Two groups of organs:
- alimentary canal (gastrointinal or GI tract)
- accessory digestive organs
Alimentary canal (gastrointestinal or GI tract) includes:
- small intestine
- large intestine
Alimentary canal (gastrointestinal or GI tract) does what to food?
digest and absorbs food
Accessory digestive organs include:
- digestive glands
Digestive glands include:
- salivary glands
6 essential activities of digestive processes:
- mechanical digestion
- chemeical digestion
Adjacent segments of alimentary tract organs alternately contract and relax, which moves food along the tract distally.
Nonadjacent segments of alimentary tract organs alternately contract and relax, movign food forward then backward. Food mixing and slow food propulation occurs.
Serious membrame of the abdominal cavity.
- visceral peritoneum: on external surface of most digestive organs
- partietal peritoneum: lines the body wall
Peritoneal cavity is found _____ the two _____. And _____ lubricates mobile _____.
Double layer of peritoneum.
Two functions of the mesentary:
- routes for blood vessels, lymphatics, and nerves
- holds organs in place and stores fat
Organs that lie posterior to the peritoneum.
Organs that are surrounded by the peritoneum.
Fout basic layers (tunics):
- muscularis externa
- serosa and/or adventitia
The mucosa lines the _____.
Three functions of mucosa:
- secretes mucus, digestive enzymes and hormones
- absorbs end products of digestion
- protects against infectious disease
Three sublayers of mucosa:
- lamina propria
- muscularis mucosae
Simple columnar epithelium and mucus-secreting cells; may secrete enzymes and hormones (e.g., in stomach and small intestine)
Two functions of epithelium mucosa:
- protects digestive organs from enzymes
- eases food passage
Loose areolar connective tissue.
lamina propria mucosa
Lamina propria mucosa are capillaries for _____ and _____; also lymphoid _____.
Smooth muscle that produces local movements of mucosa.
Dense connective tissue. Includes: blood and lymphatic vessels, lymphoid follicles, and submuscosal nerve plexus
Responsible for segmentation and peristalsis. Includes inner circular and outer longitudinal layers, myenteric nerve plexus and sphincters in some regions.
Replaces by the fibrous adventitia in the esophagus. Retropertitoneal organs have both an adventitia and serosa.
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.
Median attachment of each lip to the gum.
Palatine boes and palatine procces of the maxillae; slightly corrugated to help create friction against the tongue.
Fold formed mostly of skeletal muscle; closes off the nasopharynx during swallowing and uvula projects downward from its free edge
Three functions of the tongue:
- repositioning and mixing food during chewing
- formation of the bolus
- initiation of swallong, speech, and taste
Part of tongue that attaches to the floor of the mouth.
Three types of salivary glands:
- intrinsic (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 mouth
- moistens and dissolves food chemicals
- aids in bolus formation
- contains enzymes that begin the breakdown of starch
Primary and permanent dentitions are formed by age ___.
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.
All except third molars erupt by the end of adolescence (32 of them)
Chisel shpaed for cutting.
Fanglike teeth that tear or pierce.
Have broad crowns with rounded cusps for grinding or crushing
- premolars (bicuspids)
The exposed part above the gingiva (gum).
The crown is covered by _____ which is the hardest substance in the body (calcium salts and hydroxyapatite crystals)
Portion embedded in the jawbone; connected to crown and neck.
Calcified connective tissue; covers root and attaches it to the periodontal.
Forms fibrious joint called a gomphosis.
Groove where gingiva borders the tooth.
Bonelike material under enamel; maintained by odontoblasts of pulp cavity.
Cavity surrounded by dentin.
Connective tissue, blood vessels, and nerves.
Extends from pulp cavity to the apical foramen of the root.
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.
Four digestive processes of the mouth:
- mechanical digsestion
- chemical digestion
Mastication is partly voluntary, partly reflexive.
Contains salivary amylase and lingual lipase.
The parts of the stomach's gross anatomy:
- cardiac region (cardia)
- pyloric region
- lesser/greater curvation
- leser/greater omentum
Surrounds the cardiac orifice.
Dome-shaped region beneath the diaphragm.
Midportion of stomach.
Antrum, pyloric canal, and pylorus; pylorus is continuous with the duodenum thorugh the pyloric valve (sphincter).
Convex lateral surface.
Concave medial surface.
From the liver to the lesser curvature.
Drapes from greater curvature; anterior to the small intestine
Three factors of stomach anatomy:
- four tunics
- muscularis and mucosa are modified
Three layers of smooth muscle; inner oblique layer allows stomach to churn, mix, move, and physically break down food.
Simple columnar epithelium composed of mucous cells; layer of mucus traps bicarbonate-rich fluid beneath it; gastric pits lead into gastric glands
Four cell types of gastric glands:
- mucous neck cells (secrete thin, acidic mucus
- parietal cells - HCL
- chief cells - pepsinogen
- enteroendocrine cells
Major organ of digestion and absorption; 2-4m long; from pyloric sphincter to ileocecal valve; has subdivision.
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.
What three factors increases surface area of proximal part for nutrient absorption?
- circular folds (plicae circulares)
Motile fingerlike extension (~1mm high) of the mucosa. Includes villus epithelium; simple columnar absorptive cells (enterocytes) and globelet cells.
Projections (brush border) of absorptive cells; bear brush border enzymes.
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).
Peyer's patches protect distal part against bacteria; duodenal (Brunner's) glands of the duodenum secrete alkaline mucus.
Largest gland in the body; four lobes - right, left, caudate,a nd quadrate.
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 stomach
- hepatic artery and vein at the porta hepatis
- bile ducts
Common hepatic duct leaves the liver; cystic duct connects to gallbladder; formed by the union of the above two ducts.
Two factors of liver lobules:
- hexagonal structural and functional units
- longitudinal 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
(hepatic macrophages) in liver sinusoids.
Four functions of hepatocytes:
- process bloodborne nutrients
- store fat-soluble vitamins
- perform detoxification
- produce ~900ml bile per day
Yellow-gree, alkaline solution containing bile salts, bilirubin, cholesterol, neutral fats, phopholipids and electrolytes.
Cholesterol derivatives that function in fat emulsification and absorption.
Pigment formed from heme.
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.