Sensory Pathways - Smell and Vision

1. Where are olfactory receptors found? olfactory epithelium which is high in nasal cavity 2. What do the olfactory cell axons do? carry info to olfactory bulbs 3. Why does the regenerative basal cell divide? to replace worn-out olfactory cells 4. What do olfactory cilia contain? odorant receptors 5. What must dissolve in the mucus layer? odorant molecules 6. What type of receptors are olfactory receptors? GPCR 7. How is olfactory stimuli transduced? 1) odorant molecules enter via nasal cavity + come into contact with olfactory epithelium + bind with odorant receptors 2) triggers a cascade of biochemical events leading to AP which propagate along olfactory nerve fibres 3) axons form olfactory nerve which project directly into olfactory bulb in the brain 4) neural signals undergo processes which help to encode info about odours 5) signals are relayed to higher brain 1/4 areas for odour perception + interpretation 8. Describe the olfactory pathway: 1) odour enters nasal cavity, passes through the mucous membrane + is recognised by odorant receptors on primary olfactory neurons (PON) 2) PON extend their axons into the olfactory bulb + form synapses with mitral = tufted cells (secondary olfactory neurons/SON) 3) the axons of SON extend onto their target in brain = olfactory cortex, amygdala + hippocampus 9. What forms the olfactory tract? axons of mitral + tufted cells 10. What does the outer coat of the eye do? protect the eye 11. What are the parts of the outer eye? - sclera (opaque) - cornea (transparent) 12. What does the middle coat of the eye do? has lots of vascularity for the delivery of oxygen + nutrients 13. What are the parts of the middle coat of the eye? - choroid - ciliary bodies (cil- 2/4 iary ligaments + lens) - iris - pupil 14. What does the inner coat of the eye do? recepts light 15. What are the parts of the inner coat of the eye? - outer pigment layer (epithelial cells with melanin) - inner neural layer (rods, cones + other neurons) 16. What is the lens of the eye attached to? attached to the ciliary muscle by inelastic ligaments 17. What happens when ciliary muscle is relaxed? the inelastic ligaments pull on + flatten the lens 18. What happens when the ciliary muscle contracts? tension is released in the inelastic ligaments + lens becomes more rounded 19. What happens when objects are far from the eyes? parallel lights rays pass through a flattened lens 20. What happens when objects are closer to the eye? light rays are no longer parallel 21. How does the eye keep an object in focus was it moves closer? - lens becomes rounder - focal length shortens 22. What is hyperopia? far-sightedness 3/4 23. How does hyperopia occur? focal point falls behind the retina 24. What is myopia? near-sightedness 25. How does myopia occur? focal point falls in from the retina 26. How is hyperopia corrected? with a convex lens 27. How is myopia corrected? with a concave lens 28. What vision does the cone give? colour vision 29. What does cranial nerve III control? pupillary constriction 30. What is the optic nerve chiasma? place where optic nerves from each eye come together + partially cross to the other side of the brain 31. Describe the process of visual information: - info from the left visual (coming from the right halves of both retinas), is processed in the right hemisphere of the brain + vs 4/4