11

ReceptorsReceptors

22

Electrical signals produced by excitable cellsElectrical signals produced by excitable cells

Neurons, muscle fibersNeurons, muscle fibers

PotentialsPotentials ActionAction GradedGraded

ThresholdThreshold

33

Types of SynapsesTypes of Synapses

Excitatory and Inhibitory Post synaptic potentialsExcitatory and Inhibitory Post synaptic potentials

NeurotransmittersNeurotransmitters Neuromuscular junction-acetylcholineNeuromuscular junction-acetylcholine Biogenic Amines-epinepherine, norepinepherine, serotonin, dopamineBiogenic Amines-epinepherine, norepinepherine, serotonin, dopamine Amino AcidsAmino Acids Peptides-endorphins, substance PPeptides-endorphins, substance P

Electrical signals produced by excitable cellsElectrical signals produced by excitable cells

44

Sensation and PerceptionSensation and Perception

Sensory ModalitySensory Modality

55

Processing at the Receptor LevelProcessing at the Receptor Level---The process of sensation---The process of sensation

StimulationStimulation Transduction Transduction Generation of nerve impulseGeneration of nerve impulse IntegrationIntegration

66

Sensory input via receptorsSensory input via receptors

Types of receptors:Types of receptors:1. free nerve endings1. free nerve endings

Merkel diskMerkel disk Follicle receptorFollicle receptor Itch receptorItch receptor

2. encapsulated2. encapsulated Meissner’s corpuscleMeissner’s corpuscle PacinianPacinian RuffiniRuffini Golgi tendon organGolgi tendon organ Muscle spindlesMuscle spindles Kinesthetic receptorsKinesthetic receptors

77

Sensory input via receptorsSensory input via receptors

Types of receptors:Types of receptors:

3. 3. Separate cellsSeparate cells Hair cellsHair cells Gustatory receptorsGustatory receptors PhotoreceptorsPhotoreceptors

88

Types of ReceptorsTypes of Receptors

Stimulus:Stimulus: ThermoreceptorsThermoreceptors ChemoreceptorsChemoreceptors PhotoreceptorsPhotoreceptors MechanoreceptorsMechanoreceptors NociceptorsNociceptors

Location:

Exteroreceptors

Interoreceptors

Proprioreceptors

99

AdaptationAdaptation

Adaptation occurs when sensory receptors are subjected to an Adaptation occurs when sensory receptors are subjected to an unchanging stimulusunchanging stimulus

Exception: Nociceptors and Proprioceptors

1010

Checkpoint questions:Checkpoint questions:

12.25 How are graded potentials and the action potential threshold related?12.25 How are graded potentials and the action potential threshold related?

12.26 What is the all or none principle? Are graded potentials all-or-none?12.26 What is the all or none principle? Are graded potentials all-or-none?

12.36 Explain the effects of excitatory and inhibitory postsynaptic potentials on 12.36 Explain the effects of excitatory and inhibitory postsynaptic potentials on the postsynaptic neuron.the postsynaptic neuron.

15.2 Distinguish between general and special senses.15.2 Distinguish between general and special senses.

15.4 What four events must occur for a sensation to occur?15.4 What four events must occur for a sensation to occur?

15.5 What is transduction?15.5 What is transduction?

15.7 What is adaptation? How does it occur?15.7 What is adaptation? How does it occur?

15.10 Why do we need pain receptors? How are they activated?15.10 Why do we need pain receptors? How are they activated?

15.13 What is the function of joint kinesthetic receptors?15.13 What is the function of joint kinesthetic receptors?