Ch. 24 Digestive System Flashcards Preview

Human Anatomy > Ch. 24 Digestive System > Flashcards

Flashcards in Ch. 24 Digestive System Deck (37):


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


GI tract consists of...

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


Functions of Digestive System

- 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



- 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



- 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



- 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)



- 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


Peritoneal Folds relationship to other organs

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


Other organs in Dig.

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



- 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


Salivary Glands

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


Stensen, Wharton, Rivinus

Parotid, Submandibular, Sublingual



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



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


Centitions and Times of Eruptions

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



- 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


Functions of Esophagus

- 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



- 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


Functions of Stomach

- 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


Anatomy of Stomach

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


Gastric Glands

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)


Functions of Pancreas

- 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


Anatomy og Pranceas

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


Relationship of Pancrea, lover, Gallbladder and Duodenum

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


Histology of Pancreas

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


Anatomy of Gallbladder

- fundus
- body
- neck
Function: storage of bile


Functions of Liver

- 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


Histology of the Liver

- 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


Histology of Liver and Gallbladder

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


Hepatic Blood Flow

- 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


Functions of Small Intestine

- 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


Anatomy of Small Intestine

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


Histology of Small Intestine

- 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


Histology of Small Intestine Con't

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)


Functions of Large Intestine

- 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


Anatomy of Large Intestine

- 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


Histology of Large Intestine

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