Chapter 10Chapter 10

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Dee Unglaub Silverthorn, Ph.D.

H ^UMAN P ^HYSIOLOGY H ^UMAN P ^HYSIOLOGY

PowerPoint^® Lecture Slide Presentation by

Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University

AN INTEGRATED APPROACH

T H I R D E D I T I O N

Chapter 10 Chapter 10

Sensory Physiology

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About this Chapter About this Chapter

• What are the senses

• How sensory systems work

• Body sensors and homeostatic maintenance

• Sensing the external environment

• Mechanisms and pathways to perception

(3)

• Stimulus

• Internal

• External

• Energy source

• Receptors

• Sense organs

• Transducer

• Afferent pathway

• CNS integration

General Properties of Sensory Systems

(4)

The Human

(5)

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• Simple receptors

• Complex neural

• Special senses

• Chemoreceptors

• Mechanoreceptors

• Thermoreceptors

• Photoreceptors

Sensory Receptor Types

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Sensory Receptor Types Sensory Receptor Types

Figure 10-1: Sensory receptors

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The Cerebral Cortex The Cerebral Cortex

• Three kinds of functional areas

• Motor areas

• Sensory areas

• Association areas: integrate incoming sensory information and also form

connections between sensory and motor

areas

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Functional and Structural Areas of the Cerebral Cortex

Functional and Structural Areas of the Cerebral

Cortex

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Functional and Structural Areas of the Cerebral Cortex

Functional and Structural Areas of the Cerebral

Cortex

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• Vision

• Hearing

• Taste

• Smell

• Equilibrium

Special Senses – External Stimuli

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Special Senses – External Stimuli

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Homunculus

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Sensory Areas – Sensory Homunculus

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Inc., publishing as Benjamin Cummings

Motor Homunculus Motor Homunculus

Figure 13.10

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• Touch

• Temperature

• Pain

• Itch

• Proprioception

• Pathway

Somatic Senses – Internal Stimuli

(17)

• Receptor

• Threshold

• Action potential

• Sensory neurons

• Primary – medulla

• Secondary – thalamus

• Tertiary – cortex

• Integration

• Receptive field

• Multiple levels Somatic Pathways

Somatic Pathways

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Somatic Pathways

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• Tonic receptors: Adapt slowly

• Phasic receptors: Adapt quickly Sensory Modality

Sensory Modality

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Sensory Modality Sensory Modality

Figure 10-3: Two-point discrimination

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• Mechanoreceptors

• Free nerve endings

• Pacinian corpuscles

• Ruffini corpuscles

• Merkel receptors

• Meissner's corpuscles

• Baroreceptors

Touch (pressure)

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Touch (pressure) Touch (pressure)

Figure 10-11: Touch-pressure receptors

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• Free nerve endings

• Cold receptors

• Warm receptors

• Pain receptors

• Sensory coding:

• Intensity

• Duration

Temperature

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Temperature Temperature

Figure 10-7: Sensory coding for stimulus intensity and duration

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• Nocioceptors

• Reflexive path

• Itch

• Fast pain

• Slow pain

Pain and Itching

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Pathways of Itch from Skin to Brain.

Yosipovitch G, Bernhard JD. N Engl J Med 2013;368:1625-1634.

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Gate Control Theory of Pain

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• Ischemia

• Other visceral pain

• Modulation

• Thalamus

• Gate control

• Magnification

• Analgesic drugs

• Aspirin

• Opiates Pain

Pain

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Referred Pain

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• Olfactory cell

• Chemoreceptor- Humans have about 400 different types of odorant receptors,

Mice 1200

• Olfactory cilia

• Olfactory bulb

• Olfactory nerve

• CNS integration

• Amygdala

• Hippocampus

• Olfactory

Olfactor: Sense of Smell

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Odor Receptors Odor Receptors

• According to an analysis of data derived from the human genome project, humans have approximately 400 functional genes coding for olfactory receptors

• Most odors activate more than one type of odor receptor

• The # of combinations and permutations of

olfactory receptors is almost limitless thus

the olfactory receptor system is capable of

detecting and distinguishing between a

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Olfactor: Sense of Smell Olfactor: Sense of Smell

Figure 10-14a, b: ANATOMY SUMMARY: Olfaction

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Olfactor: Sense of Smell

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• 5 Tastes

• Taste buds

• Taste cells

• Mechanism

• Transduction

• Integration

• Thalamus

• Gustatory cortex

• "Specific hunger"

Taste: Chemoreceptors Taste: Chemoreceptors

Figure 10-16: Summary of taste transduction

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Taste Receptor Physiology Taste Receptor Physiology

• In the last 15 years, advancements in molecular biology have unraveled the proteins that function as taste receptors. There are at least five taste qualities that are consciously perceived, sweet, sour, salty, bitter, and umami. Of these five, sour and salty are mediated by ion channels, whereas the perception of sweet, umami, and bitter tastes is mediated by G protein-

coupled receptors (GPCRs). These taste GPCRs belong to the TAS1R and TAS2R gene families. It has been suspected for more than a century that the gut can sense the chemical

composition of foods. The description of multiple taste GPCRs in gastrointestinal (GI) cells suggests that there are nutrient- sensing mechanisms in the GI tract, oral, gastric, and intestinal mucosa. Oral sensing seems to mainly influence food

discrimination and nutrient appetite, while post-oral

chemosensors may relate to nutrient utilization and inhibition

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• Sound waves

• Conduction

• Air

• Bone

• Fluid

• Membranes

• To hair cell

Hearing: Mechanoreceptors

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Hearing: Mechanoreceptors Hearing: Mechanoreceptors

Figure 10-19: Sound transmission through the ear

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• Fluid wave moves

• Tectoral membrane

• Steriocilia move

• Ion channels open

• Depolarization

• NT release

• Sensory nerve AP

Hearing: Hair Cell Transduction

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Hearing: Hair Cell Transduction Hearing: Hair Cell Transduction

Figure 10-20: The cochlea

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Hearing: Hair Cell Transduction

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• Pitch

• Intensity

• Localization

• Integration

• Medulla

• Thalamus

• Auditory cortex

• Deafness

• Conductive

• Sensorineural

Hearing: Integration and Problems Hearing: Integration and Problems

Figure 10-5: Localization of sound

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Localization of Sound Underwater Localization of Sound Underwater

• Hearing threshold and the ability to localize sound sources are reduced underwater. The resonance frequency of the external ear is lowered when the external ear canal is filled with water, and the

impedance-matching ability of the middle ear is significantly reduced due to elevation of the

ambient pressure, the water-mass load on the

tympanic membrane, and the addition of a fluid-air interface during submersion. Sound lateralization on land is largely explained by the mechanisms of intensity differences and temporal or phase

differences. During submersion, these differences

are largely lost due to the increase in underwater

sound velocity and cancellation of the head's

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Hearing: Integration and Problems Hearing: Integration and Problems

Figure 10-22: Sensory coding for pitch

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• Body balance

• Body position

• Body movement

• Propioceptors

• Vision

• Vestibular apparatus

Equilibrium: Mechanoreceptor

(49)

• Integration

• Medulla

• Cerebellum

• Thalamus

• Cortex

Equilibrium: Mechanoreceptor Equilibrium: Mechanoreceptor

Figure 10-26: Central nervous system pathways for equilibrium

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• Otolith organs: sense linear acceleration

• Gravity

• Calcite crystals

• Hair cells

• Semicircular canals: sense rotational acceleration

• Endolymph Fluid moves which stimulates Each Crista which consists of:

Cupula

Equilibrium: Vestibular Apparatus

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Semicircular Canals of the Vestibular Apparatus Semicircular Canals of the Vestibular Apparatus

• Have Posterior, Horizontal and Superior Semicircular Canals

• They sense Rotational Acceleration in various directions

• The Cristae within the Ampula (enlarged chamber at the end of each canal) are the sensory receptors

• Endolymph moves the gelatinous cupula with the hair cells embedded in it and

stimulates vestibulocochlear nerve (CN

VIII)

(52)

Equilibrium: Vestibular Apparatus

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Otolith Organs of the Vestibular Apparatus Otolith Organs of the Vestibular Apparatus

• Otolith Organs of the Utricle and Saccule Sense Linear Acceleration and Head

Position

• They are arranged horizontally (Utricle-if head tips back gravity causes othliths to slide) and vertically (Saccule-senses

vertical forces such as an elevator dropping)

• Macula are the sensory receptors of the utricle and saccule

• Otoliths are crystals that move in response

to gravitational forces

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Equilibrium: Vestibular Apparatus

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• Reflected light translated into mental image

• Pupil limits light, lens focuses light

• Retinal rods and cones are photoreceptors Vision: Photoreceptors

Vision: Photoreceptors

Figure 10-36: Photoreceptors in the fovea

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Cataract

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Retina (Right Eye)

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Retina (Left Eye)

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Hypercholesterolemia Hypercholesterolemia

• Accumulations of lipids leak from surrounding

capillaries and

microaneuryisms,

they may form a

circinate pattern.

(67)

Hypertension

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Proliferative diabetic retinopathy

(69)

Panretinal laser photocoagulation

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• Rods – night vision

• Cones – color & details

• Bipolar & ganglion cells converge, integrate APs

Photoreception and Local Integration

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Photoreception and Local Integration Photoreception and Local Integration

Figure 10-35: ANATOMY SUMMARY: The Retina

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• Rod cells: monochromatic

• Cone cells: red, green, & blue

• Discs: visual pigments

• Pigmented epithelium

• Melanin granules

• Prevents reflection Retina: More Detail

Retina: More Detail

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Retina: More Detail Retina: More Detail

Figure 10-38: Photoreceptors: rods and cones

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• Bipolar

• Ganglion

• Movement

• Color

• Optic nerve

• Optic chiasm

• Optic tract

• Thalamus

Vision: Integration of Signals to Perception

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Chapter 10Chapter 10

H UMAN P HYSIOLOGY H UMAN P HYSIOLOGY

Chapter 10 Chapter 10

Sensory Physiology

About this Chapter About this Chapter

• What are the senses

• How sensory systems work

• Body sensors and homeostatic maintenance

• Sensing the external environment

• Mechanisms and pathways to perception

• Stimulus

• Internal

• External

• Energy source

• Receptors

• Sense organs

• Transducer

• Afferent pathway

• CNS integration

General Properties of Sensory Systems

General Properties of Sensory Systems

The Human

• Simple receptors

• Complex neural

• Special senses

• Chemoreceptors

• Mechanoreceptors

• Thermoreceptors

• Photoreceptors

Sensory Receptor Types

Sensory Receptor Types

Sensory Receptor Types Sensory Receptor Types

The Cerebral Cortex The Cerebral Cortex

• Three kinds of functional areas

• Motor areas

• Sensory areas

• Association areas: integrate incoming sensory information and also form

connections between sensory and motor

areas

Functional and Structural Areas of the Cerebral Cortex

Functional and Structural Areas of the Cerebral

Cortex

Functional and Structural Areas of the Cerebral Cortex

Functional and Structural Areas of the Cerebral

Cortex

• Vision

• Hearing

• Taste

• Smell

• Equilibrium

Special Senses – External Stimuli

Special Senses – External Stimuli

Special Senses – External Stimuli

Special Senses – External Stimuli

Homunculus

Homunculus

Sensory Areas – Sensory Homunculus

Sensory Areas – Sensory Homunculus

Motor Homunculus Motor Homunculus

• Touch

• Temperature

• Pain

• Itch

• Proprioception

• Pathway

Somatic Senses – Internal Stimuli

Somatic Senses – Internal Stimuli

• Receptor

• Threshold

• Action potential

• Sensory neurons

• Primary – medulla

• Secondary – thalamus

• Tertiary – cortex

• Integration

• Receptive field

• Multiple levels Somatic Pathways

Somatic Pathways

Somatic Pathways

Somatic Pathways

H ^UMAN P ^HYSIOLOGY H ^UMAN P ^HYSIOLOGY