THE MF DIGESTIVE SYSTEM Flashcards
Histology of the mouth
Non-keratinized stratum squamous epithelium
Classifications of teeth
-Incisors: Cutting
-Canines: tearing & piercing
-Premolars: Grinding
-Molars: Grinding
Saliva
Mucurs & serous fluid used to form a bolus, dissolve chemicals for digestion, and contains salivary amylase.
Salivary amylase
Enzyme in mouth to breakdown starch into maltose
Pharynx histology
Stratified squamous epithelium
Histology of esophagus
Non-keratinized stratified squamous epithelium
4 layers of alimentary canal
-Mucosa
-Submucosa
-Muscularis externa
-Serosa
Mucosa
-Non-keratinized stratified squamous epithelium
-Lamina propria (Areolar CT): where vessels, lymph vessels, and immune cells enter
-Muscularis mucosae: Thin layer that creates local movement
Submucosa
Provides support and blood vessels, lymph vessels, and nerves.
Muscularis
-Circular muscle
-Longitudinal (Superficial) muscle
Serosa
-Prevents friction between abdominal organs and other structures in the abdominal cavity
-Epithelium
-Areolar CT
Process of swallowing
- Buccal phase: Tongue presses against hard palate to force food down oropharynx
- Pharyngeal-esophageal phase: Uvula, larynx, and tongue prevent upwards movement of food and bolus presses upper esophageal sphincter to enter esophagus
3.Upper esophageal sphincter contracts for food entry - Peristalsis moves food through esophagus of stomach
- Gastro-esophageal sphincter opens for food to enter stomach
Rugae
Internal folds of mucosa in stomach
Muscularis externa of the stomach
-3 layers of smooth muscle
-Inner layer allowing stomach to churn, mix, and brake down food
Mucosa of stomach
-Simple columnar epithelium and secratory cells
-Lined with mucous cells
-Dotted with gastric puts, gastric glands, and gastric juice
Mucous cells of stomach
Secrete 2-layer coat of alkaline mucus to prevent hydrochloric acid from damaging mucosa lining
4 secretory cells of stomach mucosa
-Mucous neck cells
-Chief cells
-Parietal cells
-Enteroendocrine cells
Chief cell secretions in stomach
-Lipases: 15% of lipid digestion
-Pepsinogen: Inactive form of pepsin for protein metabolism
-Rennin: Digesting milk proteins in infants
Parietal cell secretions in stomach
-Intrinsic Factor: Vitamin B12 absorption
-Hydrochloric acid: Keep stomach pH low and activate pepsinogen into pepsin
Enteroendocrine cell secretions
-G cells secrete gastrin
-D cells secrete somatostatin
-ECL cells secrete histamine
3 reflex pathways to stimulate H+/K+ pumps to increase HCl secretions
-Parasympathetic nervous system
-Gastrin by G cell
-Histamine from EnteroChromaffin-like cells
Cephalic phase of gastric secretion
-Cephalic phase
-Sensory information to brain associated to food triggers PSNS (Vagus nerve) to prepare gastric secretions to receive food from stomach
Regulation of cephalic stage
Loss of appetite signals to the cerebral cortex to no longer stimulate parasympathetic center
Gastric phase of gastric secretion
-Mechano/stretch/chemo receptors in stomach wall stimulate parasympathetic nervous system to secrete
Regulation of gastric phase
-Excess acidity cause gastrin secretion to decline
-Emotional distress causes sympathetic NS activation which overrides PSNS causing secretion inhibition
Intestinal phase of gastric secretions
-Chemoreceptors in the wall of duodenum trigger PSNS causing intestinal gastrin to release in blood causing stomach secretion