1 Receptors

2 Electrical signals produced by excitable cells Neurons, muscle fibers Potentials Action Action Graded GradedThreshold

3 Types of Synapses Excitatory and Inhibitory Post synaptic potentials Neurotransmitters Neuromuscular junction-acetylcholine Neuromuscular junction-acetylcholine Biogenic Amines-epinepherine, norepinepherine, serotonin, dopamine Biogenic Amines-epinepherine, norepinepherine, serotonin, dopamine Amino Acids Amino Acids Peptides-endorphins, substance P Peptides-endorphins, substance P Electrical signals produced by excitable cells

4 Sensation and Perception Sensory Modality

5 Processing at the Receptor Level ---The process of sensation Stimulation Stimulation Transduction Transduction Generation of nerve impulse Generation of nerve impulse Integration Integration

6 Sensory input via receptors Types of receptors: 1. free nerve endings Merkel disk Merkel disk Follicle receptor Follicle receptor Itch receptor Itch receptor 2. encapsulated Meissner’s corpuscle Meissner’s corpuscle Pacinian Pacinian Ruffini Ruffini Golgi tendon organ Golgi tendon organ Muscle spindles Muscle spindles Kinesthetic receptors Kinesthetic receptors

7 Sensory input via receptors Types of receptors: 3. Separate cells  Hair cells  Gustatory receptors  Photoreceptors

8 Types of Receptors Stimulus:  Thermoreceptors  Chemoreceptors  Photoreceptors  Mechanoreceptors  Nociceptors Location:  Exteroreceptors  Interoreceptors  Proprioreceptors

9Adaptation Adaptation occurs when sensory receptors are subjected to an unchanging stimulus Exception: Nociceptors and Proprioceptors

10 Checkpoint questions: How are graded potentials and the action potential threshold related? What is the all or none principle? Are graded potentials all-or-none? Explain the effects of excitatory and inhibitory postsynaptic potentials on the postsynaptic neuron Distinguish between general and special senses What four events must occur for a sensation to occur? 15.5 What is transduction? 15.7 What is adaptation? How does it occur? Why do we need pain receptors? How are they activated? What is the function of joint kinesthetic receptors?