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Physio Exam 2
Week 4 Info
| Question | Answer |
|---|---|
| These are neurons that carry sensory signals toward CNS | Affrent neurons |
| These are neurons that carry motor signals away from CNS | Efferent neurons |
| Afferent neurons are present in... | Skin, eyes, ears, tongue, and nose |
| Efferent neurons are present in... | Muscles and glands |
| What do sensory receptors do? | Receive stimuli from the external or internal environment |
| What do neural pathways do? | Conduct info from the receptors to the brain or spinal cord |
| Smell goes to what part of the brain? | Ofactory cortex |
| Vision, hearing, taste, and equilibrium go to what part of the brain? | Thalamus |
| What is transduction? | Conversion of one form of energy into another |
| What are the 5 general types of sensory receptors? | -Photoreceptors -Mechanoreceptors -Thermoreceptors -Chemoreceptors -Nociceptors (pain) |
| What parts are associated with photoreceptors? | Rods and cones |
| What parts are associated with mechanoreceptors, nociceptors, and thermoreceptors? | Free nerve ending and meissner corpuscle |
| What parts are associated with chemoreceptors? | Smell and taste |
| What are transducers? | Devices that transform energy from one type to another |
| What is a receptor potential? | Where a sensory receptor transfers stimulus energy into electrical signals |
| The receptor potential is propagated... | Passively towards the neuron's trigger zone |
| What does affrent neuron firing frequency do? | Reflects the magnitude of the receptor potential which reflects the magnitude of stimulus |
| What is Primary sensory coding? | The conversion of stimuli into action potentials in the CNS and the AP frequencies |
| What are the 4 key questions in coding? | -What is it? -How strong is it? -How long is it? -Where is it? |
| What is Modality? | The specific form of energy of a stimulus (temp, sound, pressure, etc) |
| What is Receptor specificity? | Receptors are designed to respond best to specific modalities |
| Stimulus intensity is coded by the frequency of APs generated in the... | First order neuron |
| AP frequency is determined by the size of the... | Receptor potential that is generated |
| Stronger stimuli excite more receptors and afferents= | Recruitment of sensory units |
| What is Sensory adaptation? | Occurs when sensory receptors change their sensitivity to the stimulus |
| Adaptation involves a decrease in the size of the... | Receptor potential with a constant stimulus |
| What does Labelled line codes do? | Connect the peripheral receptor to the cortex via series of neuron |
| What is the 3rd order neurons? | Thalamus |
| What are 2nd order neurons? | Spinothalamic tract, dorsal column system, dorsal horn, dorsal ganglia, and brain stem |
| What are 1st order neurons? | Spinal cord and nerve terminals |
| All sensory signals are subject to extensive what at synapses? | Modification |
| What is Synesthesia? | Crossovers in the senses activity in one sensory modality, such as vision or hearing |
| What is Prosopagnosia? | Face blindness |
| Information at each stage of sensory signals along the pathway is modified by what kind of influences? | Top-down |
| What are motor neurons? | Nerve cells in the spinal cord that send their axons to innervate muscles |
| Where is Acetylcholine released? | In the neuromuscular junction |
| What are the final common pathways out of the CNS? | Motor neurons |
| All coordinated contractions of muscles, timing, duration, strength are throught what? | The motor neuron AP |
| What is a motor unit? | Made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals (Primary building block of all movements) |
| The contraction strength is determined by the what of motor units? | AP frequency and recruitment |
| What is Innervation ratio? | Number of fibers innervated by an axon |
| Do actions become more involuntary or voluntary as the actions are repeated? | Involuntary |
| What are Rhythmic motor patterns? | Starting and stopping are voluntary, sequence of stereotyped, repetitive movements. |
| Where are reflexes stored? | Spinal cord |
| Where are Rhythmic motor patterns stored? | Thalamus, basal ganglia, and cerebellum |
| Where are voluntary movements stored? | Cerebral cortex motor areas |
| What % of interneurons are spinal cord neurons? | 90% |
| What do interneurons do? | Can be inhibitory or excitatory and can function as switches to turn motor neurons on or off |
| What is a reflex arc? | Shortest route from a sensory neuron to an effector |
| What is the speed of monosynaptic reflex? | Fast |
| What is the speed of polysynaptic reflex? | Slow, more controlled |
| What does a spinal interneuron do? | Relays signals between (afferent) sensory neurons, and (efferent) motor neurons |
| What is Reciprocal innervation? | The activation of neurons to one muscle with the simultaneous inhibition of neurons to its antagonistic muscle |
| What is Proprioreception? | The collection of info about body movements and position |
| What are Muscle-spindle stretch receptors? | Mechanoreceptors monitoring muscle stretch |
| What are Golgi tendon organs? | In the fibrous tendons that connect muscles to bone monitoring muscle tension |
| Tension straigtens the collagen bundles and... | Distorts the recpetor endings, activating them and induce receptor potential and APs |
| Golgi tendon reflex | -Tendon receptors monitor tension -Prevents muscle damage -Override stretch reflex |
| The brainstem pathways start from brainstem, but do not cross... | Midline |
| Relative sizes of body structures are proportional to the number of... | Neurons dedicated to their motor control |
| What is a Motor program? | For a particular class of actions is stored in memory and that a unique pattern of activity will result whenever the program is executed. |
| Reflex Circuits are important in... | Refining ongoing movements |
| If a complex movement is repeated, learning takes place and the movement becomes... | Skilled (improved program) |
| Voluntary movement circuitry is decided by... | Prefrontal cortex |
| Voluntary movement circuitry is selected by... | Premotor cortex |
| Voluntary movement circuitry is executed by... | Motor area of cerebral cortex |
| The selecttion of desired movements and suppression of unwanted movements involves... | Basal nuclei circuits that inhibit thalamic projections to motor cortex |
| What corrects errors in ongoing movements via exciting thalamic projections to the motor cortes? | Cerebellum |
| The subcortical nuclei include the paired... | Basal nuclei/basal ganglia |
| What treats Parkinson's? | L-Dopa |
| What caused Parkinson's? | Loss of dopaminergic neurons in substantial nigra, basal ganglia cannot send signals to the motor cortex. |
| What % is how much we learn through our eyes? | 80% |
| What is the visual signal? | Light |
| What is Visual perception? | Ability to detect light and interpret it |
| What is Visual transduction? | Light converted into electrical signals in the rod and cone cells of the retina |
| What is Wavelength? | Distance between successive peaks of EM radiation |
| What stimulates the receptors of the eye? | Wavelength |
| What is Reflection? | Light waves strike and bounce off surfaces that we see |
| What is Refraction? | Light waves bend as they pass through transparent materials of different densities |
| What is the Iris? | Muscle that controls the size of the pupil and amount of light that enters the eye |
| What is the Retina? | Layer of tissue containing the photoreceptors |
| What is the Optic nerve? | Axons of ganglion neuons in the retina that carry visual info to the brain |
| What is Foveal centralis? | Center of Macula Lutea and packed with cones |
| What regulates the diameter of the pupil? | Iris |
| In weak light, what muscle contracts when stimulated by parasympathetic nerves? | Radially arranged |
| In strong light, what muscle contracts when stimulated by sympathetic nerves? | Circular muscle fibers |
| What 2 parts of the eye have convex surfaces to focus light rays onto the retina? | Cornea and lens |
| What is the basis for light focusing on the retina? | Refraction |
| How is Visual information that reaches the retina arranged? | Reversed right to left and upside down |
| What is Accommodation? | refers to normal ability of lens to adjust its curvature to view near or far objects |
| Light rays that enter the eye from distant objects are... | Nearly parallel and require little bending or refraction to focus on the retina |
| Light rays from close objects are... | Diverging as they enter the eye and require more refraction |
| What determines the shape of the crystalline lens and thus the focus of light? | Activity of the ciliary muscle and resulting tension on the zonular fibers |
| What do Zonular fibers do? | Exert a tension on the lens that causes it to flatten and have a lesser curvature for distant objects |
| What do Ciliary muscles do? | When viewing close objects, they contract releasing the tension of the lens |
| Because of the elasticity of the fibers in the lens, the lens... | Rounds up and the curvature and refractive power increases |
| What determines the point where light rays converge? | Cornea, lens shape, and eyeball length. Only lens shape can be adjusted |
| What is Near-sightedness? | Eyeball too long, can only see near. Correction: Concave lenses |
| What is Far-sightedness? | Eyeball too short, can only see far. Correction: Convex lenses (Presbyopia) |
| What are the 3 layers of the retina? | Outer- Photoreceptors and pigmented epithelium Middle- Bipolar cells Inner- Ganglion celss |
| What is Fovea Centrais (Depression)? | In the center of the macula containing with highest density of cones for visual activity |
| What is Macuala Lutea (Yellow-spot)? | Area with high concentration of cones |
| Where does the concentration of cones decrease? | Toward periphery where there are more rods |
| What is the Blind spot? | Optic nerve |
| What is the Direct pathway in the retina? | Photoreceptors-->Bipolar cells-->Ganglion neurons |
| What are the 2 types of photoreceptors? | Rods and cones |
| What is the Outer segment? | Has membranous discs or folds with photopigments which absorb light |
| What is the Inner segment? | Basic cell machinery |
| What neurotransmitter does vision use? | Glutamate |
| What photoreceptors are specialized for dim light (night vision)? Have more photo pigment? | Rods |
| What photoreceptors are specialized for day vision? Have less photo pigment? | Cones |
| If dark rhodopsin is inactive, cGMP is high and ion channels are... | Open |
| Light bleaches... | Rhodopsin |
| If Opsin decreases cGMP Na+ channels... | Close and cell is hyperpolarized |
| What results in reduction of neurotransmitter release in proportion to the light intensity? | Hyperpolarization |
| What are Monocular zones? | Area viewed by only one eye |
| What are Binocular zones? | The overlapping area visible by both eyes |
| The optic nerves from 2 eyes form the... | Optic chiasm where some of the axons cross to the opposited side of the brain |
| Axons synapse on second order neurons and prokect to... | Primary visual cortex |
| What is it called when some ganglion cells carry visual info from info to suprachiasmatic nucleus? | Biological clock |
| Where is visual infor sent to when it is used in the coordination of eye and head movements, fixation of gaze, change in pupil size, maintaining posture, etc? | Brainstem and cerebellum |
| What exist as variations of pressure in a medium such as air? | Sound waves |
| What is Amplitude of sound wave? | Maximum pressure difference between zones of compression and refraction |
| What is Loudness of sound directly related to? | Amplitude |
| What is the pitch of a sound related to? | Frequency |
| What are the units of Sound pressure level? | Decibel |
| >100dB causes... | Damage |
| >120dB causes... | Pain |
| How is Frequency measured? | Cycles per second/Hz |
| What is the frequency range for human ear? | 20Hz-20,000Hz |
| What is Infrasound? | Frequency below human audible range |
| What is Ultrasound? | Frequency greater than the human audible range |
| Where do sound waves enter? | Through external auditory canal |
| What is the Middle ear cavity? | Air-filled space between eardrum and inner ear cochlea |
| What is the Auditory tube (Eustachian)? | Between middle ear and pharynx maintains pressure in middle ear at equilibrium with pressure outside |
| What are Ossicles? | A chain of small bones(malleus, incus, and stapes) that transmit sound energy to membrane over oval window at the entrance to cochlea |
| How much is Sound amplified during transmission across middle? | 15-20x |
| What is the Cochlea? | A spiral-shaped, fluid-filled space in the temporal bone |
| What are the 3 chambers of the cochlea? | -Scala vestibuli -Cochlea duct -Scala tympani |
| Where are hair cells located? | Organ of Corti |
| What do hair cells have on apical surface? | Hairlike stereocilia |
| Where to Stereocilia of outer hair cells attach to? | The overhanging tectorial membrane, but inner hair cells do not |
| What neurotransmitter is used in hearing? | Glutamate |
| When stereocilia bends in direction of the tallest stereocilium, channels... | Open and cell depolarizes, releasing glutamate |
| When stereocilia bends in the direction of the shortest stereocilium, channels... | Close, and cell hyperpolarizes, stopping release of glutamate |
| What does the Basilar membrane vibration produce? | Bursts of release of glutamate by hair cells' APs |
| Region of maximum vibration of the basilar membrane varies with... | Sound frequency |
| Is sound frequency related to AP frequency? | No |
| How is the vestibulocochlear nerve arranged? | The axons of the afferent neurons join to form the cochlear branch |
| What is used to determine the direction of the sound source? | The different arrival times and different intensities of inputs from the two ears |
| Describe neural pathways in hearing | Cochlear nerve fibers enter brainstem, thalamus, then the auditory cortex |
| What does the Vestibular apparatus consist of? | 3 Membranous semicircular canals oriented in 3 nearly perpendiculat planes AND 2 saclike swellings (otolith organs), the utricle and saccule |
| What is the Ampula? | A slight buldge in the wall of each semicircular canal |
| Receptor cells contain stereocilia that are incapsulated with in a gelatinous mass, the... | Cupula |
| What does bending the Stereocilia do? | -Increase/decrease of a neurotransmitter release from resting state -Increase/decrease of AP frequencies -Directions of rotation and acceleration |
| What do the semicircular canals detect along 3 perpendicular axes? | Angular acceleration |
| What do the utricle and saccule detect? | Linear acceleration and head orientation |
| What are the tiny stones in the gelatinous fluid? | Otoliths |
| What is Vestibulo-oculart reflex (VOR)? | Controls the eye muscles to stabilize images on the retina during head movement |
| How is info relayed to nuclei within the brainstem? | Via vestibulocochlear nerve |
| Where are the vestibular centers located? | Parietal lobe |
| What do vestibular afferents that go directly to the cerebellum do? | Coordinates the movements that maintain balance |
| What does vestibular info integrated from eyes, joints, skin, tendons, muscles, and skin do? | Helps with sense of posture (proprioception) and movement |
| What can a mismatch of info from various sensory systems cause? | Nausea and dizziness |
| What is Conductive hearing loss? | Hearing loss caused by problems with transmission of sound info across the middle ear to the cochlea |
| What is Senorineural hearing loss? | Hearing loss because of damage to the nerve |
| What is Presbycusis hearing loss? | Age-related loss of hearing especially of higher frequencies |
| What is Tinnitus? | Ringing in ears that often accompanies hearing loss |
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