upper digestive system - oral cavity and esophagus

there are two main groups of digestive organs

alimentary canal

accessory organs

what is the alimentary canal also called

gastrointestinal (GI) tract

what is the GI tract

a continuous muscular tube

• digests and absorbs food

what are the organs of the GI tract

• mouth

• pharynx

• esophagus

• stomach

• small intestine

• large intestines that ends in the anus

accessory digestive organs are?

• teeth

• tongue

• gallbladder

• salivary glands

• liver

• pancreas

what do the glands in the accessory digestive organs produce

• saliva

• bile

• digestive enzymes

the digestive system function

• propulsion

• secretion

• absorption

• excretion

• immunologic protection

• hormone production

the digestive tract is divided into

• upper tract

• lower tract

what does the upper digestive tract include

• oral cavity

  • lips, teeth, palate, tongue cheeck

• pharynx & esphogus

the lower tract mostly deals with?

digestion absorption and excretion

• stomach

• small and large intestine

• anal canal

oral cavity is an…

entrance to the digestive system

the oral cavity is a….

chamber in food is mechanically fragmented by teeth, chemically modified by enzymes and lubricated by saliva

the oral cavity contains a narrow space called? and are in btwn?

vestibule that are between lips and teeth

oral cavity bound by

hard and soft palates above

oral cavity bounded also by

back of gums and teeth anteriorly and palatoglossal folds of cheeks laterally

the gi wall consists of how many layers

4

• mucosa

• submucosa

• tunica muscularis or muscularis externa

• serosa (NOT IN ESOPHAGUS - called adventitia)

the oral mucosa is classified into

1. lining mucosa

2. masticatory mucosa

3. specialized mucosa

lining mucosa

forms inner lining of lips, cheeks, soft palate, floor of mouth and undersurface of tongue

• nonkeratinzed stratified squamous epithelium

masticatory mucosa

in gingivae (gums) and hard palate

• lightly keratinized stratified squamous epithelium

specialized mucosa

on the dorsal surface of tongue

• nonkeratinized stratified squamous epithelium

the tongue is a highly

mobile muscular structure

what does the tongue engage in

• mastication

• swallowing

• speed and taste

what kind of epithelium does the tongue have

nonkeratinized stratified squamous

what kind of muscles does the tongue have?

striated muscles

• the muscles are oriented, horizontally, longitudinally and vertically

since the muscles of the tongue are oriented, horizontally, longitudinally and vertically this provides

a high degree of mobility

what is the v shaped groove that our tongue has

sulcus terminalis

• btwn anterior oral and posterior pharyngeal

what are the lingual papillae

surface projections

what are the three main types of lingual papillae on the roughened dorsal

• filiform

• fungiform

• circumvallate

filiform

most in number, with slender and conical projections

• heavily keratinized cells

• grey in color due to keratin

fungiform

narrow base, scattered among filiform papillae and have connective tissue core

circumvallate

in row of 8-12

• on posterior side of tongue

• largest in size

• nonkeratinized or incompletely keratinized

• serous glands of von ebner

taste buds are found

on lateral surfaces of epithelium of fungiform and circumvallate papillae

about how many taste buds we got?

• 5,000 on tongue

• 2,500 on soft palate

• 900 on epiglottis

• 600 in larynx and pharynx

taste buds are special sensory receptors that

transduce chemical stimuli

the chemical stimuli transduces into nerve impulses that are perceived as?

gustatory sensations

taste buds

• pale ovoid bodies with 50-75 fusiform cells

• wider on base

• narrower on the apex

what does the apex have?

a taste pore

what are the three cell types found in our taste buds

• dark cells (type I)

• light cells (type II)

• pale cells (type III)

how are our cell types identifies

by staining properties

dark cells (type I)

• long microvilli

• apical cytoplasmic granules

• are supporting cells and lie in periphery

light cells (type II)

• lie centrally

• long microvilli

• granules

• abundant smooth er and little rough er

pale cells (type III)

• light staining

• long apical processes that are several times the diameter of microvilli - contain gustatory cells

what are the four basic taste sensatios

• sweet & salty

• bitter and sour

sweet and sour

taste bunds abundant near tip of tongue

bitter and sour

taste buds abundant in back of tongue

adult human had ____ permanent teeth, _____ incisor, ____ canines, ___ premolars and ___ molar teeth in each jaw.

32, 4, 2, 4, 6

what is the structure of a tooth

• crown

• neck

• root

crown

portion of tooth that project above gum or gingiva

neck

portion in between crown and root

root

portion that fits into the underlying bone, one or more roots in a bony socket or alveolus of the jaws,

what kind of complex process is teeth developed by

odontogenesis

odontogenesis is derived by 2 embryonic processes

• enamel

• dentin

enamel arises

from oral ectoderm

dentin, pulp, cementum & periodontal membrane arise

from mesenchyme

what does the bulk of teeth consist of

dentin that is covered by enamel in the crown area

where is enamel absent

in the root area

what is dentin covered by

thin layer of cementum that is enclosed in a periodontal membrane

the crown of tooth has a small…

central pulp cavity that reaches all the way down to the root as the root canal

when acid forms as bacteria and dissolves the enamel what happens?

tooth decay or dental caries

what dramatically reduces the incidence of caries

fluoridation

what is added to drinking water or oral hygiene product?

fluoride (F-)

what do the F- ions replace

the OH ions in the hydroxypatite crystals of enamel to form fluoroapatite

fluoroapatite is

chemically more stable (stronger), less soluble (wont break down as easy), and more resistant to acid that is made by the bacteria plaque

dentin is

• avascular

• mineralized tissue

• harder than bone mineral but same in composition

dentin is what type of collagen

type I (18%) and the rest is 12% water

what is the dentin composed of?

70% hydroxyapatite

how is dentin synthesized (made)

by odontoblasts

what are odontoblasts

tall columnar cells that line the pulp cavity

enamel

• hardest substance in the body

• 96% hydroxyapatite

the 4% rest of the enamel is made up of

amelogenins and enamelins

what does enamel lack

collagen

what is enamel composed of?

rods or prisms that radiate from dentin

how is enamel produced

ameloblasts

when do amelobalsts degenerate

after the complete formation of enamel

periodontal membrane or ligament

• layer of collagen that envelope roots of tooth

• interposed btwn cementum and surround alveolar bone

• anchors tooth into socket

gingiva

• thicker portion or oral mucous membrane bound by periosteum

what is gingiva separated from

enamel forming gingival crevice with squamous epithelium

what prevents the entry of bacteria

the seal btwn epithelium and enamel

minor salivary glands

• short and numerous in mucosa

• open directly or via short ducts on surface of oral epitheloum

the minor salivary galnds

secrete continuously and contribute saliva that moistens and lubricates oral cavity

major salivary galnds

• 3 pairs

  • parotid

  • submandibular

  • sublingual

where is the major salivary glands located

away from oral epithelium and connected to it by branching system of ducts

what does the major salivary glands produce

LARGE volume of secretions

• on mechanical and chemical stimulation of nerve ending in mucosa

  • some will secret in response to olfactory stimuli

major salivary glands are?

mixed glands

• mucous

• serous

• sero-mucous (mixed)

secretions differ in composition

what layers does mucous acini have

single layers of pyrimidal cells

• cytoplasm with mucigen

• abundant rer

• with viscous secretion

what are the products of serous acini

• amylase

• lysozyme

• peroxidase

• DNAse

• RNAse

what does mixed acini have?

both mucous (proximal) and serous (distal) acini

saliva is

a mixture of products of several kinds of salivary glands

saliva is a…

viscous, colorless and opalescent fluid

composition of saliva

• 97-99% water

• inorganic ions

• proteins

• salivary corpuscles

what is the basal rate of salivary secretion

0.5 to 1ml/minute

how is the basal rate affected (increased)

through the response to presence of food in mouth

total secretion (daily)

1 liter or more

what is the function of saliva

• moistens and lubricates mouth

• initiates digestion of carbohydrates

• controls bacteria in the oral cavity

tonsils is the, with what obvoius

simplest lymphoid organs with obvious germinal centers

tonsils are named according

to their location

tonsils form what?

form a ring of lymphatic tissue around entrance of pharynx

palatine tonsils

largest and most infected

lingual tonsils

at base of tongue

pharyngeal tonsils

adenoids are enlarged