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Lecture 9: Comp Phys
Lecture outline 10: Comparative Physiology USD Fall 2018 Dr. Kenneth Renner
| Question | Answer |
|---|---|
| What is the primary role of the nervous system? (3) | take in information from the environment and internal structures, process the information and relay messages for the appropriate response |
| What are the initial signals of the nervous system detected by? | 3 types of receptors |
| What are the three types of receptors? | mechanoreceptors, radioreceptors, chemoreceptors |
| what are mechanoreceptors? | detetion of touch, pressure, and low frequency vibrations (sounds) |
| What are Radioreceptors? | detection of high frequency vibrations, heat, and light |
| What are some examples of radioreceptors? | eyes, pit organs on rattlesnakes |
| What are chemoreceptors? | detection of chemical agents |
| What are some examples of chemoreceptors? | Alfactory epithelium and taste buds |
| How do sensory receptors typically respond to stimulus? | by an increase in membrane permeability to sodium |
| What does in increase in membrane permeability to sodium result in in sensory receptors? | local depolarization |
| What are the two types of potentials created by local depolarization of sensory receptors? | Receptor potentials and generator potentials |
| What is a receptor potential? | a potential generated by isolated receptors |
| What is a receptor potential response graded with respect to? | stimulus sstrength |
| True or False: like AP, receptor potentials can't be summed in magnitude | False, receptor potentials can be summed in magnitude |
| What do receptor potentials impact? | sensory afferent fibers |
| What does afferent mean? | signals sent to the CNS |
| How does receptor potentials typically occur? | through chemical NT |
| What is a generator potential? | signal activates voltaged gated channels on the terminal of an afferent sensory fibers |
| What can generator otentials generate? | An AP at the terminal |
| What is receptor adaptation? | the ability of some sensory receptors to adapt if exposure to stimulus is prolonged |
| True or False: degree of adaptation in receptor adaptation is variable | true |
| What are tonic receptors? | receptors that don't adapt or adapt slowly |
| What are examples of tonic receptors? | pain receptors and chemoreceptors |
| Why is it important that pain receptors are tonic receptors? | Because the non-adapted signal allows you to not use something when in pain (which probably needs to heal) |
| What are phasic receptors? | receptors that adapt rapidly and function to convey information about changes in stimulus intensity |
| How do phasic receptors adapt? | After the initial depolarizing, the receptor response to a continued constant stimulus stops |
| What is the vertebrate eye covered with? | three layers of outer wall |
| What are the three layers of outer wall of the vertebrate eye? | tunic, uvea, retina |
| What is the fibrous layer of the vertebrate eye? | tunic |
| What is the vascular layer of the vertebrate eye? | uvea |
| What is the inner layer of hte vertebrate eye? | retina |
| What is the unic divided into? | the sclera and the cornea |
| True or False: the layers of the tunic have distinct embryological origins | true |
| What is the sclera made of? | white, fibrous connective tissue |
| Where is the sclera found? | posterior region of the eye |
| What is the sclera derived from? | mesoderm |
| What are the functions of the sclera? (4) | Gives the eye shape and protects inner part, withstands intraocular pressure, receives extrinsic eye muscle insertions, optic nerve enters |
| True or False: the cornea is transparent | true |
| What is the function of the cornea? | provides an interface between the environment and internal structures of the eye |
| What is the cornea deried from? | The ectoderm |
| What is the function of eye lids? | it protects the eye from dust and maintain a moist surface |
| What is the lacrimal gland? | source of fluid for the eye |
| What type of organisms are eyelids found? | terrestrial |
| What type of organisms are lacrimal glands found? | terrestrial |
| What is the function of eye lashes? | to trap dust |
| What types of organisms have eye lashes? | mammals |
| What is a nictitating membrane? | membrane found in reptiles that flicks laterally across the eye |
| What hapens whene light hits a medium perpendicular to the rays? | The rays will slow down, but they will stay in parallel |
| What happens if light hits an angulated surface? | some rays will reach the surface before others |
| What happens when an angulated surface has a different density than air? | The light that hits will slow down and bend perpendicular to angle of medium |
| What does the degree of bend in light rays depend on? | angulation of medium and refractive index of mediu |
| What is refractive index? | ratio of light velocity in a vacuum vs. light velocity in a given medium |
| True or false: velocity of light increases in any given medium | false, decreases |
| What does decrease in velocity of light depend on? | depends on the nature of medium and wave length of light |
| What is the cornea used for in terrestrial vertebrates? | light refraction |
| What is the lens used for in terrestrial vertebrates? | fine focusing |
| How is an aquatic environment different than air? | there is dissolved and suspended materials blocking light and limiting vision and light intensity decreases as depth increaese |
| True or false: in aquatic environments, wavelengths are equally absorbed | false, selectively, UV first and blue last |
| Why does the cornea have a minor role in light refraction in aquatic vertebrates? | because water and the cornea have similar refractive index |
| What is the shape of the cornea in aquatic organisms and why? | the cornea is flat to decrease resistance while swimming |
| What is the lens used for in aquatic organisms? | used to bend light |
| What is the shape of the lens in aquatic vertebrates? | large and spherical |
| What is the outer layer of the cornea made of? | epithelial cell that is continuous with the cells of the conjunctiva |
| What is the conjunctiva? | epithelial cell layer that covers the sclera |
| What is the function of the conjuctiva? | mediates immune response and mucous production |
| What is the Uvea? | the vascular middle layer of the eye |
| What are the three layers of the Uvea? | choroid layer, ciliary body, and iris |
| What is the choroid layer of the uvea? | vascular, pigmented layer that lines the interior surface of the sclera |
| What color is the choroid? | thin, dark brown |
| What is the function of the choroid layer in diurinal verterats? | absorbs light and prevents reflection back out of the eye |
| What is the function of the choroid layer of the uvea in nocturnal vertebrates? | improves light detection |
| What is the imporved light detection from teh choroid layer in nocturnal vertebrates called? | tapetum lucidum |
| Waht are the two general functions of the choroid layer? | light absorption and vascular supply to the retina |
| What is the ciliary body? | a vascular tunic that contains the ciliary muscle |
| What is the ciliary muscle involvedi n? | altering lens shape |
| What are the functions of the ciliary body? | vascular supply for the retina and contains ciliary muscle to alter shape of lens |
| Where is the iris located? | betweens the lengs and the cornea |
| What is the iris? | color of the eye |
| What is located at the center of the iris? | the pupil |
| What is the function of the pupil? | allows light to enter the eye |
| What is the function of the iris? | regulates the amount of light that enter the eye |
| How does the iris regulate the light entering they eye? | regulation of the circular andradial smooth muscle fibers |
| What do the radial and circular muscle fibers do? | regulate the pupillary operture of the eye |
| What are the radial muscle fibers controlled by? | sympathetic nervous system |
| What are teh NT associated with radial muscle fibers? | norepinephrine and epinephrine |
| What does contraction of radial muscle fibers do in the eye? | increase the aperture |
| What does contraction of the radial muscle fibers do? | enhance the light gathering capabilities of the eye |
| What are the circular muscle fibers controlled by? | parasympathetic Nervous system |
| What is the NT associated with circular muscle fibers? | Acetylcholine |
| What does contraciton of the circular muscle fibers do? | decreases the pupillary operture and limits light entry |
| What is the retina? | innermost layer of the eye |
| What are the two layers of the retina? | outer and inner layer |
| What is the outer layer of the retina? | pigmented and non-nervous |
| What is the inner layer of the retina? | contains 3 zones of neruons |
| Where are photorecepts found? | in the retina |
| What are the two types of photoreceptors? | rods and cones |
| What is the function of the outer segment of photoreceptors? | specialized for photo transduction |
| Where is the series of membranes located? | in the outer segment of photoreceptors |
| What is the set up for the series of membranes in photoreceptors? | either interconnecting or free floating discs (rods) |
| What are the two benefits of the folding of the series of membranes in photoreceptors? | increaes surface area |
| Where are photopigments found? | in the folding of the series of membranes of photoreceptors in the retina |
| Why does in increase in SA matter in the series of membranes in photoreceptors of the retina? | it increases the amount of membrane to house photopigments |
| What does in increase in photopigments do? | increases light trapping efficiency and increases light sensitivity |
| What is the protein called that is found in photopigments | opsin |
| What is the chromophobe in photopigments called? | retinene |
| What is retinene derived from? | vitamin A |
| True or false: opsin is the same accross all four pigments | false, it differs between the fours |
| What is the opsin in rods called? | rhodopsin |
| What is rhodopsin sensitive to? | light/dark |
| How many types of chone pigments are there? | 3 |
| What is the red range pigment? | erythrolabe |
| What is the green range pigment? | chlorolabe |
| What is the blue range pigment? | cyanolabe |
| What are the 4 neuronal layers? | bipolar neurons, amacrine cells, horizontal cells, and ganglina cells |
| What is the pathway of bipolar neurons? | vertical pathway |
| What is the function of the bipolar neurons? | transfer input from the photosensitive cells to ganglion cells |
| What is the pathway of amacrine cells? | horizontal pathways |
| What is the contact of amacrine cells? | other amacrine cells and bipolar cells |
| What is the function of amacrine cells? | excite or inhibit adjacent cells |
| What is the pathway of horizontal cells? | horizontal pathway |
| What is the contact for horizontal cells? | other horizontal cells or bipolar cells |
| What do ganglion cells receive? | net responses of neuronal pathways |
| What happens if ganglion cells are excited? | they gnerate and action potential to the CNS |
| What do te axons of ganglion cells form? | the optic nerve |
| What type of retinal cell that conveys information to the brain? | ganglion cells |
| What does light reach before the photoreceptors? | ganglion cells and bipolar cells |
| What is considered an extension of the brain? | retina |
| What is the optic disk? | region where the optic nerve exits the retina |
| What is another name for the optic disk? | blindspot |
| Why is the optic disk termed the blind sot? | because this region is devoid of rods and cones |
| What is the fovea? | region of the retina that is devoid of rods |
| What is the fovea highly packed with? | cones |
| True or False: blood vessels are displacedin the fovea | true |
| Why are blood vessels displaced in the fovea? | so that light can hit the cones directly |
| What is the region of highest visual acuity? | fovea |
| What do nocturnal animals have instead of a fovea? | visual streak |
| What does a visual streak contain? | cones and ganglion cells |
| What is a visual streak associated with? | visual acuity over horizons |
| Where is the lens found? | just behind the iris and pupil |
| What is the lens made of? | laers of transparent proteins |
| What is the lens held in place by? | suspensory ligaments |
| What are the suspensory ligaments called that hold the lens in place? | zonal fibers |
| What is the function of hte lens? | to refract and focus light on the retina |
| What is the point called where light rays converge? | focal point |
| What is the distance from lens to the focal point? | focal length |
| What is the focal length measured in? | dipoters/ meters |
| Waht does the lens separate? | the anterior and posterior cavities of the eye |
| What is the anterior chamber filled with? | aqueous humor |
| What is aqueous humor similar to? | CSF |
| What is the pathway of flow for aqueous humor? | through the camber and out through venous circulation |
| True or false: aqueous humor is continuously produced | true |
| What is the function of aqueous humor? | waste removal and aids in reducing intraocular pressure |
| What is the posterior chamber of the eye filled with? | vitreous humor |
| What is vitreous humor like? | jelly-like fluid |
| True or false: vitrious humor ins continuously produced | false |
| What is the function of vitrous humor? | maintain eye shape |
| What is myopia? | near sighted |
| Where is the focal pint in myopia? | anterior to retina |
| What is the fix for myopia? | concave lenses |
| What is hyperopia? | far sighted |
| Where is the focal point in hyperopia? | posterior to the retina |
| What is the fix for hyperopia? | convex lenses |
| What is presbyopia? | loss of lens elasticity with age |
| What is the fix for presbyopia? | bifocals |
| What is accomodation? | primary mechanism of focusing for fine image detection by altering the shape of lenses |
| What does accomodation occur in response to? | blurred vision |
| What controls accomodation in mammals? | smooth muscles |
| True or false: smooth muscle control makes accomodation slow in mammals | true |
| Why is accomodation faster in birds and reptiles? | they use striated muscles instead of smooth muscles |
| What is the lens shape when ciliary muscles are relaxed? | lens is flat |
| When is ciliary muscle reaction used? | distance vision |
| What is the lens shape when ciliary muscle is contracted? | curved |
| When is ciliary muscle contraction used? | near vision |
| What happens when the ciliary muscle contracts? | the ciliary body is moved forward the the zonal fibers relax allowing the lens to curve |
| What happens when the ciliary muscle is relaxed? | the ciliary body causes tension in the zonal fibers and the lens is flat |
| What is the primary refractory structure in aquatic vertebrates? | lens |
| What is focus in aquatic organisms dependent on? | lens position |
| What type of muscle is used in accommodation in aquatic verbrates | retractor muscle |
| What does the retractor muscle do in aquatic organisms? | the retractor muscle moves the lens forward and baackwards |
| Does contraction/relaxation of retractor muscle move the lens forward or backwards? | it depends on the species as to whether or not the contraction/relaxation moves the lens forward/backwards. |
| In aquatic organisms, where is the lens located in relation to the cornea? | they are located in close proximity |
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