digestive system I and II Flashcards
what does digestive system consist of
digestivetract (oral cavity, pharinge, esophagus, stomach, small and large intestines & Rectum-terminal partof LI)
associated glands (salivary glands, liver and pancreas)
what is function of digestive system
obtain from ingested food the metabolites for growth & energy requirements before being stored (in fat) or used as energy, the food must be digested and transformed into small (mini) molecules that can be easily absorbed through lining of digestive tract
which enzymes are in stomach and small intestines
both digest food
stomach - stomach enzymes
small intestine - pancreatic enzymes
describe first step of digestion
occurs in mouth
where food is moistened by saliva and ground by teeth into smaller pieces
saliva also initiates digestion of carbohydrates - sugars - not much since food isnt in mouth for long
what is oral cavity lined with
non keratinized stratified squamous epithelium and lamina propria of loose ct = oral mucosa
describe lp of oral cavity
transitions to keratinized at level of lip
lp is coontinous with submucosa of denser ct with diffuse small salivary glands - serous or mucous
describe gingiva
parakeratinized
skin on external aspect of lip is orthokeratinized - rest of oral mucosa = nonkeratinized
where does oral mucosa start
starts in inner aspect of lip = covers all internal parts - reflected at level of tongue and bones
describe area of gingiva
gingival suculus
mucosa very folded interdigitating with lamina propria
small area covers part of tip and crown
describe oral mucosa
non keratinized stratified squamous
superficial layer - ct of flat cells - squamous
no stratum granulosum or cornuem
mid layer = polygonal or multisided cells
stratum basal = basal layer, cuboidal or columnar
describe tongue
mass of striated muscle covered by layer of oral mucosa
muscle fibers are usually cut in the 3 planes of section
mucosa = nonkeratinized stratified squamous epithelium and a lamina propria strongly attached to muscles
dorsal surface is irregular due to presence of small eminences called papillae
name the 2 tonsils
palatine tonsil
lingual tonsil
both lymphoid tissue
name the 3 kinds of papilla
fungiform
filiform
Circumvallate
describe fungiform papilla
smaller mushroom like at base of protrusions
narrow stalk
covered by oral mucosa
describe circumvallate papilla
at base of tongue, inverted v shape, 10-18, most important
lp of loose ct
plunge in mucosa = creates groove spaces = where taste buds are
sruface covered by oral mucosa- base of peithelium very folded
von ebners glands
describe von ebner’s glands
collection of serous acinus
secretion of lipase
activate in stomach
duct opens at base of circumvallate papilla
describe filiform papilla
tongue not smooth due to these
lp = loose ct
pointy, 1-2 tips
covered by oral mucosa
submucosa = dense irregular ct, glands, striated skeletal muscle
sometimes keratin found at tip
name parts of taste bud
sensory pale cells - type 2
supporting cells - type 1
afferent fibers and schwann cell
basal cells - type 4
type 3 - intermediate cells
describe sensory pale cells - type 2 of taste bud
most are these cells
Synapse with nerve afferent fibers
columnar - start at bm and end at level of pore = small opening, allows food to come into contact with digestive contents, allows food and chemicals to contact
has microvilli on top
describe supporting cells - type 1 of taste bud
dark cells
describe afferent fibers and schwann cell of taste bud
sensory cells synapse with afferent fibers - not axons or dendrites
when pieces of food - chemical of food like glutamate - causes action potential that is transmitted to nerve afferents, which are covered by schwann cells but do not form myelin
nerve transmits action potential to brain via facial nerve, glossopharyngeal nerve and vagus nerve, takes info to brain and back to mouth
describe basal cells - type 4
of taste bud
short cells
stem cell precursors
describe of taste bud type 3 - intermediate cells
4th type of cell
not shown
name and describe taste bud mutations
familial dysautomia = lack of taste sensation & dsgeusia not life threatening but causes nutrition issues, especially in babies (since will not like food)
how to know if have it? =
phenylthiocarbamide (ptc) -bitter substance =puts drop of it in babies mouth & if baby has normal taste sensation they will frown
describe qualities of taste perceptions and aspects of taste
saltiness
sweetness
sourness
bitterness
umami
taste map is wrong- taste is equally distributed everywhere
taste buds are in palate, circumvallate papillae and a few in fungiform papillae - in animals = no tastes buds in fungiform
describe function of salivary gland
wet and lubricate oral cavity and its contents
initiate digestion of
carbs - not much since short time
secrete amylase - destroys glycogen
lysozyme - destroy bacterial wall
IgA - control germs in mouth
lactoferrin - sequester iron needed for protein synthesis so germs will not multiply
flora regulation
name the salivary glands
parotid - mainly serous
submandibular - serous and serous mucous
sublingual gland -mainly mucous - sometimes serous too
what are the salivary glands
compound acinar
branches, and mainly acini, could be tubular
describe division of salivary glands
capsule = ct, subdivides into lobes
interlobar ct and ducts = between loves
thin subdivisions of lobe into smaller compartments = lobules
interlobular ct and duct = ct, smaller, between lobules
describe parotid gland
well stained acinus
no mucous
bit basophilic
describe submandibular gland
mixed acini
serous demilunes
no myoepithelial cells for mucous
cells for mucous = bigger, more pyramidal, nuclei compressed against base of cell, does not stain well since has many glycoproteins
describe sublingual gland
mucous acini
not well stained, due to cytoplasm
nuclei pushed up against base
not much ct
striated intralobular duct = continuous as read end = intercalated duct in longitudinal section, very tiny, cells become cuboidal
what are intercalated and striated ducts
intralobular ducts
describe serous cell
thinner proteinaceous secretion = watery
zymogenic granules - secretory granules, pyramidal, round nucleus
much ER at base, prominent golgi
describe mucous cell
columnar shape
active when stressed during exam
viscous carbohydrate rich, produce mucin, much thicker glycoprotein
describe teeth of humans
2 sets of teeth= diphyodonty
baby or deciduous = 20 teeth
permanent dentition = 32 teeth
upper maxillary and lower mandibular teeth form 2 dental arches
each arch symmetrically divided into 2 quadrants
how many of each tooth does baby and adult have
center incisors = 1, 1
lateral incisors = 1, 1
canines = 1,1
premolars = 0,2
molars = 2,3
x4 because 4 quadrants
describe mucogingival junction
epithelium attaches to enamel, plaque formed here
Attachment of gingiva to enamel, if bacteria get in = can compromise periodontal ligament = can lose tooth
how is tooth suspended
in pocket of alveolar bone
root of tooth suspended by periodontal ligament - goes from cementum to alveolar bone
describe enamel
very hard tissue
describe clinical crown
visual crown
very acidophilic
describe anatomical crown
real crown from start of enamel
describe pulp
middle of root
loose ct
many blood vessels and nerve terminals - provide vitality to tooth
describe odontoblasts
linning inner aspect of root
Synthesizes dentin
describe cementum
contains cementocytes - hard tissue, trapped in lacunae
synthesizes cementin
describe epithelium of tooth
from stratified squamous non keratinized to parakeratinized as approaching gingiva - transitions
describe enamel - tooth composition
99% inorganic matrix - practically mineral
hardest tissue
Hydroxyapatite
1% proteins, enamelins, amelogenins, water
describe dentin - tooth composition
70% inorganic matrix, 30% organic matrix
proteins, proteoglycans - collagen type 1
Similar to bone in mineral composition
describe decalcification
for sectionning and staining
5% nitric acid - dangerous so now use 250nM EDTA = calcium trapper, looks like rubber after
enamel is gone now
what are sharpeys fibers
collagen type 1 fibers
from periodontal ligament penetrating periosteum and cementum
what do odontoblasts do
odontoblasts synthesized dentin, line layer of dentin
withdraw to center of pulp and space becomes smaller and smaller as get older
Describe predentin
not calcified and paler
more acidophilic = if calcified, becomes dentin
describe processes of odontoblasts
long processes of cells that go all the way either to cementum at level of root or enamel at level of crown, looks columnar but not
synthesized in ecm = processes of odontoblasts, become canaliculi of odontoblasts, technically modified sensory cells since odontoblasts derived from nerve cells = why temp produces pain for teeth,
canaliculi contain processes of odontoblasts
describe a cavity
bacteria penetrate via canaliculi
if reach pulp = worse, inflammation of pulp = pulpitis, not good
root canal treatment = pulp must be leaned, dont want cavity to reach dentin
describe step 1 of tooth formation
neuroectoderm cells migrate from neural crest
go from ct under arch and causes stimulation of epithelium to undergo mitosis - divide more and start invading ct
what is stomadeum
pocket cavity all surrounded. by ectoderm
all mouth forms from this, developing tongue and including teeth
describe step 2 of tooth formation
neuroectoderm cells induce formation of epithelial tooth buds - 10 future baby/deciduous teeth = 20 epithelial tooth buds, since there is also 10 above at level of maxilla
describe neuroectoderm
cells at level of neural crest or plate - has 2 layers like tube
some cells penetrate through mesoderm and reach stomadeum region
stomadeum = space with ectoderm located between pericardium - around developing heart and developing brain
describe step 3 of tooth formation
epithelial structure - oral ectoderm - will form future enamel organ
describe step 4 of tooth formation
neuroectoderm cells mix with mesoderm cells and form neural crest mesoderm
eventually neural ectoderm cells will differentiate into odontoblasts
describe step 5 of tooth formation
future enamel organ remains connected to oral ectoderm by dental lamina and orginates a second second bud for permanent tooth
will undergo same steps as later on
describe step 6 of tooth formation
cells of enamel organ differentiate into define layers = inner and outer dental epithelium
ode = connected to ectoderm by dental lamin
IDE = thinner, cells become columnar, later = makes enamel
some cells form stratum intermedium and some will be inbetween stratum intermedium and ODE
describe step 7 of tooth formation
some of neural crest mesoderm - mainly neuro crest ectoderm cells - start differentiating into odontoblasts
what is SR and SI
stellate reticulum = star like cells
stratum intermedium = layer of cuboidal epithelial cells
describe ode
connected to dental lamina that is connected to ectoderm
describe ide
columnar
synthesizes enamel
describe step 8 of tooth formation
in addition to ode and ide - enamel organ differentiates into si and sr
describe step 9 of tooth formation
ide is formed by ameloblasts (differentiates into)
which synthesize enamel
crown shapes at bell stage - future shape of crown
describe step 10 of tooth formation
cervical loop marks position of neck of tooth - crown root junction
= where root will grow
recruits ameloblasts- synthesize enamel and will become layer of odontoblasts = synthesizes dentin
describe step 11 of tooth formation
odontoblasts become aligned and primitive dental papilla - future pulp - is formed
describe step 12 of tooth formation
junction of ide and odontoblasts marks dentino enamel junction
from this point on = odontoblasts grow inwardly
ide does not form enamel in this region - involved in recruitment of odontoblasts for future root
ameloblasts continuous with ide
odontoblasts synthesize predentin and then dentin
describe step 13 of tooth formation
ode and ide eventually disappear (deteriorates and dies) and odotoblasts induce mesenchyme to form cementoblasts and cementum
describe step 14 of tooth formation
forming tooth is within a pocket of alveolar bone
between bone and cementum the periodontal ligament is formed
describe step 15 of tooth formation
baby tooth functions until 5-6 years of age
describe step 16 of tooth formation
permanent tooth awaits further development until baby tooth is scheduled to fall out
describe step 17 of tooth formation
Permanent tooth develops in same way as baby tooth
describe step 18 of tooth formation
odontoclasts - osteoclasts
erode root of baby tooth and new permanent tooth grows as root of baby tooth is eroded
describe dentinoenamel junction
future root- dentin joins enamel - from this point = future root
becomes dentino-enamel junction = called ide not ameloblasts anymore
what are tomes processes.
on ameloblasts
during synthesis of enamel ameloblast moves away from dentin and forms a project surrounded by developing enamel - gives ameloblasts a fence look under microscope
what are odontoblast processes called
tome’s fibers or tomes fibrils
located in dentinal tubule
