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Master’s Degree in Veterinary Medicine Maria João Soares www.egasmoniz.com/pt 8th February 2024  www.egasmoniz.com/pt...

Master’s Degree in Veterinary Medicine Maria João Soares www.egasmoniz.com/pt 8th February 2024  www.egasmoniz.com/pt Summary This presentation is for educational purposes only - Understand the components of the sensory system - Know the different types of receptors related to the Sense of touch, Proprioception and Enteroception - Revision of the gustatory organs - Revision of the olfactory organs - References Master’s Degree in Veterinary Medicine - König, HE, Liebich, HG. (2014).Veterinary Anatomy of Domestic Mammals:Textbook and Color Atlas (6th ed.). Stuttgart: Schattauer. - Evans, HE, Miller, ME (2013).Miller's Anatomy of the Dog(4th ed.). St. Louis, Missouri: Elsevier. Dyce, KM - (2010).Textbook of veterinary anatomy (4)thed.). St. Louis, Missouri: Elsevier. Thomson, C., Hahn, C. (2012). - Veterinary Neuroanatomy. A clinical approach. St. Louis, Missouri: Elsevier. - de Lahunta, G. (2009).Veterinary neuroanatomy and clinical neurology (3th ed.). St. Louis, Missouri: Elsevier. - Lorenz, MD, Coates, JR, Kent, M. (2011). Handbook of veterinary neurology. St. Louis, Missouri: Elsevier. Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt - Components: This presentation is for educational purposes only - Receptor organs - Neural transmission pathways - Processing centers (grey matter of the brain) Master’s Degree in Veterinary Medicine - Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt - Structures that are able to detect specific changes like changes in the pressure, light, sound or stretch This presentation is for educational purposes only - Can be divided into: - Exteroreceptors: detects stimuli in the skin and other external surfaces (eye, ear, taste buds and olfactory tissue) - Proprioreceptors: receptor cells that detect movement and changes in the tension of muscle, tendons and joints. Include also sensory cells that regulate balance - - Entereceptors: transmit stimuli from the internal organs Master’s Degree in Veterinary Medicine - Receptors can be classified as primary or secondary - Primary receptor are nerve cells where the stimuli are detected by dendrites. E.g. neurosensory cells of the olfactory epithelium, photoreceptor cell of the retina, unmyelinated free nerve endings in the epidermis - Secondary receptor are modified epithelial cells that synapse with dendritic processes of the afferent neurons. E.g. taste buds, hair cells of the inner ear Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt - Structures that are able to detect specific changes like changes in the pressure, light, sound or stretch This presentation is for educational purposes only - Can be divided into: - Exteroreceptors: detects stimuli in the skin and other external surfaces (eye, ear, taste buds and olfactory tissue) Cutaneous sense - Dyce, 2018 Receive stimuli in touch, pressure, vibration, pain and change in Master’s Degree in Veterinary Medicine temperature. These receptors can present a simple morphology or a more complex one: - Free nerve endings - Simple receptors - Lamellar receptors Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Receptors - Structures that are able to detect specific changes like changes in the pressure, light, sound or stretch This presentation is for educational purposes only - Can be divided into: - Exteroreceptors: detects stimuli in the skin and other external surfaces (eye, ear, taste buds and olfactory tissue) Cutaneous sense - - Free nerve endings → Simple morphology. Terminal dendritic branches of neuronal axons. They penetrate the Master’s Degree in Veterinary Medicine basal lamina towards the epithelium. Locations: epidermis, non-glandular mucosa, corneal epithelium, hair follicles Receive stimuli associated with touch and pain Some free nerve endings are associated with Merkel cells (specialized tactile epithelial cells; neuroendocrine cells) Liebich, 2019 These complexes (nerve ending + epithelial cells) → Merkel’s corpuscles: are pressure sensors → mechanoreceptors Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Receptors - Structures that are able to detect specific changes like changes in the pressure, light, sound or stretch This presentation is for educational purposes only - Can be divided into: - Exteroreceptors: detects stimuli in the skin and other external surfaces (eye, ear, taste buds and olfactory tissue) Cutaneous sense Liebich, 2019 - - Simple receptors → Complex morphology Are found in the connective tissue. Master’s Degree in Veterinary Medicine Free nerve endings surrounded by an outer layer of connective tissue Present a bulbous terminal expansion. Meissner’s corpuscle Location: papillary layer of the dermis and around the hair follicles. Types: - Meissner’s corpuscles: Incomplete capsule of connective tissue. Touch receptors - Ruffinni corpuscles: Completely encapsulated. Can be present in other locations (hypodermis, joint capsules, etc.). Mechanoreceptors, cold and pain receptors Ruffinni corpuscle  – www.egasmoniz.com/pt Receptors - Structures that can detect specific changes like changes in the pressure, light, sound or stretch This presentation is for educational purposes only - Can be divided into: - Exteroreceptors: detects stimuli in the skin and other external surfaces (eye, ear, taste buds and olfactory tissue) Cutaneous sense Maria Soares - - Lamellar receptors → complex morphology Vater’s corpuscles or Pacinian corpuscles Master’s Degree in Veterinary Medicine Are found in the connective tissue. Consist of an axon surrounded by 10-60 concentric lamellar, resembling the layers of an onion - Inner lamellae – flattened Schawann cells - Outer lamellae - fibrocytes Locations: hypodermis, hoof and claw, mesenteries, nasolabial plate (ox), pancreas (cat) Detect stimulli associated with pressure and vibration  – www.egasmoniz.com/pt - Exteroreceptors: detects stimuli in the skin and other external surfaces (eye, ear, taste buds and olfactory tissue) This presentation is for educational purposes only - Proprioreceptors: receptor cells that detect movement and changes in the tension of muscle, tendons and joints. Include also sensory cells that regulate balance - Convey information about position and movement of the body segments - Joints – proprioceptive stimulus are detected by free nerve endings, Ruffini corpuscles and modified lamellar corpuscles Master’s Degree in Veterinary Medicine Tendons – Golgi tendon organ → stretch receptors Golgi organ detects changes in tension of the tendons and help to regulate the amount of effort required to perform movements that need a variable amounts of muscular force. Mescher, 2018 Muscle – Muscle spindle →stretch receptors Sensory nerve axons penetrate each muscle spindle and detect changes in length (distension). These information will help maintain posture and to regulate the activity of opposing muscle groups involved in motor activities (e.g. walk) Animal Body Function VIII 2023/2024  www.egasmoniz.com/pt Receptors - Exteroreceptors: detects stimuli in the skin and other external surfaces (eye, ear, taste buds and olfactory tissue) This presentation is for educational purposes only - Proprioreceptors: receptor cells that detect movement and changes in the tension of muscle, tendons and joints. Include also sensory cells that regulate balance Maria Soares - Entereceptors: transmit stimuli from the internal organs - - Free sympathetic and parasympathetic nerve endings in the Master’s Degree in Veterinary Medicine different viscera → provide autonomic regulation of organ function E.g. Carotid body (chemoreceptors) and carotid sinus (baroreceptors) – receive information regarding changes in the blood chemical composition and regarding blood pressure Several receptors in the viscera receive information concerning the stretch or pain. Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Liebich, 2019 Receptors – Taste buds ABF II Chemoreceptors This presentation is for educational purposes only - Intra-epithelial clusters of cells: - Sensory cells (6) - Supporting (sustentacular) cells (11) - - Basal cells Master’s Degree in Veterinary Medicine Secondary sensory cells Bacha, 2012 - The substances (tastants) are dissolved in saliva. They contact with the sensory cells (microvilli) through the taste pore (12).  – www.egasmoniz.com/pt Receptors – Taste buds ABF II Chemoreceptors This presentation is for educational purposes only Liebich, 2019 - Intra-epithelial clusters of cells: - Sensory cells (6) – Microvilli serve as the site of excitation. Basolaterally the receptor cells synapse with Bacha, 2012 - axons → initial fibers of the gustatory neural pathway Master’s Degree in Veterinary Medicine - Supporting (sustentacular) cells (11) – can differentiate into sensory cells - Basal cells – undifferentiated cells provide continuous replacement of sensory and supporting cells - Lamina propria – contains serous, tubulo-acinar glands (gustatory glands) - Clean the secretion and allows the detection of new stimuli Liebich, 2019 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Receptors – Taste buds ABF II Chemoreceptors This presentation is for educational purposes only Neural transmission pathways - Rostral 2/3 of the tongue – Nerve VII - Caudal 1/3 of the tongue – Nerve IX ABF VII - - Epiglottis – Nerve X Master’s Degree in Veterinary Medicine Processing centers - Gustatory area In the cerebrum, located near the somatosensory area (near the coronal sulcus) Temporal lobe Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Olfactory sense is important for: This presentation is for educational purposes only - Acquisition of food, - Identification of the others and of the environment - Sexual behaviour Liebich, 2019 - Domestic animals are macro-osmatic animals present a high development of the organs of smell Master’s Degree in Veterinary Medicine Receptors – neurosensory cells → bipolar neurons The neurosensory cells detect olfactory stimuli and are member of the olfactory epithelium. - Olfactory region of the nasal cavity; - Vomeronasal organ ABF VI  – www.egasmoniz.com/pt Receptors – neurosensory cells → bipolar neurons This presentation is for educational purposes only The neurosensory cells detect olfactory stimuli and are member of the olfactory epithelium. ABF VI - Neurosensory olfactory cells - - Sustentacular cells - Basal cells Master’s Degree in Veterinary Medicine Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Receptors – neurosensory cells → bipolar neurons This presentation is for educational purposes only The neurosensory cells detect olfactory stimuli and are member of the olfactory epithelium. Liebich, 2019 - Neurosensory olfactory cells - Present chemoreceptors – located in the ciliary membrane Master’s Degree in Veterinary Medicine These cilia (cellular processes) are covered by a thin mucus layer produced by the sustentacular cells and by the glands of the olfactory mucosa (Bowman’s gland) Odoriferous chemicals → chemoreceptor in the ciliary membrane (dendrites) The action potential is transmitted to the axon, that extend from the basal lamina and form bundles of myelinated nerve fibers → Cranial nerve I Bacha, 2012 Animal Body Function VIII 2023/2024  – www.egasmoniz.com/pt Receptors – neurosensory cells → bipolar neurons ABF VI This presentation is for educational purposes only The neurosensory cells detect olfactory stimuli and are member of the olfactory epithelium. Neural transmission pathways - - Cranial nerve I (Olphactory nerve) - Vomeronasal and terminal nerve → from the Master’s Degree in Veterinary Medicine Vomeronasal organ - Pass the cribiform plate of the ethmoid bone to reach the olfactory bulb (cerebrum) Processing centers - Olfactory area (Piriform lobe) ABF VII - Located in the rhinencephalon (cerebrum) Master’s Degree in Veterinary Medicine - www.egasmoniz.com/pt This presentation is for educational purposes only !