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60 Cards in this Set
- Front
- Back
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define: perception
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making sense out of something
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What is the function of sensory organs?
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• monitor the internal and external environment
• transmit signals from periphery to CNS for processing • critical for homeostasis |
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What do chemoreceptors respond to?
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changes in chemical concentration
• in the external environment (producing sensations of taste & smell) • in the internal environment (producing reflex responses to blood, CO₂, pH, and O₂) |
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What do thermoreceptors respond to?
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respond to temperature changes
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What do mechanoreceptors respond to?
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respond to mechanical energy (touch, pressure vibration)
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What do photoreceptors respond to?
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respond to light
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What do nociceptors respond to?
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respond to tissue damage (pain)
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define: tonic receptors
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• slow adapting
• maintain constant firing rate as long as stimulus is applied Examples: nociceptors & proprioceptors |
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define: phasic receptors
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• fast adapting
• firing rate of receptor (# of action potentials) decreases with constant stimulus Examples: olfaction, temperature, and touch |
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What are the four steps to sensation?
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1. stimulation
2. transduction 3. conduction 4. perception |
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What is the first step to sensation?
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Stimulation
• application of stimulus • must be strong enough to induce action potential in sensory neuron • sensors are most sensitive to one particular stimulus modality |
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What is the second step to sensation?
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Transduction
• induction of an action potential in a sensory neuron • stimulation of a sensor induces graded potentials in sensory neuron • generator neuron (receptor potentials) • If strong enough depolarization, an action potential occurs • If you increase the stimulus strength above threshold then you will increase the firing rate |
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What is the third step to sensation?
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Conduction
• relay information through a sensory pathway to a specific central nervous system region |
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What is the fourth step to sensation?
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Perception
• awareness of environmental change by CNS • evaluation of nature and magnitude of stimulus |
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What are the classifications of sensory input?
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1. somatesthetic senses
2. special senses |
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define: somatestheic senses
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• sensors located over wide areas of the body (skeletal muscle and skin)
• information is usually conducted to the spinal cord first (then possibly the brain) Example: touch, temperature and proprioception |
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define: special senses
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• changes detected only by specialized sense organs in the head
• information conducted directly to the brain Example: vision, hearing, smell & equilibrium |
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What are proprioceptors?
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• sensory receptors in muscles, tendons and joints
• detect stretching of muscles, limb movements, position of body parts, etc. Example: spindle fibers, Golgi tendon organ |
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What are cutaneous receptors?
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• sensory receptors present in the skin
• touch and pressure • heat and cold • pain |
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Receptors for heat, cold and pain are _____ of specialized neurons.
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simply naked dendrites
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Nociceptors are _____; when these neurons are activated by mechanical stimuli that damage cells, their axons convey _____.
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free sensory dendrites; sense of pain
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Hot temperatures can produce sensations of pain through the action of a _____ in the sensory dendrite
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particular membrane protein
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define: capsaicin receptor
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serves as both an ion channel and a receptor for the molecule capsaicin
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define: projection
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ability of the brain to know where the stimulus came from
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What is referred pain?
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it hurts in one place but it's not the location of the pain
Example: angina pectoris - pain in the left pectoral region and left arm produced by damage in the heart |
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What is phantom pain?
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brain misinterprets neuronal messages
Example: if your leg itches even if its not there • Advantage to phantom pain: when fitting for a prosthetic, you adjust to the prosthetic better |
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What is the cutaneous sensory structure for heat, cold and pain?
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free dendritic endings of sensory neurons
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What is the cutaneous sensory structure for touch?
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• dendrites wrapped around hair follicles
• expanded dendritic endings (Ruffini endings and Merkel's discs) |
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What is the cutaneous sensor structure for pressure?
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encapsulated ending (Meissner's corpuscle and Pacinian corpuscles)
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Pacinian corpuscles
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provide a sense of deep pressure
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Meissner's corpuscles
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provide cutaneous information related to changes in texture
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Pacinian corpuscles, Merkel discs, Meissner's corpuscles and Ruffini endings are associated with a ___.
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sensory (afferent) neuron
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Free nerve endings are ___.
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naked, dendritic branches that serve a variety of cutaneous sensations, including heat.
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What are the the special senses?
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1. taste
2. smell 3. equilibrium 4. hearing 5. vision |
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Receptors for taste and smell are classified as ___.
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exteroceptors
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Chemoreceptors that respond to molecules within the body are called ___.
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interoceptor
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For something to be tasted it has to be ____.
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dissolved in saliva
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Taste buds are ___ within barrel-shaped taste buds.
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modified epithelial cell
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What is gustation?
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detection of chemical concentrations in the oral cavity
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Taste cells
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(chemoreceptors)
• clustered into taste buds • contain microvilli that project to the external surface of the tongue • cells depolarize when stimulated and release neurotransmitter to associated sensory neurons |
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How is the taste sensation relayed for perception?
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Information is relayed (via cranial nerves VII and IX) to the inferior postcentral gyrus for perception
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What cranial nerve is innervated by the anterior 2/3 of the tongue?
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Cranial Nerve VII
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What cranial nerve is innervated by the posterior 1/3 of the tongue?
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Cranial Nerve IX
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What are the five different taste sensations?
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1. salty
2. sour 3. sweet 4. bitter 5. umami |
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How is salty determined?
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high Na⁺ concentration
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How is sour determined?
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high H⁺ concentration
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How is sweet determined?
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various organic molecules
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How is umami determined?
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glutamate (MSG)
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Different tastes are derived from activation of ___ within the cells.
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different signaling pathways
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How is saltiness and sourness determined?
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depolarization of taste cells driven by direct flow of Na⁺ or H⁺ into the cel through ion channels
• opens Na⁺ and H⁺ gates |
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How is sweetness, bitterness, and umami?
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binding of molecules in receptor proteins activates second messenger pathways leaning to depolarization
Example: cyclic AMP |
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True/False: Olfactory receptors can be regenerated from stem cells.
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True
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What is the cranial nerve that olfactory receptors combine to?
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Cranial nerve I
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Smells are airborne and dissolve in the ___.
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nasal mucosa
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What is olfaction?
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• detection of chemicals in vapor state
• olfactory receptors are bipolar neurons (dendrite extends into nasal epithelium and ends in a ciliated bulb • odorants bind to receptor proteins on cilia (activated G-protein/cAMP second messenger system & depolarizes olfactory receptor) • APs in olfactory receptor axons travel to the olfactory bulb • Synapse with associated neurons in glomeruli (each glomerulus receives signals from one type of receptor) • Information is relayed to olfactory cortex (temporal lobe) and limbic system |
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True/False: Olfactory receptors are unipolar neurons.
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False, they are bipolar
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Action potentials in olfactory receptor axons travel to the ___.
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olfactory bulb
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How is olfactory information relayed?
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Information is relayed to the olfactory cortex (temporal lobe) and limbic system
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How many different genes are there for olfactory?
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1000s for olfactory receptors (only ~300 functional proteins are produced)
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Where is the sense of smell directed to?
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the cerebral cortex
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