Transcript Taste cells

Senses and Sensibility
I. Sensory modalities
II. Physiology of sensation
III. Thermal homeostasis
IV. Physiology of taste
V. Physiology of smell
Sensory Modalities
• Chemoreceptors
(e.g., taste, smell, O2 level in blood)
Sensory Modalities
• Chemoreceptors
(e.g., taste, smell, O2 level in blood)
• Mechanoreceptors
(e.g., touch, hearing, equilibrium, proprioreception)
Sensory Modalities
• Chemoreceptors
(e.g., taste, smell, O2 level in blood)
• Mechanoreceptors
(e.g., touch, hearing, equilibrium, proprioreception)
• Photoreceptors
(vision, photoperiod)
Sensory Modalities
• Chemoreceptors
(e.g., taste, smell, O2 level in blood)
• Mechanoreceptors
(e.g., touch, hearing, equilibrium, proprioreception)
• Photoreceptors
(vision, photoperiod)
• Thermoreceptors
Communication by
Sensory Neurons
• Sensory stimuli cause
graded potentials
Axon
Hillock
Communication by
Sensory Neurons
• Sensory stimuli cause
graded potentials
• AP triggered in sensory
neuron if graded
potentials reach threshold
Axon
Hillock
Communication by
Sensory Neurons
• Sensory stimuli cause
graded potentials
• AP triggered in sensory
neuron if graded
potentials reach threshold
• Sensory neurons synapse
onto neurons of CNS
Axon
Hillock
Properties of Sensory Neurons
• Selectivity
Vision
Hearing
Taste
Properties of Sensory Neurons
• Selectivity
• Transduction
– convert stimulus into graded potential
– Na+ channels open or close
– AP created in sensory neuron
Senses and Sensibility
I. Sensory modalities
II. Physiology of sensation
III. Thermal homeostasis
IV. Physiology of taste
V. Physiology of smell
Range of Sensory Perception
• Sensory Adaptation
Thalamus filters out some stimuli
Range of Sensory Perception
• Range Fractionation
- neurons differ in range of sensitivity
Senses and Sensibility
I. Sensory modalities
II. Physiology of sensation
III. Thermal homeostasis
IV. Physiology of taste
V. Physiology of smell
Thermoreceptors
• Peripheral Thermoreceptors
- epithelial tissue
• Central Thermoreceptors
- hypothalamus
Thermal Homeostasis
Stimulus: Cold Air
Stimulus: High Core Temp
Peripheral
Thermoreceptor
Central
Thermoreceptor
Hypothalamus
Motor Neuron
Sympathetic NS
Muscle (Shivering)
Sweat Glands
Senses and Sensibility
I. Sensory modalities
II. Physiology of sensation
III. Thermal homeostasis
IV. Physiology of taste
V. Physiology of smell
Chemoreceptors
• Chemoreceptors respond to chemicals in an
aqueous solution
The Chemical Senses:
• Taste
– 5 receptor types
– cells are highly generalized
Taste Buds are Located in Papillae
Taste Buds are Located in Papillae
Gene Simmons has LOTS
of papillae!
Taste Buds are Located in Papillae
Taste buds line the papillae of your tongue.
Taste Buds are Located in Papillae
Taste buds line the papillae of your tongue.
I Rock & Roll all
Night and Party
Every Day!
Anatomy of Taste Buds
Taste cell
Support cell
Basal cell
Anatomy of Taste Buds
Taste cell
Support cell
Basal cell
1) Taste cells form receptor surface and synapse with
cranial nerves
Anatomy of Taste Buds
Taste cell
Support cell
Basal cell
1) Taste cells form receptor surface and synapse with
cranial nerves
2) Supporting cells provide support for taste buds
Anatomy of Taste Buds
Taste cell
Support cell
Basal cell
1) Taste cells form receptor surface and synapse with
cranial nerves
2) Supporting cells provide support for taste buds
3) Basal cells produce new _________
Hypothetical Distribution of Taste Cells
Hypothetical Distribution of Taste Cells
Distribution of Taste
Taste cell
Support cell
Basal cell
• Most taste cells respond to only 1 of the 5 tastes
Transduction in Taste Cells
• Salty & Sour flavors
- Na+ or H+ ions enter cells through existing channels
Transduction in Taste Cells
• Sweet , Bitter & Umami more complicated
– Bind to receptors and activate secondary messengers,
which open Na+ channels
Senses and Sensibility
I. Sensory modalities
II. Physiology of sensation
III. Thermal homeostasis
IV. Physiology of taste
V. Physiology of smell
Jerry made the ice cream but Ben would test all the new
flavors because Ben has hardly any sense of smell
JERRY GREENFIELD:
He kept making me put in these bigger and bigger pieces
of chunks.
BEN COHEN:
Jerry always wanted to make them smaller so that there
would be better chunk distribution in each scoop, or in each
pint, and I insisted that it was critical that the chunks be
really, really huge. And he said, “but Ben, somebody might
take a spoonful and they won't get a chunk at all.” And I
said, “that's OK, that's a sacrifice you have to make. It's
worth it, for the big chunk they'll get in the next spoon.”
Olfaction (Smell)
• Smell enhances the sense of Taste
Olfaction (Smell)
• Smell enhances the sense of Taste
Olfaction (Smell)
• Smell enhances the sense of Taste
Olfaction (Smell)
• Smell enhances the sense of Taste
• Olfactory cells
Olfaction (Smell)
• Smell enhances the sense of Taste
• Olfactory cells
• Mucus
Anatomy of Olfaction
Olfactory nerve
olfactory bulb
Ethmoid
olfactory
epithelium
basal cell
olfactory cell
support cell
Chemoreceptors
• Chemoreceptors respond to chemicals in an
aqueous solution
The Chemical Senses:
• Taste
– 5 receptor types
– cells are highly generalized
• Smell
– Thousands of receptor types
– cells are highly specialized
Olfactory Cells Are Specialists
• The nose can distinguish ~10,000 odors
Olfactory Cells Are Specialists
• The nose can distinguish ~10,000 odors
10,000 Odors!
How does
your nose
knows?
Olfactory Cells Are Specialists
• Nose can distinguish ~10,000 odors!
• Each olfactory cell expresses a different
receptor protein (only one type per cell)
Olfactory Cells Are Specialists
• Nose can distinguish ~10,000 odors!
• Each olfactory cell expresses a different
receptor protein (only one type per cell)
• Cells with a given receptor are randomly
distributed in the olfactory epithelium
Olfactory Cells Are Specialists
• Nose can distinguish ~10,000 odors!
• Each olfactory cell expresses a different
receptor protein (only one type per cell)
• Cells with a given receptor are randomly
distributed in the olfactory epithelium
• All neurons of a given type converge in the
olfactory bulbs of the brain
Convergence of Olfactory
Cells
nasal epithelium
point of convergence
(in olfactory bulb)
Ethmoid Bone
Physiology of Olfaction
1. Volatile odor enters nasal cavity
Physiology of Olfaction
1. Volatile odor enters nasal cavity
Physiology of Olfaction
1. Volatile odor enters nasal cavity
2. Odor dissolves in mucus lining
Physiology of Olfaction
1. Volatile odor enters nasal cavity
2. Odor dissolves in mucus lining
3. Bind to receptor protein
Physiology of Olfaction
1. Volatile odor enters nasal cavity
2. Odor dissolves in mucus lining
3. Bind to receptor protein
4. Na+ channels open
Physiology of Olfaction
1. Volatile odor enters nasal cavity
2. Odor dissolves in mucus lining
3. Bind to receptor protein
4. Na+ channels open
5. AP sent to Olfactory Bulb
Physiology of Olfaction
1. Volatile odor enters nasal cavity
2. Odor dissolves in mucus lining
3. Bind to receptor protein
4. Na+ channels open
5. AP sent to Olfactory Bulb
6. To the Brain
Hmmm…
That smells
like bacon
The Dirty Secret Behind Flavor
• So why do McDonald’s fries taste soooooo good?
New Jersey Smells Great!
McDonalds French Fries:
Potatoes, partially hydrogenated
soybean oil, natural flavor (beef,
wheat and dairy sources),
dextrose, sodium acid
pyrophosphate (to preserve natural
color). Cooked in partially
hydrogenated vegetable oils (may
contain partially hydrogenated
soybean oil and/or partially
hydrogenated corn oil and/or partially
hydrogenated canola oil and/or
cottonseed oil and/or sunflower oil
and/or corn oil). Contains derivatives
of wheat and dairy.