What are the two categories of digestive system organs?

Alimentary canal and accessory organs

Alimentary canal

continuous muscular digestive tube that runs through the body digesting and absorbing food. They includes mouth, pharynx, esophagus, stomach, small and large intestine

Accessory digestive organs

aid digestion physically and produce secretions that break down food. They include teeth, tongue, gallbladder, salivary glands, liver, and pancreas

Ingestion

Act of putting food in the mouth

Propulsion

moves food through the alimentary canal and includes swallowing and peristalsis

Peristalsis

waves of contractions and relaxation of muscle in organ walls to push food along

Mechanical digestion

PHYSICAL process of breaking food down in preparation for digestion. Involves chewing, mixing, churning, and segmentation

Chemical digestion

series of catabolic steps where complex food molecules are broken down to their chemical building blocks by enzymes

Absorption

digested products pass from lumen of GI tract through mucosal cells into blood and lymph (small intestine)

Defecation

eliminates indigestible substances from the body as feces

Digestive activities are triggered by
Control of digestive activity are

mechanical and chemical stimuli
extrinsic and intrinsic (nervous and hormonal)

Visceral peritoneum covers
Parietal peritoneum covers

External surfaces of most digestive organs
Lines the wall of the abdominal cavity

Peritoneal cavity

Located between the visceral and perietal peritoneums and is filled with serous fluid

Messentery

Double layered peritoneum that extends to the digestive organs from the body wall and allows vessels, lymphatics, and nerves to reach the digestive organs, hold organs in place, and store fat.

Retroperitoneal organs

posterior to messentery lying against dorsal abdominal wall

The splanchic circulation serves

digestive system and includes the arteries that branch off the abdominal aorta to serve the digestive organs and hepatic portal circulation

Mucosa membrane
Funtion

inner most epithelial membrane that lines the entire digestive tract
secretes mucus, digestive enzymes, and hormones. Absorbs digestive end products into the blood.
Protects against infectious disease.

Submucosa membrane

Dense connective layer containing blood and lymphatic vessels, lymphoid follicles, and nerve fibers

Muscularis externa

consists of smooth muscle and is responsible for peristalsis and segmentation

Serosa

protective outer later of the intraperitoneal organs and is the visceral peritoneum

The mouth is composed of
Boundaries

stratified squamous epithelial mucosa lined cavity
lips, cheeks, palate, tongue

The palate

forms the roof of the mouth and contains both the soft palate and hard palate

The tongue is made of
Function

Interlacing bundles of skeletal muscle
Reposition food when chewing, mix food with saliva, initiate swallowing, and help for consonants for speech

Salivary glands
Function

Produce saliva
cleanses the mouth, dissolves food chemicals for taste, moistens food, and contains chemicals that begin to break down starches.

Salivary Amalayse
Lingual Lipase

starts starch digestion in the mouth
destroys microbes in the mouth

Pharynx

provides a passageway for foods, fluid, and air

Esophagus

provides a passageway for foods and fluids

Mastification

begins the mechanical breakdown of food and mixes food with saliva (chewing)

Deglutition-
2 phases

Swallowing
Buccal phase
Pharyngeal-esophageal phase

Buccal phase
Pharyngeal-esophageal phase

Voluntary and occurs in the mouth when the bolus is forced into the oropharynx
Involuntary and occurs when food is squeezed through the pharynx and into the esophagus

The stomach

temporary storage tank where chemical break down of proteins in initiated and food is converted into chyme

Stomach length and diameter

About 15-25 cm long but its diameter varies from person to person

Major stomach regions

cardiac region, fundus, body, and pyloric

Greater Curvature
Lesser Curvature

Convex lateral surface
Convex medial surface

The surface epithelium of the stomach is

simple columnar composed of goblet cells that secrete a two layer coat of alkaline mucus

Gastric stomach glands

produce gastric juices composed of mucus, hydrochloric acid, intrinsic factor, pepsinogen, and a variety of hormones