Digestive system Flashcards
The digestive tract begins and ends where?
begins - oral cavity - mouth
ends - anus
what are the six functions of the digestive system?
- Ingestion – takes place when food enters the mouth (oral cavity).
- Mechanical processing (or mechanical digestion) – involves crushing and shearing food and then propelling the food along the digestive tract.
- Digestion (or chemical digestion) – chemical breakdown of food into small molecules that are suitable for absorption.
- Secretion – release of water, acids, enzymes, buffers, and salts by the epithelium of the digestive tract, glandular organs, and the gallbladder.
- Absorption – movement of substances across the digestive epithelium that lines the small intestine. Substances move from the lumen to the interstitial fluid.
- Excretion (or defecation) – removal of waste products from body.
What are the Major organs of the digestive system?
oral cavity small intestine large intestine stomach pharynx esophagus
What are the accessory organs of the digestive system?
teeth salivary glands gallbladder pancreas tongue liver
The digestive tract contains four layers of tissue. What is the name of each layer of tissue and where is each layer located relative to the lumen?
- mucosa - closest to the lumen
- submucosa - 2nd closest to lumen
- muscularis externa (or muscular layer) - 3rd closest to lumen
- serosa - furthest from lumen
Which layer of the digestive tract wall contains epithelial cells?
Mucosa
What type of epithelial cells are found in the stomach and intestines and what is the function of these epithelial cells?
simple columnar epithelial cells; absorption and/or secretion
What types of specialised epithelial cells are found in the epithelial lining of the stomach and intestines?
stem cells
enteroendocrine cells
goblet cells
Paneth’s cells
What is the function of the muscularis externa (or muscular layer) of the digestive tract?
involved in the mechanical processing of food and movement of materials along the digestive tract
Name the two types of motility (movement) in the digestive tract.
segmentation
peristalsis
Describe peristalsis
peristalsis - a propulsion process involving waves of smooth muscle contraction that move compacted ingested materials (e.g. bolus) along the digestive tract.
Describe segmentation
cycles of smooth muscle contraction and relaxation that churns and fragments the bolus to mix the contents of the bolus with secretions (e.g. enzymes).
The oral cavity (mouth) is the first part of the digestive tract that is exposed to food. What are the functions of the oral cavity (mouth)?
ingestion of food
sensory analysis of ingested material
mechanical processing of ingested material
limited chemical digestion
lubrication
what are the functions of saliva?
lubrication of the mouth and pharynx
- cleanse the mouth and teeth
- moistening of food
- limited chemical digestion (i.e. break down starch (carbohydrate) and lipids)
Which glands produce saliva?
Sublingual glands
Submandibular glands
parotid glands
After leaving the oral cavity (mouth), which structures does food pass through on the way to the stomach?
Food passes from the oral cavity (mouth) to the pharynx, esophagus, and then the stomach.
The stomach performs mechanical processing (or mechanical digestion) of materials that enter the digestive tract. Which of the following terms describes the partially-digested food/fluid in the stomach?
Chyme
Function of the Stomach
Carbohydrates digestion
Protein Digestion
Storage and mixing chamber
triglyceride digestion
What type of muscular tissue is found in the walls of the stomach?
Smooth muscle only
The mucosa of the stomach contains four types of secretory cells. What is the name of each type of secretory cell and what substance does each type secrete?
Mucous cells - mucus
Parietal cells - hydrogen chloride (HCl)
Chief cells - pepsinogen
G cells - gastrin