Ch. 24 Digestive System

Question 1

FuCharacteristics

Answer 1

food- nutrients to body- synthesis

• enzymes, growth, cell division, repair, heat
• food must be mechanically and chemically reduced to different forms to absorb through intestinal wall and then transported to body cells by the blood

Question 2

GI tract consists of…

Answer 2

• mouth, pharynx, esophagus, stomach, small and large intestine
  accessory: teeth, tongue, salivary glands, liver, gallbladder, pancreas

Question 3

Functions of Digestive System

Answer 3

• ingestion
• secretion: water, acid, buffers and enzymes into lumen cells of GI tract and accessory dig. organs
• mixing and propulsion: alternate contraction and relaxation of smooth muscles to mix the food and secretion that lines GI tract
• digestion: mechanical and chemical; CHO, lipids, and proteins
• absorption: entrance of ingested and secreted fluid in lumen of blood or lymph through epithelial cells that line GI tract
• defecation

Question 4

Mucosa

Answer 4

• inner lining of GI tract, is a mucous membrane composed of:
  epithelial cells: specialized for absorbing digestive nutrients containis enteroendocrine cells
  lamin propria: areolar connective tissue, blood vessels and lymphatic vessels and contains MALT
  muscularis mucosa: smooth muscle fibers increases surface

Question 5

Submucosa

Answer 5

• thin meshwork of collagenous fibers, nerves and blood vessels
• areolar connective tissue binds the mucosa to middle layer, the muscularis
• highly vascular and contains the submucosal plexus, or plexus of Meissner, portion of ANS called enteric nervous system
• submucosal plexus regulated movements of mucosa and vasoconstriction of blood vessels
• innervated secretory cells of mucosal glands

Question 6

Muscularis

Answer 6

• consists of smooth muscle, inner sheet of circular fibers and outer sheet of longitudinal fibers
• contains the myenteric plexus, or plexus of Auerbach
• plexus mostly controls GI tract motility (movement)

Question 7

Serosa

Answer 7

• superficial layer of those portions of GI tract that are suspended in abdominopelvic cavity
• serous membrane composed of areolar connective tissue and simple squamous epithelium (mesothelium)
• secretes a serous fluid
• epithelial portion is also called visceral peritoneum

Question 8

Peritoneal Folds relationship to other organs

Answer 8

• largest serous membrane of body
• divided into parietal and visceral peritoneum
• retroperitoneal organs
• greater omentum
• falciform ligament
• leser omentum
• mesentery
• mesocolon

Question 9

Other organs in Dig.

Answer 9

Greater omentum: largest peritoneal fold, drapes over transverse colon and coils the small intestine
falciform ligament: attaches liver to anterior abdominal wall and diaphragm
lesser omentum: suspends the stomach and duodenum from the liver
mesentery: binds the jejunum and ileum of small intestine to posterior abdominal wall
mesocolon: bind transverse colon and sigmoid colons of large intestine to posterior abdominal

Question 10

Mouth

Answer 10

• buccal cavity
• formed by cheeks, hard and soft palates and tongue
• cheeks covered externally by skin and internally by a mucous membrane
• buccinator muscles and connective tissue lie between the skin and mucous membranes of cheeks
• labia, labial frenulum, oral vestibule, fauces, hard and soft palate, uvula

Question 11

Salivary Glands

Answer 11

3 pairs:

• parotid glands: parotid duct
• submandibular glands: submandibular ducts
• sublingual glands: lesser sublingual ducts
• salivary glands receive both sympathetic and parasympathetic innervation
• salvia: salivary amylase plays minor role in breakdown of starch; lingual lipase and mucus are secreted by lingual glands

Question 12

Stensen, Wharton, Rivinus

Answer 12

Parotid, Submandibular, Sublingual

Question 13

Tongue

Answer 13

• accessory digestive system organ composed of skeletal muscle covered with mucous membrane
• extrinsic muscles of tongue
• intrinsic muscles of tongue
• lingual frenulum (ankyloglossia)

Question 14

Teeth

Answer 14

• dentes
• gingivae
• gum
• periodontal ligament or membrane
  composed of: crown, neck, dentin, enamel, pulp cavity

Question 15

Centitions and Times of Eruptions

Answer 15

Deciduous teeth (milk): first and second diciduous molars; central or lateral incisors
Permanent teeth: first and second premolars (bicuspids)

Question 16

Pharynx

Answer 16

• extends from internal nares to esophagus posteriorly and larynx anteriorly
• composed of skeletal muscle and lined by mucous membrane
  naso/oro/laryngo pharaynx: naso is only resp.
• deglutition/swallowing: mechanism hat moves food from mouth to stomach

Question 17

Functions of Esophagus

Answer 17

• secretes mucus and transport food into stomach
• upper esophageal sphincter (UES)
• elevation of larynx causes sphincter to relax, allowing bolus to enter the esophagus
• peristalsis
• mucus secreted by esophageal glands lubricates the bolus and reduces friction
• Lower esophageal sphincter (LES), called gastroesophageal or cardiac sphincter

Question 18

Stomach

Answer 18

• enlargment of GI tract and lies inferior to diaphragm in epigastric, umbilical and left hypochondirac region of abdomen
• connects esophagus to duodenum
• functions as mixing area and holding reservoirs
• position and size vary continually
• digestion of starch that began in mouth continues, digestions of proteins and triglycerides begins, semisolid bolus is converted to liquid, and certain substances are absorbed
• accommodate a large quantity of food, upto 6.4 iters

Question 19

Functions of Stomach

Answer 19

digestion

• mixes saliva, food and gastric juice to form chyle
• serves as reservoir for food before release into stomach
• secrete gastric juice that contains HCL, pepsin, intrinsic factros
• secretes gastrin into blood
• propulsion and retropulsion (peristaltic waves)
• chyme
• gastric emptying
• pepsin: protein digesting enzyme
• gastric lipase: trigylceride digesting enzyme
• pancreatic lipase: fat digesting enzyme

Question 20

Anatomy of Stomach

Answer 20

4 main regions:
- Cardia
- Fundus: storage of food
- Body
- Pyloric part: 
consists of 3 regions:
pyloric antrum (connects to body of stomach)= food mixing
pyloric canal (leads to pylorus)
plyrous (connects to duodenum)
- rugae= mucosal folds
- pyloric sphincter
- lesser curvature
- greater curvature

Question 21

Gastric Glands

Answer 21

3 types of exocrine gland cells:

• mucous neck cells, chief cells, parietal cells
• chief (zymogenic) cells
• gastric juice
• G cell
• secretion of parietal, chief, and mucous is gastric juice (2000-3000 ml/day)

Question 22

Functions of Pancreas

Answer 22

• pancreatic amylase= starch digesting enzyme
  enzymes that digest protein:
• trypsin, chymotrypsin, carboxypeptidase, elastase
• principle triglyceride (digesting enzyme in adults): pancreatic lipase, RNA and DNA digesting enzyme called ribonuclease and deoxyribonuclease

Question 23

Anatomy og Pranceas

Answer 23

• head
• body
• tail
• pancreatic duct (duct of Wirsung)
• hepatopancreatic ampulla (ampulla of Vater)
• major duodenal papilla
• accessory duct (duct of Santorini)

Question 24

Relationship of Pancrea, lover, Gallbladder and Duodenum

Answer 24

right and left hepatic duct- common hepatic duct from liver
cystic duct from gallbladder-
- common bile duct- pancreatic duct from pancreas- sphincter- common bile duct- cystic duct from gallbladder

Question 25

Histology of Pancreas

Answer 25

- Acini= cluster of cells - Pancreatic Juice - Pancreatic islets (islets of Langerhans)

Question 26

Anatomy of Gallbladder

Answer 26

- fundus - body - neck Function: storage of bile

Question 27

Functions of Liver

Answer 27

- emulsification: break down large lipid gobules into small droplets - absorption - bile storage: sphincter of hepatopancreatic ampulla - carbohydrate metabolsim - lipid metabolism - protein metabolism - processing of drugs and hormones - excretion of bilirubin= derived from herne of RBC - synthesis of bile salts= emulsification - storage= vitamins A, B12, D, E and K - Phagocytosis= Kuffer cells (reticuloendothelial cells) are immune cels - Activation of vitamin D

Question 28

Histology of the Liver

Answer 28

- divided into two lobes by falciform ligament - quadrate and caudate lobes mostly belong to the left lobe - ligamentum teres (round ligament) - coronary ligaments - liver - hepatocytes= continuously produce bile; hapetic laminae - bile canaliculli - bile ductulesand bile ducts - right and left hepatic ducts - common hepatic duct - cystic duct - common bile duct

Question 29

Histology of Liver and Gallbladder

Answer 29

Hepatic Sinusoids: highly permable blood capillaries between hepatic laminae - central vein - hepatic veins - portal triad hepatocytes, bile duct system, and hepatic sinusoids can be organized into anatomical and functional units in 3 different ways: - hepatic lobule, portal lobule, hepatic acinus

Question 30

Hepatic Blood Flow

Answer 30

- oxy. blood from hepatic artery and nutrient-rich, deoxygenated blood from hepatic portal vein- hepatic sinusoids- central vein- hepatic vein- inferior vena cava- right atrium of heart

Question 31

Functions of Small Intestine

Answer 31

- completeion of digestion and absorption occurs in small intestine - intestinal juice: clear, yellow fluid secreted in amounts; provides a vehicle for absorption of substances from chyme - brush-border enzymes: alpha-dextrinase, maltase, sucrase, and lactase; peptidases; nucleosidases and phosphatases - segmentations and peristalsis

Question 32

Anatomy of Small Intestine

Answer 32

3 regions - duodenum - jejnumun - ileum - illeocecal sphincter - valve

Question 33

Histology of Small Intestine

Answer 33

- mucosa is composed of epithelium, lamina propria, and muscularis muscle - absorptive cells of epithelium digest and absorb nutrients in small intestine - goblet cells secrete mucus - small intestinal mucosa contains many deep cervices lined with glandular epithelium - intestinal glands secrete intestinal juice - paneth cells secrete lysozyme

Question 34

Histology of Small Intestine Con't

Answer 34

``` 3 types of enteroendocrine cells found in intestinal glands: S cells (hormone secretion), CCK cells, K cells (glucose dependent insulinotrophic peptide) - groups of lymphatic nodules referred to as aggregated lymphatic follicles present in ileum - submucosa of duodenum contiains duodenal (Brunner's) glands which secrete alkaline mucous - muscularis of small intestine consists of 2 layers of smooth muscle: outer (thinner of longitudinal fibers); inner (thicker of circular fibers) ```

Question 35

Functions of Large Intestine

Answer 35

- haustral churning= contraction and squezzing the contents into the nexthoustrum - peristalsis=slower wave of contraction - mass peristalsis= occurs in transverse colon and stronger wave - final stage of digestion occurs in colon: mucus, chyme, flatus, bacteria, bilirubin, stercobilin, feces

Question 36

Anatomy of Large Intestine

Answer 36

- extends from ileum to anus - mesocolon - 4 principle regions of the large intestine: cecum, colon, rectum, canal - ileocecal sphincter - cecum - appendix or vermiform appendix - mesoappendix= mesentary of appendix

Question 37

Histology of Large Intestine

Answer 37

- wall of intestine contains typical four layers found in rest of GI tract: mucosa, submucosa, muscularis, serosa - intestinal glands - teniae coli - haustra