3.1 Oral Cavity & stomach

Question 1

what are the functions of saliva

Answer 1

􏰃 Cleanses mouth
􏰃 Moistens & dissolves food chemicals

􏰃 Aids in bolus formation
􏰃 Contains enzymes to begin digestion

􏰃 Buffers pH (bicarbonate)
􏰃 Lubrication

Question 2

what are the 2 types of salivary glands

Answer 2

intrinsic (buccal): sacttered in oral mucosa

Extrinsic: parotid, submadnibular and sublingual

Question 3

Answer 3

Question 4

what cells are found in salivary galnds

Answer 4

serous cells: procue watery secretion of enzymes, ions and some mucin

*stin pink

mucous cells: dont stain well

Question 5

what are the 4 salivary galnds, describe theri cell composition

Answer 5

• Submandibular: serous and mucous cells

*make 60-70% of saliva volume

• Parotid glands: mostly serous cells
• Sublingual glands: mucous cells
• Intrinsic (buccal) glands: serous & mucous cells

Question 6

what is saliva compsed of

Answer 6

* rpoduce 1-1.5L a day

-97-99.5% water -> almsot neutral

contains:

electrolyes: Na, K, Cl, PO4^3-, HCO3^-
- enzymes: salivary amylase (starch-> maltose) & lingual lipase (fat breakdown)
- proteins: mucin , lysozyme, IgA, albumin
- metabolic wastes: urea and uric acid
- lysozyme, IgA, defensins & cyandide comp to protect aginst microorganisms

Question 7

how is salivation controlled

Answer 7

• intrinsic gland continuously keep mouth moist
• extrinsic glands produce secretions due to smell, taste, sound or sight or pressure in mouth
• > higher centers of brain -> salivary nucleus of medulla -> PSNS -> CN IX and CN VII

* sleep, fatigue and fear inhibtis it

Question 8

describe the structure of the tooth

external neatures

Answer 8

• Crown: exposed part above gingiva, covered by enamel (hardest substance in body: calcum salts and hydrozyapatite crystals)

Neck: conencts crown and root

Root: portion embedded in mandible amd maxilla bone

Question 9

descibre the strcuture of a tooth: internal features

Answer 9

dentin: bonelife materail maintained by odontoblasts of pulp cavity

^ extends trhu all 3 regions

Pulp: connective tissue, blood vessels and nerves

^contains pulp cavity (crown cavity w/ pulp) and root canal (pulp in root)

Cementum: calcified connective tissue: holds teeth in bone, covers root, anchord by peridontal ligament

Question 10

describe eruption times of human dentition

Answer 10

around 6, 12 and 24

deciduous (milk) teeth:

• central incisor, lateral, first molar, canine, second molar

Permanet teeth: Central incisor + first molar, lateral incisor, 1st and 2nd premolars/bicuspid + second molar, 3rd molar/wisdom tooth

Question 11

pharynx in the digestive system

Answer 11

• oropharynx and laryngopharynx (naso not part of digestive)
• allows passage of food, fluids and air

Question 12

describet he esophagus

Answer 12

• inner lumen -> mucosa (stratified squamous epithelium) -> submucosa (aerolat conenctive tissue) -> muscularis externa (circular layer and longitudinal layer) -> Adventita (fibrous connective tissue)
• flat muscule tube (25cm long)
• > pierces diaphagm at esophageal hiatus
• > collased when not involved in food propulsion
• glands in submucosa secrete mucus (lubircation)

Question 13

desrcibe the buccal phase of deglutition

Answer 13

*chewing- mechanically breaking down

• upper esophageal sphincter is contracted
• tongue presses against hard palate (voluntary)
• bolus forced into oropharyx (involuntary phase begins)

Question 14

describe the pharyngeal esophageal phase of of deglutition

Answer 14

*Esophageal Phase - involuntary no control

• Uvula & larynx rise -> epiglottis closes larynx (blocks larynx)
• tongue blocks off anterior mouth
• upper esophageal sphincter relaxes
• constrictor muscles of pharynx contract (food forced into esophagus)
• Upper esophageal sphincter contracts
• uvula drops back
• food mvoes through esophagus by peristalsis
• gastroesophageal sphincter opens (food enters stomach)

Question 15

descibr pharynxgeal esophgeal phase (getting to stomach)

Answer 15

• food mvoes through esophagus by peristalsis
• gastroesophageal sphincter opens (food enters stomach)

Question 16

anatomy of infant vs adult

(swallowing)

Answer 16

• infant: small oral cavity, tongue palate is flatter, epiglottis almost attached to soft palate

*airway and foodway are separated except when swallowing

• in adult, larynx is lower in neck, food and airway cros in pharynx

*infants can drink and breathe at the same time

Question 17

descrube the vomiting reflex

Answer 17

• start w/ salivation and nausea
• reverse peristalsis from upper SI & stomach
• glottis closes (prevents aspiration), breath held mid inspiration
• diaphragm & abdominal wall muscles contract, inc intra0abdominal pressure
• esophagus and sphincters relax
• gastric contents ejected

Question 18

what are the digestive processes of the stomach

Answer 18

1. Mechanical breakdown
2. Denaturation of proteins
3. Enzymatic digestion of proteins by pepsin (+ rennin in infants)
4. Secretes intrinsic factor
5. Absorption of lipid-soluble substances
6. Delivers chyme to small intestine

Question 19

how does the body respond to the stomach filling

Answer 19

• can hold 50mL to 4L
• stomach pressure remains constant until about 1.5L of food is ingested
• relatice uncahnging pressure results from
• > receptive relaxation: as food travels in esophagus, stomach muscles relax
• > Gastric accommodation: intrinsic ability of smooth muscle to exhibit stress- relaxation response

Question 20

gross anaomy of the stoamch

Answer 20

Question 21

decsibr the mucsa epithelial cells in the stomach

Answer 21

*Gastric mucosa produced 3L of gastric jucie/day

• it surface have mucus surface cells that secrete alkaline mucus
• then into mucuous neck cells: secrete acidic mucus (less protective, more activating)
• as go further get 3 pronged parietal cells (secrete HCL and intrinsic factor -> inc stomach acidity)
• further into gland get cheif cells: secretes pepsinogen to activate into pepsin
• bottom have some enteroendocrine cells: hormone producitng G cells: secrete gastrin

Question 22

describe mucosal proection

Answer 22

• layer of bicarbonate rich mucus (protects epithelial cells so juice doesnt eat away at you
• in tight junctions between epithelial cells
• damaged epithelial cells are qucily replaced by dividion of stem cells (surface wells lifespan is 3-6 days)

Question 23

describe the secretions from parietal cells

Answer 23

• intrinsic factor:: Glycoprotein requred for absorption of vitamin B12 in SI (w/o intrinsic factor cant abs B12)
• HCl: stomach pH 1.5-3.5, deatures protein in food, activates pepsin and kills many bacteria

Question 24

how do parietal cells produce HCl

Answer 24

1. CO₂ — from interstitial fluid to parietal cell —> CO₂ + H₂O
2. CO₂ + H₂O — carbonic anhydrase —> H₂CO₃
   3a. H₂CO₃ -> H+ can be pumped into stoach lumen while K+ pumped in (H+ K+ ATPase) or
   3b. H₂CO₃ -> leaves cell goes itno interstitial fluid and Cl- pumped in

Question 25

how is secretion of HCl regulated

Answer 25

• 3 chemicals (ACh, histamine and gastrin)

* ALL # required for max action of proton pump to make HCl

*stiulate parietla cells through second messenger systems

*if lacking onw is shuts downt he process significantly not just be 1.3

Question 26

decrese the secretions of chief cells

Answer 26

• inactive enzyme pepsinogen: activated to pepsin by HCl

(HCl made by parietal cells)

• also secretes small amounts of lipases
• secretes rennin in infants (help with breast milk digestion