Physiology of sensory systems
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Sensory receptors convert different types of energy like touch, pressure, heat, and light into electrical signals that are transmitted to the central nervous system. There are several classes of sensory receptors including mechanoreceptors, nociceptors, chemoreceptors, and photoreceptors. The somatosensory system contains mechanoreceptors that detect touch, vibration, and proprioception. Sensory information is coded by modality, location, intensity and duration. Laws of specific nerve energies and projection state that sensation is determined by the receptor and referred to its location. Clinical tests of vibration sense and stereognosis examine somatosensory function.
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Sensory Physiology
The document summarizes sensory physiology, including the structure and function of sensory receptors and neural pathways. It discusses how different sensory receptors transduce various stimuli like touch, temperature, sound, and light into nerve impulses. The receptors are categorized based on their modality and location. The pathways from receptors to the central nervous system are described for each sensory system. Adaptation and processing of sensory information in the brain is also overviewed.
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This document discusses receptors and neurons that detect sensory information. It begins by defining perception and describing how sensory information is transmitted from receptors to the central nervous system. It then categorizes the different sensory modalities like touch, pain, temperature, and proprioception. The document goes on to describe the different types of sensory receptors, including their locations, the stimuli they detect, and whether they adapt rapidly or slowly. It provides examples of specific receptors like Meissner corpuscles, Pacinian corpuscles, and thermoreceptors. In closing, it notes the uneven distribution of receptors in the skin and modalities detected in the skin.
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Physiology of Sensory system
The sensory system enables perception of changes in the external and internal environment through three departments - peripheral, conducting, and central. The peripheral department contains receptors that code information and perform primary analysis. The conducting department conveys impulses to the cortex and performs secondary analysis through reflexes. The central/cortex department enables higher-level analyses and perceptions. Receptors are classified based on their mechanism, location, stimulus type, and sensations caused. Coding of information in receptors uses a binary code to represent parameters like force, duration, and thresholds of sensitivity.
Receptors
Sensory receptors detect stimuli from the internal and external environment and transmit this information to the central nervous system via sensory neurons. There are several types of sensory receptors that detect different modalities like touch, pressure, vibration, temperature, and pain. Mechanoreceptors include receptors that detect touch and pressure like free nerve endings, Meissner's corpuscles, Merkel's discs, hair receptors, Ruffini endings, and Pacinian corpuscles. Tactile signals are transmitted via myelinated A-beta fibers while pain and itch signals use small diameter C fibers. The dorsal column medial lemniscus pathway transmits tactile, proprioceptive, and vibratory signals from the periphery to the thalamus and som
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Sensory system
The document summarizes the human sensory system. It describes the general senses associated with skin, muscles, and organs, as well as the special senses located in the head like eyes, ears, nose and mouth. It then discusses sensory receptors that detect stimuli and transmit signals to the brain, as well as the sensations and perceptions that result. Different receptor types respond to stimuli like chemicals, pain, temperature, and mechanical forces. The pathways and processing of sensory signals in the central nervous system are also outlined.
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Sensory receptors detect stimuli from the internal and external environment and transmit this information to the central nervous system via sensory neurons. There are several types of sensory receptors that detect different modalities like touch, pressure, vibration, temperature, and pain. Mechanoreceptors include receptors that detect touch and pressure like free nerve endings, Meissner's corpuscles, Merkel's discs, hair receptors, Ruffini endings, and Pacinian corpuscles. Tactile signals are transmitted via myelinated A-beta fibers while pain and itch signals use small diameter C fibers. The dorsal column medial lemniscus pathway transmits tactile, proprioceptive, and vibratory signals from the periphery to the thalamus and som
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I. This document discusses sensory receptors and their classification.
II. Sensory receptors are specialized nerve endings that convert stimuli into receptor potentials. There are three main types of receptors structurally: bare nerve endings, capsulated nerve endings, and sense organs.
III. Receptors can be classified in several ways, including by the source of the stimulus (exteroceptors, enteroceptors, telereceptors), the type of stimulus (mechanoreceptors, thermoreceptors, chemoreceptors, nociceptors), or their anatomical location (superficial, deep, visceral).
Thalamus .ppt
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Anatomically, the thalamus is divided into anterior, lateral, and medial groups of nuclei. The lateral group contains sensory relay nuclei that project to sensory cortices. Association nuclei in the medial and dorsal groups integrate sensory and limbic inputs and project to association cortices. Nonspecific nuclei in the intralaminar and midline regions are involved in arousal, emotions, and alertness.
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Somatosensory System
Here are the answers to your questions:
1a) A transection on the left side at T4 would impair fine touch, proprioception and vibration sense on the right side of the body below the level of the lesion.
1b) A transection on the left side at T4 would impair pain, temperature and crude touch sensation on the left side of the body below the level of the lesion.
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Sensory system receptors.hussein f.sakr
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The document outlines different types of sensory modalities and receptors. It discusses the differences between sensation and perception. There are multiple ways to classify sensory receptors based on their structure, location, stimuli detected, and response type. Somatic sensations include tactile sensations like touch, pressure, vibration, itch, and tickle detected by various receptors. Thermal sensations detect temperature via free nerve endings. Pain sensations are detected by nociceptors. Proprioceptive sensations provide awareness of body position and movement via receptors in muscles, tendons, and joints.
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this ppt comprises the basics of sensory physiology,properties of sensory receptors and sensory pathways
Receptor by Pandian M, Tutor, Dept of Physiology, DYPMCKOP, MH. This PPT for ...
I. This document discusses sensory receptors and their classification.
II. Sensory receptors are specialized nerve endings that convert stimuli into receptor potentials. There are three main types of receptors structurally: bare nerve endings, capsulated nerve endings, and sense organs.
III. Receptors can be classified in several ways, including by the source of the stimulus (exteroceptors, enteroceptors, telereceptors), the type of stimulus (mechanoreceptors, thermoreceptors, chemoreceptors, nociceptors), or their anatomical location (superficial, deep, visceral).
Thalamus .ppt
The thalamus is located in the center of the cerebral hemispheres. It receives sensory input from various areas and projects to different cortical regions. The thalamus and cortex work as a single functional unit, with the thalamus integrating inputs and the cortex performing higher-level processing.
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Motor system
1) The motor cortex and corticospinal tract provide conscious control of voluntary skeletal muscle movements. The corticospinal tract contains fibers that cross to the opposite side of the body and fibers that remain on the same side.
2) Sensory information travels through ascending tracts in the spinal cord including the posterior, lateral, and spinocerebellar tracts to the brain.
3) The medial and lateral motor pathways issue subconscious motor commands through tracts like the rubrospinal and reticulospinal tracts to control gross movements and posture.
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The document discusses the general properties and structure of sensory systems. It describes how sensory systems are composed of peripheral, conductive, and central parts. The peripheral part contains receptors that detect stimuli and generate receptor or generator potentials. The conductive part transmits excitation through pathways and neurons. The central part analyzes information through subcortical and cortical structures. It also discusses the classification, properties, and functions of different receptor types involved in mechanical sensation, including Pacinian corpuscles, Ruffini's corpuscles, Meissner's corpuscles, and Merkel's disks.
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The spinal cord contains neurons that control motor functions and reflexes. There are anterior motor neurons that innervate skeletal muscles, and interneurons that connect motor neurons. The cord contains reflex circuits mediated by propriospinal fibers and interneurons. Sensory receptors like muscle spindles and Golgi tendon organs detect changes in muscle length and tension, eliciting stretch and withdrawal reflexes. Spinal cord lesions initially cause spinal shock and loss of reflexes, which gradually recover over weeks.
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Sensory physiology covers general and special visceral senses. General visceral senses include pain and temperature sensations while special visceral senses are smell and taste. Tactile senses allow for localization of stimuli, identification of object features through stereognosis, discrimination of two nearby points through two-point discrimination, and perception of vibration.
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Sensory receptors detect stimuli and transmit data about them to the brain. There are several types of sensory receptors located throughout the body that detect senses like touch, temperature, sound, smell, and taste. Sensory receptors respond to stimuli by generating receptor potentials that trigger action potentials along sensory neurons to the central nervous system. The main types of sensory receptors include mechanoreceptors, chemoreceptors, photoreceptors, and thermoreceptors. Specific receptors like Pacinian corpuscles, Meissner's corpuscles, and Merkel cells are mechanoreceptors in the skin responsible for detecting touch, pressure, and vibration.Olfactory system
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Here are the answers to your questions:
1a) A transection on the left side at T4 would impair fine touch, proprioception and vibration sense on the right side of the body below the level of the lesion.
1b) A transection on the left side at T4 would impair pain, temperature and crude touch sensation on the left side of the body below the level of the lesion.
2) In response to an increase in temperature from 35oC to 40oC: Cold receptors would increase their firing rate initially but then adapt to the new temperature. Warm receptors would increase their firing rate initially and maintain an elevated firing rate as long as the temperature is sustained at 40oC. Both receptor
THALAMUS
The document discusses the thalamus and its functions. It begins with objectives and physiological anatomy of the thalamus. It then discusses the internal structure of the thalamus including its white and grey matter. Next, it covers the connections of the thalamus including its sensory, motor, visceral, and integrative nuclei. It lists the functions of the thalamus such as acting as a sensory relay center and in arousal, perception, emotions, and motor integration. Finally, it discusses some applied aspects including thalamic syndrome, Korsakoff's syndrome, and frontal lobotomy.
Sensory system receptors.hussein f.sakr
The document discusses the central nervous system and sensory system. It describes the main components of the sensory unit including sensory axons, peripheral branches, and receptors. The main types of sensory receptors are described based on the stimuli they detect such as mechanoreceptors, chemoreceptors, photoreceptors, and thermoreceptors. The properties of sensory receptors including specificity, excitability through receptor potentials, adaptation, rate of discharge, and neural coding of sensory information are explained.
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This document discusses the human sensory systems. It describes four types of sensations - superficial, deep, visceral, and special. It then provides details on the receptors, pathways, and neural connections involved in touch, pain, temperature, proprioception, and other senses. Specifically, it outlines the locations and functions of mechanoreceptors like Meissner's corpuscles and Merkel endings, as well as nociceptors that detect pain. It also compares the dorsal column-medial lemniscus pathway and spinothalamic tract, noting their roles in transmitting different sensory signals to the cortex.
Nerve impulse conduction
Nerve impulse conduction involves the generation and propagation of action potentials along neurons. At rest, neurons maintain a negative resting potential due to an unequal distribution of ions across the cell membrane. When stimulated, the opening of voltage-gated sodium channels causes rapid depolarization and the generation of an action potential. This potential then propagates along the axon as adjacent regions are depolarized, triggering their own action potentials. At synapses, the action potential is converted to a chemical signal via neurotransmitter release, which can then trigger a new action potential in the post-synaptic cell. Myelination and large axon diameters increase conduction velocity.
Somatic sensory system
The document summarizes somatic sensations and the somatosensory system. It describes:
1) The general organization of the somatosensory system including receptors, pathways to the brain, and processing of sensations. Mechanoreceptors, nociceptors, and thermoreceptors are discussed.
2) Classification of somatic sensations based on function, stimulus, and location. Tactile sensations are subdivided based on the specific receptors.
3) Pathways for transmitting sensory information including the dorsal column-medial lemniscal system and anterolateral system.
4) Organization of the somatosensory cortex and somatosensory homunculus representation of the body.
Lecture 6 sensory
The document outlines different types of sensory modalities and receptors. It discusses the differences between sensation and perception. There are multiple ways to classify sensory receptors based on their structure, location, stimuli detected, and response type. Somatic sensations include tactile sensations like touch, pressure, vibration, itch, and tickle detected by various receptors. Thermal sensations detect temperature via free nerve endings. Pain sensations are detected by nociceptors. Proprioceptive sensations provide awareness of body position and movement via receptors in muscles, tendons, and joints.
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This document discusses the human sensory system, including sensory receptors, pathways, and cortex. It describes the different sensory modalities and sensations. The main sensory pathways are the dorsal column-medial lemniscus pathway and spinothalamic pathway, which transmit signals from receptors to the thalamus and sensory cortex. Within the cortex, different body regions are represented in a distorted map called a sensory homunculus. The document provides details on various mechanoreceptors, transduction of stimuli to action potentials, and coding of sensory information.
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Merkel's disc
Diameter: Myelin: Velocity: mechanoreceptors
1-5 μm Partial 5-30 m/s or nociceptors.
C(paleospinothalamic -Skin, especially
tract) fingertips
Diameter: Myelin: Velocity: -Detect fine touch
0.2-1.5 No 0.5-2.0 and pressure
μm m/s
Aδ(Neospinothalamic slow high
Tract)
Diameter: Myelin: Velocity:
1-
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The thalamus is divided into anterior, medial, and lateral parts by the internal medullary lamina. The lateral part contains dorsal and ventral tiers of nuclei that relay sensory and motor information between the brainstem and cortex. The thalamus plays key roles in sensory relay, motor control, emotion/memory, and vegetative functions by transmitting information between different brain regions. Lesions of the ventral posteromedial and ventral posterolateral nuclei can cause loss of sensation on the opposite side of the body.
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This document contains lecture slides on physiology of vision. It covers topics such as eye anatomy, accommodation, the retina, photoreceptors, visual pathways, and cortical visual areas. Diagrams are presented on eye structures, tear drainage, blood supply, lens function, the retinal layers, rod and cone sensitivity, refractive errors, and visual field deficits. Principles of light, vision, and the spectrum are also discussed.
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The thalamus acts as a relay center and plays a key role in sensory and motor functions. It is divided into nuclear groups including anterior, medial, lateral, and intralaminar. Specific nuclei relay information from particular sensory pathways to corresponding cortical areas, while nonspecific nuclei have broader connections. The thalamus receives subcortical inputs and sends outputs to widespread areas of cortex, regulating cortical activity and integrating sensory, motor, and limbic functions. Damage to different thalamic regions can cause sensory deficits, involuntary movements, or pain syndromes on the opposite side of the body.
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1. The document discusses how sensory systems encode information about stimuli, including modality, location, intensity, and timing. It focuses on how the somatosensory system encodes touch and proprioception.
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Physiology of sensory systems
- 1. PHYSIOLOGY OF SENSORY SYSTEMS Dr Serge Eddy Mba Neurosurgery Registrar UZ- CHS
- 2. OUTLINE •SENSORY RECEPTOR PHYSIOLOGY •ANATOMY OF SOMATIC SENSORY SYSTEM •CORTICAL INTEGRATION OF SENSORY PERCEPTION
- 3. SENSORY RECEPTOR PHYSIOLOGY • Information about the internal and external environment activates the CNS via a variety of sensory receptors • Receptors are transducers that convert different type of energy into action potentials in neurons • CLASSIFICATION • Numerous, none is perfect • Mechanoreceptors: for touch and pressure • Nociceptors codes for potentially harmful stimuli such as extreme heat and extreme cold • Chemoreceptors: mediates changes in chemical composition of the environment in which they are localized • Photoreceptors like the cones and rods responds to light
- 4. Sensory system Modality Stimulus energy Receptor class Receptor cell types somatosensory touch Tap, flutter 5-40Hz C* mechanoreceptor Meissner corpuscles somatosensory touch motion C* mechanoreceptor Hair follicle receptors somatosensory touch Deep pressure, vibration 60-300Hz C* mechanoreceptor Pacinian corpuscles somatosensory touch Touch, pressure C* mechanoreceptor Merkel cells somatosensory touch Sustained pressure C* mechanoreceptor Ruffini corpuscles somatosensory proprioception stretch mechanoreceptor Muscle spindle somatosensory proprioception tension mechanoreceptor Golgi tendon organ somatosensory temperature thermal thermoreceptor Cold n warm receptors somatosensory pain Chemical, thermal, mechanical Chemo, thermo, mechanoreceptor polymodal somatosensory itch chemical chemoreceptor Chemical nociceptors visual vision light photoreceptor Rods and cones auditory hearing sound mechanoreceptor Hair cells (cochlea) vestibular balance Angular acceleration mechanoreceptor Hair cells (semicircular canals) vestibular balance Linear acceleration, gravity mechanoreceptor Hair cell(Otolith organs) olfactory smell chemical chemoreceptor Olfactory sensory neuron gustatory taste chemical chemoreceptor Taste buds
- 5. Transduction of stimulus into neural energy
- 6. Sensory coding• MODALITY: type of energy transmitted by the stimulus • LOCATION: site of the body where the stimulus originated • INTENSITY: response amplitude or frequency of action potential generation • DURATION: time from start to end of a response in the receptor
- 7. • MODALITY: The unique stimulus that activates a specific receptor at a low energy level is called an adequate stimulus. The specificity of response in receptors underlies the labeled line code, the most important coding mechanism for stimulus modality • LOCATION: sensory unit is a single sensory axon and all its peripheral branches. Receptive field: spatial distribution from which a stimulus produces a response. lateral inhibition: two point discrimination
- 8. • INTENSITY: Weber-Fechner law R= KSA • DURATION: adaptation and desensitization, phasic vs tonic receptors receptor morphology influences adaptation pacinian corpuscle is rapidly adapting receptor composed of concentrically fluid filled lamellae capsule deflects steady pressure each vibratory cycle generate an action potential
- 9. LAW OF SPECIFIC NERVE ENERGIES • First enunciated by Mϋller in 1835 • One of the cornerstones of sensory physiology • The specific sensory pathways are discrete from sense organ to cortex • The modality of sensation is not determined by the proximal stimulus • “when the nerve pathways from a particular sense organ are stimulated, the sensation evoked is that for which the receptor is specialised no matter how or where along the pathway the activity is initiated”
- 10. LAW OF PROJECTION • “no matter where a particular sensory pathway is stimulated along its course to the cortex, the conscious sensation produced is referred to the location of the receptor” e.g: cortical experiment during neurosurgical procedures on conscious patients
- 11. CLINICAL EXAMINATION • test for vibratory sensibility is done by applying a vibrating(128Hz) tuning fork to the skin of the fingertip • Pallesthesia is the ability to feel mechanical vibration • Receptors involved are Pacinian corpuscles • Elevation of the threshold for vibratory sense is an early sign post column degeneration e.g in Pernicious Anaemia • Stereognosis: perception of the form and nature of an object without looking at it. Depends on intact touch and pressure sensation carried by dorsal colum • stereoagnosia: defect along the sensory pathway, even lesion in parietal lobe posterior to postcentral gyrus • Visual, tactile, auditory, color, position ….agnosia
- 13. ANATOMY OF SOMATOSENSORY SYSTEM • The sodium channel BNC1 is closely associated with touch receptors • DEGENERINS
- 19. CORTICAL INTEGRATION OF SENSORY PERCEPTION
- 23. references Dr S. E Mba
- 24. THANK YOU Contact: Dr Mba mbasedy@yahoo.fr
Editor's Notes
- They are five different modality for taste: sweet, salt, sour, bitter and umami
- all sensory systems code for four basic types of information M L, I T
- e.g we easily perceive that 1$ is different from 2$ but it is difficult to distinguish 49$ from 49.99$ yet bot differ by 1$
- Bnc1 basonuclin 1 The channel is one of the degenerins. So called because when they are overexpressed, they cause the neurons they are in to degenerate
- TWO SYSTEMS: spinothalamic and medial lemniscus
- Pathway for conscious proprioception:
- The somatic sensory cortex has three major divisions: the primary and secondary somatosensory cortices and the posterior parietal cortex.
- Each region of the somatic sensory cortex receives inputs from primarily one type of receptor.
- PENFIELD HOMUNCULUS Because of their novelty at the time, this Homonculus was hailed as the "E=mc² of Neuroscience"