264504
Description
Flashcards by alex.ostapchuk, updated more than 1 year ago
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Created by alex.ostapchuk
over 10 years ago
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| Question | Answer |
| What is the purpose of the affarent division of the PNS? | send internal and external info to the PNS |
| What are the 2 types of afferent information? | Visceral afferent and sensory afferent |
| What info is sent from visceral afferent divisions? Is is consciously percieved? | incoming info from body organs in cavities. Not consciously percieved. |
| What info is brought in by the sensory afferent division of the PNS? (2) | Somatic sensation: - bodily surfaces (proprioception) - special senses (eyes, ear) |
| What is perception? | Conscious interpretation of the external world from sensory input. |
| Why isn't perception always accurate? (3) | - humans have sensory receptors that detect limited #s of energy forms (e.g. can't detect infrared) - info channels in brains are not high-fidelity recorders (some input highlighted, some ignored) - Cerebral cortex further manipulates the data (creates logical perception based on previous experiences to extract significant features) |
| What causes optical illusions? | Visual perception is not always accurate. Illusions illustrate how the brain interprets reality. Previous schemas also aid in interpretation (e.g. S_x) |
| What are receptors? | Structures at peripheral nerve endings of afferent neurons OR Separate cells closely attached to peripheral nerve endings |
| How do receptors detect and conduct stimuli? | TRANSDUCTION: Convert heat, temperature, pressure, etc. into electrical signals to create action potentials to be sent to CNS |
| Name the 6 types of receptors and what they are responsible for.Give an example of each. | -Photoreceptors: lightwaves (eye) -Mechanoreceptors: pressure/movement (muscle stretch organs, ear hairs) - Osmoreceptors: detect changes in water level (found in kidney maybe?) - nocireceptors: pain signals - thermoreceptors: heat/cold (tactile in skin) |
| Name 4 types of receptors found beneath the skin. Are they found in the epidermis or the dermis layer? | ALL DERMIS LAYER: - vibration - light touch - pressure skin stretch |
| Why is sensory input from receptors useful? (4) | - afferent info needed to control efferent output - process of sensory info by reticular activating system in brain stem is critical for cortical arousal/consciousness - central processing of sensory info gives rise to our perceptions of the world - selected info may be stored for future reference (create schemas) - sensory stimuli impact emotions (smell of loved one) |
| Describe how the membrane permeability of a receptor changes when its stimulated by info. | - small ion channels open - Na+ rushes in - creates graded "receptor potential" -can be of varying magnitude/duration - if magnitude high enough, generates an action potential. |
| What does the magnitude of the receptor potential represent? | The intensity of the stimulus. The more intense, the more it will summate (since it's a graded potential), creating a higher frequency of action potentials firing. |
| Where are action potentials generated within a neuron for: - afferent N - interneuron efferent N | Afferent- peripheral end away from cell body Efferent and interneuron: axon hillock |
| What is adaptation? | Receptors diminish the extent of their depolarization despite sustained stimulus strength. Therefore, less action potentials are generated. So, the receptor "adapts" to the stimulus by no longer responding to the same degree. |
| What are the 2 types of receptors in accordance to their speed of adaptation? | Tonic Receptors: do not adapt at all/adapt slowly -> maintain information about a stimulus Phasic Receptors: adapt quickly -> adapts to stimulus (quick spike in receptor potential) then a slight spike during "off-response" when it depolarized a little when the stimulus is removed. Receptor signals change in stimulus intensity. |
| What is an example of a tonic and phasic receptor? | Tonic: muscle stretch receptors, joint proprioception, posture/balance Phasic: tactile receptors in skin (quickly become accustomed to what's on you). |
| What are somatosensory pathways? | Convey somatic sensation to the brain through afferent pathways in the spinal cord. |
| What's the difference between 1st, 2nd, 3rd order neurons? Where are they located? | 1st order- peripheral end is receptor that first detected stimulus 2nd order: found in spinal cord or medulla 3rd order: found in the thalamus |
| What is "phantom pain"? Why does it occur? | Activation of sensory pathways at any point that rises the same stimulation as produced when the receptors were there. As the brain remodels, signals from somewhere else can feel like they are coming from old limb. |
| What is acuity? What are the 2 factors that influence it? | Discriminative ability between sensations. Influenced by: - receptor size (number of receptors in a receptor field) - lateral inhibition (ability to distinguish localization and sharpness of a sensation) - best in vision and touch. |
| What is pain? What type of receptors are associated with pain? | Protective mechanism bringing conscious awareness that tissue damage is occurring. |
| What factors influence pain? (3) | Nocireceptors! -memories (to help prevent reoccurance) - subjective perception (it hurt last time) - subject to emotional and behavioural changes- lead by hypothalamus |
| What is the difference between acute and chronic pain? List 4 characteristics of each. | ACUTE: - fast - occurs from mechanical nocireceptors (damage) and thermal nocireceptors - myelinated A-delta fibers - produces sharp, prickling sensation - easily localized - occurs first CHRONIC -slow - polymodal receptors (detect all damage) - unmyelinated C-fibers - poorly localized - occurs 2nd |
| What are prostaglandins? What do they do? | When present, lower nocireceptor threshold for activation to enhance receptor response to stimuli- make you more aware of pain |
| What are the two pain neurotransmitters associated with the Afferent division of the PNS? | Substance P, Glutamate |
| What is Substance P, and what does it do? | Pain neurotransmitter- activates ascending pathways that transmit nociceptive signals to high levels for further processing (to cortex/reticular formation/thalamus) |
| What is glutamate, and what does it do? | Pain neurotransmitter- excitatory *, easier to synthesize |
| What is the analgesic system? What kind of proteins does it need in order to function? | Suppresses pain transmission pathways as they enter the spinal cord NEED endogenous receptors- for opiates to bind to receptors on the affarent pain fibre. (endorphins-running, enkephalins) -similar to morphine |
| Trace the pathway of pain perception from the noxious stimulus to the somatosensory cortex, without being stopped by analgesic pathways. | Noxious Stimulus Afferent pain fibre Synapse to spinal cord neuron Thalamus -> Somatosensory cortex (pain localization) & Reticular formation -> Hypothalamus (behavioural response/emotional) |
| Where does the analgesic pathway stop pain information? | From entering the spinal cord |
| Name the 4 protective mechanisms of the eye | -bony socket - eyelids -eyelashes (trap debris) -tears (continuous, lubricate, cleanse) |
| Name and describe the 3 tissue layers of the eye. | 1. Sclera- white part of eye Cornea- ant. transparent- let light thru 2. Choroid- middle layer, BV for retina ant: creates cillary body and iris (constricts to let light in) 3. Retina: outer pigmented layer, inner nervous-tissue layer. Contains Rods and Cones |
| What is refraction? | The bending of light when light strikes a surface of a new medium at an angle other than perpendicular. (Light slows down in a dense medium and changes shape) |
| What creates refraction within the eye? How? | LENS: greater curve, greater bending. Convex to converge light onto focal point. |
| What is on either side of the visual spectrum on the energy wavelength continuum? | Ultra Violet - Infrared |
| What is accommodation? What part of the eye does this? | The ability to adjust the shape of your lens of your eye to change the strength. Cilliary muscle + suspensory ligaments |
| How do cateracts happen? | If the lens of the eye gets aggregated (clouded) |
| How does light refract onto the retina in focus and out of focus? | Sharp- into focus on retina Blurred- 1 point appears as two (comes into focus in front or behind retina) |
| When is Emmentropia? | normal vision (all images focus on retina) |
| What is myopia? | Nearsighted- can see near (far source focuses in front of retina) eye too long/lens too strong |
| What is hyperopia? | Farsighted- can see far. (near source focuses behind retina) Eye too short, lens too weak. |
| What are the 3 layers of the RETINA? | - rods and cones (outermost)- at the back - bipolar cells (middle) - ganglion cells (inner) |
| Explain retinal visual processing and how it faces backward, from the time light passes into the retina until it reaches the optic nerve. | -Light goes to back of retina, (near choroid layer) - photoreceptors (rods, cones) detect different wavelengths of light - bipolar cells - ganglion cells -> fibres join to create Optic Nerve (leaves retina at OPTIC DISC -blind spot - no rods or cones here) |
| Why are eyes red after camera flash? | Reflection of BV in the back of the retina (choroid layer) |
| What is the Fovea? Where is it found? | Pinhead-sized depression in exact centre of retina. Point of most distinct vision (HAS ONLY CONES) - no other structures. |
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