Human Digestive System, Exams of Nursing

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Human Digestive System

Organs: The digestive system consists of the

alimentary canal and its accessory organs.

The alimentary canal consists of:

• Oral cavity Esophagus
• Stomach Small intestine
• Large intestine
• Accessory organs : Liver, gall bladder & pancreas

Functions

• Breaks food down into absorbable units that enter

the blood.

• Indigestible food elimination as feces

The Alimentary Canal

• The digestive system consists of: 1 - The alimentary canal (from the mouth to the anal opening). 2 - Accessory digestive organs.
• Its wall consists of four main tissue layers :
• Mucosa
• Submucosa
• Muscularis
• Serosa

The Mouth

• **It contains the teeth and tongues
• is bounded by lips, cheeks, and palate.** - Tonsils guard its posterior margin.

Minor Salivary Glands

- The pharynx: Is a muscular tube that provides a passageway for food and air.

• The Esophagus: is a muscular tube that completes the passageway from the pharynx to the stomach.
• The Stomach: is a C-shaped organ located on the left side of the abdomen beneath the diaphragm.
• Gastric glands produce:
  • Hydrochloric acid - Pepsin
    • Renin - Mucus
    • Gastrin - Intrinsic factor
• Mucus protects the stomach from

Small Intestine

• Its subdivisions are the:
  • duodenum - jejunum - ileum.
• Pancreatic juice and bile enter the duodenum through a sphincter at the distal end of the bile duct.
• Microvilli, villi, and circular folds increase the surface area of the small intestine for enhanced absorption

The large intestine

• Subdivided into the:
• **Cecum - Appendix
• Ascending colon - Transverse colon
• Descending colon - Sigmoid colon
• Rectum - Anal canal.**
• The large intestine delivers undigested food residue (feces) to the body exterior.

• About 1.5 meters

long

• Accepts what

small intestines

don’t absorb

• Rectum (short

term storage

which holds feces

before it is

expelled).

• Parts of Colon 1 - Ascending Colon 2 - Transverse Colon 3 - Descending Colon 4 - Sigmoid Colon
• The Rectum
• Forms last 15 cm ( 6 in.) of digestive tract.
• The anal canal is the last portion of the rectum - Contains small longitudinal folds called anal columns.
• Anus: Also called anal orifice,
• Is exit of the anal canal. Has
• keratinized epidermis like skin