Psio Block 5
Block 5.1
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5.2
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Identify (on a model, picture, or diagram) the list of terms related to the ear from Figure 24.13 in the lab manual as well as the structures discussed in PlayPosit Bulb 5.3a.
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(related to last question) Explain important physiological terms related to these tests
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List the steps associated with the transduction of sound stimuli
1. Sound wave arrives at tympanic membrane 2. Sound waves vibrate tympanic membrane 3. Vibration move auditory ossicles 4. (and 6.-9.) Stapes depresses oval window, generates pressure wave in cochlear ducts (vestibular & tympanic) 5. Pressure wave distorts basilar membrane (different regions by different wavelengths) 5. Vibration of basilar membrane excites overlying hair cells -produces receptor potentials
List and describe the events that result in the propagation of the action potential.
Going down the length of the axon, the action potential is propagated because more voltage-gated Na+ channels are opened as the depolarization spreads. ... The action potential must propagate toward the axon terminals; as a result, the polarity of the neuron is maintained, as mentioned above.
what are each sensory receptors (6) H (harry) M. (men) N. (never) M. (make) R. (red) P. (pasta)
Hair root plexus, Meissner's corpuscle, Nociceptor, Merkel disc, Ruffini's corpuscle, Pacinian corpuscle
What are the Importance of Refractory Periods
Importance of Refractory Periods 1.Establish maximum rate (frequency) of Action Potentials 2.Influence the characteristics of AP propagation -ensures forward propagation from axon hillock to axon termin
Describe how the activity of the Na+/K+ ATPase maintains these gradients.
In living cells, the sodium potassium ATPase pump (Na+/K+ ATPase) maintains the ion concentration gradients for Na+ and K For each ATP it uses, it pumps out 3 Na+ ions (+ + +) while at the same time pumping in 2 K+(++) ions
Describe how differences in ionic gradients across the membrane contribute to electrical gradients (i.e. electrochemical gradients).
The active transport of ions across the cell membrane causes an electrical gradient to build up across this membrane
Describe the basis of absolute and relative refractory periods and explain their importance.
There are two types of refractory periods; the absolute refractory period, which corresponds to depolarization and repolarization, and the relative refractory period, which corresponds to hyperpolarization.
Thermoreceptors
hot & cold (respond between temps that are 10-30 degrees Celsius)
Draw a picture showing the structure of a synapse
https://docs.google.com/document/d/1OeovRLuz8nyQaSd_I84vLrvuOGgoGzpdZEQYGgv0ojk/edit?usp=sharing
Ruffini endings
in the Demis, respond to stretch in the skin, intern aid appropriate position (awareness of the piston and movement in the body)
Pacinian corpuscle
respond to deep pressure and high frequency vibration located deep in the skin
Define the phrase 'all-or-none' in the context of the neuronal action potential.
(in the steps of action potential) once step 2 is reached, there is no turning back. Action potentials are "all-or-none" in that once you start them they are designed to travel all the way to the end of the axon
List and describe (in order) the physiological events associated with synaptic transmission.
1) Action potential arrives at the synaptic end bulb of a presynaptic neuron 2) The action potential opens voltage -gated calcium channels 3) Calcium entry into the synaptic end bulb triggers the fusion of neurotransmitter -containing vesicles (synaptic vesicles) with the pre-synaptic membrane 4)Neurotransmitter diffuses across the synaptic cleft where it will encounter neurotransmitter receptors (on ligand-gated ion channels) on the post-synaptic membrane 5) The binding of neurotransmitter to the receptors on ligand-gated ion channels will typically result in the movement of ions across the postsynaptic membrane, generating a graded potential 6 a) Depolarization of post-synaptic cells will result if the ion channels opened are for positive ions that enter cells (Na+) Resulting graded potential is an Excitatory Post -Synaptic Potential (EPSPs) b) Hyperpolarization of post -synaptic cells will result if the ion channels opened are for positive ions that exit cells (K+). Resulting graded potential is an Inhibitory Post-Synaptic Potential (IPSP) 7) Entry of enough positive ions (this is typically Na+)enter the post-synaptic cell, it will cause the initiation of an action potential i
List (and describe) in order the principal events associated with an action potential
1) First Resting or Baseline membrane potential 1) Local changes in the cell's membrane potential called graded potentials 2) At the axon hillock, depolarization to a "threshold' value will induce a population of voltage -gated Na+channels within that region of membrane to open. 3) Shortly after voltage-gated Na +channels open, They spontaneously close (inactivate) 4) Depolarization also opens (more slowly) a second population of channels: Voltage-gated K+ channels
Define graded potential
A change in the electrical potential on the membrane of an excitable cell (e.g. a nerve cell) in response to a stimulus, and where the magnitude of change is proportional to the strength of the stimulus
Describe the underlying issue that impairs vision
Common defects -Hyperopia and Myopia (consequences of the shape of the eye) Aka Farsighted & Near Sighted normal is called emmetropia
Define the terms depolarization, repolarization, and hyperpolarization
Depolarization: change in potential that makes the membrane less polarized than at resting potential Repolarization: The membrane returns to restingpotential after having been depolarized Hyperpolarization A change in potential that makes the membrane more polarized (more negative) than at resting potentia
describe the difference between EPSPs and IPSPs.
EPSPs (excitatory postsynaptic potential): -a voltage change approaches threshold making an AP more likely depolarization usually a result of opening a Na+ channel IPSPs: Inhibitory postsynaptic potential -voltage change away from threshold making an AP less likely hyperpolarization making it more negative usually a result of opening Cl- or K+ gates
Compare and contrast the characteristics of graded vs. action potentials.
Graded potentials are brought about by external stimuli (in sensory neurons) or by neurotransmitters released in synapses, where they cause graded potentials in the post-synaptic cell. Action potentials are triggered by membrane depolarization to threshold.
Describe the normal concentration gradients for Na+ and K+ that exist across the membrane of all cells
Ion gradients require a diff. in concentration on either side of the plasma membrane.
Nociceptor
Located in the epidermis, responds to pain (a type of thermo receptor for extreme temp)
Oligodendrocytes vs Schwann cells which is CNS & which is PNS
Oligodendrocytes are to CNS as Schwann cells are to PNS.
List and describe the structures that light must refract/pass through in order to be detected by the eye.
Optics of the Eye 1) Light rays arrive from an object 'focused' onto sensory surface of the eye: 'retina' 2) focusing involves 'bending' of light rays: refraction refraction occurs when light passes from one medium (e.g., air) into another (e.g., water)
How is loudness and pitch of sound are detected differently.
Pitch (frequency) and loudness (amplitude) Whereas loudness depends on the energy of thewave. In general, the pitch is the reason behind the difference in voice quality of different individuals. The pitch of a sound depends on the frequency while loudness of a sound depends on the amplitude of sound waves.
Describe presbyopia and the underlying issue that impairs vision
Presbyopia -As lens ages, it loses elasticity -even when tension on the suspensory ligaments is relieved, lens retains its elongated shape -Failure to 'round up' means the image of close-up objects cannot be focused on the retina -Loss of this ability to accommodate means the 'aged' eye can't focus on close-up objects AKA its It's time for reading glasses
Describe how receptive field size is related to sensory resolution/discrimination.
Receptive Field •Smaller receptive fields (increased density of receptors) permit high resolution/discrimination
Golgi tendon organs
Receptors sensitive to change in tension of the muscle and the rate of that change
Describe the principal differences between rods and cones
Rods detect intensity, black and white vision. only function in dim light. have a lower (sharpness) acuity. Cones, detect wave lengths, color vision, only function in bright light. require a higher light intensity, Cones have greater acuity (sharpness)
Explain the concept of ''appropriate stimulus' with respect to interpretation within the CNS of incoming sensory information. (aka Sensory Transduction steps)
Sensory Transduction steps 1) Stimulus arrives at receptor and alters membrane potential of receptor 2)The rate of EPSPs generation in the sensory neuron determines the rate of nerve impulse (AP) production in them 3) APs travel to CNS along a specific afferent pathway 4) CNS interprets/processes these incoming sign 5)Interpretation of afferent (sensory) input The brain 'assumes' that any signals coming in along a sensory afferent from a particular receptor (e.g., touch; photoreceptor) reflects stimulation by the appropriate stimulus (i.e.,pressure; photon)
how does spatial and temporal summation they contribute to neuron activation.
Spatial summation The closer a pre-synaptic neuron's influence is to the Trigger zone, the more influential that pre-synaptic neuron is over activation Temporal summation Increased frequency of action potentials arriving at synapses for one pre-synaptic neuron will cause increased influence
Deifne spatial and temporal summation
Spatial: Occurs when two or more graded potentials from different locations on the neuron's cell body or dendrites reach the trigger zone simultaneously Increase in number across the cell temporal So temporal summation is possible, and it is a strategy that increases a pre-synaptic neuron's influence on the post-synaptic neuron
Differentiate between general and special senses.
Special senses: have specialized sense organs and include vision (eyes), hearing (ears), balance (ears), taste (tongue), and smell (nasal passages). vs General senses: are all associated with touch and lack special sense organs
Describe the specific sensory events associated with olfaction and gustation (i.e. what cellular events happen when a molecule is detected).
Taste (Gustation) •Specialized sense organ is: tongue -Taste buds in papillae house sensory ability •Specialized sensory cell required? Yes: gustatory receptor cell -------- Taste (Gustation) • Types of receptors used: chemoreceptors (for tastants) •Three types of taste buds: 1. Vallate 2. Fungiform 3. filiform
Describe the relevant general sense tests
The general senses tested in the Standard neurological examination (NE) consist of touch, pain, temperature, position, vibration, and stereognosis. Unique receptors and unique central pathways mediate each of the special senses. receptors distributed throughout body (particularly on body surfaces, and not collected within specialized 'sense organs.
Compare and contrast 'continuous' and 'saltatory' conduction.
The key difference between Saltatory conduction is the propagation of action potential along myelinated axons while Continuous conduction is the propagation of action potential along unmyelinated axons also: (Saltatory carries impulses at a faster rate than continuous propagation.)
Predict what will happen to the membrane potential of a cell if the permeability of the membrane increases or decreases for Na+, K+, or Cl-.
The key point is that the increase in Na+, K+, or Cl- permeability would produce a greater depolarization, which will lead to an even greater number of Na+, K+, or Cl- channels opening and the membrane potential becoming even more depolarize
Describe the importance of myelination and the function of oligodendrocytes and Schwann cells.
The major function of oligodendrocytes and Schwann cells is the formation of myelin. Myelin allows for myelination of the axons, which then acts as an insulator of axonal segments and speeds up action potential
Describe the basic mechanism of hair cells and explain how this relates to the general process of sensory transduction
The outer hair cells mechanically amplify low-level sound that enters the cochlea. The inner hair cells transform the sound vibrations to electrical signals in the fluids of the cochlea. Sensory transduction is the process of converting that sensory signal to an electrical signal in the sensory neuron.
Describe the factors that influence the speed of propagation of the action potential.
The speed is affected by 3 factors: Temperature - The higher the temperature, the faster the speed. ... Axon diameter - The larger the diameter, the faster the speed. Myelin sheath - Only vertebrates have a myelin sheath surrounding their neurones
Describe the following special sense tests and explain how each assesses function of sensory systems: Visual Acuity Test (Snellen Eye Chart), Astigmatism Test Blind Spot Test Color Blindness Test Hearing (Tone) Test
Visual Acuity Test (Sentinel Eye Chart), - Vision - cover your eye with one hand and read the different sized letters off of a chart (the lower the denominator number is the better the vision ex 20/10) Astigmatism Test - Vision - caused by irregularities in the cavature of the cornea or lens (aka parts of an image are blurry) -a chart and it looks like a clock with 3 lines drawn out to each number. if one eye is covered and you still see darken lines your good, but if you see it less distinct or curvey you may have a stigmatism (of cornea or lends) Blind Spot Test - Vision - the very back of our eye the optic disc - (O.D) all of the axons of the photoreceptors of the retina start to merge together to form the Optic nerve - a lack of photoreceptors so we can't make out and image -focusing light on our blind spot - cross on left circle on right, then extend out infront, cover your let eye and bring images closer to your face. the circle will disappear Color Blindness Test - Vision - (red/green) a nascence of red/green cone that are found in the retina -inherited disorder (common in boys) -use plate of many circles one standard color and then another color mixed in to form a number. Hearing (Tone) Test - Hearing -humans can only hear tones with in a certain range -as we get older we decline in the ability to hear higher frequencies sensorineural hearing loss -loosing receptors that can recognizes those frequencies
hair root plexus
a collection of dendrites of neurons surrounding each hair follicle that are sensitive to touch (located on hair ball ) (respond when the hair follicles are moved)
what is a special sense
a sense that specifically have specialized organs smell, taste, hearing, equilibrium/balance, vision
Describe in general how the intensity or duration of a stimulus is coded and relayed to the nervous system
all other characteristics of the stimulus (e.g.,intensity, duration) are conveyed by the frequency and pattern of the incoming signal Intensity: Stimulus intensity is encoded in two ways: 1) frequency coding, where the firing rate of sensory neurons increases with increased intensity and 2) population coding, where the number of primary afferents responding increases (also called RECRUITMENT)
Merckel disc
also in the epidermis, deals with light touch and pressure (can be lost when we burned)
Describe the basic structure of a rod photoreceptor including the function of rhodopsin.
function of rhodopsin. visual purple, pigment in photoreceptor cells of the retina that is responsible for the first events in perception of light
Identify (on a model, picture, or diagram) and describe the structure/function of structures related to the eye:
https://quizlet.com/14182013/eye-parts-and-functions-flash-cards/
Meissner's corpuscle
in the dermis, responds to light tough & low frequency vibrations (bulb)
Compare and contrast the characteristics of leak-channels, voltage-gated, chemically-gated, and mechanically-gated channels.
leak-channels: -has no gate so ions can leak in and out, - found throughout the entire neuron in the plasma membrane, -potassium leaks out of the cell -sodium leaks into the cell voltage-gated: -types of voltage gated channels are Sodium and Potassium -open an close in response to membrane potential chemically-gated: -open with specific binding of a specific neurotransmitter mechanically-gated channels: -open and close in response to physical deformation of receptors
muscle spindles
receptors sensitive to change in length of the muscle and the rate of that change
Define equilibrium potential and explain how the equilibrium potential for different ions relates to the membrane potential.
the membrane potential that exactly opposes the concentration gradient of an ion Equilibrium potential. When electrical force (diffusion potential) increases to the point that it exactly balances or opposes the chemical force (tendency for ion to go down its concentration gradiant)
Describe the mechanism of accommodation
when image is focused on the retina change of lens shape called "accomodation" 1. The lens becomes more round. 2. The entering angle of the light increases 3. The light gets more refracted (bent), so the focused image now falls onto the retina.
Describe the physiology of vision -how light influences sodium channel activity, neurotransmitter release, and action potential generation
when light is detected, the integral membrane protein, rhodopsin 'retinal' -absorbs photon, which activates 'opsin' Na+ -channels in outer segment membrane (normally open) -opsin causes the breakdown of chemical messengers' that are required to keep the Na+channels open
