Digestive System

Digestive tract (GI tract)

Muscular tube from the oral cavity to the anus

Accessory organs

Organs that support digestion (teeth, tongue, salivary glands, liver, gallbladder, pancreas)

Ingestion

Taking food into the mouth

Mechanical digestion

Physical breakdown of food (chewing, mixing)

Chemical digestion

Breaking down food with enzymes and acids

Secretion

Release of water, acids, enzymes, and salts

Absorption

Movement of nutrients into the bloodstream

Defecation

Elimination of waste as feces

Peritoneum

Serous membrane lining the abdominal cavity

Visceral peritoneum

Covers organs

Parietal peritoneum

Lines body wall

Peritoneal fluid

Lubricates organs to reduce friction

Mesenteries

Double layers that suspend and stabilize digestive organs

Lesser omentum

Stabilizes stomach

Greater omentum

Protects and insulates abdominal cavity with fat

Mesentery proper

Suspends small intestine

Mesocolon

Suspends large intestine

Falciform ligament

Stabilizes liver

Mucosa

Inner lining; protection, secretion, absorption

Submucosa

Connective tissue with blood vessels, nerves, glands

Muscular layer

Smooth muscle for movement and digestion

Serosa

Outer covering of digestive tract

Peristalsis

Wave-like movement pushing food forward

Segmentation

Mixing movement that churns food

Bolus

Ball of food being swallowed

Oral vestibule

Space between lips/cheeks and teeth

Gingivae (gums)

Mucosal ridges around teeth

Uvula

Prevents food from entering pharynx too early

Tongue

Muscular organ that forms bolus and helps digestion

Lingual lipase

Enzyme that begins fat digestion

Salivary glands

Produce saliva for lubrication and digestion

Parotid glands

Produce saliva with amylase for carbohydrate digestion

Sublingual glands

Produce mucus for lubrication

Submandibular glands

Produce both mucus and enzyme-rich saliva

Saliva

Mostly water with enzymes, buffers, and antibodies

Teeth

Mechanically break down food by chewing

Dentin

Hard tissue similar to bone

Pulp cavity

Contains blood vessels and nerves

Root canal

Passageway for vessels and nerves

Cement

Bone-like covering of tooth root

Periodontal ligament

Anchors tooth to bone

Crown

Visible part of tooth

Enamel

Hardest substance in the human body

Incisors

Cut food

Canines (cuspids)

Tear food

Premolars (bicuspids)

Crush and grind food

Molars

Heavy grinding of food

Deciduous teeth

Baby teeth (20 total)

Permanent teeth

Adult teeth (32 total)

Pharynx

Common passageway for food, liquid, and air

Nasopharynx

Upper region (air only)

Oropharynx

Middle region (food and air)

Laryngopharynx

Lower region (food passage)