1. Chapter 16: Sensory, Motor, and Integrative Systems
Copyright 2009, John Wiley & Sons, Inc.

2. Sensation ,Perception & Integration
Sensation is the detection of stimulus of internal or external receptors. It can be either conscious or subconcious
Components of sensation: Stimulation of the sensory receptor → transduction of the stimulus (energy-to-graded potential) → generation of nerve impulses → integration of sensory input.
Perception is the awareness and conscious interpretation of sensations. It is how the brain makes sense of or assigns meaning to the sensation.
We not aware of X-rays, ultra high frequency sound waves, UV light
- We have no sensory receptors for those stimuli
Integration of sensory and motor functions occurs at many sites:
□spinal cord □brain stem □cerebellum □basal nuclei □cerebral cortex
Disruption of sensory, motor, or integrative structures or pathways can cause disruptions in homeostasis

3. Classification of Sensory Receptors
General senses: somatic and visceral.
Somatic- tactile, thermal, pain, pressure and proprioceptive sensations.
Visceral- provide information about conditions within internal organs.
- example: pH. Osmolarity, O2 and CO2 levels
Special senses- smell, taste, vision, hearing and equilibrium or balance.
Alternate Classifications of Sensory Receptors
Structural classification
Type of response to a stimulus
Location of receptors & origin of stimuli
Type of stimuli they detect
Copyright 2009, John Wiley & Sons, Inc.

4. Alternate Classifications of Sensory Receptors
Structural classification
Type of response to a stimulus
Location of receptors & origin of stimuli
Type of stimuli they detect
Principles of Human Anatomy and Physiology, 11e

5. Structural Classification of Receptors
Free nerve endings
bare dendrites
pain, temperature, tickle, itch & light touch
Encapsulated nerve endings
dendrites enclosed in connective tissue capsule
pressure, vibration & deep touch
Separate sensory cells
specialized cells that respond to stimuli
vision, taste, hearing, balance
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Structural Classification of Receptors
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7. Unencapsulated Nerve Endings Encapsulated Nerve Endings vs
Naked nerve endings surrounded
by one or more layers
Free nerve endings
Pacinian corpuscle
skin, bones, internal organs, joints
Deeper tissue, muscles

8. free nerve endings
Merkel disc
Meissner’s corpuscles
Ruffini corpuscle
root hair plexus
Pacinian corpuscles

9. Classification by Stimuli Detected
Mechanoreceptors
detect pressure or stretch
touch, pressure, vibration, hearing, proprioception, equilibrium & blood pressure
Thermoreceptors detect temperature
Nociceptors detect damage to tissues (pain)
Photoreceptors detect light
Chemoreceptors detect molecules
taste, smell & changes in body fluid chemistry
Principles of Human Anatomy and Physiology, 11e

10. Classification by Location
Exteroceptors
near surface of body
receive external stimuli
hearing, vision, smell, taste, touch, pressure, pain, vibration & temperature
Interoceptors
monitors internal environment (BV or viscera)
not conscious except for pain or pressure
Proprioceptors
muscle, tendon, joint & internal ear
senses body position & movement
Principles of Human Anatomy and Physiology, 11e

11. 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
Principles of Human Anatomy and Physiology, 11e

12. Table 15.1 pt 1

13. Table 15.1 pt 2

14. Table 15.1 pt 3

15. Adaptation of Sensory Receptors
Most sensory receptors exhibit adaptation – the tendency for the generator or receptor potential to decrease in amplitude during a maintained constant stimulus.
Receptors may be rapidly or slowly adapting.
Rapidly adapting receptors: detect pressure, touch and smell.
- specialized for detecting changes
Slowly adapting receptors: detect pain, body position, and chemical composition of the blood.
-nerve impulses continue as long as the stimulus persists
– Pain is not easily ignored.
Change in sensitivity to long-lasting stimuli decrease in responsiveness of a receptor
bad smells disappear
very hot water starts to feel only warm
potential amplitudes decrease during a maintained, constant stimulus
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Somatic Sensations
Sensory receptors in the skin (cutaneous sensations), muscles, tendons and joints and in the inner ear.
Uneven distribution of receptors. (tongue, lips, fingertips)
Four modalities: tactile, thermal, pain and proprioceptive.
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17. Sensory Receptors in the Skin
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Tactile Sensations
Include touch, pressure, vibration, itch and tickle.
Tactile receptors in the skin are Meissner corpuscles, hair root plexuses, Merkel discs, Ruffini corpuscles, pacinian corpuscles, and free nerve endings.
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19. Meissner Corpuscles or Corpuscles of Touch
Egg-shaped mass of dendrites enclosed by a capsule of connective tissue.
Rapidly adapting receptors.
Found in the dermal papillae of hairless skin such as in the fingertips, hands, eyelids, tip of the tongue, lips, nipples, soles, clitoris, and tip of the penis.
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Hair Root Plexuses
Rapidly adapting touch receptors found in the hairy skin.
Free nerve endings wrapped around hair follicles.
Detect movements on the skin surface that disturb hairs.
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21. Merkel Discs or Tactile Discs
Also known as type I cutaneous mechanoreceptors.
Slowly adapting touch receptors.
Saucer-shaped, flattened free nerve endings.
Found in the fingertips, hands, lips, and external genitalia.
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Ruffini Corpuscles
Also called as type II cutaneous mechanoreceptors.
Elongated, encapsulated receptors.
Located deep in the dermis and in ligaments and tendons.
Found in the hands, and soles.
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23. Pacinian or Lamellated Corpuscles
Large oval structure composed of a multilayered connective tissue capsule that encloses a dendrite.
Fast adapting receptors.
Found around joints, tendons, and muscles; in the periosteum, mammary glands, external genitalia, pancreas and urinary bladder.
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Thermal Sensations
Thermoreceptors are free nerve endings.
Two distinct thermal sensations:
cold receptors-
warm receptors-
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Pain Sensations
Protective.
Sensory receptors are nociceptors.
Free nerve endings.
Two types of pain: fast and slow.
Fast pain: acute, sharp or pricking pain.
Slow pain: chronic, burning, aching or throbbing pain.
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Referred Pain
Pain is felt in or just deep to the skin that overlies the stimulated organ or in a surface area far from the stimulated organ.
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27. Distribution of Referred Pain
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28. Proprioceptive Sensations
Receptors are called proprioceptors.
Slow adaptation.
Weight discrimination.
Three types: muscle spindles, tendon organs and joint kinesthetic receptors.
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Muscle Spindles
Interspersed among most skeletal muscle fibers and aligned parallel to them.
Measure muscle stretching.
Consists of intrafusal muscle fibers- specialized muscle fibers with sensory nerve endings and motor neurons called gamma motor neurons.
Extrafusal muscle fibers- surrounding muscle fibers supplied by alpha motor neurons.
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30. A Muscle Spindle and a Tendon Organ

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Tendon Organs
Located at the junction of a tendon and a muscle.
Protect tendons and their associated muscles from damage due to excessive tension.
Consists of a thin capsule of connective tissue that encloses a few tendon fascicles.
Copyright 2009, John Wiley & Sons, Inc.

32. Joint Kinesthetic Receptors
Found within or around the articular capsules of synovial joints.
Free nerve endings and Ruffini corpuscles in the capsules of joints respond to pressure.
Pacinian corpuscles respond to acceleration and deceleration of joints during movement.
Copyright 2009, John Wiley & Sons, Inc.

33. 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 neuron (somatic receptor to the brain stem or spinal cord)
- either spinal or cranial nerves
→ second order neuron(brain stem/spinal cord→thalamus; decussate
→ third-order neuron(thalamus→primary somatosensory cortex).
Axon collaterals of somatic sensory neurons simultaneously carry signals into the cerebellum and the reticular formation of the brain stem.
Major Somatic Sensory Pathways:
The posterior column-medial lemniscus pathway.
The anterolateral (spinothalamic) pathway.
The trigeminothalamic pathway.
The anterior and posterior spinocerebellar pathway.

34. The Posterior Column-Medial Lemniscus Pathway
Conveys nerve impulses for touch, pressure, vibration and conscious proprioception from the limbs, trunk, neck, and posterior head to the cerebral cortex.
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35. The Anterolateral (spinothalamic) pathway
Conveys nerve impulses for pain, cold, warmth, itch, and tickle from the limbs, trunk, neck, and posterior head to the cerebral cortex.

36. Trigeminothalamic Pathway
Conveys nerve impulses for most somatic sensations from the face, nasal cavity, oral cavity and teeth to the cerebral cortex.

37. Somatic Sensory Pathways to the Cerebellum
The posterior spinocerebellar and the anterior spinocerebellar tracts are the major routes whereby proprioceptive impulses reach the cerebellum.
impulses conveyed to the cerebellum are critical for posture, balance, and coordination of skilled movements.
Subconscious information used by
cerebellum for adjusting posture, balance
& skilled movements
Signal travels up to same side inferior
cerebellar peduncle
Principles of Human Anatomy and Physiology, 11e

38. Somatosensory Map of Postcentral Gyrus
Relative sizes of cortical areas
proportional to number of sensory receptors
proportional to the sensitivity of each part of the body
Can be modified with learning
learn to read Braille & will have larger area representing fingertips
Principles of Human Anatomy and Physiology, 11e

39. Motor Pathways
CNS issues motor commands in response to information provided by sensory systems sent by the somatic nervous system (SNS) and autonomic nervous system (ANS)
SNS → skeletal muscle contraction
ANS→innervates visceral effectors (smooth muscle, cardiac muscle, glands)
Motor pathways usually contain 2 neurons
Somatic nervous system (SNS)
- upper motor neuron – cell body lies within the CNS
- lower motor neuron – located in a motor nucleus of the brain stem or SC only axon extends to the effector
Autonomic nervous system (ANS)
- preganglionic neuron
- ganglionic neuron

40. Somatic Motor Pathways
Upper motor neurons(UMN) → lower motor neurons(LMN) → skeletal muscles.
Neural circuits involving basal ganglia and cerebellum regulate activity of the upper motor neurons.
Lower motor neurons are called the final common pathway because many regulatory mechanisms converge on these peripheral neurons
Organization of Upper Motor Neuron Pathways:
Direct motor pathway- originates directly from the cerebral cortex.
Corticospinal pathway: to the limbs and trunk.
Corticobulbar pathway: to the head.
Indirect motor pathway- originates in the brain stem ; includes synapses
in basal ganglia, thalamus, reticular formation & cerebellum
Copyright 2009, John Wiley & Sons, Inc.

41. Principles of Human Anatomy and Physiology, 11e
Paralysis
Flaccid paralysis = damage lower motor neurons
no voluntary movement on same side as damage
no reflex actions
muscle limp & flaccid
decreased muscle tone
Spastic paralysis = damage upper motor neurons
paralysis on opposite side from injury
increased muscle tone
exaggerated reflexes
Principles of Human Anatomy and Physiology, 11e

42. Mapping of the Motor Areas
Located in the precentral gyrus of the frontal lobe.
More cortical area is devoted to those muscles involved in skilled, complex or delicate movements.

43. The Corticospinal Pathways
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44. The Corticobulbar Pathway
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45. Indirect or Extrapyramidal Pathways
Originate in the brain stem.
Include:
Rubrospinal tract
Tectospinal tract
Vestibulospinal tract
Reticulospinal tract
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46. Table 5.4 pt 1

47. Table 5.4 pt 2

48. Modulation of Movement from the Basal Ganglia and Cerebellum
basal ganglia help establish muscle tone & integrate semivoluntary automatic movements
cerebellum helps make movements smooth & helps maintain posture & balance
Basal ganglia and cerebellum provide input and control activity of upper motor neurons
Copyright 2009, John Wiley & Sons, Inc.

49. Sagittal
plane
Motor areas of
cerebral cortex
Corrective
feedback
Pons
Direct pathways
Indirect pathways
Signals to lower
motor neurons
Sagittal section through brain and spinal cord
Sensory signals from
proprioceptors in muscles
and joints, vestibular
apparatus, and eyes
Cortex of
cerebellum 1 2 4 3
Thalamus
Motor centers in
brainstem
Pontine nuclei
Sagittal
plane
Motor areas of
cerebral cortex
Corrective
feedback
Pons
Direct pathways
Indirect pathways
Signals to lower
motor neurons
Sagittal section through brain and spinal cord
Sensory signals from
proprioceptors in muscles
and joints, vestibular
apparatus, and eyes
Cortex of
cerebellum 1 2 3
Thalamus
Motor centers in
brainstem
Pontine nuclei
Sagittal
plane
Motor areas of
cerebral cortex
Corrective
feedback
Pons
Direct pathways
Indirect pathways
Signals to lower
motor neurons
Sagittal section through brain and spinal cord
Sensory signals from
proprioceptors in muscles
and joints, vestibular
apparatus, and eyes
Cortex of
cerebellum 1 2
Thalamus
Motor centers in
brainstem
Pontine nuclei
Sagittal
plane
Motor areas of
cerebral cortex
Thalamus
Corrective
feedback
Motor centers in
brainstem
Pons
Pontine nuclei
Direct pathways
Indirect pathways
Signals to lower
motor neurons
Sagittal section through brain and spinal cord
Sensory signals from
proprioceptors in muscles
and joints, vestibular
apparatus, and eyes
Cortex of
cerebellum 1

50. Principles of Human Anatomy and Physiology, 11e
Final Common Pathway
Lower motor neurons receive signals from both direct & indirect upper motor neurons
Sum total of all inhibitory & excitatory signals determines the final response of the lower motor neuron & the skeletal muscles
Principles of Human Anatomy and Physiology, 11e

51. Integrative Functions of the Cerebrum
Wakefulness and sleep-
Learning and memory-
Emotional responses
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52. Principles of Human Anatomy and Physiology, 11e
Wakefulness and Sleep
Role of the Reticular Activating System (RAS)
Sleep and wakefulness are integrative functions that are controlled by the reticular activating system
Arousal, or awakening from a sleep, involves increased activity of the RAS.
When the RAS is activated, the cerebral cortex is also activated and arousal occurs.
The result is a state of wakefulness called consciousness.
Principles of Human Anatomy and Physiology, 11e

53. Reticular Activating System
RAS has connections to cortex & spinal cord.
Many types of inputs can activate the RAS---pain, light, noise, muscle activity, touch
Coma is sleep-like state
A person in a deep coma has no reflexes.
Principles of Human Anatomy and Physiology, 11e

54. The role of Reticular Activating System (RAS) in Awakening
Consists of neurons whose axons project from the reticular formation through the thalamus to the cerebral cortex.
Increased activity of the RAS causes awakening from sleep (arousal).
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55. Copyright 2009, John Wiley & Sons, Inc.
Sleep
A state of altered consciousness.
Two components: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep.
NREM sleep consists of four stages:
Stage min transitional
Stage 2- light sleep
Stage 3- tem and blood pressure decrease, occures about 20 minutes after sleep
Stage 4- deepest – sleep walking lowest brain metabolism
Dreaming occurs during REM sleep
Triggers for sleep are unclear
adenosine levels increase with brain activity
adenosine levels inhibit activity in RAS
caffeine prevents adenosine from inhibiting RAS
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56. Non-Rapid Eye Movement Sleep
Stage 1
person is drifting off with eyes closed (first few minutes)
Stage 2
fragments of dreams
eyes may roll from side to side
Stage 3
very relaxed, moderately deep
20 minutes, body temperature
& BP have dropped
Stage 4 = deep sleep
bed-wetting & sleep walking
Principles of Human Anatomy and Physiology, 11e

57. Principles of Human Anatomy and Physiology, 11e
REM Sleep
Most dreams occur during REM sleep
In first 90 minutes of sleep:
go from stage 1 to 4 of NREM,
go up to stage 2 of NREM
to REM sleep
Cycles repeat until total REM sleep totals 90 to 120 minutes
Neuronal activity & oxygen use is highest in REM sleep
Total sleeping & dreaming time decreases with age
Principles of Human Anatomy and Physiology, 11e

58. Principles of Human Anatomy and Physiology, 11e
Learning and Memory
Learning is the ability to acquire new knowledge or skills through instruction or experience.
Memory is the process by which that knowledge is stored & retrieved.
For an experience to become part of memory, it must produce persistent functional changes that represent the experience in the brain.
The capability for change with learning is called plasticity.
Memory occurs in stages over a period and is described as immediate memory, short term memory, or long term memory.
Immediate memory is the ability to recall for a few seconds.
Short-term memory lasts only seconds or hours and is the ability to recall bits of information; it is related to electrical and chemical events.
Long-term memory lasts from days to years and is related to anatomical and biochemical changes at synapses.
Memory consolidation – frequent retrieval of a piece of information
Principles of Human Anatomy and Physiology, 11e

59. Learning & Memory Stimulus Sensory organs perception Sensory Memory
(millisecond-1)
attention
Short-Term Memory
Working Memory
(< 1 minute)
forgetting
repetition
Long-Term Memory
( days, months, years)

60. Amnesia – Loss of Memory
Anterograde amnesia - loss of memory for events that occur after the trauma; the inability to form new memories.
Retrograde amnesia - loss of memory for events that occurred before the trauma; the inability to recall past events.
Principles of Human Anatomy and Physiology, 11e