Digestive system anatomy

Digestive System Anatomy

1: Digestive tract

it is also known as Alimentary tract or canal. It is a tube that extend from the mouth to the anus. Sometimes also known as digestive tract.

2: Accessory organs

These are primarily glands, present outside the digestive tract that secrete fluids into it.

Regions of digestive tract   

1: Mouth or oral cavity  

2:  Pharynx or throat

3: Esophagus

4: Stomach

5: Small intestine -- duodenum, jejunum, and ileum

6: Large intestine -- cecum, colon, rectum

7: Anus

1: Mouth or oral cavity

Vestibule: It is a space between lips or cheeks and alveolar processes.

Lips (labia) and cheeks

Palate: It is the Oral cavity roof

Hard and soft

Palatine tonsils are in the lateral walls

Tongue: It is Involved in speech, taste, mastication, swallowing

Teeth

Two sets

Childhood: Primary, deciduous, milk

Adult (32): Permanent or secondary

Types

The incisors, canine, premolar, and molars

Teeth composition

A tooth is composed of a crown, a neck, and a root.

The root is wrapped with cementum.

The tooth is confined in the socket by periodontal ligaments.

Vessels and nerves enter and exit the tooth through the apical foramen.

 Salivary glands

They produce saliva, prevents bacterial infection, and lubricate food.

They contain salivary amylase which breaks down starch covalent bond

Three pairs

Parotid is Largest

Submandibular

Sublingual is Smallest

2: Pharynx

It consists of nasopharynx, oropharynx that transmits food normally and laryngopharynx and transmits food normally.

3: Esophagus

It transports food from pharynx to stomach. The food is squeezed down by peristaltic movements.

Sphincters inhibit upward movement of food from stomach.

4: Stomach Anatomy

Openings of stomach

1: Gastroesophageal: To esophagus

2: Pyloric: To duodenum

Regions of stomach

·         Cardiac

·         Fundus

·         Body

·         Pyloric

Layers of stomach

1: Serosa or visceral peritoneum: Outermost

2: Muscularis: It consist of three layers outer longitudinal, middle circular and Inner oblique.

3: Submucosa

4: Mucosa

 Liver

Lobes of liver

Major: Left and right

Minor: Caudate and quadrate

5: Small intestine

It is site of greatest amount of digestion and absorption

It consists of duodenum, jejunum and ileum.

Small intestine secretions

·         Mucus

·it protects against digestive enzymes and stomach acids.

·         Digestive enzymes

·Disaccharides: they break down disaccharides into monosaccharides

·Peptidases: it hydrolyzes peptide bonds

·Nucleases: it breaks down nucleic acids

·         Duodenal glands

·Stimulated by vagus nerve

·Release secretin

6: Large Intestine

It extends from ileocecal junction to anus. It composed of cecum, colon, rectum, anal canal.

Cecum

It is a blind sac, with an attached smaller, blind tube of nine cm length known as vermiform appendix attached

Colon

It is about 1.5–1.8 m long. It has ascending colon, transverse colon, sigmoid colon, and transverse colon.

Rectum

It is straight muscular tube.

The rectum mucosal lining is simple columnar epithelium, and the muscular tunic is relatively thick, compared with rest of digestive tract.

Anal canal

The last 2–3 cm of the digestive tract is called anal canal.

Internal anal sphincter.

External anal sphincter.