Please enable JavaScript.
Coggle requires JavaScript to display documents.
Taste & smell (Taste bud (Taste buds consist of taste receptor cells…
Taste & smell
Taste bud
Taste buds consist of taste receptor cells (TRCs)
Neuroepithelial, spindle-shaped cells surrounded by support and stem cells
-
Cranial nerves: VII, IX and X
-
Tastants (chemicals) stimulate gustatory receptor cells:
- Once dissolved in saliva contact plasma membrane of gustatory 'hairs'.
- Results in receptor potential stimulating exocytosis of synaptic vesicles
- Trigger nerve impulses in synapsed sensory neurones
Tastes - Salty, sweet, bitter, sour and umami
Tastes vary due to patterns of activity and different groups of neurons being activated by different tastes
Olfactory epithelium
-
-
-
-
-
-
Binding of scent signal to olfactory receptor activates receptor potential. Triggers impulses in CN I. Frequency depends on conc. of stimulating molecules
Olfactory pathways
-
-
- Axons from epithelia and VNO pass through cribriform plate and synapse on olfactory bulb neurons
- Travel caudally in olfactory peduncle
- Trunk splits - Lateral axons synapse in olfactory tubercle and pass into cortex of piriform lobe. Most medial fibres pass to hypothalamus and reticular formation in brainstem. Fibres decussate and pass to contralateral olfactory bulb
-
-
Chemoreception
-
-
Functions: Social recognition of kin (retained/scent marking and pheromones), taste, smell
-
Papillae
-
Gustatory
Vallate (aka circumvallate) - Circular, inverted V-shaped row at back of tongue, large, flattened, lined by sulci. Many taste buds, serous and mucous glands in sulci.
Fungiform - Mushroom shaped elevations, scattered amongst filiform papillae, non-keratinied
Foliate - Leaf shaped, on margin of tongue, folds separated by sulci, serous glands lie deep to sulci. Absent in ruminants
Mechanical
Filiform - Pointed, threadlike, keratinized, large, pointed keratinized spines in cat, most numerous of all papillae
Conical - cone, root of tongue, not highly keratinized
Lenticular - Lens shaped, flattened, found in ruminants, keratinized
Gustatory pathway
Pathway:
- Tongue
- Facial (rostral 2/3 of tongue), glossopharyngeal (serving caudal 1/3 of tongue) and vagus (taste at root of tongue/epiglottis)
- Impulses propogate to medulla
- Some then carry impule to limbic system and hypothalamus, others to thalamus then to primary taste area in frontal lobe (conscious perception)
-
Olfactory communication
Finding direction, shelter, seeking prey, avoiding predators, sexual attraction
Pheromones = small olfactory signals
- Passed from one animal to another
- Trigger characteristic behavioral and physiological responses
- Powerful regulators of social and reproductive behaviours
Olfactory/VNO
-
Many olfactory cells synapse to single mitral cells (neurons) in olfactory bulb. Called a glomerulus. Each olfactory bulb lined with glomeruli. The glomeruli only synapse to a specific receptor type each so form 'smell files'. Mitral cells refine smell signals and relay to brain for further processing