Sensory, Motor, and Integrative Systems Chapter 16

Peripheral Nervous System Flow to the CNS Flow out of the CNS

Peripheral Nervous System Integration occurs at many locations along the pathway. stimulus - environmental change sensation - awareness of stimulus perception - interpretation of the meaning of the stimulus

Sensory Modalities General senses: somatic and visceral Special senses smell,hearing/equilibrium taste, vision, and hearing

Classification of Sensory Receptors Structural classification Type of response to a stimulus Location of receptors & origin of stimuli Type of stimuli they detect

Structural Classification of Receptors 1. Unencapsulated free nerve endings Merkel discs root hair plexus 2. Encapsulated Meissner’s corpuscles Krause’s end bulbs Pacinian corpuscles Ruffini’s corpuscles Muscle spindles Golgi tendon organs 3. Sensory cells vision taste hearing balance

Structural Classification of Receptors

Classification by Response to Stimuli Generator potential free nerve endings, encapsulated nerve endings & olfactory receptors produce generator potentials when large enough, it generates a nerve impulse in a first-order neuron Receptor potential vision, hearing, equilibrium and taste receptors produce receptor potentials receptor cells release neurotransmitter molecules on first-order neurons producing postsynaptic potentials PSP may trigger a nerve impulse Amplitude of potentials vary with stimulus intensity

Classification by Location 1. Exteroceptors 2. Interoceptors 3. Proprioceptors

Classification by Stimuli Detected 1. Mechanoreceptors 2. Thermoreceptors 3. Photoreceptors 4. Chemoreceptors Nociceptors Osmoreceptors

Classification of Receptors

Adaptation Adaptation - generator potential or receptor potential decreases in amplitude during a maintained stimulus. Rapidly adapting - e.g. pressure, touch, smell Slowly adapting - e.g. pain, body position

Somatic Sensations Tactile Pain Thermal Proprioceptive touch, pressure,vibration, itch and tickle Pain fast and slow Thermal warm and cold Proprioceptive muscle spindles, tendon organs, joint receptors

Sensory Receptors

Referred Pain

Proprioceptive Senses

Receptors - Summary

Somatic Sensory Pathways Somatic sensory pathways relay information from somatic receptors to the primary somatosensory area in the cerebral cortex. The pathways consist of three neurons first-order: conduct impulses to the CNS (brainstem or spinal cord) either spinal or cranial nerves second-order: conducts impulses from brain stem or spinal cord to thalamus cross over to opposite side of body third-order: conducts impulses from thalamus to primary somatosensory cortex (postcentral gyrus of parietal lobe) Axon collaterals of somatic sensory neurons simultaneously carry signals into the cerebellum and the reticular formation of the brain stem.

Somatic Sensory Pathways Posterior Column - Medial Lemniscus Pathway

Somatic Sensory Pathways Spinothalamic Pathways

Somatic Sensory Pathways Trigeminothalamic Pathways

Somatosensory Map of Postcentral Gyrus

Somatic Sensory Pathways

Somatic Motor Pathways

Direct Motor Pathways

Direct and Indirect Motor Pathways

Cerebellum Input/Output

Reticular Activating System

Stages of Sleep Nonrapid eye movement (NREM) Rapid eye movement (REM)

Learning and Memory Learning is the ability to acquire new information or skills through instruction or experience. Memory is the process by which information acquired through learning is stored and retrieved. Immediate memory- recall for a few seconds. Short-term memory- temporary ability to recall. Long-term memory- more permanent. Memory consolidation.

Clinical Terms analgesia syphilis paralysis coma paraplegia hemiplegia quadriplegia transection hemisection spinal shock cerebral palsy Parkinson’s disease bradykinesia hypokenesia ataxia Huntington’s insomnia narcolepsy sleep apnea