GI tract

Question 1

function of alimentary tract

Answer 1

take in raw food material, fragment it into small portions

secretions (mainly enzymes) convert larger molecules into smaller ones -> absorption into blood and lymph circulation

Question 2

small molecules

Answer 2

mainly amino acids, small peptides, carbohydrates, sugars and lipids
transported to liver by blood and lymph - used in synthesis of essential proteins, carbohydrates and lipids

Question 3

three functional components of alimentary tract

Answer 3

oral cavity, simple transport passages and digestive tract

Question 4

oral cavity

Answer 4

food is ingested and fragmented by teeth, softened by saliva and moved around by jaws and tongue
bolus is transferred by deglutition to eosophagus

Question 5

deglutition

Answer 5

swallowing

Question 6

simple transport passages

Answer 6

contractile conduit to pass semisolid material from one area to another
pharynx, oesophagus, stomach, anal canal

Question 7

control of eosophagus

Answer 7

long

bolus forced along it by smooth muscle action in peristalsis - involuntary nervous control

Question 8

control of anal canal

Answer 8

transports semi solid undigested waste material
involuntary due to increasing distension of the rectum
evacuation of faeces usually controllable by voluntary (skeletal) muscle in external sphincter

Question 9

lubrication of simple transport passages

Answer 9

lubricated by mucus - mucus glands secrete oesophageal mucus

in anus, faeces are lubricated by mucus secreted by goblet cells in colonic epithelium

Question 10

digestive tract

Answer 10

stomach, small intestine and large intestine

Question 11

stomach

Answer 11

resevoir - ingested food held up by sphincter until acid and enzymatic secretions of stomach mucosa has broken up food into semiliquid slurry (chyme). passes through sphincter into small intestine

Question 12

chyme

Answer 12

food is broken up by acid and enzymatic secretions into semiliquid slurry

Question 13

small intestine

Answer 13

enzymes and chemicals secreted by small intestine and auxiliary glands (liver and pancreas) - enter via ducts.
absorbs breakdown products

Question 14

large intestine

Answer 14

fluid content mostly reabsorbed until waste material converted into semisolid material, lubricated by mucus

Question 15

auxiliary gland systems

Answer 15

salivary glands, pancreas and liver

secretions through ducts

Question 16

oral cavity lining and contents

Answer 16

mouth lined by stratified squamous epithelium
underlying submucosa contains: salivary glands secreting serous and mucous fluids, skeletal muscle fibres alter size and shape of cavity, skeletal muscles form bulk of tongue and cheeks
deep tissues: small plates of bone (hard palate), modified bone (teeth)

Question 17

lips lining and contents

Answer 17

vermilion - non keratinising stratified squamous epithelium, rete ridge formation, papillae between epithelial downgrowths contain prominent blood vessels
inner surface of lips lined by non-keratininising squamous epithelium, less developed rete ridge formation, small clumps of salivary tissue - secretions
sebaceous glands - near angles of mouth, open onto mucosal surface
deeper parts of lips: bundles of striated muscle fibres (orbicularis oris muscle) - concentric around orifice - opens and closes it.

Question 18

orbicularis oris muscle

Answer 18

bundle of striated muscle fibres in deeper parts of lips

Question 19

cheeks lining and contents

Answer 19

thick non-keratinising squamous epithelium
cells rich in glycogen
areas of keratinisation arise from chronic friction
submucosa: minor salivary glands (buccal glands), occasional sebaceous glands (Fordyce’s spots)
deep tissues: skeletal muscle fibres

Question 20

palate lining and contents

Answer 20

non-keratinising squamous epithelium
hard palate - rete ridge due to frictional shear
submucosa - tethered to periosteum of palatal bone plate. non-keratinising stratified squamous epithelium - extends to ciliated columnar epithelium on nasal surface

Question 21

floor of mouth lining and contents

Answer 21

covered by thin non-keratinising stratified squamous epithelium - continuous w/ ventral tongue
minor sublingual glands (salivary)
major sublingual glands on sides of midline frenulum of ventral tongue

Question 22

tongue lining and content

Answer 22

muscular organ
ventral surface: thin non-keratinising stratified squamous epithelium continuous w/ floor of mouth
dorsal surface - thick keratinising stratified squamous epithelium

Question 23

divisions of tongue

Answer 23

anterior 2/3s and posterior 1/3
separated by v shaped line of 6-10 dome shaped protrusions (circumvallate papillae), flattened - surrounded by channel of taste buds

Question 24

circumvallate papillae

Answer 24

dome-shaped protrusions on v shaped line dividing tongue

surrounded by channel of taste bud epithelium

Question 25

posterior third of tongue

Answer 25

MALT - low smooth dome shaped elevations MALT, palatine tonsils and pharyngeal adenoids protect oral portal of entry non keratinising stratified squamous epithelium w/ lymphocytes small salivary glands

Question 26

three types of papillae

Answer 26

filiform, circumvallate, fungiform

Question 27

filiform papillae

Answer 27

most numerous dorsum of anterior 2/3 of tongue tall, narrow, pointed, keratinised (esp. at tips) no taste buds

Question 28

fungiform papillae

Answer 28

scattered randomly among filiforms mushroom shape taste buds - anterior tip of tongue ones detect sweet tastem behind tip and along lateral borders salty taste

Question 29

taste buds

Answer 29

full thickness of epithelium pale-staining spindle shaped cells in oval cluster luminal surfaces open into defect in epithelium (taste pore) microvilli

Question 30

taste receptor cells

Answer 30

synaptic vesicles | small afferent nerve fibres

Question 31

supporting sustentacular cells

Answer 31

electron-dense cytoplasm scanty secretory granules near surface may secrete glycosaminoglycans into taste pore

Question 32

cells resembling taste receptor cells

Answer 32

lack synaptic vesicles and afferent nerve fibres

Question 33

turnover of cells

Answer 33

10-14 days | small rounded stem cells at base of taste bud

Question 34

tastes detected by dorsal tongue

Answer 34

acid, sweet, bitter and salty

Question 35

skeletal muscle in tongue

Answer 35

bands run longitudinally, vertically, transversely and obliquely - adipose tissue in-between mobility for food and speech

Question 36

junction between posterior one third and anterior two thirds

Answer 36

abundant islands of salivary tissue in submucosa between muscular core and surface epithelium

Question 37

teeth

Answer 37

hard, heavily mineralised structures embedded in raised alveolar ridges of maxilla and mandible

Question 38

arrangement of teeth

Answer 38

free surface of lower ones oppose and contact upper ones - food material can be trapped between them

Question 39

anterior teeth

Answer 39

incisor and canines - narrow, pointed free edges

Question 40

posterior teeth

Answer 40

premolars and molars - broader, flatter free surfaces. grind from medium to small

Question 41

mandible joint to body of skull

Answer 41

temporomandibular joint - slides backwards and forwards, side to side

Question 42

tooth division

Answer 42

crown protrudes into oral cavity | root embedded in bone of mandible or maxilla

Question 43

junction between crown and root

Answer 43

neck

Question 44

mature tooth components

Answer 44

central pulp cavity, dentine, enamel, cementum, periodontal ligament

Question 45

central pulp cavity | -matrix, vessels and nerves, width, outer surface

Answer 45

soft central core of tooth collagen and fibroblasts in acellular matrix acellular matrix composed of glycosaminoglycans blood vessels for odontoblasts nerve twigs for dental sensation enter and leave through apical foramen at tip of root narrow through most (root canal) expands in neck and crown (pulp chamber) outer surface: odontoblasts producing dentine - diminishing in size