Anatomy – Digestive System Quick Review

Digestive system

Processes:

1)      Ingestion – Food enters the mouth or the Oral Cavity.

2)      Mastication – Chewing action is called Mastication.

3)      Digestion – Chemical process of breaking down food into smaller molecules

4)      Secretion – Acids, Buffers, Enzymes and water are secreted to aid breakdown.

5)      Absorption –  Once broken down, nutrients are absorbed.

6)      Excretion  - Elimination of waste through defecation.

The oral cavity

-Lips or Labia act as doors to the oral cavity.

-Hard and soft Palates create the roof and tongue creates the floor.

Tongue:

-Taste, Sense of temperature and texture, manipulates food and aids in swallowing.

-Lingual Frenulum – Aids in speech, swallowing and keeping tongue intact.

Salivary Glands:

-Parotid Salivary Gland- inferior and anterior to the ear. Swell when you get mumps.

-Sublingual Salivary Glands – Located under the tongue.

-Submandibular Salivary Glands- Located along the inner surface of the mandible.

Saliva contains antibodies, buffers, ions, waste products and enzymes.

Salivary Amylase (Ptyalin) – is a digestive enzyme that speeds up break down of carbohydrates.

Teeth:

Deciduous Teeth- First set of teeth also known as baby teeth. Age: 6months – 12years.

Incisor- Located in the front used to cut food.

Canine – Used for holding and tearing or slashing food.

Next are Cuspids and Bicuspids

Molars – Responsible for crushing and grinding.

-All teeth have a crown, neck and root. The crown is covered by a hard substance called Enamel.

-The inner part of the tooth there is Pulp which contains blood vessels and nerves.

Cementum – Soft version of bone helps in securing the Periodontal Ligament.

-gums are also known as Gingiva.

Pharynx:

Main structure located here is the Epiglottis which blocks food from entering the trachea.

Esophagus:

-10 inches long (25 centimeters)

-Extends from the pharynx, through the thoracic cavity and diaphragm, to the stomach.

Pharyngoesophagel Sphincter – Blocks the entrance to the Esophagus.

Peristalsis-  The rhythmic contractions of muscles to move food down.

Lower Esophagel Sphincter- Also known as the cardia sphincter relaxes to let food into the stomach. Heart burn (pyrosis ) occurs when the door is inadvertently opened.