Tongue In the buccal cavity of the digestive system

Transcription

1 Tongue In the buccal cavity of the digestive system same layers as those of tubular organs Mucosa, submucosa, and muscularis muscularis = the muscularis externa no muscularis mucosa 1

2 Tongue ling = tongue Mucosa: apical surface Dorsal surface irregular; lingual papillae (pl.) singular: papilla short projections-several types lower surface smooth and straight Very slick 3 Tongue Different types of papillae Filiform Conical, numerous, no taste buds, keratinized at tips Increase friction for food manipulation Fungiform Mushroom shaped- near tongue tip Poorly keratinized Between filiform Scattered taste buds on lateral surface 4

3 Tongue Different types of papillae Foliate Poorly developed in humans two rows on dorsal-lateral surface lots of taste buds ~150 Circumvalate 7-12 in V-shaped region on posterior dorsal Up to ~3mm diameter Non-keratinized Taste buds present~250 make lingual lipase 5 Tongue Epithelium Mostly non-keratinized stratified squamous epithelium Deals with potentially abrasive activities Lumenal surfaces of Buccal (oral) cavity Oropharynx Between mouth and throat esophagus to the stomach. 6

4 Tongue Epithelium of lower surface; Non-keratinized Flat basal surface No papillae Upper surface of tongue Parakeratinized (partial) on the outer filiform papillae depending on mammal type Primates little papillar keratinization cats have a high degree 7 Wrong! 8

5 Tongue Taste buds (gustatory-receptor sensory organs) Lateral epithelium of the fungiform and circumvallate papillae. Taste buds ~5000- tongue ~2500- soft palate ~900- epiglottis ~ 600- larynx, pharynx Span thickness of epithelium Elongate and narrowing from the widest point to pointed ends Made of two cell types: 1-Gustatory receptor cells 2- Support cells 10

6 Tongue Gustatory receptor cells (taste sensory cells) ~20-40 per taste bud A few microvilli not distinguishable with the light microscope; at distal end microvilli membrane has molecule receptor-sites chemoreceptors Generate impulses at the other end of the cell sent to the cerebrum perception of a general flavor Support cells (sustenticular cells) ~20-40 per bud 11 Tongue 1-Gustatory cell light cytoplasm oval nucleus 2-supporting cell darker cytoplasm elongated nucleus Taste pore Opening to lumen 1 4- Nerve fibers Hypogeusia Reduced sense of taste Age, infections, meds, damage to cranial nerve VII (facial) 12

7 Tongue Lamina propria dense connective tissue Lower surface, thin Upper surface, thicker Interior of papillae Between adjacent papillae. 13 Tongue Mucosal epithelium ducts extend into the submucosa and muscularis both upper and lower surfaces, to mucus or seromucous glands Produce mucus for protective coating No muscularis mucosa 14

8 Tongue Submucosa of the tongue Submucosa not divided from lamina propria; collagen; richly eosinophilic contains small arteries and small veins, etc. 15 Tongue Muscularis Mostly skeletal myofibers in bundles oriented in 3 directions: Allows the tongue to assume a wide variety of shapes Pattern is unique Also present: mucus or seromucous glands, nerves blood vessels sometimes adipose tissue, etc. 16

9 Soft palate Small organ posterior end of the mouth roof Mostly hard palate palatine bone separates buccal from nasal cavity soft palate no bone tissue projects posteriorly 17 c. Soft palate Contains skeletal muscle tissue function; flex upward activities swallowing block the passageway from pharynx to nasal cavity 18

10 Soft palate Mucosa; Oral (buccal) side stratified squamous epithelium ducts into submucosa and muscularis to serous and mucous glands non-keratinized LP is very thin; dense CT no muscularis mucosae 19 Soft palate Nasal side pseudostratified ciliated columnar epithelium glandular; produce mucus ducts into submucosa and muscularis to serous and mucous glands LP same as buccal 20

11 Soft palate Submucosa Thin layer boundary with LP not defined less cellular LP small arteries, etc. Ducts of serous and mucous glands and sometimes glands 21 Soft palate Muscularis mostly parallel skeletal muscle tissue longitudinal may be very difficult to distinguish from the dense CT of submucosa. 22

12 Soft palate Serous and mucous glands usually present elongate, branched mucous acini. usually intermingled with skeletal muscle fibers. 23 Salivary glands General characteristics Compound tubuloacinar exocrine glands produce digestive juices saliva ~ ml water, mucus, ions, antibodies ph solvent for taste, wetting agent Alpha-amlyase- carb digestion Glands develop by extensions of lumenal epithelium produce small branches that become exocrine acini 24

13 Salivary glands Two kinds of glandular cells: mucous and serous. Acini are sometimes either purely one or other sometimes mixed acini; form a "serous demilune" (serous halfmoon) around clump of mucous cells 25 Salivary glands Single layer of squamous-shaped contractile myoepithelial cells surround the acini impulses from nerve endings trigger contraction squeezing the salivary juice into the duct then oral cavity 26

14 27 Salivary glands Tubuloacinar tissue divided into lobes and lobules separated by CT septa contain blood vessels and nerves thin layers of dense CT between acini also capillaries, arterioles, venules, smallest nerves, lymphatic vessels. Organ has a thin capsule of dense CT 28

15 Salivary glands Salivary glands differ on types of glandular cells of acini ratio of types of glandular cells and acini abundance of small ducts 29 Salivary glands Submandibular gland or submaxillary gland (sublingual) Sublingual; smallest; ~5% of saliva Serous cells = mucous cells three kinds of acini mucous, serous and mixed serous acini are distorted by mucous acini Small ducts abundant moderately high viscosity of the digestive juice 30

16 d. Salivary glands 31 Salivary glands Parotid gland Largest, floor of oral cavity ~60% of saliva; branched tubuloacinar Almost all serous cells; basal nuclei; granular cytoplasm small ducts are scarce Our example of parotid gland is an H&Epreparation thin-section with unusually light staining not obvious that the glandular epithelial cells are arranged in acini, and initially the relatively scarce small ducts may not be noticed consequently the section tends to be difficult to recognize as being of parotid gland; there is a strong tendency to misidentify it as liver. 32

17 Salivary glands Parotid gland Epidemic parotiditis (mumps) acute viral infection by paramyxovirus transmitted by infected saliva Swollen and painful parotids Tissue infiltrated by plasma cells and macs 33