L6: Digestive 1 Flashcards
Digestive system overview of function
responsible for processing, digestion, and absorption of food material
also elimination of wastes or indigestible residue
Epithelium lining of digestive tube and associated glands is derived from endoderm
gut lining secretes mucus which functions to aid passage of contents down the digestive tract, protect against corrosive HCL and protect against enzymatic degradation of epithelial lining
what are the 3 general sections of the digestive tract
oral cavity (mouth)
digestive tube (esophagus, stomach, small and large intestines)
digestive glands (pancreas and liver)
Tongue and oral cavity (epithelium, submucosa structure)
lined by stratified squamous epithelium (nonkeratinizing); except keratinized on gums, dorsal surface of tongue, and hard palate
epithelium (mucosa) underlain by submucosa of dense irregular CT with collagen and elastic fibers
- contains small mucous and mucoserous glands (in submucosa). These glands secrete mucus and digestive enzymes (salivary amylase –> breaks down carbs)
- underlying CT is immunologically active (tonsils=collections of lymphoid tissue in submucosa in pharynx region)
Muscles of the tongue
composed of skeletal muscle sheathed in a mucous membrane continuous with that of the oral cavit
muscle fibers are both intrinsic (confined to the tongue) and extrinsic (originate outside of tongue)
between muscle fibers are mucous glands (at base of tongue), serous glands (in the body of the tongue), and mixed acinar glands (at tip of tongue)
serous glands of the tongue are called von Ebner’s glands= act to wash taste buds free of stimulus molecules to allow new tasting
Von ebner’s glands
act to wash taste buds free of stimulus molecules to allow new tasting
Lingual papillae
projections of mucosal surface with submucosal core
anterior 2/3 of the tongue covered with these
filiform papillae
located over entire surface, slender and conical
fungiform
located singly among rows of filiform, more numerous towarsd tip.
mushroom shaped with secondary papillae of CT
circumvallate
only 10-14 in humans
located along central sulcus of tongue
surrounded by circular furrow
taste buds present in lateral walls
foliate papillae
leaf-like folds on posterolateral margins
taste buds occur in grooves between folds
rudimentary in humans
well developed in rabits
tongue muscle: dorsoventral intrinsic
move tip of tongue
tongue muscle: lateral intrinsic
move tongue sideways, cup tongue
tongue muscle: extrinsic
protrude tongue
taste buds
barrel-shaped neuroepithelium (taste receptor cells, sustentacular cells, basal cells); opens via taste pore
taste receptor cells
chemoreceptors, respond to dissolved molecules
salivary glands, general
compound exocrine glands, developed from epithelial lining
Parotid salivary gland
located below and anterior to ear in humans
ducts open to cheek opposite 2nd upper molar, ducts prominent
serous secretion (enzymes [amylase] and polysaccharides)
compound tubuloalveolar
enclosed by dense irregular CT capsule
secretory unit empties to intercalary duct –> secretory ducts (modify ionic composition) –> excretory ducts –> main duct
divided into lobes and lobules by septa (from capsule)
submandibular salivary gland
lies in floor of mouth beneath the body of the mandible (lower jaw)
duct opens below tip of tongue- ducts prominent
mixed secretion (mostly serous)
mucous secretory units often capped with cresent-shaped serous demilunes
compound alveolar or tubuloalveolar, encapsulated.