Question 1

Learning Outcomes (for general perusal)

Accepted Answer

General principles of sensation Receptor types, coding, general properties Mechanoreceptors Chemoreceptors Thermoreceptors Nociceptors Describe nerve pathways involved in somatrosensory perception Explain the role of the somatosensory cortex in sensory processing Have an overview of common somatosensory defects

Question 2

What are sensory receptors?

Accepted Answer

Specialized cells providing CNS with info about world outside or inside our bodies Respond to several types of stimuli Stimuli converted to action potentials in the process of TRANSDUCTION that carry information to CNS CNS interprets this info as various sensations

Question 3

1. What is a 'somatic sense'? 2. What are the somatic senses? 3. What are the 'special senses?

Accepted Answer

1. General sensory mechanisms that collect information from all over body 2. •pain Temperature Touch Pressure Vibration proprioception 3. •Vision Hearing Smell Taste Equilibrium

Question 4

Describe the specificity and modality of the receptors

Accepted Answer

Receptors show high specificity to one type of stimulus Touch receptor very sensitive to pressure, relatively insensitive to chemical stimuli Action potentials in specific nerves always interpreted according to the receptor that nerve connected to (ie, modality) –photo stimulation of the retina gives visual sensation –stimulation of optic nerve with other stimuli (pressure, electrical) also gives visual sensation (will respond to other stimuli when strong enough)

Question 5

Receptor potential and sensory coding 1. When is an action potential generated? 2. When is the sensation percieved? 3. What happens as the receptor is stimulated? 4. What is the strength of a stimulus coded by?

Accepted Answer

1. If the stimulus and receptor potential is great enough for the amount of sodium ion entry to reach threshold for depolarization 2. when the stimulus is sufficient to cause a large enough receptor potential and threshold is exceeded. 3. As receptor stimulated, more action potentials propagated 4. an increase in the frequency of action potentials in the primary afferent nerve

Question 6

Mechanoreceptors 1. What type of membrane channels do they have? 2. What do they respond to? 3. Outline the 3 groups of Mechanoreceptors

Accepted Answer

1. All have stretch-sensitive membrane channels 2. Respond to distortion this membrane 3. Tactile receptors Proprioceptors - Muscle spindles, golgi tendon organs, joint receptors Baroreceptors - Carotid sinus, aortic arch

Question 7

Temperature Receptors 1. What are they? 2. What are they sensitive to? 3. Where are they, what do they do? 4. What underlying mechanism do these receptors rely upon?

Accepted Answer

1. Free nerve endings 2. either hot or cold 3. Hypothalamus - the major determinant of temperature regulation Dermis - also contribute to temperature regulation, and also provide temperature sensation Liver, Spine, Skeletal Muscle - provide smaller contributions to temperature sensation and thermoregulation 4. the activity of a specific set of sensory nerve membrane proteins, the transient receptor potential, TRP channels. Different TRP channels are active (produce receptor potentials) at different temperatures. For example, moderate cold sensation is caused by activation of the TRPM8 channel at temperatures increasingly below 27˚C, whereas for moderate warm sensation, by temperatures increasingly exceeding above 25˚C and 31˚C in TRPV3 and TRPV4 channels, respectively. Some of these channels may transduce noxious temperatures and are involved in pain perception as well (see later). The TRPM8 channel is also activated by menthol, thus dental products (tooth paste, creams, etc), gum, mints, shaving products, liniments, etc that contain menthol give a cool sensation.

Question 8

Chemoreceptors 1. Give examples 2. What do they do?

Accepted Answer

1. Carotid and aortic bodies monitor blood pH, CO2, O2 (involved in control of respiration and blood gasses ) Medulla oblongata surface monitors CSF pH and CO2 2. Elicit respiratory, cardiovascular and behavioural responses

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L10 Sensory Receptors Sensory Pathways and Peripheral Sensation Flashcards

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