M15: Digestive System - Histology, Peritoneum & Mouth Flashcards
2 groups of organs that make up digestive tract
- GASTROINTESTINAL TRACT (mouth to anus)
- ACCESSORY DIGESTIVE ORGANS (chemical breakdown of food)
- teeth, tongue, salivary glands, liver, gall bladder, pancreas
components of GI tract
- oral cavity
- pharynx
- esophagus
- stomach
- small intestine (duodenum, jejunum, ilium)
- large intestine (ascending, transverse, descending and sigmoid colon, cecum)
- appendix
- rectum
- anus
6 basic processes of digestion
- INGESTION
- SECRETION (add things to chemically break down food)
- MOTILITY (mixing and propulsion of food and secretions)
- DIGESTION
- ABSORBTION
- DEFECATION
4 layers of GI tract
deep to superficial
1. MUCOSA
- 3 layers
2. SUBMUCOSA
3. MUSCULARIS
4. SEROSA
- contain folds of visceral and parietal membrane where blood vessels and nerves are
nervous supply to GI tract
Enteric nervous system
- SUBMUCOSAL PLEXUS
- submucosa layer
- signals to glands to release secretions into lumen - MYENTERIC PLEXUS
- muscularis layer
- signals smooth muscle to contract
layers of mucosa
deep to superficial
EPITHELIUM
- cell type changes depending on location
- mouth, pharynx, esophagus, anus = stratified squamous (protection)
- stomach and intestines = simple columnar (secretion + absorbtion)
- ENTEROENDOCRINE cells: secrete hormones controlling organ function
- glands & ducts that lead to accessory organs
LAMINA PROPRIA
- thin layer loose areolar CT
- capillaries
- immune response: mucosa-associated lymphatic tissue (MALT)
MUSCULARIS MUCOSAE
- thin layer of smooth muscle
- creates little folds in mucosal layer to increase surface area
components of submucosa
Loose areolar CT
- arteries and veins
- glands
- lymphatic tissue
SUBMUCOSAL PLEXUS (ENS)
- motor function: stimulates mucosal secretions
components of muscularis
Double layer of smooth muscle - creates PERISTALTIC movement
1. CIRCULAR LAYER
2. LONGITUDINAL LAYER
Muscle type depends on location
- mouth, pharynx, esophagus, external anal sphincter = skeletal muscle (in control of swallowing and defecation)
- everywhere else = smooth muscle
MYENTERIC PLEXUS (ENS)
- motor function: stimulates muscular contraction
components of serosa
aka visceral peritoneum!
deep to superficial
- areolar CT
- epithelium
covers everywhere in GI tract, except esophagus (only areolar CT called ADVENTITIA)
serosa folds in small intestine
mesentary folds
retroperitoneal organs
classification for tissues not covered by visceral peritoneum
- kidneys, ascending/descending colon, pancreas
greater and lesser omentum
peritoneal folds
Greater (“fatty apron”)
- runs from stomach to transverse colon
- layer of protection in front of organs
- 4 layer membrane, lined with adipose tissue
Lesser
- runs from stomach to liver
5 major peritoneal folds
- Greater Omentum “fatty apron” (stomach to transverse colon)
- Falciform Ligament (liver to anterior wall of abdominal cavity, inferior diaphragm)
- Lesser Omentum (stomach to liver)
- Mesentaries (small intestine)
- Mesocolon (transverse and sigmoid colon to posterior abdominal wall)
structures of oral cavity
- superior and inferior labia (lips)
- cheek: contains BUCCINATOR MUSCLES (manipulate food, speech production)
- ORAL VESTIBULE: space between cheeks, gums and teeth. Not oral cavity proper (teeth to throat)
- GINGIVAE (gums)
- inferior/superior LABIAL FRENULUM: middle of gums, attaches lip to gums
- 32 adult teeth
- tongue
- LINGUAL FRENULUM: membrane that attaches under tongue
- hard palate (bones), soft palate (muscular): roof of mouth
- UVULA: prevents food from going to nasal cavity
- FAUCES: opening to oropharynx
number of teeth in adults vs children
adult: 32
child: 20 baby
