While working with each slide in this unit, not only should you learn to recognize the organ, but you should learn to relate the function of the organ to its tissues and structures. This page summarizes organ and tissue functions for the assigned slides. Use this summary page in conjunction with your Histology Supplement Sheet in reviewing this unit. The organs included are:

TONGUE

INTESTINE

TRACHEA

ESOPHAGUS

PANCREAS

LUNG

STOMACH

[DIGESTIVE AND RESPIRATORY HISTOLOGY] [UNIT 3 TEST] [HOME]

TONGUE WITH TASTE BUDS: The "taste sensations" of sour, sweet, bitter and salty are picked up from molecules in food dissolved in saliva that come in contact with the gustatory cells of the taste buds. These sensations are relayed to the post central gyrus of the cerebrum. This muscular organ moves the food around during mastication and initiates swallowing by moving the food to the pharynx.

stratified squamous epithelium - lines the tongue: it is a very protective epithelium, wearing away as the tongue moves food around the mouth

muscle - skeletal muscle for movement

[TOP] [TONGUE MICROGRAPH] [HOME]


ESOPHAGUS: This organ moves the swallowed food to the stomach by peristalsis.

stratified squamous epithelium lines this organ: it is very protective, especially as we eat crusty and hot foods

muscles layers - superior 1/3 of the esophagus is skeletal muscle, the lower 2/3 is smooth muscle in two layers, inner circular and outer longitudinal. The circular muscles decrease the diameter of the esophagus and the longitudinal muscles shorten the organ as they push food to the stomach.

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STOMACH: This organ stores the food that was eaten, churn its contents into a chyme, partially digests protein, absorbs water, aspirin and alcohol, and produces the intrinsic factor important for Vitamin B12 absorption in the small intestine.

mucosa - simple columnar epithelium composed entirely of mucus producing goblet cells

gastric pits - these depressions interrupt the stomach lining and contain gastric glands that produce HCl, intrinsic factor and pepsinogen

muscle layers - smooth muscle in three layers: innermost - oblique, middle - circular, outer - longitudinal

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INTESTINE: Digestion of all groups of food continue here, digested food is absorbed and indigestible foods are moved to the large intestine.

villi - fingerlike folds of the mucosa - increase surface area thereby increasing absorption

muscle layers - two smooth muscle layers, inner circular and outer longitudinal, move the contents primarily by segmentation.

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PANCREAS: enzymes from this organ digest all of the food groups

acini - are clusters of cells around ducts which secrete pancreatic juice. These are exocrine glands as compared to the pancreatic islets which are endocrine.

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TRACHEA: air passageway with a lining designed to catch impurities found in the inhaled air

pseudostratified ciliated columnar epithelium with goblet cells - secretes mucus which traps the impurities and the cilia move the impurities to the mouth for swallowing

hyaline cartilage - in "c" shaped rings which hold the trachea open

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LUNG: for exchange of CO2 and O2

alveoli - with simple squamous epithelial lining for rapid diffusion

bronchioles - small air passageways - with thicker epithelium and smooth muscle

[TOP] [LUNG MICROGRAPH]
[DIGESTIVE AND RESPIRATORY HISTOLOGY] [UNIT 3 TEST] [HOME]

This page was last updated in August, 1997.

All micrographs are the property of Sherri Wick. Students of Biology 2740 and 2840 are welcome to use this page in the study and review of lecture and lab materials in the Human Physiology and Anatomy courses.

Please e-mail or hand deliver suggestion for changes to this web site that would make the site more helpful to you in your learning and review.

Author: Sherri Wick, Coordinator and Instructor - Human Physiology and Anatomy Laboratories
University of Nebraska at Omaha
Allwine Hall 211E, 554-2343
swick@cwis.unomaha.edu