DOC PREVIEW
UWL BIO 312 - Special senses: vision and hearing

This preview shows page 1 out of 2 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 2 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 2 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Lecture 17 Lecture Outline:1) Visiona) Photoreceptionb) Color blindness2) Hearinga) Anatomyb) Physiology3) Autonomic Nervous systema) Classificationb) Basic conceptsc) Sympathetic nervous systemVision:- Photoreception: rods and cones contain light sensitive visual pigments that breakdown when they absorb lighto Retinal molecules absorb light with various types of proteins called opsinso Rhodopsin: only light sensitive pigments found in rods (Rhodopsin  opsin + retinal- In the dark:o Gated channels open, allowing cation influx; the rod depolarizeso Voltage gated Ca2+ channels open in synaptic terminalso Inhibitory neurotransmitter is releasedo Neurotransmitter causes IPSPs in bipolar cell; hyperpolarization occurso Hyperpolarization closes calcium channels stopping neurotransmitter- In the light:o Gated cation channels close so cation influx stops; photoreceptors hyperpolarizeo Voltage gated calcium channels close in synaptic terminalso No inhibitory neurotransmitter is releasedo Lack of IPSPs in bipolar cell results in depolarizationo Depolarization opens voltage gated calcium channels; excitatory neurotransmitter is releasedo EPSPs occur in ganglion cello At threshold action potentials propagate along the optic nerve- In bright light conditions all the rhodopsin gets consumed so the rods shut down and the cones take over (light adaptation)- When going from bright light to dark conditions, cones are no longer effective. It takes a while for rhodopsin in rods to regenerate. As it does, you can start to see more in the darko Dark reaction: Opsin + retinal  rhodopsin- Color blindness: inherited condition resulting in lack of one or more cone typeso Most common is red-green color blindness (red and green appear as same color)o Achromatopsia: total lack of cones, goes blind in bright light- Visual pathway: optic nerve  optic chiasma  optic tract  lateral geniculate body  occipital lobe  superior colliculus- Hearing: o Tensor tympani muscles: tense up during high amplitude sounds to protect middle earBio 312o Pharyngotympanic tube: used to equilibrate pressures between outer and middle earo Vestibule/Semicircular canals: used for balanceo Properties of sound: pressure disturbances originating from a vibrating object and transmitted by some mediumo Frequency: how many sound waves produced per second, determines pitch Normal human hearing ranges from 20-20,000 hzo Amplitude: determines loudness or intensity Pressure difference between compressed and decompressed areas, measured in decibelso Sound Pathway: Sound waves strike and vibrate tympanic membrane Auditory ossicles move acting like a piston against the oval window Pressure waves created by the stapes move through the cochlear duct- Different frequency sound waves vibrate the basilar membrane in different areas allowingfor differentiation of sound Displacement of basilar membrane by pressure waves causes hairs on hair cells to bend and generate receptor potentials Action potentials travel through vestibulocochlear to cochlear nucleus  inferior colliculus medial geniculate nucleus (thalamus)  auditory cortexo Deafness: loss of hearing Conduction deafness: interference with conduction of vibrations to fluid of inner ear- Ear wax, ruptured eardrum, middle ear infection, otosclerosis (ossicles fuse) Sensorineural deafness: damage to any neural structure in auditory pathwayAutonomic Nervous System: don’t ever forget any of this- Efferent division controls hear, smooth muscles, glands- Exerts major influence over most organ systems- sometimes called visceral or involuntary nervous system- Involved in regulation of most internal activitieso Heart rate, strength of heart beat, stroke volume, cardiac output, blood pressure, body temperature- Many autonomic effector cells have inherent activity: meaning that they do not need stimulation to continue activity- ANS exerts a modulating effect over effector organ’s baseline activity (increase or decrease)- ANS is the efferent pathway of many physiological control systems involved in homeostasis- Most organs receive innervation from both sympathetic and parasympathetic divisions of ANSo Sympathetic and parasympathetic are both excitatory or inhibitory in different organso Work inversely to each other, one goes up, other goes down- Sympathetic Nervous system: Most active during times of physical, emotional and/or psychological stresso Prepares the body for intense physical activity that might be required to increase survival chances Fight or flight response: increased heart rate, stroke volume, cardiac output, free fatty acid mobilization (more usable energy), hepatic glucose release, pupil and airway dilation- Parasympathetic Nervous system: most active during quiet, relaxed, non-threatening conditionso Stimulates digestiono Slows down everything that the sympathetic ns speeds


View Full Document

UWL BIO 312 - Special senses: vision and hearing

Download Special senses: vision and hearing
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Special senses: vision and hearing and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Special senses: vision and hearing 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?