digestive system Flashcards
functions of digestive system (6)
- ingestion
- mechanical digestion and propulsion
- chemical digestion
- secretion
- absorption
- defecation
digestive organs part of digestive tract
mouth, pharynx, oesophagus, stomach, small intestine, large intestine
mouth
ingestion, start of mechanical digestion with teeth and tongue, moistening, mixing with salivary glands
pharynx
muscular propulsion of materials into the esophagus
esophagus
transport materials to stomach
stomach
chemical digestion with acids and enzymes, mechanical digestion by muscular contraction
large intestine
dehydration and compaction of indigestible material in preparation for elimination
accessory organs
teeth, tongue, salivary glands, liver, gall bladder, pancreas
mesenteries
-two sheets of serous membrane
- tissue between sheets
-nerve, blood and lymphatic supply
-stabilises and attaches digestive organs to the peritoneal cavity and stops the organs from entangling
Histological organisation
4 layers
-mucosa
-submucosa
-muscular layer
-serosa
layers of mucosa layer
-mucosal/digestive epithelium
-lamina proper
-muscularis mucosae
digestive epithelium (2 types)
- stratified squamous
-oral cavity, pharynx and oesophagus
-mechanical stresses - simple columnar
-stomach, intestines
-absorption
BOTH: PROTECTION AGAINST
-digestive acids and enzymes
-mechanical stresses, such as abrasion
-bacteria are ingested with food and reside in the digestive tract
what is lamina proper?
areolar tissue containing
-blood and lymphatic vessels
-sensory nerve endings
-lymphoid tissue
4 types of specialized epithelial cells
-stem cells (cell renewal)
-enteroendocrine cells (secrete hormones)
-goblet cells (secrete mucous)
-panteth’s cells (secrete antimicrobial peptides)
submucosa
-dense, irregular connective tissue
-large blood vessels and lymphatic vessels
-may contain exocrine glands that secrete buffers and enzymes in the digestive tract
submucosal plexus
-nerve plexus
-innervates the mucosa and submucosa
-sensory neurons, parasympathetic neurons and parasympathetic neurons
muscular layer (muscularis externa)
-two big layers of smooth muscle cells
-arranged in an inner circular layer and an outer longitudinal layer
-involved in mechanical processing and movement of materials along the digestive tract
-movements are coordinated by enteric nervous system, (ENS) and primarily innervated by the parasympathetic division of the ANS.