Physiology of Balance, Taste and Smell Flashcards
1
Q
Organisation of the Peripheral Vestibular System
- Peripheral vestibular system are part of the … ear
- … in the scala media in the cochlea is continuous with the lymph of the apical surfaces of the vestibular hair cells
A
- Peripheral vestibular system are part of the inner ear
- Endolymph in the scala media in the cochlea is continuous with the lymph of the apical surfaces of the vestibular hair cells
2
Q
Organisation of the Peripheral Vestibular System
- Peripheral vestibular system are part of the inner ear
- Endolymph in the scala … in the cochlea is continuous with the lymph of the … surfaces of the vestibular hair cells
A
- Peripheral vestibular system are part of the inner ear
- Endolymph in the scala media in the cochlea is continuous with the lymph of the apical surfaces of the vestibular hair cells
3
Q
Orientation and structure of the semi-circular canals and otolith organs
- The six semicircular canals are oriented at … angles to one another to detect head rotation in all directions
- The left and right lateral … canals are functionally paired
- The left … (= superior) and right … canals are functionally paired, as are the left … and right … canals
- The four otolith organs are not exactly at right angles, to enable them to resolve head … and linear … in all directions
- The sensory cells in the ampullae of the semicircular canals are embedded in a cupula
- The sensory cells in the otolith organs (sacculus and utriculus) are embedded in a gelatinous sheet covered with ‘heavy’ crystals of calcium carbonate: the otoliths
A
- The six semicircular canals are oriented at right angles to one another to detect head rotation in all directions
- The left and right lateral semicircular canals are functionally paired
- The left anterior (= superior) and right posterior canals are functionally paired, as are the left posterior and right anterior canals
- The four otolith organs are not exactly at right angles, to enable them to resolve head tilt and linear acceleration in all directions
- The sensory cells in the ampullae of the semicircular canals are embedded in a cupula
- The sensory cells in the otolith organs (sacculus and utriculus) are embedded in a gelatinous sheet covered with ‘heavy’ crystals of calcium carbonate: the otoliths
4
Q
Orientation and structure of the semi-circular canals and otolith organs
- The six semicircular canals are oriented at right angles to one another to detect head rotation in all directions
- The left and right lateral semicircular canals are functionally paired
- The left anterior (= superior) and right posterior canals are functionally paired, as are the left posterior and right anterior canals
- The four otolith organs are not exactly at right angles, to enable them to resolve head tilt and linear acceleration in all directions
- The sensory cells in the ampullae of the semicircular canals are embedded in a …
- The sensory cells in the otolith organs (… and …) are embedded in a gelatinous sheet covered with ‘heavy’ crystals of calcium carbonate: the …
A
- The six semicircular canals are oriented at right angles to one another to detect head rotation in all directions
- The left and right lateral semicircular canals are functionally paired
- The left anterior (= superior) and right posterior canals are functionally paired, as are the left posterior and right anterior canals
- The four otolith organs are not exactly at right angles, to enable them to resolve head tilt and linear acceleration in all directions
- The sensory cells in the ampullae of the semicircular canals are embedded in a cupula
- The sensory cells in the otolith organs (sacculus and utriculus) are embedded in a gelatinous sheet covered with ‘heavy’ crystals of calcium carbonate: the otoliths
5
Q
… are small particles, composed of a combination of a gelatinous matrix and calcium carbonate in the viscous fluid of the saccule and utricle
A
otoliths are small particles, composed of a combination of a gelatinous matrix and calcium carbonate in the viscous fluid of the saccule and utricle
6
Q
The vestibular system includes the parts of the … ear and brain that process the sensory information involved with controlling … and eye ….
A
The vestibular system includes the parts of the inner ear and brain that process the sensory information involved with controlling balance and eye movements.
7
Q
Vestibular hair cells come in two types
- Both the semicircular canals and the otolith organs contain two types of vestibular hair cells:
- most are type … vestibular hair cells, which receive both afferent and efferent innervation
- the type … vestibular hair cells are surrounded by an afferent nerve calyx and the hair cells are not directly contacted by efferent nerve fibres
- The functional differences between these two cell types are still somewhat unclear, but the type II cells appear to be more sensitive
A
- Both the semicircular canals and the otolith organs contain two types of vestibular hair cells:
- most are type II vestibular hair cells, which receive both afferent and efferent innervation
- the type I vestibular hair cells are surrounded by an afferent nerve calyx and the hair cells are not directly contacted by efferent nerve fibres
- The functional differences between these two cell types are still somewhat unclear, but the type II cells appear to be more sensitive
8
Q
Vestibular hair cells come in two types
- Both the semicircular canals and the otolith organs contain two types of vestibular hair cells:
- most are type II vestibular hair cells, which receive both afferent and efferent innervation
- the type I vestibular hair cells are surrounded by an … nerve calyx and the hair cells are not directly contacted by … nerve fibres
- The functional differences between these two cell types are still somewhat unclear, but the type II cells appear to be more …
A
- Both the semicircular canals and the otolith organs contain two types of vestibular hair cells:
- most are type II vestibular hair cells, which receive both afferent and efferent innervation
- the type I vestibular hair cells are surrounded by an afferent nerve calyx and the hair cells are not directly contacted by efferent nerve fibres
- The functional differences between these two cell types are still somewhat unclear, but the type II cells appear to be more sensitive
9
Q
Semicircular canal receptors detect … of the head
A
Semicircular canal receptors detect rotation of the head
10
Q
What is nystagmus?
A
Nystagmus- slow eye movements followed by fast ones during continuous head rotation – fast phase defines direction of nystagmus
11
Q
Nystagmus
- It is - slow eye movements followed by fast ones during continuous head rotation – … phase defines direction of nystagmus
- In normal individuals, rotating the head elicits physiological nystagmus due to the …-… reflex (1).
- Spontaneous nystagmus (2), where the eyes move rhythmically from side to side in the absence of any … ….
- occurs when one of the canals is damaged
- net differences in vestibular nerve firing rates exist even when the head is stationary because the vestibular nerve innervating the intact canal fires steadily when at rest, in contrast to a lack of activity on the damaged side.
A
- It is - slow eye movements followed by fast ones during continuous head rotation – fast phase defines direction of nystagmus
- In normal individuals, rotating the head elicits physiological nystagmus due to the vestibulo-ocular reflex (1).
- Spontaneous nystagmus (2), where the eyes move rhythmically from side to side in the absence of any head movements.
- occurs when one of the canals is damaged
- net differences in vestibular nerve firing rates exist even when the head is stationary because the vestibular nerve innervating the intact canal fires steadily when at rest, in contrast to a lack of activity on the damaged side.
12
Q
Nystagmus
- It is - … eye movements followed by … ones during continuous head … – fast phase defines direction of nystagmus
- In normal individuals, rotating the head elicits physiological nystagmus due to the vestibulo-ocular reflex (1).
- Spontaneous nystagmus (2), where the eyes move rhythmically from side to side in the absence of any head movements.
- occurs when one of the … is damaged
- net differences in vestibular nerve firing rates exist even when the head is … because the vestibular nerve innervating the intact canal fires steadily when at rest, in contrast to a lack of activity on the damaged side.
A
- It is - slow eye movements followed by fast ones during continuous head rotation – fast phase defines direction of nystagmus
- In normal individuals, rotating the head elicits physiological nystagmus due to the vestibulo-ocular reflex (1).
- Spontaneous nystagmus (2), where the eyes move rhythmically from side to side in the absence of any head movements.
- occurs when one of the canals is damaged
- net differences in vestibular nerve firing rates exist even when the head is stationary because the vestibular nerve innervating the intact canal fires steadily when at rest, in contrast to a lack of activity on the damaged side.
13
Q
Caloric testing
- Can be used to test the function of the … in an … patient
- Slow eye movements resulting from … water … in one ear for three different conditions: (1) with the brainstem intact; (2) with a lesion of the medial longitudinal fasciculus (MLF; note that irrigation in this case results in movement of the eye only on the irrigated side); and (3) with a low brainstem lesion.
A
- Can be used to test the function of the brainstem in an unconscious patient
- Slow eye movements resulting from cold water irrigation in one ear for three different conditions: (1) with the brainstem intact; (2) with a lesion of the medial longitudinal fasciculus (MLF; note that irrigation in this case results in movement of the eye only on the irrigated side); and (3) with a low brainstem lesion.
14
Q
Caloric testing
- Can be used to test the function of the … in an … patient
- Slow eye movements resulting from … water … in one ear for three different conditions: (1) with the brainstem …; (2) with a lesion of the medial … fasciculus (MLF; note that irrigation in this case results in movement of the eye only on the irrigated side); and (3) with a … brainstem lesion.
A
- Can be used to test the function of the brainstem in an unconscious patient
- Slow eye movements resulting from cold water irrigation in one ear for three different conditions: (1) with the brainstem intact; (2) with a lesion of the medial longitudinal fasciculus (MLF; note that irrigation in this case results in movement of the eye only on the irrigated side); and (3) with a low brainstem lesion.
15
Q
Why does caloric testing work?
A
- Irrigating an ear with water slightly warmer or colder than body temperature generates convection currents in the canal that mimic the endolymph movement induced by turning the head to the irrigated side or away from it, respectively.
- These currents result in changes in the firing rate of the associated vestibular nerve, with an increased rate on the warmed side and a decreased rate on the chilled side. As in head rotation and spontaneous nystagmus, net differences in firing rates generate eye movements.
16
Q
Why does caloric testing work?
- Irrigating an ear with water slightly warmer or colder than body temperature generates convection currents in the canal that mimic the … movement induced by turning the head to the irrigated side or away from it, respectively.
- These currents result in changes in the firing rate of the associated … nerve, with an increased rate on the warmed side and a decreased rate on the chilled side. As in head rotation and spontaneous …, net differences in firing rates generate eye movements.
A
- Irrigating an ear with water slightly warmer or colder than body temperature generates convection currents in the canal that mimic the endolymph movement induced by turning the head to the irrigated side or away from it, respectively.
- These currents result in changes in the firing rate of the associated vestibular nerve, with an increased rate on the warmed side and a decreased rate on the chilled side. As in head rotation and spontaneous nystagmus, net differences in firing rates generate eye movements.
17
Q
The receptors in the otolith organs detect linear acceleration and tilting of the head
- … and … acceleration provide the same stimulus to the otolith organs, according to Newtons second law (F= m x a)
A
- Gravity and linear acceleration provide the same stimulus to the otolith organs, according to Newtons second law (F= m x a)
18
Q
Central vestibular pathways:
A
19
Q
Central vestibular pathways:
A
27
Q
Location and organisation of the olfactory epithelium:
- The sense of smell is well developed in humans and is important for:
- … interactions (perfumes, deodorants)
- … of poisons / noxious gases
- smell plays a major role in the enjoyment of …
- The human olfactory epithelium has an area of 2-3 cm2 on each side of the nose
- The ciliated receptor cells send their own … axons to the brain without synapsing through the cribriform plate synapsing at olfactory bulb
- There are more than 1000 different odorant receptor proteins, with each receptor cell expressing just one of these.
- Each receptor cell responds to several different odours with action-potential firing
- Olfactory information is coded not by individual receptor types but in the pattern of … that the brain learns to interpret- no rotten egg smell receptor but rotten egg pattern exists
A
- The sense of smell is well developed in humans and is important for:
- social interactions (perfumes, deodorants)
- avoidance of poisons / noxious gases
- smell plays a major role in the enjoyment of food
- The human olfactory epithelium has an area of 2-3 cm2 on each side of the nose
- The ciliated receptor cells send their own afferent axons to the brain without synapsing through the cribriform plate synapsing at olfactory bulb
- There are more than 1000 different odorant receptor proteins, with each receptor cell expressing just one of these.
- Each receptor cell responds to several different odours with action-potential firing
- Olfactory information is coded not by individual receptor types but in the pattern of stimulation that the brain learns to interpret- no rotten egg smell receptor but rotten egg pattern exists
28
Q
Location and organisation of the olfactory epithelium:
- The sense of smell is well developed in humans and is important for:
- social interactions (perfumes, deodorants)
- avoidance of poisons / noxious gases
- smell plays a major role in the enjoyment of food
- The human olfactory epithelium has an area of …-… cm2 on each side of the nose
- The ciliated receptor cells send their own afferent axons to the brain without synapsing through the … plate synapsing at … …
- There are more than 1000 different odorant receptor proteins, with each receptor cell expressing just one of these.
- Each receptor cell responds to … different odours with action-potential firing
- Olfactory information is coded not by individual receptor types but in the … of stimulation that the brain learns to interpret- no rotten egg smell receptor but rotten egg pattern exists
A
- The sense of smell is well developed in humans and is important for:
- social interactions (perfumes, deodorants)
- avoidance of poisons / noxious gases
- smell plays a major role in the enjoyment of food
- The human olfactory epithelium has an area of 2-3 cm2 on each side of the nose
- The ciliated receptor cells send their own afferent axons to the brain without synapsing through the cribriform plate synapsing at olfactory bulb
- There are more than 1000 different odorant receptor proteins, with each receptor cell expressing just one of these.
- Each receptor cell responds to several different odours with action-potential firing
- Olfactory information is coded not by individual receptor types but in the pattern of stimulation that the brain learns to interpret- no rotten egg smell receptor but rotten egg pattern exists
29
Q
Mechanism of olfactory transduction:
- Olfactory transduction depends on a second messenger process, with … being activated in response to an odorant molecule
- This leads to opening of …-dependent ligand-gated ion channels
- non-selective cation channels, permeable to Na+ and Ca2+
- Na+ and Ca2+ influx (inward current in the figure) … the olfactory receptor cells, signalling the binding of an odorant molecule, and leading to … …
- The Ca2+ influx indirectly opens Cl- channels which, due to the unusually high intracellular Cl- concentration of the olfactory receptors, contributes to the depolarization
A
- Olfactory transduction depends on a second messenger process, with cAMP being activated in response to an odorant molecule
- This leads to opening of cAMP-dependent ligand-gated ion channels
- non-selective cation channels, permeable to Na+ and Ca2+
- Na+ and Ca2+ influx (inward current in the figure) depolarizes the olfactory receptor cells, signalling the binding of an odorant molecule, and leading to action potentials
- The Ca2+ influx indirectly opens Cl- channels which, due to the unusually high intracellular Cl- concentration of the olfactory receptors, contributes to the depolarization
30
Q
Mechanism of olfactory transduction:
- Olfactory transduction depends on a … messenger process, with cAMP being activated in response to an odorant molecule
- This leads to opening of cAMP-dependent …-gated ion channels
- non-selective cation channels, permeable to Na+ and Ca2+
- Na+ and Ca2+ influx (inward current in the figure) depolarizes the olfactory receptor cells, signalling the binding of an odorant molecule, and leading to action potentials
- The Ca2+ influx indirectly opens …- channels which, due to the unusually high intracellular …- concentration of the olfactory receptors, contributes to the …
A
- Olfactory transduction depends on a second messenger process, with cAMP being activated in response to an odorant molecule
- This leads to opening of cAMP-dependent ligand-gated ion channels
- non-selective cation channels, permeable to Na+ and Ca2+
- Na+ and Ca2+ influx (inward current in the figure) depolarizes the olfactory receptor cells, signalling the binding of an odorant molecule, and leading to action potentials
- The Ca2+ influx indirectly opens Cl- channels which, due to the unusually high intracellular Cl- concentration of the olfactory receptors, contributes to the depolarization
32
Q
Central pathways of the olfactory system
A
36
Q
Organisation of the gustatory system:
- The … is the principal organ of taste
- Five different modalities of taste can be distinguished:
- salty, sour, sweet, bitter and umami
- There is regional variation in the sensitivity to different tastes, but there is considerable overlap so that most parts of the … can detect all five modalitie
A
- The tongue is the principal organ of taste
- Five different modalities of taste can be distinguished:
- salty, sour, sweet, bitter and umami
- There is regional variation in the sensitivity to different tastes, but there is considerable overlap so that most parts of the tongue can detect all five modalitie
37
Q
Mechanisms of taste transduction:
- … sensation depends on the eqbm potential for sodium ions across taste receptors
- … sensation depends on pH with H+ ions closing K+ channels either directly or indirectly via CAMP as second messenger. This leads to depoarisation of the taste receptors.
- … sensation come about via a second messenger system that closes K+ channels leading to depolarisation of taste receptors
- … and … sensation due to a second-messenger induced increase In intraceullar calcium in the receptors the calcium increase leads to neurotransmitter release
A
- Salt sensation depends on the eqbm potential for sodium ions across taste receptors
- Sour sensation depends on pH with H+ ions closing K+ channels either directly or indirectly via CAMP as second messenger. This leads to depoarisation of the taste receptors.
- Sweet sensation come about via a second messenger system that closes K+ channels leading to depolarisation of taste receptors
- Bitter and umami sensation due to a second-messenger induced increase In intraceullar calcium in the receptors the calcium increase leads to neurotransmitter release
38
Q
Mechanisms of taste transduction:
- Salt sensation depends on the eqbm potential for … ions across taste receptors
- Sour sensation depends on pH with H+ ions closing K+ channels either directly or indirectly via CAMP as second messenger. This leads to … of the taste receptors.
- Sweet sensation come about via a second messenger system that closes K+ channels leading to … of taste receptors
- Bitter and umami sensation due to a second-messenger induced increase In intraceullar calcium in the receptors the calcium increase leads to … release
A
- Salt sensation depends on the eqbm potential for sodium ions across taste receptors
- Sour sensation depends on pH with H+ ions closing K+ channels either directly or indirectly via CAMP as second messenger. This leads to depoarisation of the taste receptors.
- Sweet sensation come about via a second messenger system that closes K+ channels leading to depolarisation of taste receptors
- Bitter and umami sensation due to a second-messenger induced increase In intraceullar calcium in the receptors the calcium increase leads to neurotransmitter release
39
Q
Mechanisms of taste transduction:
- … sensation depends on the eqbm potential for sodium ions across taste receptors
- … sensation depends on pH with H+ ions closing K+ channels either directly or indirectly via CAMP as second messenger. This leads to depoarisation of the taste receptors.
- …. sensation come about via a second messenger system that closes K+ channels leading to depolarisation of taste receptors
- … and … sensation due to a second-messenger induced increase In intraceullar calcium in the receptors the calcium increase leads to neurotransmitter release
A
- Salt sensation depends on the eqbm potential for sodium ions across taste receptors
- Sour sensation depends on pH with H+ ions closing K+ channels either directly or indirectly via CAMP as second messenger. This leads to depoarisation of the taste receptors.
- Sweet sensation come about via a second messenger system that closes K+ channels leading to depolarisation of taste receptors
- Bitter and umami sensation due to a second-messenger induced increase In intraceullar calcium in the receptors the calcium increase leads to neurotransmitter release
40
Q
Central pathways of the gustatory system:
- Taste is signalled by cranial nerves …. (front 2/3 of the tongue), … and … (both rear 1/3 of the tongue) to the nucleus of the solitary tract in the brainstem.
- Fibres (red lines) from second-order taste neurons project ipsilaterally to the ventral posterior nucleus of the thalamus.
- Thalamic efferents (green lines) then project to the insula, defining the primary gustatory cortex which, in turn, projects (black lines) to the … cortex, sometimes defined as a secondary cortical taste area.
- The parabrachial nuclei of the pons are shown in orange. The parabrachial nuclei have a dorsal thalamocortical projection and also a ventral projection that terminates in amygdalar and hypothalamic nuclei, among others.
A
- Taste is signalled by cranial nerves VII (front 2/3 of the tongue), IX and X (both rear 1/3 of the tongue) to the nucleus of the solitary tract in the brainstem.
- Fibres (red lines) from second-order taste neurons project ipsilaterally to the ventral posterior nucleus of the thalamus.
- Thalamic efferents (green lines) then project to the insula, defining the primary gustatory cortex which, in turn, projects (black lines) to the orbitofrontal cortex, sometimes defined as a secondary cortical taste area.
- The parabrachial nuclei of the pons are shown in orange. The parabrachial nuclei have a dorsal thalamocortical projection and also a ventral projection that terminates in amygdalar and hypothalamic nuclei, among others.
41
Q
Central pathways of the gustatory system:
- Taste is signalled by cranial nerves VII (front 2/3 of the tongue), IX and X (both rear 1/3 of the tongue) to the nucleus of the solitary tract in the brainstem.
- Fibres (red lines) from second-order taste neurons project ipsilaterally to the ventral posterior nucleus of the thalamus.
- Thalamic efferents (green lines) then project to the …, defining the primary gustatory cortex which, in turn, projects (black lines) to the orbitofrontal cortex, sometimes defined as a secondary cortical taste area.
- The parabrachial nuclei of the pons are shown in orange. The parabrachial nuclei have a dorsal … projection and also a ventral projection that terminates in amygdalar and hypothalamic nuclei, among others.
A
- Taste is signalled by cranial nerves VII (front 2/3 of the tongue), IX and X (both rear 1/3 of the tongue) to the nucleus of the solitary tract in the brainstem.
- Fibres (red lines) from second-order taste neurons project ipsilaterally to the ventral posterior nucleus of the thalamus.
- Thalamic efferents (green lines) then project to the insula, defining the primary gustatory cortex which, in turn, projects (black lines) to the orbitofrontal cortex, sometimes defined as a secondary cortical taste area.
- The parabrachial nuclei of the pons are shown in orange. The parabrachial nuclei have a dorsal thalamocortical projection and also a ventral projection that terminates in amygdalar and hypothalamic nuclei, among others.
