Two groups of organs:
alimentary canal (gastrointinal or GI tract)accessory digestive organs
Alimentary canal (gastrointestinal or GI tract) includes:
mouthpharynesophagusstomachsmall intestinelarge intestine
Alimentary canal (gastrointestinal or GI tract) does what to food?
digest and absorbs food
Accessory digestive organs include:
teethtonguebladderdigestive glands
Digestive glands include:
salivary glandsliverpancreas
6 essential activities of digestive processes:
ingestionpropulsionmechanical digestionchemeical digestionabsorptiondefecation
Adjacent segments of alimentary tract organs alternately contract and relax, which moves food along the tract distally.
peristalsis
Nonadjacent segments of alimentary tract organs alternately contract and relax, movign food forward then backward. Food mixing and slow food propulation occurs.
segmentation
Serious membrame of the abdominal cavity.
peritoneum
Peritoneum includes:
visceral peritoneum: on external surface of most digestive organspartietal peritoneum: lines the body wall
Peritoneal cavity is found _____ the two _____. And _____ lubricates mobile _____.
betweenperitoneumsfluidorgans
Double layer of peritoneum.
mesentary
Two functions of the mesentary:
routes for blood vessels, lymphatics, and nervesholds organs in place and stores fat
Organs that lie posterior to the peritoneum.
retroperitoneal
Organs that are surrounded by the peritoneum.
intraperitoneal (peritoneal)
Fout basic layers (tunics):
mucosasubmucosamuscularis externaserosa and/or adventitia
The mucosa lines the _____.
lumen
Three functions of mucosa:
secretes mucus, digestive enzymes and hormonesabsorbs end products of digestionprotects against infectious disease
Three sublayers of mucosa:
epitheliumlamina propriamuscularis mucosae
Simple columnar epithelium and mucus-secreting cells; may secrete enzymes and hormones (e.g., in stomach and small intestine)
epithelium mucosa
Two functions of epithelium mucosa:
protects digestive organs from enzymeseases food passage
Loose areolar connective tissue.
lamina propria mucosa
Lamina propria mucosa are capillaries for _____ and _____; also lymphoid _____.
nourishmentabsorptionfollicles
Smooth muscle that produces local movements of mucosa.
muscularis mucosae
Dense connective tissue. Includes: blood and lymphatic vessels, lymphoid follicles, and submuscosal nerve plexus
submucosa
Responsible for segmentation and peristalsis. Includes inner circular and outer longitudinal layers, myenteric nerve plexus and sphincters in some regions.
muscularis externa
Replaces by the fibrous adventitia in the esophagus. Retropertitoneal organs have both an adventitia and serosa.
visceral peritoneum
Bounded by lips, cheeks, palate, and tongue. Oral orifice is the anterior opening. Lined with stratified squamous epithelium.
oral (buccal) cavity
Contains orbicularis oris, and buccinator muscles, vestibule, labial frenulum and oral cavity proper lies within the teeth and gums.
lips and cheeks
Recess internal to lips and cheeks, external to teeth and gums.
vestibule
Median attachment of each lip to the gum.
labial frenulum
Two types of palates:
hard palatesoft palate
Palatine boes and palatine procces of the maxillae; slightly corrugated to help create friction against the tongue.
hard palate
Fold formed mostly of skeletal muscle; closes off the nasopharynx during swallowing and uvula projects downward from its free edge
soft palate
Three functions of the tongue:
repositioning and mixing food during chewingformation of the bolusinitiation of swallong, speech, and taste
Part of tongue that attaches to the floor of the mouth.
lingual frenulum
Three types of salivary glands:
extrinsicintrinsic (buccal)secretion (saliva)
Glands found in parotid, submandibular, and sublingual.
extrinsic salivary glands
Glands that are scattered in the oral mucosa.
intrinsic (buccal) glands
Four fucntions of secretion (saliva):
cleanses the mouthmoistens and dissolves food chemicalsaids in bolus formationcontains enzymes that begin the breakdown of starch
Primary and permanent dentitions are formed by age ___.
21
Two sets of teeth:
deciduouspermanent
Erupts at 6-24 months of age (20 of them); and roots are resorbed, teeth fall out at 6-12 years as permanent teeth develop.
deciduous teeth
All except third molars erupt by the end of adolescence (32 of them)
permanent
Chisel shpaed for cutting.
incisors
Fanglike teeth that tear or pierce.
canines
Have broad crowns with rounded cusps for grinding or crushing
premolars (bicuspids)molars
The exposed part above the gingiva (gum).
crown
The crown is covered by _____ which is the hardest substance in the body (calcium salts and hydroxyapatite crystals)
enamel
Portion embedded in the jawbone; connected to crown and neck.
root
Calcified connective tissue; covers root and attaches it to the periodontal.
cementum
Forms fibrious joint called a gomphosis.
periodontal ligament
Groove where gingiva borders the tooth.
gingival sulcus
Bonelike material under enamel; maintained by odontoblasts of pulp cavity.
dentin
Cavity surrounded by dentin.
pulp cavity
Connective tissue, blood vessels, and nerves.
pulp
Extends from pulp cavity to the apical foramen of the root.
root canal
Allows passage of food, fluids, and air; stratified squamous epithelium lining; made up skeletal muscle layers.
oropharynx and laryngopharynx
Inner longitudinal, outer pharyngeal constrictors.
skeletal muscle layers of pharynx
Flat muscular tube from laryngopharynx to the diaphragm to the gastroesophageal sphincter in the superior aspect of the stomach; approximately 25cm long; has adventitia instead of serosa.
esophagus (gullet)
Four digestive processes of the mouth:
ingestionmechanical digsestionchemical digestionpropulsion
Mastication is partly voluntary, partly reflexive.
mechanical digestion
Contains salivary amylase and lingual lipase.
chemical digestion
Deglutition (swallowing).
Propulsion
The parts of the stomach's gross anatomy:
cardiac region (cardia)fundusbodypyloric regionlesser/greater curvationleser/greater omentum
Surrounds the cardiac orifice.
cardiac region
Dome-shaped region beneath the diaphragm.
Fundus
Midportion of stomach.
body
Antrum, pyloric canal, and pylorus; pylorus is continuous with the duodenum thorugh the pyloric valve (sphincter).
pyloric region
Convex lateral surface.
greater curvature
Concave medial surface.
lesser curvature
From the liver to the lesser curvature.
greater omentum
Drapes from greater curvature; anterior to the small intestine
greater omentum
Three factors of stomach anatomy:
four tunicsmuscularis and mucosa are modifiedmucosa
Three layers of smooth muscle; inner oblique layer allows stomach to churn, mix, move, and physically break down food.
muscularis externa
Simple columnar epithelium composed of mucous cells; layer of mucus traps bicarbonate-rich fluid beneath it; gastric pits lead into gastric glands
mucosa
Four cell types of gastric glands:
mucous neck cells (secrete thin, acidic mucusparietal cells - HCLchief cells - pepsinogenenteroendocrine cells
Major organ of digestion and absorption; 2-4m long; from pyloric sphincter to ileocecal valve; has subdivision.
small intestine
Subdivision of small intestines:
duedenum (retroperitoneal)jejunum (attached posteriorly by mesentery)ileum (attached posteriorly by mesentery)
The bile duct and main pancreatic duct. Joined at the hepatopancreatic ampulla, enters the duodenum at the major duodenal papilla and are controlled by the hepatopancreatic sphincter.
Duodenum
What three factors increases surface area of proximal part for nutrient absorption?
circular folds (plicae circulares)villimicrovilli
Motile fingerlike extension (~1mm high) of the mucosa. Includes villus epithelium; simple columnar absorptive cells (enterocytes) and globelet cells.
villi
Projections (brush border) of absorptive cells; bear brush border enzymes.
microvilli
Secretory cells that produce intestinal juice; enteroendocrine cells; intraepithelial lymphocytes (IELs); paneth cells; stem cells
intestinal crypt epithelium
Release cytokines that kill infected cells
intraepithelial lymphocytes (IELs)
Secretes antimicrobial agents (defensis and lysozyme).
paneth cells
Peyer's patches protect distal part against bacteria; duodenal (Brunner's) glands of the duodenum secrete alkaline mucus.
submusoca
Largest gland in the body; four lobes - right, left, caudate,a nd quadrate.
liver
Separates the (larger) right and (smaller) left lobes; suspends liver from the diaphragm and anterior abdominal wall.
falciform ligament of liver
Remnant of fetal umbilical vein along free edge of falciform ligament.
round ligament (ligamentum teres) of liver
Three types of ssociated structures of liver:
lesser omentum anchors liver to stomachhepatic artery and vein at the porta hepatisbile ducts
Common hepatic duct leaves the liver; cystic duct connects to gallbladder; formed by the union of the above two ducts.
bile ducts
Two factors of liver lobules:
hexagonal structural and functional unitslongitudinal central vein
Filter and process nutrient-rich blood; composed of plates of hepatocytes (liver cells).
hexagonal structural and functional units of liver lobules
Bile duct receives bile from bile canaliculi; portal arteriole is a branch of the hepatic artery; hepatic venule is a branch of the hepatic portal vein.
portal triad at each corner of lobule
Leaky capillaries between hepatic plates
liver sinusoids
(hepatic macrophages) in liver sinusoids.
Kupffer cells
Four functions of hepatocytes:
process bloodborne nutrientsstore fat-soluble vitaminsperform detoxificationproduce ~900ml bile per day
Yellow-gree, alkaline solution containing bile salts, bilirubin, cholesterol, neutral fats, phopholipids and electrolytes.
bile
Cholesterol derivatives that function in fat emulsification and absorption.
bile salts
Pigment formed from heme.
bilirubin
Thin-walled muscular sac on the ventral surface of liver; stores and concentrates bile by absorbing its water ions; releases bile via the cystic duct, which flows into the bile duct.
gallbladder