Introduction to AHE II: Sensory Overview, Gustation, Olfaction PDF

Introduction to AHE II  Changes Liaison Open, optional, labs Identification manual Order of Content Block 1 Block 3 Heart Lymphatic System Respiratory System Digestive System Block 2 Block 4 Blood Vessels...

Introduction to AHE II  Changes Liaison Open, optional, labs Identification manual Order of Content Block 1 Block 3 Heart Lymphatic System Respiratory System Digestive System Block 2 Block 4 Blood Vessels Reproductive System Endocrine System Urinary System  Required Collaborative Activities and Optional Labs Required Collaborative Activity Dates Open Lab Opportunities – Must Sign- 1/21 Up- 10:30 – 12:30 2/18 1/23- Heart and Respiratory System 3/20 2/11- Head, Neck, and Upper Limb Vessels 4/15 2/18- Thorax, Abdomen, Pelvis, and Lower Limb Vessels 3/18- Digestive Tract Optional 3/25- Digestive Vessels and Accessory 1/21 @ 12:00 pm- Pig Heart Dissection- Organs Lecture Hall 2 4/15- Reproductive System 4/22- Urinary System  Heart and Respiratory System- Thoracic Cavity Blood Vessels and Endocrine Systems Lymphatic and Digestive Systems Reproductive and Urinary Systems  Sensory Overview, Gustation, Olfaction Course Learning Objectives Nervous: Describe how the body communicates with itself by identifying anatomical structures and tracing pathways of the nervous system in order to aid in medical diagnoses when these systems are compromised. Special Senses: Identify micro- and macroscopic structures involved in the special senses using virtual microscopy and 3-dimensional to link these processes to the larger nervous system.  Lecture Learning Objective 1. Review the structures and pathways of somatic and visceral sensory innervation 2. Define receptors type and transduction method 3. Link gustatory structures (papilla, tastebuds) to their role in the gustation pathway 4. Chart the gustation pathway 5. Identify listed structures on special senses histology slides 6. Describe olfaction including the role of olfactory epithelium, associated structures, and its pathway  LO 1 Somatic Sensation Somatic sensation travels from body in peripheral nerves → dorsal root ganglia → dorsal roots → spinal cord. Sensation from: Face- CN V Neck and posterior head- cervical plexus Upper limbs- brachial plexus Gray’s Basic Anatomy, Drake et al., 2018 Thorax and abdomen- spinal nerves (no plexuses) Lower limb- lumbar and sacral plexuses  Afferent Spinal Cord Pathways LO 1 Dorsal column → Fine touch, vibration (some proprioception) Spinothalamic → Crude touch, temperature and pain Spinocerebellar- Proprioception Somatic sensation is filtered by the thalamus→ Postcentral gyrus of parietal lobe The Ascending Tracts - DCML - Anterolateral - TeachMeAnatomy  Clinical Application: Phantom Pain Sensation, often pain, associated with body parts that have been removed (e.g., amputation) Sensory (afferent) pathway from the removed limb still remains alive and active Propagates nerve impulses reach the CNS Cortex interprets them as coming from missing limb Which sensory pathway would be associated with phantom pain the upper limb? From M Ortiz-Catalan et al: Phantom motor execution facilitated by machine learning and augmented reality as treatment for phantom limb pain: A single group, clinical trial in patients with chronic intractable phantom limb pain. Lancet 388:2885, 2016.)  LO 1 Visceral Sensation Most visceral sensation travels with parasympathetic fibers. Parasympathetic sensory innervation CN IX (carotid body) CN X (pharynx, larynx, thorax, and abdomen) Pelvic splanchnic nerve (pelvis). Most visceral pain travels with sympathetic fibers. Sympathetic sensory innervation enters the sympathetic trunk via splanchnic nerves Head- cervical arterial- Superior cervical ganglia Heart and lungs- cardiopulmonary splanchnic nerves- Superior cervical ganglia to-T5 Abdominal and pelvic viscera- Greater, lesser, least thoracic, lumbar, and sacral splanchnic nerves  LO 2 Sensory Receptors Structures that detect stimuli to monitor internal and external environment and vary in complexity Mechanoreceptors Respond to touch, pressure, vibration, and stretch Skin, inner ear Thermoreceptors Respond to changes in temperature Nociceptors Respond to internal and external pain stimuli Somatic- chemical, heat, or mechanical damage to skin or skeletal muscle Visceral- internal damage to organs due to excessive stretching of smooth muscle, oxygen deprivation to tissue, or chemicals released from damaged tissue  LO 2 Sensory Receptor Photoreceptors Only located in the eye Detect changes in light intensity, color, and movement Chemoreceptors Detects chemicals in internal and external environments Taste, oxygen and carbon dioxide in blood, interstitial fluid Baroreceptors Respond to changes in pressure within body structures Branched receptors in CT that detect deformation Carotid body Stomach  LO 2 Receptors Tonic: Continued exposure, sensitivity remains constant Strength of response Transducers- structures that transform the energy of one system into a different form of energy (e.g., heat into nerve impulse). Time All receptors act as transducers Stimulus Tonic receptors- continuous response to stimuli at a constant rate Phasic: Continued exposure, sensitivity diminishes Strength of response Phasic receptors- detect new stimuli or a change in stimulus that has already been applied; sensitivity decreases over time; can lead to adaptation Time Special Senses  Special sense- Gustation, Olfaction, Vision, Hearing and Equilibrium Gustation- taste Vision CN____ and ____ CN ____ Structures- Cerebral lobe: Cerebral lobe: Olfaction- smell Structures- Equilibrium and hearing CN____ CN ____ Cerebral lobe: Cerebral lobe: Other CNS structure? Gustation  LO 3 Special Sensory: Gustation (taste) Contact chemoreception Papillae- elevations of epithelia and CT on the dorsal side of tongue Gustatory cells- taste receptors housed in special sensory organs called taste buds located in papillae and tongue surface  LO 3 Special Sensory: Gustation (taste) Filiform papilla Located on anterior 2/3 of tongue Do not have taste buds, sensitive to touch Fungiform papilla Located on tips and sides of tongue Few taste buds Vallate papilla Posterior aspect of tongue along the sulcus terminalis Least numerous but largest and contain the most taste buds  LO 3 Taste Buds Not restricted to papillae, scattered elsewhere on tongue Comprised of numerous chemoreceptors called gustatory cells Gustatory cells have microvilli that project into taste pore Gustatory cells synapse with sensory axons  LO 4 Gustatory Pathway Anterior 2/3 of tongue CN VII (facial) Chorda tympani Posterior 1/3 of tongue CN IX (glossopharyngeal) Larynx CN X (vagus) From cranial nerves to: Solitary nucleus in medulla Thalamus Primary gustatory cortex in insula Taste requires integration of taste sensation with temperature, texture, and smell  LO 5 Histology: Gustation 1. Filiform papillae 2. Fungiform papillae 1 2  LO 5 1 Histology: Gustation 1. Vallate papillae 2. Taste buds 2  LO 5 Histology- Gustation a. Taste buds a b. Gustatory cells c. Supporting cells c d. Taste pore d b Olfaction  LO 6 Special Sense: Olfaction (smell) Remote chemoreceptor Afferent innervation travels via CN I (olfactory nerve) Olfactory epithelium Located in superior portion of nasal septum and walls of nasal cavity Contain receptor cells, supporting cells, and basal cells (function as stem cells and can undergo mitosis) Olfactory glands in underlying lamina propria produce constant flow of fluid Clinically Oriented Anatomy, Moore et al., 2018  LO 6 Olfactory Pathway Olfactory receptor cells/ neurons Modified bipolar neurons (primary neurons) Olfactory hairs project into olfactory epithelium and overlying mucous Detect airborne molecules dissolved into mucous Afferent information travels in olfactory receptor cells project through cribriform plate to synapse with fibers in olfactory bulbs (sensory ganglia) Junqueira's Basic Histology, Mescher (2018) Fibers travel from olfactory bulbs via olfactory tract (secondary neurons) to primary olfactory cortex in temporal lobe May then project to, Thalamus and frontal lobe Hypothalamus and limbic system Olfactory Histology LO 5