1. Sensory, Motor and Integrative Systems
Chapter 16
Sensory, Motor and Integrative Systems

3. Nervous System Functions
Chapter 16
Integration of
Nervous System Functions

4. Sensation
Senses: Means by which brain receives information about environment and body
General: Distributed over large part of body
Somatic: Touch, pressure, temperature, proprioception, pain
Visceral: Internal organs and consist mostly of pain and pressure
Special senses: Smell, taste, sight, hearing, balance
Sensation or perception: Conscious awareness of stimuli received by sensory receptors

5. Types of Sensory Receptors
Mechanoreceptors: Compression, bending, stretching of cells
Chemoreceptors: Smell and taste
Thermoreceptors: Temperature
Photoreceptors: Light as vision
Nociceptors: Pain
Exteroreceptors: Associated with skin
Visceroreceptors: Associated with organs
Proprioceptors: Associated with joints, tendons

6. Sensory Nerve Endings Free nerve endings: Cold receptors and warm
Merkel’s disk: Light touch, superficial pressure
Hair follicle receptor: Light touch, bending of hair
Pacinian corpuscle: Deep cutaneous pressure, vibration and proprioception
Meissner’s corpuscle: Two-point discrimination
Ruffini’s end organ: Continuous touch or pressure
Muscle spindle: Proprioception as to muscle stretch and control of muscle tone
Golgi tendon organ: Important in muscle contraction and tendon stretch proprioception

7. Sensory Nerve Endings in Skin

8. Two-Point Discrimination

9. Tactile Localization The ability to determine which portion of the skin has been touched

10. Muscle Spindle and Golgi Tendon Organ

11. Responses of Sensory Receptors
Receptor: Interaction of stimulus with sensory receptor produces a local potential
Primary: Have axons that conduct action potential in response to receptor potential
Secondary: Have no axons and receptor potentials produced do not result in action potentials but cause release of neurotransmitters
Accommodation or adaptation: Decreased sensitivity to a continued stimulus
Proprioceptors
Tonic: Example is know where little finger is without looking
Phasic: Example is you know where hand is as it moves

12. Sensory Nerve Tracts
Transmit action potentials from periphery to brain
Each pathway involved with specific modalities
First half of word indicates origin, second half indicates termination

13. Spinothalamic System Conveys cutaneous sensory information to brain
Unable to localize source of stimulus
Divisions
Lateral for pain and temperature
Anterior for light touch, pressure, tickle, itch

14. Dorsal-Column/ Medial-Lemniscal System
Carries sensations of
Two-point discrimination
Proprioception
Pressure
Vibration
Tracts
Fasciculus gracilis
Fasciculus cuneatus

15. Spinocerebellar System
Carry proprioceptive information to cerebellum
Actual movements can be monitored and compared to cerebral information representing intended movement
Tracts
Posterior
Anterior

16. Sensory Areas of Cerebral Cortex

17. Pain
Types
Referred: Sensation in one region of body that is not source of stimulus
Phantom: Occurs in people who have appendage amputated or structure removed as tooth
Chronic: Not a response to immediate direct tissue injury

18. Somatic Sensory Cortex

19. Primary Motor Cortex

20. Descending Spinal Pathways
Direct
Control muscle tone and conscious skilled movements
Direct synapse of upper motor neurons of cerebral cortex with lower motor neurons in brainstem or spinal cord
Tracts
Corticospinal
Lateral
Anterior corticobulbar

21. Descending Spinal Pathways
Indirect
Synapse in some intermediate nucleus rather than directly with lower motor neurons
Tracts
Rubrospinal
Vestibulospinal
Reticulospinal

22. Cerebellar Comparator Function

23. Speech Speech area normally in left cerebral cortex
Wernicke’s area: Sensory speech
Broca’s area: Motor speech
Aphasia: Absent or defective speech or language comprehension

24. Brain Waves and Sleep
Electroencephalogram (EEG): Record of brain’s electrical activity
Brain wave patterns
Alpha: Resting state with eyes closed
Beta: During intense mental activity
Theta: Occur in children but also in adults experiencing frustration or brain disorders
Delta: Occur in deep sleep, infancy, and severe brain disorders

25. Memory Sensory Short-term Long-term
Very short-term retention of sensory input
Short-term
Information retained for few seconds to minutes
Long-term
Explicit or declarative
Retention of facts
Accessed by hippocampus and amygdaloid (emotional)
Implicit or procedural
Development of skills as riding a bicycle

26. Long-Term Potentiation

27. General CNS Disorders Infections Other disorders
Encephalitis: Inflammation of the brain
Rabies: Viral disease transmitted by bite of infected animal
Multiple sclerosis: Possibly involves autoimmune response to viral infection
Other disorders
Stroke: CVA or cerebrovascular accident caused by hemorrhage, thrombosis, embolism
Aneurysm: Dilation or ballooning of an artery
Alzheimer’s disease: Severe type of dementia
Epilepsy: Group of brain disorders that have seizures

28. Effects of Aging on Nervous System
Gradual decline in sensory and motor function
Reflexes slow
Size and weight of brain decrease
Decreased short-term memory in most people
Long-term memory unaffected or improved