Digestive System

Two groups of organs:

Alimentary canal (gastrointestinal or GI tract) includes:

Alimentary canal (gastrointestinal or GI tract) does what to food?

Accessory digestive organs include:

Digestive glands include:

6 essential activities of digestive processes:

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.

Peritoneum includes:

Peritoneal cavity is found _____ the two _____. And _____ lubricates mobile _____.

Double layer of peritoneum.

Two functions of the mesentary:

Organs that lie posterior to the peritoneum.

Organs that are surrounded by the peritoneum.

Fout basic layers (tunics):

The mucosa lines the _____.

Three functions of mucosa:

Three sublayers of mucosa:

Simple columnar epithelium and mucus-secreting cells; may secrete enzymes and hormones (e.g., in stomach and small intestine)

Two functions of epithelium mucosa:

Loose areolar connective tissue.

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.

Contains orbicularis oris, and buccinator muscles, vestibule, labial frenulum and oral cavity proper lies within the teeth and gums.

Recess internal to lips and cheeks, external to teeth and gums.

Median attachment of each lip to the gum.

Two types of palates:

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:

Part of tongue that attaches to the floor of the mouth.

Three types of salivary glands:

Glands found in parotid, submandibular, and sublingual.

Glands that are scattered in the oral mucosa.

Four fucntions of secretion (saliva):

Primary and permanent dentitions are formed by age ___.

Two sets of teeth:

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

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.

Inner longitudinal, outer pharyngeal constrictors.

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:

Mastication is partly voluntary, partly reflexive.

Contains salivary amylase and lingual lipase.

Deglutition (swallowing).

The parts of the stomach's gross anatomy:

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:

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:

Major organ of digestion and absorption; 2-4m long; from pyloric sphincter to ileocecal valve; has subdivision.

Subdivision of small intestines:

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?

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

Release cytokines that kill infected cells

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.

Remnant of fetal umbilical vein along free edge of falciform ligament.

Three types of ssociated structures of liver:

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:

Filter and process nutrient-rich blood; composed of plates of hepatocytes (liver cells).

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.

Leaky capillaries between hepatic plates

(hepatic macrophages) in liver sinusoids.

Four functions of hepatocytes:

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.