Part 2 Properties of the Receptors Adequate stimulus Transduction Adaptation Encoding
Part 2 Properties of the Receptors • Adequate Stimulus • Transduction • Adaptation • Encoding
1. Adequate(适宜) Stimulus The type of stimulus the receptor is highly sensitive Receptor specially designed for one kind of stimulus The lowest threshold Insensitive to other stimulation
1. Adequate (适宜) Stimulus • The type of stimulus the receptor is highly sensitive • Receptor: specially designed for one kind of stimulus – The lowest threshold – Insensitive to other stimulation
2. Transduction(换能) a process by which an environmental stimulus becomes encoded as a sequence of nerve impulses in an afferent nerve fiber Transduce sensory energy into neural(bioelectrical) energy Receptor potentials: Changes in the transmembrane potential of a receptor caused by the stimulus Generator Potential: A receptor potential that is strong enough(reaches threshold)to generate an action potential The stronger the sitmulus(above threshold ) the more APs are fired over a given time period translated by the cns as a strong sensation
2. Transduction (换能) – A process by which an environmental stimulus becomes encoded as a sequence of nerve impulses in an afferent nerve fiber • Transduce sensory energy into neural (bioelectrical) energy – Receptor potentials: Changes in the transmembrane potential of a receptor caused by the stimulus. – Generator Potential: A receptor potential that is strong enough (reaches threshold) to generate an action potential • The stronger the sitmulus (above threshold) the more APs are fired over a given time period; • translated by the CNS as a strong sensation
Receptor potential and generator Potential Action potentials +30 0 30 Receptor potential 后-60 Threshold 90 F- Resting membrane potential 0102030406080100120140 Milliseconds Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition Copyright 2011 by Saunders, an imprint of Elsevier, Inc. All rights reserved
Receptor Potential and Generator Potential
Action Receptor potential potential Deformed area +++++ ++++++++++++++ ++++ +++++ ++++|++++++++++ Node of Ranvier Hall: Guyton and Hall Textbook of Medical Physiology, 12th Edition Copyright o 2011 by Saunders, an imprint of Elsevier, Inc. All rights reserved