Physiology 206 Lecture 8 Outline of Last Lecture I. HypothalamusII. Cerebral cortexIII. MemoryIV. CerebellumV. Brain stemVI. Spinal cordVII. Peripheral nervous systemOutline of Current Lecture I. Sensory receptorsII. PainIII. Sympathetic and Parasympathetic NSIV. Ganglions, ganglionic cellsCurrent Lecture1/31/14- Receptors respond to different stimuli- When a receptor that is attached to a neuron (but is not a neuron itself) is stimulated it undergoes a change in potential = receptor potential o i.e. touch receptor- generator potential- receptor is a specialized neurono i.e. pain receptorThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- When you stimulate a sensory receptor, it becomes leaky to sodium, the membrane potential is less negativeo If it’s significantly leaky, it fires an action potential- Label-line codedo Sensory information is going to the brain is labeled to correspond to different parts of the body- Referred paino You perceive pain in a different part of the body than where it actually is Ex: heart attack: feel pain in left arm Pain pathways for the heart and the left arm are the same Ex: appendicitis: feel pain in the surface of the abdomen- Sensory amplitude: can tell the difference between strong and weak signalso Frequency coding: strength of stimulus increases = frequency of action potential increases Ex: bright light and dim lighto Population coding: as stimulus intensity increases, the number of neurons that fire increases- Adaptation: If you continue to stimulate a stimulus for a long time at the same intensity, the stimulus stops respondingo Usually occurs 30sec-1minute- Phasic receptors: change in stimulus strength results in rapid stimulation increase (big increase inactivity), and then it fades back to normal (rapid decrease)- Tonic response: responses continue to be elicited even if the stimulus continueso Ex: joints in body- Receptive fieldo Area over which a stimulus can be detected o Ex: touch receptive fields differ over body (small in finger, large in back)- Acuity: ability to discriminate between several (2) stimuli that are very close togethero High acuity: able to discriminate, small receptive fieldo Low acuity: not able to discriminate, large receptive field- Paino Pain receptors: nociceptorso A-Delta fiber: 1st flash of brief, intense, localized pain Fast, fiber pain Naked nerve endingso C-fiber: non-adaptive, throbbing pain Slow, second pain Naked nerve endings- Perception of paino Analgesia: not feeling paino Endorphins-similar effects to morphine Endogenous to brain Leave you insensitive to pain when released Released by drugs, running, etc.o Battlefield analgesia: in combat, participants can receive injuries and not realize it till later Athletes (contact sports) experience this as well- Nervous systemo Autonomic (sympathetic and parasympathetic) and somatico Efferent branch: Sympathetic (arousal) Fight or flight- In response to perceived threat/danger/stress- Heart rate, breathing, vision increaseo Parasympathetic Vegetative state- Become sleepy, blood flow to muscles decrease- Sympathetico Ganglion: bundle of cell bodieso Pre-ganglionic cell: originates in CNS, sends impulse to ganglion, shorto Post-ganglionic cell: synapses with pre-ganglionic cell, longo Spinal trunk ganglia: sympathetic, short- Parasympathetico Pre-ganglionic fibers: long, brain -> organo Post-ganglionic fibers: short, reach from the target cell to the organ
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