Special Senses (Test 2) Flashcards
What range can we see on the visible light spectrum?
- 390-700 nm
What is our maximum sensitity to light?
- About 100 photons
What is the pathway of light?
- Cornea –> iris –> anterior chamber –> lens –> posterior chamber –> retina –> fovea
Nicotinic receptors cause pupils to?
- Constrict (Parasympathetic)
Gq receptors cause pupils to?
- Dilate (Sympathetic)
What is the structure of the Retina?
- Photoreceptors
- Interneurons
- Output neurons
Inter-neurons are known as?
- Bipolar cells
Where do bipolar cells receive their signal from?
- Receive input from horizontal cells and communicate with dendrites of Ganglion cells not by action potentials but by graded potentials.
How many types of cone bipolar cells are there?
- 10
How many types of rod bipolar cells are there?
- 1
What are the 3 types of photoreceptor?
- Rods
- Cones
- Intrinsically photoreceptive retinal ganglion cells
What are Intrinsically photoreceptive retinal ganglion cells?
- They detect light at 482 nm via melanopsin and send that info to the SCN and govern circadian rhythms
What do horizontal cells do?
- Regulate bipolar signals near photoreceptors
What do amacrine cells do?
- Regulate bipolar signals near ganglion cells
How many photons to excite rods?
- 1 photon
How many photons to excite cones?
- 100 photons
How many photons to excite cones?
- 100 photons
What are the 3 types of cones?
- Shortwave cones (445 nm)
- Meddlewave cones (535 nm)
- Longwave cones (575 nm)
How does light activate photoreceptors?
- Light causes the activation of a phosphodiesterase which converts cGMP to GMP to close sodium channels and cause the cell to polarize
- A lack of light causes a buildup of cGMP, thereby sodium channels open
How does optogenetics work?
- A light sensitive protein from algae (responds to blue light) is taken and inserted into the DNA of specific neurons in the brain
How can optogenetics be used in neuroscience?
- With the right combo of neurons, you can activate/deactivate (hyperpolarize) an entire brain circuit to control specific behaviors like movement
What cells create the optic nerve?
- The axons from ganglion cells and are myelinated by oligodendrocytes
Where do signals from the optic nerve project to?
- The occipital lobe
Receptors on the tongue can double as?
- Taste receptors
- Temperature receptors
Receptors on the tongue can double as?
- Taste receptors
- Temperature receptors
How many genes are involved in odor reception?
- Over 800
What was an unexpected finding regarding olfactory receptor cells?
- Every single one expresses only one gene of all the genes that code for olfactory receptor molecules
How many odors can the nose detect?
- 1 trillion odors
How do genes aid to odor receptor complexity?
- Genes are alternatively spiced to aid in odor molecule detection
Where does the olfactory nerve send information?
- The olfactory cortex
- The limbic system
What do channelrhodopsins do?
- Conduct cations and depolarize neurons upon illumination
What do halorhodopsins do?
- Conduct chloride ions into the cytoplasm upon yellow light illumination
What is the range of human hearing?
- 20 Hz - 20,000 Hz
What organ can interpret pressure changes in the ear?
- The cochlea
Pressure waves enter the ___ (ear) and concentrate sound onto the ___ (eardrum)?
- Pinna
- Tympanic membrane
What are the 3 smallest bones in the body?
- The malleus
- The incus
- The stapes
What do the 3 smallest bones in the body press against to transfer pressure waves?
- The oval window
How do pressure waves convert into chemical signals?
- Pressure waves move the cilia of the cochlea to allow mechanically gated potassium channels to open and depolarize the cell
Which system provides information about acceleration?
- The vestibular system
What are the horizontal semicircular canals?
- Provide info about vertical axis rotation
What are the superior semicircular canals?
- Detect movement about the lateral axis
What is the posterior semicircular canal?
- Detects movement about the coronal plane
How do stimulation of hair cells in the semicircular cells differ from hair cell stimulation in the cochlea?
- They are actually very similar
How does alcohol affect interactions between the endolymph and cupula?
- You spin because alcohol diffuses into the endolymph fluid and changes the density of the fluid, thereby causing the cupula to move and tell the brain that you are moving
What are the different types of mechanosensory receptors?
- Merkel receptors
- Meissner’s corpulscles
- Pacinian’s corpuscles
- Ruffini cylinder
What are merkel receptors?
- Slow adapting skin receptors that record deep touch
What are meissner corpuscles?
- Fast adapting receptors that record light touch
What are pacinian corpuscles?
- Fast adapting receptors that record deep touch
What are ruffini cylinders?
- Slow adapting receptors that record stretch
What do AMPA receptors mostly depolarize?
- OFF bipolar cells
What do Metabatropic mGluR6 mostly depolarize?
- ON bipolar cells
Does the fovea contain mostly rods or cones?
- Coness
