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Physiology XiaoLan HU (胡晓兰), MD & PhD

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Presentation on theme: "Physiology XiaoLan HU (胡晓兰), MD & PhD"— Presentation transcript:

1 Physiology XiaoLan HU (胡晓兰), MD & PhD
Associate Professor of Department of Physiology

2 Two Chapters Functions of the Sensory Organs
Functions of the Nervous System

3 Functions of the Sensory Organs
Section 1: Physiology of the Receptor and Sensory Organs Section 2: Somatic Sensation Section 3: Visual Function of the Eye Section 4: Function of the Auditory System Section 5: Vestibular function

4 Section 1: Physiology of the Receptor and Sensory Organs
What is Receptor? Some structure or device that is distributed inside body surface or internal tissue, specifically sense the change from internal and external environment.

5 Pacinian corpuscle Meissner's corpuscle Muscle spindle
Section 1: Physiology of the Receptor and Sensory Organs Pacinian corpuscle Meissner's corpuscle Muscle spindle

6 Section 1: Physiology of the Receptor and Sensory Organs

7 Classification of Receptors
Section 1: Physiology of the Receptor and Sensory Organs Classification of Receptors 1.By Location Exteroceptor: Visceral receptor: Proprioceptor: receive 2. By Stimulus Type *Mechanoreceptor:. *Thermoreceptor: *Nociceptor : *Photoreceptor: *Chemoreceptor: 3. By Complexity *Simple receptor: *Complex receptor:

8 Adequate Stimulus of the receptor
Section 1: Physiology of the Receptor and Sensory Organs Adequate Stimulus of the receptor Conception: each receptor has its own the most sensitive stimulus. when the stimulus act on some receptors, the minimal intensity stimulus that can cause the corresponding sensation, is called adequate stimulus of the receptor.

9 Sensory threshold Intensity threshold: Temporal threshold:
Section 1: Physiology of the Receptor and Sensory Organs Sensory threshold Intensity threshold: Temporal threshold: Area threshold: Discrimination threshold:

10 Transducer function of the receptor
Section 1: Physiology of the Receptor and Sensory Organs Transducer function of the receptor Conception: Receptor detect a stimulus and convert the stimulus energy (light, pressure) into electrical signals (action potentials) in afferent nerve, this kind of energy conversion is called transducer function of the receptor. brain only deals with bioelectrical impulses so transducer must occur Sense organs convert sensory energy into neural (bioelectrical) energy transduction process is that one type energy is converted into another type energy

11 Transducer function of the receptor
Section 1: Physiology of the Receptor and Sensory Organs Transducer function of the receptor Receptor potential and generator potential Receptor potential: membrane potential in receptor cells. Generator potential: membrane potential in afferent nerve endings. Features of receptor potential: like local potential  Not “all or nothing”  Electrotonic propagation  Temporal & spatial summation

12 Coding function of the receptor
Section 1: Physiology of the Receptor and Sensory Organs Coding function of the receptor Conception: Receptors not only convert the external stimulus into nerve action potential, but also convert the environmental changes into the sequence of action potential signals, this is the coding function of the receptor. In same sensory system, stimulus intensity or quantity are how to be coded?

13 Code pattern of stimulus intensity in the frog muscle spindle
Section 1: Physiology of the Receptor and Sensory Organs Code pattern of stimulus intensity in the frog muscle spindle Dynamic stage Static stage time Tetrodotoxin Frequency of action potentials Receptor potential Receptor potential Stimulus (stretch) Stimulus (Stretch) stimulus intensity can be encoded by the frequency of action potential in single nerve fiber

14 Adaptation of the receptor
Section 1: Physiology of the Receptor and Sensory Organs Adaptation of the receptor Conception: When a fixed strength stimulus act on a receptor, the frequency of the action potentials in afferent nerve fiber will gradually reduce. This phenomenon is called adaptation of the receptor Classification: rapidly adapting receptor(touch) and slowly adapting receptor(stretch and pressure )

15 General Characteristics of the Receptors
Section 1: Physiology of the Receptor and Sensory Organs General Characteristics of the Receptors Adequate Stimulus of the receptor Transducer function of the receptor Coding function of the receptor Adaptation of the receptor

16 Section 2: Somatic Sensation
Conception: The body accept different stimulus through the skin receptors and its affiliation, and produce various kinds of sensation Classification: Superficial somatic sensation: touch or pressure, temperature and pain Deep somatic sensation: proprioception (position and movement )

17 Proprioception Conception:
Section 2: Somatic Sensation Proprioception Conception: Proprioceptor: in the muscle, tendon and joint Muscle spindle: Tendon organ:

18 Section 2: Somatic Sensation
Touch and pressure Conception: a kind of sensation that caused by mechanical stimulus (touch and pressure) Receptor types:

19 Touch and pressure Adequate stimulus: mechanical stimulus Mechanism.
Section 2: Somatic Sensation Touch and pressure Adequate stimulus: mechanical stimulus Mechanism.

20 Temperature Conception: caused by cold and warm stimulus
Section 2: Somatic Sensation Temperature Conception: caused by cold and warm stimulus Receptor: cold receptor and warm receptor. Warm receptor is free nerve endings, the warm sensory signals are transmitted by C fibers Cold receptor is also free nerve endings, the cold sensory signals are transmitted by Aδ fibers Which factors will impact on our temperature senses? When we have a temperature senses?

21 Section 2: Somatic Sensation
Pain Conception: caused by internal and external noxious stimulus, often accompanied by emotion activities and defense response. Biological significance: defense response Receptor: nociceptor The characteristics of nociceptor: *No adequate stimulus. *Slowly adapting receptor. Discovered by Charles Scott Sherrington in 1906

22 Pain Classification of nociceptor
Section 2: Somatic Sensation Pain Classification of nociceptor *Mechanical nociceptor: only response to strong mechanical stimulus. Especially sensitive to needle stimulus *Mechanical temperature nociceptor: moderate responses to mechanical stimulus, especially responses to the temperature between 40 and 51 ℃ stimulus. With the temperature increase , reaction gradually strengthen *Polymodal nociceptor: responses to various nociceptive stimulus(mechanical, warm, and chemical ), is widely distributed in the skin, skeletal muscle, joint and internal organs.

23 Pain The afferent fibers of pain sense
Section 2: Somatic Sensation Pain The afferent fibers of pain sense Aδ fibers for fast pain & C fibers for slow pain Fast pain Slow pain Time early late Property sharp stabbing pain burning dull pain pathway specific projection system non specific projection system area first somatic sensory area secondary somatic sensory area 、limbic lobe characteristic Clear both sense and location Fast both appear and disappear Without a obvious emotional reaction unclear both sense and location slow both appear and disappear With a strong emotional reaction

24 Pain Algogenic substance Conception: Classification:
Section 2: Somatic Sensation Pain Algogenic substance Conception: Classification: Exogenous algogenic substance: Endogenous algogenic substance:

25 Somatic Sensation Proprioception Touch and pressure Temperature Pain
Section 2: Somatic Sensation Somatic Sensation Proprioception Touch and pressure Temperature Pain

26 Section 3: Visual Function of the Eye

27 Section 3: Visual Function of the Eye
1.Dioptric System of Eye and its regulation 2.Photosensory and Transduction System of Eye 3. Other Visual Phenomena

28 Dioptric System of Eye and its regulation
Section 3: Visual Function of the Eye Dioptric System of Eye and its regulation Optic Characteristics of Dioptric System Reduced Eye Accommodation of Eye Error of eye refractive power

29 Optic characteristics of dioptric system
Section 3: Visual Function of the Eye Optic characteristics of dioptric system Dioptric System: Four refractive interface : anterior surface of cornea posterior surface of cornea anterior surface of crystalline lens posterior surface of crystalline lens

30 Optic characteristics of dioptric system
Section 3: Visual Function of the Eye Optic characteristics of dioptric system According to the calculating results from the geometrical optical principle, when normal adult eyes do not accommodate under quiet condition, the posterior focus of dioptric system just is on the retina. In the normal eye, light from an object more than 6 meters away may be considered as parallel rays, automatic focusing on the posterior focus (on the retina) to produce a clear image

31 Dioptric System of Eye and its regulation
Section 3: Visual Function of the Eye Dioptric System of Eye and its regulation Reduced Eye ab bn = Bn AB

32 Accommodation of Eye Far point of vision: Near point of vision:
Section 3: Visual Function of the Eye Accommodation of Eye Far point of vision: Near point of vision: The process that near objects are brought to a focus on the retina is called accommodation of eye, including the accommodations of crystalline lens, accommodation of pupil, and convergence reflex.

33 Accommodation of Eye 1. Accommodation of crystalline lens
Section 3: Visual Function of the Eye Accommodation of Eye 1. Accommodation of crystalline lens crystalline lens is a transparent, elastic ,biconvex lens

34 Accommodation of Eye 1. Accommodation of crystalline lens
Section 3: Visual Function of the Eye Accommodation of Eye 1. Accommodation of crystalline lens *The accommodation is mainly through increasing lens curvature . *The accommodation power is limited. If a object is close enough to the eye, the increased refractive power of the lens can not overcome the light divergence, and the object image will be blurred. *at near point. the accommodation is at a maximum.

35 Accommodation of Eye 2. Accommodation of pupil
Section 3: Visual Function of the Eye Accommodation of Eye 2. Accommodation of pupil Types: Pupillary accommodation reflex, Pupillary light reflex, Consensual pupillary light reflex

36 Pupillary accommodation reflex
Section 3: Visual Function of the Eye Pupillary accommodation reflex Conception: when eyes see the near object, pupil size will be reduced though neural reflex. Function: reduce the amount of light entering the eyes and reduce the spherical/chromatic aberration of dioptric system, the image on the retina is more clear.

37 Accommodation of Eye 3. Convergence reflex
Section 3: Visual Function of the Eye Accommodation of Eye 3. Convergence reflex Conception: When the eyes look at a object that move from far to near, optic axis will converge to the nasal side. Function: eyes see near object, through convergence reflex, the object can fall on symmetric point of two retina, avoiding diplopia.

38 Dioptric System of Eye and its regulation
Optic Characteristics of Dioptric System Reduced Eye Accommodation of Eye Error of eye refractive power

39 Error of refractive power
Section 3: Visual Function of the Eye Error of refractive power What is emmetropia? What is ametropia? when the dioptric power of eye is abnormal or the morphology of eye is abnormal, the parallel light rays can not be focused on the retina, this eyes are called ametropia, including myopia, hyperopia and astigmatism.

40 Section 3: Visual Function of the Eye
Myopia Conception: because the axial length of eyes are too long or the refractive power of lens are too strong, when eyes see far object, the parallel light focus in front of retina to form blurred image. Types: axial myopia and refractive myopia

41 Section 3: Visual Function of the Eye
Hyperopia Conception: because the axial length of eyes are too short or the refractive power of lens are too weak, when eyes see far object, the parallel light focus at back of retina to form blurred image. Types: axial hyperopia and refractive hyperopia

42 Section 3: Visual Function of the Eye
Astigmatism Conception:because the curvature of the cornea or lens are abnormal , Light from different direction do not be focused in the same point, form the blurred image or deformed image. Astigmatism can be corrected by the cylindrical lens.

43 Dioptric System of Eye and its regulation
Section 3: Visual Function of the Eye Dioptric System of Eye and its regulation Optic Characteristics of Dioptric System Reduced Eye Accommodation of Eye Error of refractive power

44 Section 3: Visual Function of the Eye
Dioptric System of Eye and its regulation Photosensory and Transduction System of Eye Other Visual Phenomena

45 Photosensory and Transduction System of Eye
Section 3: Visual Function of the Eye Photosensory and Transduction System of Eye Structure of Retina Two Photoreceptor System of Retina Mechanism of Photoreception of the Rod The Cone System and Color Vision

46 Structure and function of Retina
Section 3: Visual Function of the Eye Structure and function of Retina Thickness of retina is only mm

47 Main functions of four layers
Section 3: Visual Function of the Eye Main functions of four layers Pigment epithelium: Pigment epithelium do not belong to the nerve tissue, this layer contain melanin granules and VitA that have protective and nutritional effects on photoreceptor cells. Features of the layer are easy to cause detachment. In clinical practice, we see the retinal detachment, happen in this layer. Photoreceptor cell layer:: rods and cones, sensitive to light, are connected with bipolar cell through chemical synaptic connection. Bipolar cell layer: carry signal from photoreceptor to ganglion cell. Ganglion cell layer : axon of ganglion cell form the optic nerve.

48 The distribution of rod and cone cells
Section 3: Visual Function of the Eye The distribution of rod and cone cells

49 The structure of rod cells
Section 3: Visual Function of the Eye The structure of rod cells

50 The structure of cone cells
Section 3: Visual Function of the Eye The structure of cone cells synaptic terminal

51 Connection of two photosensitive cells with bipolar cells
Section 3: Visual Function of the Eye Connection of two photosensitive cells with bipolar cells Vertical connection. Horizontal connection

52 Rods Cones Quantity Outer segment Distribution Connection
Section 3: Visual Function of the Eye Rods Cones Quantity Many(1.2x108) Few(6x106) Outer segment Like rod Like cone Distribution More numerous in periphery Concentrated in fovea Connection Much convergence in retina Little convergence in retina Visual pigment Rhodopsin Three cone pigments Function Night vision Day vision Low acuity Vision in shades of gray High sensitivity High acuity Color vision Low sensitivity

53 What is physiological blind spot?
Section 3: Visual Function of the Eye What is physiological blind spot? Cones Rods Nasal retina Temporal retina Distance from the fovea number of the rods and cones Blind Distribution of cones and rods in the retina

54 Cones system Rods system
Section 3: Visual Function of the Eye Cones system Rods system Distribution Fovea and macular 6mm far away from the fovea Synaptic connections cone-bipolar-ganglion rod-bipolar-ganglion Characteristic of connections Single Convergent Characteristics of function Low sensitivity High sensitivity Bright light Dim light High acuity Low acuity Photopic vision ,color Scotopic vision, no color Photopigment Porphyropsin , iodopsin and cyanopsin Rhodopsin

55 Mechanism of Photoreception of the Rod
Section 3: Visual Function of the Eye Mechanism of Photoreception of the Rod 1. Photochemical Reaction of Rhodopsin . the outer segment of rod cells have photopigment, Photopigment is the rhodopsin. Rhodopsin is a binding protein . Rhodopsin opsin retinal VitA

56 Mechanism of Photoreception of the Rod
Section 3: Visual Function of the Eye Mechanism of Photoreception of the Rod 1. Photochemical Reaction of Rhodopsin . Rhodopsin opsin + retinal light

57 Rhodopsin Cycle Section 3: Visual Function of the Eye
outer segment of rod cells

58 Mechanism of Photoreception of the Rod 2. Receptor Potential of Rods.
Section 3: Visual Function of the Eye Mechanism of Photoreception of the Rod 2. Receptor Potential of Rods.

59 The Cone System and Color Vision
Section 3: Visual Function of the Eye The Cone System and Color Vision Photochemical components of cones: opsin and retinal. Three kinds cone pigments: the slight difference of opsin in molecular structure. Receptor Potential of cones: the hyperpolarization potentials, is similar to the receptor potential of rods. Through converting light energy into electric energy, finally generate action potentials in the ganglion cells.

60 The Cone System and Color Vision
Section 3: Visual Function of the Eye The Cone System and Color Vision Trichromatic theory of color vision Experimental evidence

61 The Cone System and Color Vision
Section 3: Visual Function of the Eye The Cone System and Color Vision Trichromatic Theory of Color Vision Cone cells (Porphyropsin) (Iodopsin) (cyanopsin) Sensation 4 1 red 2 8 green 15 blue white

62 The Cone System and Color Vision
Section 3: Visual Function of the Eye The Cone System and Color Vision 2. Color Blindness Conception: a kind of dyschromatopsia that caused by the lack of ability to distinguish all the colors or certain colors. Rare only dark and light monochromatic vision Total color blindness Types: red blindness green blindness blue blindness Partial color blindness

63 The Cone System and Color Vision
Section 3: Visual Function of the Eye The Cone System and Color Vision 2. Color Blindness Cause: a kind of genetic disease Characteristic: male>female. Sex-linked condition: Genes on X chromosome, so more common in men. red blindness: missing red photopigment green blindness: missing green photopigment Non-sex-linked condition Blue blindness: missing blue photopigment or blue cones Total color blindness: more severe

64 The Cone System and Color Vision
Section 3: Visual Function of the Eye The Cone System and Color Vision 3. Color feebleness Conception: The ability to distinguish certain color is slightly worse than that of normal person. Cause: mostly caused by acquired factors. .

65 Ishihara test for color blindness
Section 3: Visual Function of the Eye Ishihara test for color blindness Ishihara test is invented by Ishihara Shinobu, a professor of Tokyo University in Japan. The testing tool is a series of color plate , known as the "Ishihara plate". one of Ishihara plate

66 Photosensory and Transduction System of Eye
Section 3: Visual Function of the Eye Photosensory and Transduction System of Eye Structure of Retina Two Photoreceptor System of Retina Mechanism of Photoreception of the Rod The Cone System and Color Vision

67 Section 3: Visual Function of the Eye
Dioptric System of Eye and its regulation Photosensory and Transduction System of Eye Other Visual Phenomena


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