Principles of Human Anatomy and Physiology, 11e1 Chapter 16 Sensory, Motor & Integrative Systems.
Chapter 16: Sensory, Motor, and Integrative Systems Copyright 2009, John Wiley & Sons, Inc.
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Transcript of Chapter 16: Sensory, Motor, and Integrative Systems Copyright 2009, John Wiley & Sons, Inc.
Chapter 16: Sensory, Motor,
and Integrative Systems
Copyright 2009, John Wiley & Sons, Inc.
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
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.
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 4
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
Principles of Human Anatomy and Physiology, 11e 5
Copyright 2009, John Wiley & Sons, Inc.
Structural Classification of Receptors
skin, bones, internal organs, joints
Naked nerve endings surrounded by one or more layers
Pacinian corpuscle
Free nerve endings
Encapsulated Nerve Encapsulated Nerve
EndingsEndingsvsUnencapsulated Unencapsulated
Nerve EndingsNerve Endings
Deeper tissue, muscles
free nerve endings
root hair plexus
Meissner’s corpuscles
Pacinian corpuscles
Ruffini corpuscle
Merkel disc
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 9
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 10
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 11
Table 15.1 pt 1
Table 15.1 pt 2
Table 15.1 pt 3
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
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
Sensory Receptors in the Skin
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
Thermal Sensations
Thermoreceptors are free nerve endings. Two distinct thermal sensations:
cold receptors-
warm receptors-
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
Distribution of Referred Pain
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Proprioceptive Sensations
Receptors are called proprioceptors. Slow adaptation. Weight discrimination. Three types: muscle spindles, tendon organs
and joint kinesthetic receptors.
Copyright 2009, John Wiley & Sons, Inc.
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.
Copyright 2009, John Wiley & Sons, Inc.
A Muscle Spindle and a Tendon Organ
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.
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.
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.
33
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.
Copyright 2009, John Wiley & Sons, Inc.
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.
Trigeminothalamic Pathway
Conveys nerve impulses for most somatic sensations from the face, nasal cavity, oral cavity and teeth to the cerebral cortex.
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 37
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 38
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
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.
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 41
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.
The Corticospinal Pathways
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The Corticobulbar Pathway
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Indirect or Extrapyramidal Pathways
Originate in the brain stem. Include:
Rubrospinal tract Tectospinal tract Vestibulospinal tract Reticulospinal tract
Copyright 2009, John Wiley & Sons, Inc.
Table 5.4 pt 1
Table 5.4 pt 2
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.
Sagittalplane
Motor areas ofcerebral cortex
Thalamus
Correctivefeedback
Motor centers inbrainstem
Pons
Pontine nuclei
Direct pathways
Indirect pathways
Signals to lowermotor neurons
Sagittal section through brain and spinal cord
Sensory signals fromproprioceptors in musclesand joints, vestibularapparatus, and eyes
Cortex ofcerebellum
1
Sagittalplane
Motor areas ofcerebral cortex
Correctivefeedback
Pons
Direct pathways
Indirect pathways
Signals to lowermotor neurons
Sagittal section through brain and spinal cord
Sensory signals fromproprioceptors in musclesand joints, vestibularapparatus, and eyes
Cortex ofcerebellum
1
2
Thalamus
Motor centers inbrainstem
Pontine nuclei
Sagittalplane
Motor areas ofcerebral cortex
Correctivefeedback
Pons
Direct pathways
Indirect pathways
Signals to lowermotor neurons
Sagittal section through brain and spinal cord
Sensory signals fromproprioceptors in musclesand joints, vestibularapparatus, and eyes
Cortex ofcerebellum
1
2
3
Thalamus
Motor centers inbrainstem
Pontine nuclei
Sagittalplane
Motor areas ofcerebral cortex
Correctivefeedback
Pons
Direct pathways
Indirect pathways
Signals to lowermotor neurons
Sagittal section through brain and spinal cord
Sensory signals fromproprioceptors in musclesand joints, vestibularapparatus, and eyes
Cortex ofcerebellum
1
2
4
3
Thalamus
Motor centers inbrainstem
Pontine nuclei
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 50
Integrative Functions of the Cerebrum Wakefulness and sleep- Learning and memory- Emotional responses
Copyright 2009, John Wiley & Sons, Inc.
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 52
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 53
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).
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 1- 1-7 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
Copyright 2009, John Wiley & Sons, Inc.
Non-Rapid Eye Movement Sleep Stage 1
person is drifting off with eyesclosed (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 56
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 57
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 58
Learning & Memory
Sensory organs
StimulusStimulus
Sensory Memory(millisecond-1)
Sensory Memory(millisecond-1)
Short-Term MemoryWorking Memory
(< 1 minute)
Short-Term MemoryWorking Memory
(< 1 minute)
Long-Term Memory( days, months, years)Long-Term Memory
( days, months, years)
perception
attention
forgettingrepetition
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 60