from liver, gallbladder, pancreas
- mostly retroperitoneal
- few plicae circularis and small villi
- many duodenal glands secreting mucus
- main function is to neutralize acidic chyme
- coordinates gastric activity and digestive secretion according to arriving chyme characteristics (hormones)

Front 79

Jejunum

Back 79

- in peritoneal cavity
- numerous plicae circularis and abundant, long villi
- majority of chemical absorption occurs in jejunum

Front 80

Ilium

Back 80

- final segment of small intestine
- few plicae circularis, stumpy vili
- submucosa contains aggregated lymphoid nodules
- controls material flow into cecum of large intestine

Front 81

Major hormones that regulate digestive activities

Back 81

-Gastrin (only one not exclusively produced by the duodenum)
- secretin
- gastric inhibitory peptide (GIP)
- cholecystokinin (CCK)
- vasoactive intestinal peptide (VIP)

Front 82

Gastrin

Back 82

-only hormone that speeds up stomach activity
- secreted by G cells by the pyloric antrum and enteroendocrine cells of duodenum
- stimulated by food presence in the stomach and duodenum (esp. high protein)
- Increases production of gastric acids (HCL) and enzymes (pepsinogen)

Front 83

Secretin

Back 83

- released by duodenum upon arrival of chyme
- increases secretion of bile from liver and buffers from pancreas
- decreases stomach activity and secretory rates (acids/enzymes)

Front 84

Gastric Inhibitory Peptide (GIP)

Back 84

- released by duodenum when fats and carbohydrates (esp. glucose) enter small intestine
- inhibits gastric (stomach) activity while increasing insulin release
- stimulates duodenal glands, lipid synthesis in adipose, skeletal muscle glucose use

Front 85

How are fatty acids stored?

Back 85

Tryglycerides

Front 86

Cholecystokinin (CCK)

Back 86

- secreted by duodenum when chyme arrives (esp. high lipid content and partially digested proteins)
- Increase enzyme production and secretion from pancreas
- Increase release of bile from gallbladder
- inhibits gastric activity and may reduce hunger sensation in CNS

Front 87

Vasoactive Intestinal Peptide (VIP)

Back 87

- released by duodenum
- stimulate secretion of intestinal glands
- dilates regional capillaries (to increase nutrient absorption)
- inhibits gastric acid (HCL) production

Front 88

Phases of gastric secretion

Back 88

- cephalic phase
- gastric phase
- intestinal phase

Front 89

Gastric secretion - cephalic phase

Back 89

- Think about food
- begins with sensations or thoughts about food
- CNS initiates preparation for arrival of food at stomach (parasympathetic impulse down vagus nerve)
- gastric juice secretions increase

Front 90

Gastric secretion - gastric phase

Back 90

- get food in stomach
- begins with stimuli as food arrives in stomach: distension of stomach, increase in gastric content pH, presence of undigested materials (esp. proteins and peptides) in stomach
- increased gastrin secretion
- increased secretion by parietal and chief cells
- longest phase

Front 91

Gastric secretion - intestinal phase

Back 91

- empty stomach into intestine
- begins when chyme enters duodenum
- initiation of enterogastric reflex (inhibits gastrin production=decrease in gastric motility and secretion)
- stimulates contraction of pyloric sphincter decreasing chyme release into duodenum
- increase mucus production in duodenum

Front 92

Large intestine - major functions during mass movement (peristalsis)

Back 92

- reabsorption of water and compaction of contents into feces
- absorption of vitamins liberated by bacterial action
- storage of feces prior to defication

Front 93

Large Intestine - segments

Back 93

- cecum
- colon
- rectum

Front 94

Large Intestine - cecum

Back 94

- expanded pouch at beginning colon
- begins compaction
- contains ileocecal valve
- has attached appendix

Front 95

What two organs does the ileocecal valve connect?

Back 95

- ilium (sm. intestine)
- cecum (lg. intestine)

Front 96

Inflammation of appendix

Back 96

appendicitis

Front 97

What is a colic flexure?

Back 97

bend in the colon

Front 98

Large Intestine - colon

Back 98

- ascending: along right margin of peritoneal cavity from cecum to right colic flexure
- transverse: across abdomen from right to left colic flexure
- descending: along left margin of peritoneal cavity from left colic flexure to sigmoid flexure
- sigmoid: "s" shaped last segment, empties into rectum

Front 99

Large Intestine - rectum

Back 99

- expandable for temporary feces storage
- fecal matter within rectum triggers defecation urge

Front 100

Large Intestine structure - taeniae coli

Back 100

- 3 longitudinal muscle bands along outer colon surface (corresponds to muscularis externa)

Front 101

Large Intestine structure - Haustra

Back 101

- pouches along colon wall
- allow for expansion and elongation of colon

Front 102

Large Intestine structure - fatty appendices

Back 102

- teardrop shaped fat sacs attached to serosa

Front 103

Large intestine vs. small intestine

Back 103

Large intestine:
- diameter is larger and wall is thinner
- lack of villi
- abundance of mucus cells (mucus provides lubrication for drier and more compact fecal material)
- no digestive enzymes produces

Front 104

Function of large Intestine

Back 104

- 10% of overall absorption
- absorption of biotin, potassium and B5 (from bacterial activity)

Front 105

Composition of ejected feces

Back 105

- 75% water
- 5% bacteria
- 20% indigestible material

Front 106

Anal canal

Back 106

- distal portion of rectum
- longitudinal folds (=anal columns)
- epithelium transitions from columnar to stratified squamous
- large network of veins in the wall
- Internal anal sphincter
- external anal sphincter
- anus (exit of anal canal) stratified epithelium becomes keratinized

Front 107

Internal anal sphincter

Back 107

- inner circular smooth muscle
- involuntary

Front 108

External anal sphincter

Back 108

- outer smooth muscle
- voluntary

Front 109

Defecation reflexes

Back 109

- begins with distension of rectum wall after arrival of feces
- involves 2 positive feedback loops: long reflex, short reflex

Front 110

Defecation - long reflex

Back 110

- covers greater area
- coordinated by sacral parasympathetic system
- stimulates mass movement of feces toward rectum from descending and sigmoid colon

Front 111

Defecation - short reflex

Back 111

- regional
- stimulation of myenteric plexus to move feces in sigmoid colon and rectum

Front 112

Accessory digestive organs - salivary glands

Back 112

- produce saliva with mucins and enzymes
- secrete through ducts in oral cavity
- parasympathetic stimulation increases salivary secretion
- 3 pairs of salivary glands: sublingual, submandibular, parotid

Front 113

What types of cells do salivary glands consist of, and what do they secrete?

Back 113

- mucus cells, secrete: mucins, water and buffers
- serous cells: secrete: salivary amylase, lysozymes and IgA antibodies

Front 114

Sublingual salivary glands

Back 114

- located under the tongue
- secrete into sublingual ducts

Front 115

Submandibular salivary glands

Back 115

- located in mandibular groove
- secrete into submandibular ducts

Front 116

Parotid salivary glands

Back 116

- located inferior to zygomatic arch
- secrete into parotid duct

Front 117

Accessory digestive organs - gallbladder

Back 117

- Stores and concentrates bile
- 3 regions: fundus, body, neck
- drained by cystic duct (merges with right and left common hepatic ducts from the liver to become common bile duct)
- bile released at mealtime into duodenum when hepatopancreatic sphincter is relaxed (under control from CCK)

Front 118

Bile

Back 118

- produced by liver
- stored in pancreas
- break lipid droplets apart (emulsification)

Front 119

Hepatopancreatic sphincter

Back 119

- encircles the lumen of the common bile duct, pancreatic duct and duodenal ampulla
- resting tension in the sphincter prevents bile flow into the duodenum except at mealtimes

Front 120

Accessory digestive organs - Pancreas

Back 120

- Exocrine cells secrete buffers and digestive enzymes
- Located posterior to stomach
- retroperitoneal
- 3 parts: head, body and tail
- pancreatic duct
- pancreatic lobules
- pancreatic acini
- pancreatic islets (endocrine function)

Front 121

Where is the pancreatic head located?

Back 121

lies next to duodenum

Front 122

Pancreatic duct

Back 122

meets common duct at duodenal papilla and drains pancreatic juice (water, solutes, enzymes) into duodenum

Front 123

Pancreatic acini

Back 123

- produce enzymes
- organizational units made from pancreatic acinar cells

Front 124

Major pancreatic enzymes

Back 124

- pancreatic alpha-amylase: carbohydrates
- pancreatic lipase: lipids
- nucleases: genetic material (RNA, DNA)
- proteolytic enzymes: proteins

Front 125

Accessory digestive organs - liver

Back 125

- largest visceral organ
- 4 lobes:
- left lobe
- right lobe (separated from left lobe by falciform ligament)
- caudate lobe (separated from left lobe by inferior vena cava)
- quadrate lobe (between left lobe and gallbladder)

Front 126

Liver - associated structures

Back 126

- gallbladder: temporarily stores bile produced by liver
- common bile duct: carries bile from liver and gallbladder to duodenum
- porta hepatis: entry point for blood vessels and other structures from lesser ommentum

Front 127

Liver lobules

Back 127

- hexagonal in shape
- separated by interlobular septa
- portal area or triad at each corner
- composed of liver cells (hepatocytes)

Front 128

Liver lobules - triad consists of

Back 128

- branch of portal vein
- branch of hepatic artery
- branch of bile duct

Front 129

Liver cells (hepatocytes)

Back 129

- form plates radiating from lobule center (spokes of wheel)
- plates separated by liver sinusoids (blood vessels)
- regulate solute and nutrient levels
- secretes bile that drains into bile canaliculi then bile ductules then bile ducts of portal triad

Front 130

Liver sinusoids

Back 130

- drains into central vein (center of lobule)
- contains phagocytic kupffer cells

Front 131

Primary functions of the liver

Back 131

- synthesis and secretion of bile
- storage of glycogen and lipid reserves
- maintenance of normal concentrations of glucose, amino acids and fatty acids in the blood stream
- synthesis and interconversion of nutrient types (carbohydrates to lipids) especially with protein
- synthesis and release of cholesterol bound to transport proteins
- inactivation of toxins (de-toxification)

Front 132

Why is an acidic environment important in the stomach?

Back 132

- The stomach is acidic in order to kill any bacteria that enter the stomach.
- The stomach has to maintain its acidity for the enzyme pepsin (protein digesting) to function.

Front 133

Pathway of blood through the liver and back to circulation

Back 133

- blood enters the liver sinusoids from small branches of the hepatic vein and hepatic artery
- as blood flows through sinusoids adjacent hepatocytes regulate solute and nutrition levels
- the central vein collects blood from sinusoids
- central veins of all the lobules merge to form the hepatic veins
- hepatic veins empty into the inferior vena cava