physiology of the nose, tongue and sinuses

Question 1

function of the greater petrosal nerve

Answer 1

carries parasympathetic, taste, and sensory fibers of the facial cranial nerve

Question 2

what do the postganglionic fibres from the sphenopalatine ganglion supply

Answer 2

1. lacrimal gland
2. mucosal glands of the nose, palate and pahrynx

Question 3

function of the deep petrosal nerve (2)

Answer 3

1. carries postsynaptic sympathetic nerve fibres from the carotid plexus to the sphenopalatine ganglion
2. innervates blood vessels and mucous glands of the head and neck

Question 4

what is the vidian nerve

Answer 4

a nerve that passes through the pterygoid canal where there is a union of postsynaptic parasympathetic fibres and presynaptic sympathetic fibres

Question 5

what is the ostiomeatal complex

Answer 5

the final common channel for linking the frontal sinus, anterior ethmoid air cells and the maxillary sinus to the middle meatus, allowing airflow and mucociliary drainage

Question 6

what is the uncinate process

Answer 6

a sickle shaped piece of bone descending from the ethmoid bone that forms the medial wall o the ethmoid infundibulum; it plays an important role in mucociliary activity

Question 7

what are the 3 types of uncinate insertion

Answer 7

type A - lamina papyracea (medial wall of orbit)
type B - roof of ethmoid (base of skull)
type C - middle turbinate

Question 8

5 components of the ethmoid bone

Answer 8

1. perpendicular plate
2. crista galli
3. uncinate process
4. middle turbinate
5. anterior and posterior ethmoid cells

Question 9

after what age is the maxiallary sinus fully developed

Answer 9

3 yro

Question 10

after what age is the ethmoid sinus fully developed

Answer 10

7 yro

Question 11

between what ages does the frontal sinus develop

Answer 11

4-9 yro

Question 12

what is the nasal cycle

Answer 12

the spontaneous congestion and decongestion of the nasal mucosa during the day -> congestion of one side is generally accompanied by reciprocal decongestion of the contralateral side

one side breathes while the other filter and humidifies

Question 13

how is the nasal cycle achieved (nervous stimulation)

Answer 13

selective activation of one half of the autonomic nervous system by the hypothalamus

Question 14

what protein is key in cilia for movement

Answer 14

dynein (in the arms)

Question 15

what organ is the mucous layer continuously moving towards (ENT)

Answer 15

the pharynx

Question 16

what does the mucous layer contain (5)

Answer 16

1. enzymes
2. lysozymes
3. immunoglobulins
4. interferon
5. lactoferrin

Question 17

why is smell important (7)

Answer 17

1. occupation - many depend on a good sense of smell
2. safety - gas, food etc.
3. general well being
4. enjoyment of food
5. personal hygiene
6. attraction to partner
7. memories

Question 18

how does olfaction occur (6)

Answer 18

1. oderants bind to olfactory receptor cells in the nose (ORCs) - ORCs are bipolar cells and so it is the denrites of these cells that extend to the bottom of the epithelium and give rise to olfactory cilia
2. After an oderant binds the G-protein is acitvated which ultimately leads to the opening of Ca2+and Na+ channels, allowing Ca2+ influx
3. this allows Cl- channels to open causing an outflux of Cl- down their concentration gradient
4. both of these combined results in membrane depol and AP firing
5. impulse is transmitted up CN I and to to the glomeruli of the olfactory bulb
6. The information in the brain is processed alongside taste to result in the sensation of flavour

Question 19

what kind of receptors are olfactory receptor cells

Answer 19

chemoreceptors and work via G-protein coupled receptor mechanisms

Question 20

how many olfactory receptor proteins are there

Answer 20

There are thousands of different types of olfactory receptor proteins which all react most strongly to different oderants (but also respond to multiple oderants)

Question 21

what order neurons are CN I neurons

Answer 21

2nd order

Question 22

2 higher brain centres involved in olfaction

Answer 22

1. primary olfactory cortex (incl. piriform cortex, enthorhinal cortex and amygdala)
2. orbitofrontal cortex (secondary, signal via thalamus from primary OC)

Question 23

5 core modalities of taste

Answer 23

1. salt
2. sweet
3. sour
4. bitter
5. umami

Question 24

where are taste buds located (5)

Answer 24

1. tongue
2. palate
3. oropharynx
4. larynx (epiglottis)
5. upper oesophagus

Question 25

3 senses involved in flavour perception

Answer 25

smell, taste, touch

Question 26

5 brain systems that are involved in flavour sensation

Answer 26

1. primate neocortex (conscious, flavour perception, circuits)
2. hippocampus (limbic subconscious memory system)
3. hypothalamus (feeding circuits)
4. amygdala (emotion, motivation and craving)
5. human neocortex (language)

Question 27

what is the name of the v shape groove in the tongue that separates the anterior and posterior portions

Answer 27

sulcus terminalis

Question 28

anterior and posterior tongue innervation and what kind of papillae are they covered in

Answer 28

anterior portion is innervated by CN VII and is covered in papillae

posterior is innervated by CN IX and is covered in lingual papillae - this is lymphoid tissue and contains B +T cells

Question 29

what are the 4 types of papillae found on the tongue and which is the most common

Answer 29

1. filiform - most common
2. fungiform
3. foliate
4. circumvallate

Question 30

which papillae are involved in taste

Answer 30

fungiform, foliate and circumvallate

filiform are involved in sensation but NOT taste

Question 31

where are each of the papillae found on the tongue

Answer 31

1. filiform - they populate the anterior ⅔ of the dorsal surface
2. fungiform - tip of tongue
3. foliate - reside on the sides of the tongue
4. circumvallate - located at the back of the anterior ⅔ just in front of the sulcus terminalis

Question 32

what do the tongue papillae contain

Answer 32

multiple taste buds -> which contain taste receptor cells

Question 33

what kind of receptors are taste receptor cells

Answer 33

chemoreceptors arranged like orange wedges between supporting cells

Question 34

what is the life span of a taste receptor cell and where to new cells arise from

Answer 34

Taste receptor cells have a lifespan of about 2 weeks and so new cells arise from basal cells which differentiate into taste receptor cells

Question 35

which papillae are responsible for what tastes

Answer 35

While all three of these papillae can detect all taste sensations, each responds more strongly to certain ones:
1. Fungiform - sweet + umami;
2. foliate - salty + sour;
3. circumvallate - bitter
Complex tastes arise due to a combination of receptors working together

Question 36

what nerves are involved in taste (3)

Answer 36

1. facial - ant ⅔
2. glossopharyngeal - post ⅓
3. vagus - remainder of oral cavity, back of throat, epiglottis

Question 37

how are salty + sour tastes perceived (5)

Answer 37

1. Na+ (from salt) and H+ (from sour i.e. Brønsted–Lowry acid) enter TRCs via ion channels -> cell membrane depolarises
2. triggers VG Ca2+ channels to open and Ca2+ influx occurs
3. exocytosis of NT containing vesicles, namely 5-HT (seratonin), Ach, NA, and GABA
4. these bind to postsynaptic membranes on the corresponding nerves
5. signals sent to brain

Question 38

how are sweet, bitter and savoury tastes perceived (5)

Answer 38

1. tastants bind to G-coupled protein receptors on the TRC membrane
2. Ca2+ channels open on the endoplasmic reticulum
3. NT release into synaptic cleft
4. AP generated in post-synaptic membrane
5. signal to brain

Question 39

what part of the taste receptor cells interact w tastants

Answer 39

The TRCs have gustatotry hairs that stick out of openings on the papillae (taste pore) and it is these hairs that come into contact with tastants