1. Chapter 10
Sensory Physiology

2. 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. General Properties of Sensory Systems
Stimulus
Internal
External
Energy source
Receptors
Sense organs
Transducer
Afferent pathway
CNS integration

4. The Human Brain

5. General Properties of Sensory Systems
Figure 10-4: Sensory pathways

6. Sensory Receptor Types
Simple receptors
Complex neural
Special senses
Chemoreceptors
Mechanoreceptors
Thermoreceptors
Photoreceptors

7. Sensory Receptor Types
Figure 10-1: Sensory receptors

8. The Cerebral Cortex Three kinds of functional areas Motor areas
Sensory areas
Association areas

9. Functional and Structural Areas of the Cerebral Cortex

10. Functional and Structural Areas of the Cerebral Cortex
Figure 13.11b

11. Special Senses – External Stimuli
Vision
Hearing
Taste
Smell
Equilibrium

12. Special Senses – External Stimuli
Figure 10-4: Sensory pathways

13. Sensory Areas – Sensory Homunculus
Figure 13.10

14. Motor Homunculus
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13.10

15. Homunculus

16. Somatic Senses – Internal Stimuli
Touch
Temperature
Pain
Itch
Proprioception
Pathway
Figure 10-10: The somatosensory cortex

17. Somatic Pathways Receptor Threshold Action potential Sensory neurons
Primary – medulla
Secondary – thalamus
Tertiary – cortex
Integration
Receptive field
Multiple levels

18. Somatic Pathways
Figure 10-9: Sensory pathways cross the body’s midline

19. Sensory Modality Location Lateral inhibition Receptive field Intensity
Duration
Tonic receptors
Phasic receptors
Adaptation

20. Touch (pressure) Mechanoreceptors Free nerve endings
Pacinian corpuscles
Ruffini corpuscles
Merkel receptors
Meissner's corpuscles
Baroreceptors

21. Touch (pressure)
Figure 10-11: Touch-pressure receptors

22. Temperature Free nerve endings Cold receptors Warm receptors
Pain receptors
Sensory coding:
Intensity
Duration

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

24. Pain and Itching
Nocioceptors
Reflexive path
Itch
Fast pain
Slow pain

25. Pathways of Itch from Skin to Brain.
Figure 1. Pathways of Itch from Skin to Brain. Itch originates in the epidermis and dermal–epidermal junction and is transmitted by itch-selective C nerve fibers. Some of these fibers are sensitive to histamine, but the majority are not. A complex interplay among T cells, mast cells, neutrophils, eosinophils, keratinocytes, and nerve cells (along with increased release of cytokines, proteases, and neuropeptides) leads to exacerbation of itch. The C fibers form synapses with second-order projections in the dorsal horn, and the itch signal ascends in the contralateral spinothalamic tract, with projections to the thalamus. From the thalamus, itch is transmitted to several regions of the brain that are involved in sensation, evaluative processes, emotion, reward, and memory.
Yosipovitch G, Bernhard JD. N Engl J Med 2013;368:

26. Gate Control Theory of Pain
Figure 10-12: The gate control theory of pain modulation

27. Pain Ischemia Other visceral pain Modulation Thalamus Gate control
Magnification
Analgesic drugs
Aspirin
Opiates

28. Referred Pain
Figure 10-13: Referred pain

29. Olfactor: Sense of Smell
Olfactory cell
Chemoreceptor- Humans have about 350 different types of odorant receptors, Mice 1200
Olfactory cilia
Olfactory bulb
Olfactory nerve
CNS integration
Amygdala
Hippocampus
Olfactory

30. Olfactor: Sense of Smell
Figure 10-14a, b: ANATOMY SUMMARY: Olfaction

31. Olfactor: Sense of Smell
Figure 10-14c: ANATOMY SUMMARY: Olfaction

32. Taste: Chemoreceptors
5 Tastes
Taste buds
Taste cells
Mechanism
Transduction
Integration
Thalamus
Gustatory cortex
"Specific hunger"
Figure 10-16: Summary of taste transduction

33. Hearing: Mechanoreceptors
Sound waves
Conduction
Air
Bone
Fluid
Membranes
To hair cell

35. Hearing: Mechanoreceptors
Figure 10-19: Sound transmission through the ear

38. Hearing: Hair Cell Transduction
Fluid wave moves
Tectoral membrane
Steriocilia move
Ion channels open
Depolarization
NT release
Sensory nerve AP

39. Hearing: Hair Cell Transduction
Figure 10-20: The cochlea

40. Hearing: Hair Cell Transduction
Figure 10-21: Signal transduction in hair cells

41. Hearing: Integration and Problems
Pitch
Intensity
Localization
Integration
Medulla
Thalamus
Auditory cortex
Deafness
Conductive
Sensorineural
Figure 10-5: Localization of sound

42. Hearing: Integration and Problems
Figure 10-22: Sensory coding for pitch

43. Equilibrium: Mechanoreceptor
Body balance
Body position
Body movement
Propioceptors
Vision
Vestibular apparatus

44. Equilibrium: Mechanoreceptor
Integration
Medulla
Cerebellum
Thalamus
Cortex
Figure 10-26: Central nervous system pathways for equilibrium

45. Equilibrium: Vestibular Apparatus
Otolith organs
Gravity
Calcite crystals
Hair cells
Semicircular canals
Endolymph Fluid moves which stimulates
Each Crista which consists of:
Cupula
Embedded Hair cells: activate CN VIII

46. 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)

47. Equilibrium: Vestibular Apparatus
Figure 10-23a, b: ANATOMY SUMMARY: Vestibular Apparatus

48. 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

49. Equilibrium: Vestibular Apparatus
Figure 10-23c, d: ANATOMY SUMMARY: Vestibular Apparatus

50. Vision: Photoreceptors
Reflected light translated into mental image
Pupil limits light, lens focuses light
Retinal rods and cones are photoreceptors
Figure 10-36: Photoreceptors in the fovea

52. Cataract

55. Retina (Right Eye)

56. Retina (Left Eye)

57. Hypercholesterolemia
Accumulations of lipids leak from surrounding capillaries and microaneuryisms, they may form a circinate pattern.

58. Hypertension

59. Proliferative diabetic retinopathy

60. Panretinal laser photocoagulation

61. Photoreception and Local Integration
Rods – night vision
Cones – color & details
Bipolar & ganglion cells converge, integrate APs

62. Photoreception and Local Integration
Figure 10-35: ANATOMY SUMMARY: The Retina

63. Retina: More Detail Rod cells: monochromatic
Cone cells: red, green, & blue
Discs: visual pigments
Pigmented epithelium
Melanin granules
Prevents reflection

64. Retina: More Detail
Figure 10-38: Photoreceptors: rods and cones

65. Phototransduction
Photons "bleach" opsin, retinal released, cascade, Na+ channel closes, K+ opens , hyperpolarization
Reduces NT release

66. Phototransduction
Figure 10-40: Phototransduction in rods

67. Vision: Integration of Signals to Perception
Bipolar
Ganglion
Movement
Color
Optic nerve
Optic chiasm
Optic tract
Thalamus
Visual cortex
Figure 10-29b, c: Neural pathways for vision and the papillary reflex

71. Summary Sensory pathway: receptor, sensory neuron(s) & CNS
Somatic senses: touch, temperature, pain & proprioception communicate body information to CNS
Special senses: taste, smell, hearing, equilibrium, & vision
Outside conditions for CNS integration into perception
Receptors transduce mechanical, chemical or photon energy into GPs then to APs