B7.067 Limbic System Flashcards
taste (gustatory)receptor structure
taste buds line the circumvallate papilla
located in a row at the base of the tongue
structure of taste bud
taste pore open to environment with saliva
on opposite end of bud are sensory cells which carry signal to the CNS via neurotransmitters
supportive cells located in between
basal cells located at the base of the taste bud by the receptor cells
basal cell function
have regenerative capacity to generate new taste bud receptor cells
transduction classes of tastants
- directly ionic
2. second messenger
directly ionic tastants
salty (Na+)
sour (H+)
changes membrane potential of cell directly
second messenger tastant
sweet
bitter
umami
G protein couples receptor sets cascade in motion
end result of cascade is to depolarize cell and release neurotransmitters
central gustatory pathways
- receptors on tongue respond to stimulation
- cranial nerves VII, IX, and X carry information
- sensory afferents synapse in the solitary nucleus of the medulla oblongata
- axons of postsynaptic neurons enter the medial lemniscus
- axons synapse in the thalamus and project to the gustatory cortex
olfactory receptor structure
olfactory epithelium consists of a layer of olfactory receptor cells, supporting cells, and basal cells
odorants dissolve in the mucus layer and contact the cilia of the olfactory cells
axons of the olfactory cells penetrate the bony cribriform plate on their way to the CNS
regenerative capacity of olfactory receptor cells
one of the only parts of the brain that can undergo neurogenesis in adulthood
axonal pathfinding associated with new neurons working up to the CNS
olfactory transduction
G protein coupled
receptor neurons express receptors for many olfactants
primary secondary cells of the olfactory bulb
olfactory cells synapse in glomeruli with:
-mitral cells
-tufted cells
travel to olfactory areas of the CNS
where does the olfactory tract project
NOT to the thalamus, no synapse 1st projection spot: piriform and periamygdaloid cortex olfactory tubercle amygdala entorhinal cortex contralateral olfactory bulb
conscious odor perception pathway
olfactory bulb > piriform cortex > neocortex (orbitofrontal cortex)
amygdala olfactory pathways
olfactory bulb > amygdala > septal nuclei OR hypothalamus
hippocampal olfactory pathways
olfactory bulb > entorhinal cortex > hippocampus
anosmia
loss of olfactory sense
functions of the limbic system
homeostasis
olfaction
memory
emotions and drives
structure of cortical limbic structures
more primitive cortical architecture
fewer than 6 layers
neocortex
six layered cortex
majority of cerebral cortex
mesocortex
limbic cortex
forms gradual transition between 3 and 6 layered cortex
ex: parahippocampal gyrus, cingulate gyrus, anterior insula, orbitofrontal cortex, temporal pole
allocortex components
archicortex
paleocortex
cortex with fewer than 6 layers
archicortex
3 layered hippocampal cortex
paleocortex
3 layered olfactory cortex
piriform cortex
Papez circuit
association and cingulate cortices > (cingulum) > entorhinal cortex > (perforant pathway) > hippocampal formation > (fornix) > mammillary body > (mammillothalamic tract) > anterior nucleus of thalamus
