W5D3H3: Sensory Receptors Note W5D3H4 is also in this note set, starting on slide 30. There is a GRAT group activity in between.

Learning Objectives  1. Outline properties of sensory receptors including how intensity (strength) and duration are encoded and adaptation to stimulus.     2. Discuss the importance of the frequency of action potentials and its relationship to neurotransmitter release and stimulus coding.  3. Give examples of how sensory receptor properties are utilized by cutaneous receptors to detect and encode input. 4. Compare and contrast sensory receptor physiology (photoreceptors, olfactory receptors, gustatory receptors and hair cells). Note W5D3H4 is also in this note set, starting on slide 30. There is a GRAT group activity in between.

Learning Objective 4 (continued) Vision

Learning Objective 4 (continued) Hearing

W5D3H4: Pain and Reflexes Note W5D3H4 is also in this note set, starting on slide 30. There is a GRAT group activity in between.

Learning Objectives 1. Describe pain sensory pathways and relevant molecules involved in nociception. 2. Outline spinal reflex circuits, including those activated in the presence of a painful stimulus. 3. Describe the clinical use of reflexes as assays of motor neuron function and relate changes in pain and somatic detection to diabetic neuropathies.

LO 1. Overview of pain response to mechanical injury: Release of protease -> Bradykinin production -> activation of free nerve endings-> action potential propagated to spinal cord & axonal branches-> nociceptor axons release substance P and CGRP -> histamine release -> vasodilation and increased pain sensation. Consider drawing this out or asking students to draw it out. Some of the main components of the 'inflammatory soup' are shown, including peptides (bradykinin), lipids (prostaglandins), neurotransmitters (serotonin (5-HT) and ATP) and neurotrophins (NGF). Each of these factors sensitize (lower the threshold) or excite the terminals of the nociceptor by interacting with cell-surface receptors expressed by these neurons. Examples of these factors and representative molecular targets are indicated in the box. Activation of the nociceptor not only transmits afferent messages to the spinal cord dorsal horn (and from there to the brain), but also initiates the process of neurogenic inflammation. This is an efferent function of the nociceptor whereby release of neurotransmitters, notably substance P and calcitonin gene related peptide (CGRP), from the peripheral terminal induces vasodilation and plasma extravasation (leakage of proteins and fluid from postcapillary venules), as well as activation of many non-neuronal cells, including mast cells and neutrophils. These cells in turn contribute additional elements to the inflammatory soup. Kininogen: Made in liver, endothelial cells, platelets, and neutrophil. Involved in inflammation and coagulation.