Digestive System Flashcards
What are the digestive organs?
-Mouth
-Pharynx
-Oesophagus
-Stomach
-Small intestine
-Large intestine
(part of digestive tract: 4 layer tissue structure)
What are the accessory organs?
-Teeth
-Tongue
-Salivary glands
-Liver
-Gallbladder
-Pancreas
(provide digestive assistance, no 4 layer tissue structure)
What are the 4 layers of the digestive tract?
Mucosa
Submucosa
Muscularis Externa
Serosa
Describe what, where and function of mucosa
What is it?
-Mucous membrane
-Consisting of digestive epithelium: (simple columnar cells, enteroendocrine, mucous cells and goblet cells), lamina propria: alveolar tissue with blood vessels, sensory nerve endings, lymphatic vessels, tissues & muscular mucosa: smooth muscle
Where is it?
-Closest to lumen
Function
-Secretion & absorption
-Protection against digestive acids and enzymes
-Contraction of smooth muscle alters shape of lumen
Describe what, where and function of submucosa
What is it? -Layer of dense irregular connective tissue that contains large blood vessels, lymphatic vessels and exocrine glands Where is it? -2nd closest to lumen Function -Secretes buffers and enzymes into lumen
Describe what, where and function of muscularis externa
What is it?
-2 layers of smooth muscle innervated by enteric nervous system
Where is it?
-Furthest from lumen
Function
-Enables attachment to adjacent structures
Describe what, where and function of serosa
What is it? -Serous membrane Where is it? -Furthest from lumen Function -Enables attachment to adjacent structures
What are the functions of the digestive system?
- Ingestion
- Mechanical processing
- Digestion
- Secretion
- Absorption
- Excretion
Describe ingestion in the digestive system?
Material enters digestive tract via mouth
Describe mechanical processing in the digestive system
- Easier to propel along tract
- Increases surface area to allow easier breakdown
Describe digestion in the digestive system
- Chemical breakdown of food for absorption
- Large molecules (e.g. carbohydrates/starches) broken down to small molecules
(e. g. absorbable sugars)
Describe secretion in the digestive system
Release of water, acids, enzymes, buffers, salts
Describe absorption in the digestive system
Movement of substrates, electrolytes, vitamins and water across walls of
digestive epithelium into interstitial spaces in lamina propria
Describe excretion in the digestive system
Removal of waste products from body
What are the two processes by which materials move through the digestive tract?
Peristalsis and Segmentation
What is peristalsis?
A propulsion process involving waves of smooth muscle contraction that move compacted ingested materials (bolus) along digestive tract