Receptor Potential Lab Exercise 3 Activity 2

Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 Assuming that the resting potential of a sensory neuron is -70 mV, which of the following represents a depolarization? You correctly answered: a change to -60 mV. 2 Which of the following is a sensory modality (type of sense)? You correctly answered: all of the above. 3 Which of the following is a sensory stimulus? You correctly answered: all of the above. 4 Which of the following is true of the response of a sensory neuron to the appropriate sensory stimulus? You correctly answered: Both of the above. Experiment Results Predict Questions 1 Predict Question 1: The adequate stimulus for a Pacinian corpuscle is pressure or vibration on the skin. Which of the following modalities will induce the largest amplitude receptor potential in the Pacinian corpuscle? Your answer: moderate-intensity pressure. 2 Predict Question 2: The adequate stimuli for olfactory receptors are chemicals, typically odorant molecules. Which of the following modalities will induce the largest amplitude receptor potential in the olfactory receptor? Your answer: moderate-intensity chemical. Stop & Think Questions PhysioEx Exercise 3 Activity 2 1 Why didn't the Pacinian corpuscle respond to high-intensity light? You correctly answered: Light-transducing proteins are not present in the Pacinian corpuscle. 2 Judging from these results, does light have a smell? You correctly answered: No. 3 Why did the free nerve ending respond to several different modalities? You correctly answered: The sensory end of this nerve is less specialized. Experiment Data Receptor Pacinian corpuscle Modality --- Intensity Resting Potential (mV) --- Peak Value of Response (mV) Amplitude of Response (mV) -70 0 -70 Pacinian corpuscle Pressure Pacinian corpuscle Pressure Moderate Pacinian corpuscle Pressure High Pacinian corpuscle Chemical Pacinian corpuscle Chemical Moderate Pacinian corpuscle Chemical High -70 -70 0 Pacinian corpuscle Heat Low -70 -70 0 Pacinian corpuscle Heat Moderate Pacinian corpuscle Heat High -70 -70 0 Pacinian corpuscle Light Low -70 -70 0 Pacinian corpuscle Light Moderate Pacinian corpuscle Light High -70 -70 0 Olfactory receptor --- --- -70 -70 0 Olf Low Low -70 -70 -60 -45 -70 -70 -70 -70 -70 10 25 -30 40 -70 -70 -70 -70 0 0 0 0 PhysioEx Exercise 3 Activity 2 Olfactory receptor Pressure Olfactory receptor Pressure Moderate Olfactory receptor Pressure High Olfactory receptor Chemical Olfactory receptor Chemical Moderate Olfactory receptor Chemical High -70 -45 25 Olfactory receptor Heat Low -70 -70 0 Olfactory receptor Heat Moderate Olfactory receptor Heat High -70 -70 0 Olfactory receptor Light Low -70 -70 0 Olfactory receptor Light Moderate Olfactory receptor Light High Free nerve ending --- Low Low -70 -70 -70 -70 -70 -70 -70 -70 0 0 -70 0 -64 -58 -70 --- -70 6 12 -70 -70 0 0 -70 -70 0 -70 0 Free nerve ending Pressure Free nerve ending Pressure Moderate Free nerve ending Pressure High Free nerve ending Chemical Free nerve ending Chemical Moderate Free nerve ending Chemical High -70 -70 0 Free nerve ending Heat Low -70 -60 10 Free nerve ending Heat Moderate Free nerve ending Heat High Low Low -70 -70 -70 -70 -70 -70 -70 -70 -70 -65 0 0 5 -70 -70 -40 -20 0 0 30 50 PhysioEx Exercise 3 Activity 2 Free nerve ending Light Free nerve ending Light Moderate Free nerve ending Light High Low -70 -70 -70 -70 -70 -70 Post-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 A very intense stimulus can sometimes stimulate sensory neurons that have evolved for a different modality. Thus, with a blow to the eye, one "sees stars." In this example the photoreceptors in the eye are responding to You correctly answered: intense pressure. 2 Olfactory receptor neurons respond to low concentrations of chemical odorants because there are membrane proteins in the receptor ending of this sensory neuron that You correctly answered: can bind and respond to the specific odorant. 3 The sequence of events starting with a sensory stimulus and ending with a change in membrane potential is called You correctly answered: sensory transduction. 4 Starting at a resting membrane potential of -70 mV, a change to which of the following represents the largest receptor potential? You correctly answered: a change to -50 mV. Review Sheet Results 1 Sensory neurons have a resting potential based on the efflux of potassium ions (as demonstrated in Activity 1). What passive channels are likely found in the membrane of the olfactory receptor, in the membrane of the Pacinian corpuscle, and in the membrane of the free nerve ending? Your answer: Potassium ligand ion gated channels will be found on the olfactory receptors, the membranes of the Pacinian corpuscles, and in the membrane of the free nerve endings. What is meant by the term graded potential? 0 0 0 Your answer: Graded potentials are changes in membrane potential that vary in size, as opposed to being all-or-none. 3 Identify which of the stimulus modalities induced the largest amplitude receptor potential in the Pacinian corpuscle. How well did the results compare with your prediction? Your answer: The moderate-intensity pressure modality causes a receptor potential in the pacinian corpuscle as predicted. There was not enough pressure in a low intensity environment and too much pressure in a high intensity environment. 4 Identify which of the stimulus modalities induced the largest amplitude receptor potential in the olfactory receptors. How well did the results compare with your prediction? Your answer: The moderate intensity chemical modality causes a receptor potential to occur in the olfactory receptors. 5 The olfactory receptor also contains a membrane protein that recognizes isoamylacetate and, via several other molecules, transduces the odor stimulus into a receptor potential. Does the Pacinian corpuscle likely have this isoamylacetate receptor protein? Does the free nerve ending likely have this isoamylacetate receptor protein? Your answer: Neither the Pacinian corpuscle or Free nerve ending proved to have either the isoamylacetate receptor protein because they did not show response to the odor stimulus applied to them. 6 What type of sensory neuron would likely respond to the green light? Your answer: Optic sensory neuron will respond to green light because they are the only one that have receptors for light that we tested.