Sensory Physiology 10

Nociceptors Free nerve ending Respond to strong noxious stimulus that may damage tissue Modulated by local chemicals Substance P is secreted by primary sensory neurons Mediate inflammatory response Inflammatory pain

Nociceptors Pathways Reflexive protective response Integrated in spinal cord Withdrawal reflex Ascending pathway to cerebral cortex Becomes conscious sensation (pain or itch)

Somatosensory Nerve Fibers

Nociceptors: Pain and Itch Histamine activates C fibers causing itch Pain Subjective perception Fast pain Sharp and localized—by A fibers Slow pain More diffuse—by C fibers

The Gate-Control Theory of Pain Figure 10-12a

The Gate-Control Theory of Pain Figure 10-12b

The Gate-Control Theory of Pain Figure 10-12c

Pain: Referred Pain Figure 10-13b

Pain Ischemia Chronic pain is a pathological pain Analgesic drugs Lack of adequate blood flow Chronic pain is a pathological pain Analgesic drugs Aspirin Inhibits prostaglandins and slows transmission of pain to site of injury

Olfaction Link between smell, memory, and emotion Vomeronasal organ (VNO) in rodents Response to sex pheromones Olfactory cells Olfactory epithelium in nasal cavity Odorants bind to odorant receptors, G-protein-cAMP-linked membrane receptors

Anatomy Summary: The Olfactory System Figure 10-14a

Anatomy Summary: The Olfactory System Figure 10-14b

Anatomy Summary: The Olfactory System Figure 10-14c

Summary of Taste Transduction Figure 10-16

Summary of Taste Transduction Figure 10-16 (1 of 5)

Summary of Taste Transduction Figure 10-16 (2 of 5)

Summary of Taste Transduction Figure 10-16 (3 of 5)

Summary of Taste Transduction Figure 10-16 (4 of 5)

Summary of Taste Transduction Figure 10-16 (5 of 5)

Summary of Taste Transduction Humans and animals may develop specific hunger such as salt appetite Figure 10-16

Taste Buds Figure 10-15a–b

Anatomy Summary: The Ear The ear is a sense organ that is specialized for two functions: hearing and equilibrium Figure 10-17

Sound Waves Hearing is our perception of energy carried by sound waves Figure 10-18a

Sound Waves Figure 10-18b

Sound Transmission Through the Ear Figure 10-19 (1 of 6)

Sound Transmission Through the Ear Figure 10-19 (2 of 6)

Sound Transmission Through the Ear Figure 10-19 (3 of 6)

Sound Transmission Through the Ear Figure 10-19 (4 of 6)

Sound Transmission Through the Ear Figure 10-19 (5 of 6)

Sound Transmission Through the Ear Figure 10-19 (6 of 6)

Anatomy Summary: The Cochlea Figure 10-20 (1 of 2)

Anatomy Summary: The Cochlea Perilymph in vestibular and tympanic duct Similar to plasma Endolymph in cochlear duct Secreted by epithelial cells Similar to intracellular fluid

Anatomy Summary: The Cochlea Figure 10-20 (2 of 2)

Signal Transduction in Hair Cells The apical hair cell is modified into stereocilia Figure 10-21a

Sensory Coding for Pitch Figure 10-22a

Sensory Coding for Pitch Figure 10-22b

The Ear: Auditory Pathways Waves Electrical signals in cochlea Primary sensory neurons to brain in medulla oblongata Sound projected to nuclei Main pathway synapses in nuclei in midbrain and thalamus Auditory cortex