Mechanically and chemically breaking down foods so they can be absorbed.

(Ingestion, propulsion, digestion, absorption, and defecation)

Characteristics of the Alimentary canal

-The structure of the wall

-The wall consists of four layers

-the mucosa, submucosa, muscular layer, and serosa.

Characteristics of the Alimentary canal

Movements of the tube

-motor functions include mixing and propelling movements

-Peristalsis is responsible for propelling movements

-The wall undergoes receptive relaxation just ahead of a peristalic wave

Characteristics of the Alimentary canal

Innervation of the tube

-The tube is innervated by branches of the sympathetic and parasympathetic divisions of the autonomic nervous system.

-Parasympathetic impulses generally increase digestive activities; sympathetic impulses generally inhibit digestive activities

-sympathetic impulses contract certain  sphincter muscles, controlling movement through the alimentary canal

Mouth

cheeks and lips

-Cheeks form the lateral walls of the mouth

-Lips are highly mobile and have a variety of sensory receptors useful in judging the characteristics of food.

-the tounge is a thick, muscular organ that mixes food with saliva and moves it toward the pharynx.

-the rough surface of the tounge handles food and has taste buds.

-lingual tonsils are located on the root of the tounge

-the palate comprises the roof of the mouth and includes hard and soft portions

-the soft palate, including the uvula, closes the opening to the nasal cavity during swallowing.

-palatine tonsils are located on either side of the tounge in the back of the mouth

-tonsils consist of lymphatic tissues.

- there are 20 primary and 32 secondary teeth.

-Teeth mechanicall break food into smaller pieces increasing the surface area exposed to digestive actions

-each tooth consists of a crown and root and is composed of enamel, dentin, pulp, nerves, and blood vessels.

-A tooth is attached to the aveolar process by the periodontal ligament.

-salivary glands include serous cells that secrete digestive enzymes and mucous cells that secrete mucus.

-parasympathetic impulses stimulate the secretion of serous fluid

- the parotid glands are the largest, and they secrete saliva rich in amylase

-the submandibular glands in the floor of the mouth produce viscous saliva.

-the sublingual glands in the floor of the mouth primarily secrete mucus.

Pharynx and Esophagus

the structure

-the pharynx is divided into a nasopharynx, oropharynx, and laryngopharynx

-the muscular walls of the pharynx contain fibers in circular and longitudinal groups