Chemosensation S2M1

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What are the regenerative cells in the olfactory system

Basal Cells
What happens upon the binding of an odorant in the olfactory system
- Odorant receptor activates G-Protein
- Adenylate cyclase activates cAMP (via ATP)
- cAMP opens Na+/Ca++ channels
- Ca++ opens Cl- channels
- Membrane depolarizes
Each Olfactory neuron expresses

1 receptor protein (which can bind to different oderants)
Bowmans capsule secretes what

Olfactory binding protein
How do the neurons in the olfactory system vary
- Some are responsive to a single odorant
- Some many
- The perception of odor can change with concentration
The main output cell of the olfactory bulb is what

Mitral cell
Primary neurons of the olfactory system synapse in specific

Glomeruli (bundle of axon ends) within the olfactory bulb
What does the primary olfactory cortex consist of
- Pyriform cortex
- Entorhinal cortex
- Amygdala
- (PEA)
What does the olfactory association cortex consist of

Orbital gyri of the prefrontal cortex
What is the Medial Olfactory Tract
- Medial Olfactory Tract
- - Axons project ipsilaterally to the basal limbic forebrain structures
- - Others arise from the contralateral anterior Olfactory Nucleus (via anterior commissure)
What is the Lateral Olfactory pathway
- Lateral Olfactory Tract
- - Axons project to the primary olfactory cortex amygdala and entorhinal cortex, then to the prefrontal cortex
Anosmia

Loss of smell
Hyposmia

Decreased ability to smell
Hyperosmia

Increased ability to smell
Dysosmia

Distorted perception of smell
Phantosmia

Perception of odour where there is none
Agnosmia

Loss of verbal ability to classify, contrast and identify odour sensation even though ability to detect between odorants is present
What can cause the decline in olfactory ability
- Psychotic disorders
- Age
- Seizure
- Head trauma
- Tumor
- Alzheimers
- "PASHTA"
What are the basic taste sensations of the tongue
- Sweet
- Bitter
- Salty
- Sour
- Unami
What are the projections of the tongue called

Papillae
What are the three different papillae in the tongue
- Foliate papillae (Leaf like)
- Vallate papillae (Circle like)
- Fungiform papillae (Mushroom like)
What is the make up of a papillae
- Each has 1-100+ taste buds
- Each taste bud has 50-150 taste receptors
What cells are found in a taste bud
- Epithelial cells
- Supporting cells
- Gustatory receptor cells with gustatory hairs
- Basal cells (10 day life cycle)
The anterior 2/3 portion of the tongue has what specific taste receptors from what nerve
- Sweet, sour, salty
- Facial nerve (VII)
The posterior 1/3 of the tongue is innervated by what nerve and has what taste receptors

Glossopharyngeal nerve (IX), sour and bitter
What nerves innervate the epithelium and touch receptors of the tongue
- Trigeminal (V) - Ant. 2/3
- Glossopharyngeal (IX) - Post. 1/3
The epiglottis has taste and touch receptors innervated by

CN X Vagus
At higher concentrations most papillae become

Less selective for taste
Capsaicin
- Principle ingredient for peppers
- Activates on subset of C fibers normally used for heat
What nerve transmits the sense from Capsaicin

Trigeminal nerve through C fibers
What are the nerves that send taste from the tongue
- Facial
- Trigeminal (partially)
- Glosspharyngeal
- Vagus
What nerve tract is used for taste

Solitary
What is the taste pathway
- Cranial ganglia axons
- Solitary nucleus
- VPM
- Insula
Ageusia

Loss of taste sensation
Hypogeusia

Decreased taste sensation
Dysgeusia

Distorted taste perception
Phantogeusia

Perception of taste where there is none
What can cause a loss of olfactory ability
- Radiation
- Oral neoplasm
- Stroke
- Surgery
- Tumour
- Trauma
- "ROSS TT"

Author

lancesadams

86810

Card Set

Chemosensation S2M1

Description

Neuro

Updated

2011-08-11T21:06:23Z

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