Week 2.1 - physiology of the mouth (workbook)

Question 1

what is the mouth a way into?

Answer 1

the GI tract

Question 2

what is the function of the mouth?

Answer 2

disrupts food stuffs and mix with saliva to form boluses to be swallowed

Question 3

what is the oral mucosa and teeth vulnerable to?

Answer 3

physical and chemical damage, & infection

Question 4

what is a major function of saliva in the oral environment?

Answer 4

ensuring a moist, chemically appropriate environment with a healthy bacterial flora

Question 5

what is physical disruption of food by?

Answer 5

mastication (chewing)

Question 6

what is mastication carried out by?

Answer 6

powerful muscles - mainly the masseter muscle

generate huge forces

Question 7

what is the masseter muscle innervated by?

Answer 7

branch of trigeminal nerve

Question 8

how is the force transmitted to food?

Answer 8

via teeth

Question 9

what d the incisors and molars do?

Answer 9

incisors cut food into pieces

molars crush food and mix with saliva to form paste (to be swallowed)

Question 10

what happens to the bolus?

Answer 10

moistened and lubricated by saliva

Question 11

how much saliva do we produce each day from what?

Answer 11

1.5 litres of saliva from 3 pairs of salivary glands

Question 12

what is the function of saliva?

Answer 12

moistens and lubricates food for swallowing and also contains enzymes which begin the digestion of (particularly) carbohydrates

Question 13

what is a much more significant role of saliva?

Answer 13

protection of oral environment

Question 14

mucosa and saliva

Answer 14

mucosa is not cornified and must be kept wet (by saliva)

Question 15

what are teeth constantly at risk from?

Answer 15

from bacterial acid, which needs to be neutralised, and the bacterial ecology of the mouth needs to be maintained by mild bactericidal action

Question 16

what is zerostomia?

Answer 16

no saliva secretion in the mouth

Question 17

what happens in zerostomia?

Answer 17

we can eat without saliva, but if there is no secretion, the mouth very rapidly deteriorates

Question 18

what type of solution is saliva?

Answer 18

a hypotonic solution

Question 19

what is a hypotonic solution?

Answer 19

excess water over the other body fluids) with relatively low concentrations of Na+ & Cl-, but with excess concentrations of K+ and HCO3-

Question 20

how is resting saliva like? what can happen to it?

Answer 20

resting saliva is neutral, once stimulated, it becomes alkaline

Question 21

what does saliva contain aside from enzymes?

Answer 21

significant mucus

Question 22

where is saliva secreted from?

Answer 22

3 pairs of salivary glands

Question 23

what are the 3 pair of salivary glands?

Answer 23

parotid glands
sub lingual glands
sub maxillary glands

Question 24

how much of the saliva is secreted by the parotid glands? and what type of saliva?

Answer 24

25% of saliva by volume

serous secretion with a mixture of water, electrolytes and enzymes

Question 25

how much of the saliva is secreted by the sub lingual glands (under tongue)? what type of saliva?

Answer 25

5% of saliva (don't want too much mucous) | saliva is rich in mucus - known as mucous saliva

Question 26

how much of the saliva is secreted by the sub maxillary glands (behind & inferior tongue)? type of saliva?

Answer 26

about 70% saliva | secretes both serous and mucous components

Question 27

what are salivary glands composed of?

Answer 27

numerous blind ended tubes, with acini (secretory component of ducts) at blind end and ducts converging to outlets in the mouth

Question 28

are serous acini and mucus acini the same?

Answer 28

no, different in structure

Question 29

what type of acini does the sub maxillary gland contain?

Answer 29

mixture of both as it secretes both serous and mucus acini

Question 30

what is saliva made from and how does it compare?

Answer 30

made from plasma, but always hyPOtonic to plasma

Question 31

how is hypotonicity of saliva achieved?

Answer 31

NOT by directly pumping water by first secreting an isotonic solution (same ionic component as plasma), then removing ions from it (less ions than plasma)

Question 32

what do acinar cells secrete?

Answer 32

an isotonic fluid containing enzymes

Question 33

what do duct cells do?

Answer 33

remove Na+ & Cl- (salt) and add HCO3-

Question 34

how are the gap between ducts cells like? why?

Answer 34

tight, so water doesn't follow the resulting osmotic gradient, and saliva remains hyPOtonic

Question 35

what happens at low flow rates of saliva out of acinar cells?

Answer 35

duct cells remove most of the Na+, so saliva is VERY hypotonic

Question 36

what is the capacity of the duct cells to modify saliva? what does this mean?

Answer 36

very limited, so at high flow rates, a smaller fraction is removed, and saliva becomes less hypotonic (still lots of NaCl and not enough HCO3-, more isotonic)

Question 37

what happens to the stimulus to secrete by duct cells at high flow rates?

Answer 37

promote HCO3- secretion, so saliva becomes more alkaline, although not enough NaCl removed (not hypotonic)

Question 38

what does high flow rate (stimulated) result in, in terms of volume, hypotonicity, alkalinity & enzyme content)?

Answer 38

high volume, low hypotonicity, high alkalinity (duct cells secrete HCO3-), high enzyme content (more saliva = more enzymes)

Question 39

what is salivary secretion mostly controlled by?

Answer 39

the ANS (involuntary)

Question 40

what stimulates the acinar cells? to produce what?

Answer 40

parasympathetic nerves (rest & digest) from the otic ganglion stimulate acinar cells to produce primary secretion (of isotonic saliva)

Question 41

what stimulates the duct cells? to do what?

Answer 41

also parasympathetic nerves from the otic ganglion (same as acinar cells) to add extra HCO3- to saliva

Question 42

what does salivary volume depend on?

Answer 42

ANS control - controlling amount secreted from acinar cells

Question 43

how is ANS outflow coordinated?

Answer 43

from the brain stem in response to afferent stimuli (entering brain stem)

Question 44

what are afferent stimuli that can affect antonomic outflow?

Answer 44

smell & taste of food & conditioned reflexes (e.g. pavlov's dog)

Question 45

what does sympathetic nervous activity do to salivary glands?

Answer 45

reduces blood flow to the salivary glands (vasoconstrict), which limits salivary flow, producing the typical dry mouth of anxiety - need blood for outflow of saliva

Question 46

what is the rate of ductal recovery of Na+ increased by (taking Na+ away - produce hypotonic saliva)?

Answer 46

hormone aldosterone from adrenal cortex (zona glumerulosa - outermost layer)

Question 47

what happens once saliva is mixed with chewed food?

Answer 47

forms bolus, it must be swallowed

Question 48

how is swallowing carried out?

Answer 48

in 3 phases: 1. voluntary phase 2. pharyngeal phase 3. oesophageal phase

Question 49

what is the main purpose of the voluntary phase?

Answer 49

a bolus is moved onto the pharynx

Question 50

what happens in the pharyngeal phase?

Answer 50

afferent information from receptors in the pharynx reaches the swallowing centre in the brain stem

Question 51

what happens when afferent information from pharynx receptors reaches swallowing centre in brain stem? (pharyngeal phase)

Answer 51

triggers a set of movements, including: 1. inhibition of breathing - prevent aspiration 2. raising of larynx (to meet epiglottis) 3. closure of glottis (airways) - by epiglottis 4. opening of entrance to oesophagus (to travel to stomach)

Question 52

what type of muscle is in the upper 1/3 of the oesophagus?

Answer 52

voluntary straited

Question 53

what type of control is the muscle of the upper 1/3 of the oesophagus under?

Answer 53

somatic nerves (voluntary) - as opposed to automonic, so upper 1/3 is an active movement we choose to carry out

Question 54

what type of muscle is in the lower 2/3 of the oesophagus?

Answer 54

smooth muscle

Question 55

what type of control is the muscle of the lower 2/3 of the oesophagus under?

Answer 55

parasympathetic nervous system (part of ANS, involuntary), rest & digest

Question 56

what happens in the oesophageal phase?

Answer 56

a wave of peristalsis sweeps down the oesophagus, propelling the bolus to the stomach in about 9 seconds

Question 57

what are the oropharynx and the oesophagus essentially?

Answer 57

highways concerned with passing ingested food to the stomach and intestines for digestion (& absorption)

Question 58

what are the oropharynx and the oesophagus open to?

Answer 58

potentially hazardous environment & are potentially under threat of attack from a number of directions