13 - GI: Mouth & Esophagus

Question 1

Alimentary canal functions

names only

Answer 1

• Ingestion
• Secretion
• Mixing and Propulsion
• Digestion
• Absorption
• Defecation

Question 2

external mouth anatomy

diagram goodnotes + some info

Answer 2

label and test

frenulum: restrict lip or tongue movement
hard palate: bone, part of skull covered by stratified squamous cells (mucous membrane)
soft palate: muscular layer covered by mucous membrane
uvula: protrudes from soft P, high density of receptors for gag reflex

Question 3

gustation

basic definition + info

Answer 3

sense of taste

5 tastes: sweet, salty, bitter, sour, umami (savory)
sensed via papillae

Question 4

papillae

types, facts, location (GN)

Answer 4

roughly 10 000 tastebuds (TBs) in the tongue, located on the papillae
TYPES:
- vallate: 12, 100-300 TBs each
- fungiform: 5 TBs each, raised bumps + scattered on tongue
- foliate: in lateral margins degenerate in childhood
- filiform: tactile sensations, raised and scattered

Question 5

What happens if gustatory receptor cells are killed? (eg: tongue gets burnt)

Answer 5

They regenerate, stem cells in the tongue differentiate

Question 6

Gustation: Neural Pathways

basic structures + pathway (GN)

Answer 6

papillae to cranial nerves:
vagus (X): back of throat (epiglottis + pharynx)
glosspharyngeal (IX): back 1/3 of tongue (vallate p’s)
facial (VII): front 2/3 of tongue (fungiform p’s)
tactile – trigeminal (V): front 2/3 (filiform p’s)

medulla: gustatory nucleus
thalamus
insula of cerebrum: gustatory cortex

Question 7

Olfaction

basic definition

Answer 7

sense of smell

Question 8

Olfaction: Neural pathway

structures involved + pathway

Answer 8

molecules enter nasal cavity
olfactory glands produce mucus
odorant molecules must dissolve in mucus for neural transduction to occur

olfactory epithelium: olfactory sensory neurons
through holes in cribriform plate
olfactory bulb: olfactory tract
!!does not synapse in thalamus!!
temporal cortex in cerebrum: olfactory cortex

Question 9

Teeth

names, location, purpose

Answer 9

16 above, 16 below
Incisors: cutting (2)
Canines (cuspids): tearing (1)
Premolars: crushing (2)
Molars: grinding (3) last row is wisdom teeth

GN diagram, # is how many types (4 of each)

Question 10

Dentitions

names

Answer 10

deciduous (baby teeth set)
permanent (adult set)

supernumary teeth: extra teeth

Question 11

Tooth (internal anatomy + innervation)

diagram goodnotes

Answer 11

only highlighted labels

Question 12

Mastication

basic definition + info

Answer 12

chewing

partly involuntary (cheek muscles stretching)

Question 13

Intrinsic muscles of the tongue

names, location, innervation (diagram goodnotes)

Answer 13

all hypoglosseal (XII)
superior and inferior long: shortens tongue
transverse: contracts horizontally (tongue gets skinnier)
vertical: flattens tongue

run from the back to the front of the tongue

Question 14

Extrinsic muscles of the tongue

names, location, innervation (diagram goodnotes)

Answer 14

vagus (X)
palatoglossus
hypoglosseal (XII)
styloglossus
hyoglossus
genioglossus

attach to the base of the tongue + bones

named after the bone they connect to

Question 15

Hyoid bone

location + facts (diagram goodnotes)

Answer 15

does not attatch to any other bone
typically fractures if person is strangled

Question 16

Muscles of mastication

names, location, innervation (diagram goodnotes)

Answer 16

trigeminal (V)
act on the mandible
provide force for chewing:
- temporalis
- masseter

move mandible side to side:
- medial and lateral pterygoid

Question 17

muscles of facial expression

names, location, innervation (diagram goodnotes)

Answer 17

facial (VII)
Buccinator: tension in cheek
Orbiculator Oris: circle of fibers around the lips

Question 18

Mastication vascular supply

names, location (diagram goodnotes)

Answer 18

• superficial temporal a./v.
• external carotid a., external jugular v.
• maxillary a./v.
• facial a./v.

Question 19

Salivary glands

names, locations, saliva type (GN)

Answer 19

parotid: only serous + amylase
submandibular: mostly serous + amylase
sublingual: mostly mucous + lipase

serous = watery, more proteins
mucous = thick, more mucin

Question 20

Saliva composition

general

Answer 20

• water
• amylase (digestive)
• mucin (thickens)
• lysozyme (immune)
• defensins (immune)
• IgA (immune)
• electrolytes (sodium and chloride)

Question 21

Nervous input for saliva

Answer 21

parasympathetic (VII and IX)
- increased saliva production of watery, enzyme rich saliva
- triggered by chewing

sympathetic
- decreased saliva production in parotid and submandibular
- increased production of thick, mucin rich saliva from sublingual

Question 22

Deglutition

basic definition + phases

Answer 22

swallowing

1. Voluntary
   - oral cavity and tongue
2. Pharyngeal
   - reflex initiated by stretch of oropharynx
   - closing off nasal cavity and trachea
3. Esophageal
   - peristalsis

Question 23

Esophagus anatomy

relational, features, histology (GN)

Answer 23

• upper esophageal sphincter
• kink: trachea (left main bronchus) compresses
• kink: left atrium compresses
• through esophageal hiatus in diaphragm
• lower or gastroesophageal sphincter

Histology
- mucosa stratified squamous epithelial layer
- submucosa
- muscularis
- adventitia (connective tissue)

Question 24

Peristalsis

Answer 24

alternating waves of muscle contraction and relaxation used to move food through the GI tract

circular muscles contract above food to push it down

Question 25

Late deglutition

alternate name, steps

Answer 25

• food at bottom of esophagus
• gastroesophageal sphincter opens
• food passes into stomach

Question 26

mandible regions

!!find diagram for GN

Answer 26

• ramus
• angle
• body
• symphysis

Question 27

gastroesophageal reflux disease (GERD)

explanation, cause, mechanism (GN)

Answer 27

backflow of stomach acid into the esophagus

Cause - unknown but risk increased by:
- smoking, alcohol, coffee, chocolate, peppermint
- stress
- obesity and pregnancy

Mechanism:
- LES functions incorrectly (low pressure, relaxing at innapropriate times…)
- diaphragm isn’t pinching esophagus
- hiatal hernia (stomach protrudes from diaphragm)

LES: lower esophageal sphincter

Question 28

gastroesophageal reflux disease (GERD)

symptoms, treatment

Answer 28

Symptoms:
- heartburn (epigastric or substernal chest pain)

Treatment:
- smaller meals
- staying upright after eating
- avoid certain foods (eg: increased risk and acidic foods)
- antacids