Exam 6: Taste and Smell

Gustation is

chemical stimulation of sensory cells (taste receptors) clustered in taste buds

taste receptors are located in

taste buds

chemical stimuli of taste are called

tastants

taste buds are located in

lingulal papillae (physical bumps on tounge)

fungiform taste buds (3 things)

small (3 taste buds), ,most numerous, tongue and throughout oral cavity

Foliate taste buds (3 things)

leaf shaped in folds on side of tongue, most sensitive taste buds, decrease in number with age

Vallate taste buds (3 things)

large, 100 taste buds, form V shape

filliform papillae (3 things)

most numerous papillae, do not have taste buds, give tongue rough surface

taste buds include 3 things

taste cells, supporting cells, basal cells

basal cells in taste bud are

stem cells, multiple and replace dead taste cells

gustatory taste cells in taste bud are

epithelial cells that have specialized microvilli (taste hairs) in a narrow taste pore

to be tasted molecules must dissolve

in saliva and flood the taste pore

five primary taste sensations

sweet (carbs and sugar)

salty (minerals)

sour (acidic)

bitter

umami (meaty or savory): amino acids

Gustatory pathway (4)

1.taste buds monitored by cranial nerves (facial,glossopharngeal, vagus (first order neuron)

2.symapse with solitary nucleus of medulla oblogata (secoud neuron)

3.Go to thalamus via medial lemnicus pathway then to insula and part of the forntal lobe, sometimes to primary sensory cortex for visceral responses to taste

4.parallel pathways to tthe hypothalamus and other brain regions for reflex response like( salivation, stomach churning, emotions)

taste fibers don’t what

decussate

olfactory organ is

olfactory epithelium and olfacctory mucosa in the roof of nasal cavity

olfactory receptor cells are what

modified bipolar cells

olfactory receptor contain

specialized cilia (olfactory hairs)

olfactory receptor cell population has a lot of

turnover

each olfactory receptor cell has one what

one type of receptor that binds to specific odorant

surface of olfactory epithelium is coated by secretions from what

olfactory glands

olfactory reception involves 2 types detection

hydrophilic oderants: detecting oderants in dissovled mucosa

hydrophodic odorants: oderants bind to proteins in muscosa and bind to receptor on olfactory hair

how many chemical stimuli can olfactory receptor distinguish

>10,000

humans have how many receptors

400

CNS interprets smells based on

pattern of receptor activity

olfaction have what type of adaption

little receptor adaption, but more central adaption

granule cells in the glomeruli do what

inhibit signals going to olfactory centers

olfactory receptor activation (5)

1. odorant binds to receptor

2. receptor activates G protein

3. G protein activates adenyalate cyclase

4. adenylate cyclase convert ATP to cAMP

5. cAMP opens channels allowing NA and CA in and causing depolarisation

Olfactory pathways do not synapse where

thalamus

mitral cells and tuffted cells in olfactory bulb synaps with

bipolar cells in glomeruli (each glorus recives on type of signal)

Olfactory tracts mainly go where in brain

temporal lobe

colltralaterals of olfactory tract go where

limbic system, recticular system, and thalamus

frontal lobe allows for what in olfaction

discrimination of different oders and integrates smell and tatse

Olfactory pathway

1.olfactory signal received in olfactory bulbs

2.signals go to olfactory tracts

3.goes to temporal lobe

4. signals from each temporal lobe go to contrallateral temporal lobe to processing can be mirroed in both hemisphers

5.contrallateral signals go to limbic system, recticular system, and thalamus

6. frontal lobe descrimates oders and makes oder into flavor