Olfactory and Visual systems Flashcards
Humans can detect ______ different odors.
10,000
Describe the olfactory epithelium….what is it?
- Patch in roof of nasal cavity (bilateral)
- Contains 3 million receptor cells, supporting cells, bowman gland ducts, sensory endings.
- It is the peripheral origin of the olfactory system
What is an Olfactory receptor?
A small bipolar neuron
- dendrite ends in olfactory vesicle, from which 10-30 cilia spread over the surface in a layer of mucous secreted by Bowman’s gland.
- Stimulate chemosensitive cilia
- Unusual among human neurons. (replaced every 1-2 months)
Axons from the olfactory receptors are among the _______ and _______.
thinnest and slowest
axons from olfactory receptors collect into a series of bundles called _________.
Olfactory fila
Olfactory film travel through ______ and end ________.
- Holes in cribriform plate of ethmoid bone
- end in olfactory bulb.
________ make up cranial nerve I.
Olfactory fila
Olfactory build develops as an outgrowth of ________.
Telencephalon
Describe the structure of the olfactory bulb. (Interneurons, Mitral cells….)
Bulb has interneurons = tufted cells and granule cells.
Mitral cells = axons collect join olfactory tract, dendrites form glomeruli.
What forms the glomeruli of the olfactory bulb?
Dendrites from the olfactory tract.
Where do olfactory fibers get sorted?
In the olfactory bulb.
What are the olfactory bulb projections to the cortex? (2)
- Axons of mitral and tuft cells.
- Collateral to anterior olfactory nucleus. (thought to regulate sensitivity of olfactory bulb)
* Fibers project to both bulbs (cross in midline in anterior commissure).
Where do olfactory bulb projection fibers travel?
Some fibers end in olfactory tubercle…
MOST turn laterally and end in lateral olfactory pathway.
Where do olfactory bulb projections END?
End in 2 areas
1) Primary olfactory cortex:
- Cortex near olfactory tract (Piriform cortex)
- Cortex covering amygdala (periamydaloid cortex)
- small part of parahippocampal gyrus
2) Amygdala
Where is Olfactory information sent to?
Hypothalamus, Thalamus, hippocampus, orbital cortex and Amygdala.
- direct projections and a THALAMIC relay to the association cortex *No thalamic relay to motor cortex.
- Goes to Olfactory association cortex = orbital surface of frontal lobe and anterior insula.
_____ & _______ focus image on retina.
Cornea & lens
_____ accounts for about 1/3 of the eyes refractive power.
lens *major role is in adjusting focus for near/far objects.
Where does most refraction take place?
In the air-water interface at corneal surface (70%)
______ affects the brightness and quality of the image focused on retina.
Iris
Pupil size is controlled by what two muscles?
- Pupillary sphincter = encircles pupil (stronger than dilator)
- Smaller pupil improves ocular performance
- Pupillary dilator = arranged in radiating spokes from the pupil (sympathetic innervation)
(Retinal structure)
______ is layer of rods and cones.
Photo receptors
Where do synapses occur in the retinal structure?
In the 2 interposed layers
- one cell types brings visual info in and the other sends it out.
- another type interconnects laterally)
_____ are highly specialized cells with different structural regions.
Photoreceptors (Rods and cones)