Chapter 7

Transcription

1 Chapter 7 The Sensory Systems

2 Section A General Principles 理

3 I. Receptors () Receptors may be either specialized endings of afferent neurons or separate cells at the end of the neurons. 立

4 刺 量 (a) 刺 (b) 立 刺

5 (I) The Receptor Potential Receptors translate information from the external world and internal environment into graded potentials. 來

6 蘭 刺 刺 度

7 Receptor-potential magnitude and action-potential frequency increase as stimulus strength increases. 刺 度 度 率 Adaptation is a decrease in receptor sensitivity, which results in a decrease in the frequency of action potentials in an afferent neuron. 度 降 率 降

8 錄 刺 度

9 II. Primary Sensory Coding (I) Stimulus Type 刺 類 All receptors of a given sensory unit respond to the same stimulus modality. 刺 (II) Stimulus Intensity 刺 度 Stimulus intensity is coded by the rate of firing of individual sensory units and by the number of sensory units activated. 刺 度 率 數

10 力 力 不 度 力 刺

11 (III) Stimulus Location 刺 A stimulus may trigger activity in more than one sensory unit. 刺 不 刺 落 刺 不 度 率 不

12 Lateral inhibition is a means by which ascending pathways emphasize wanted information and increase sensory acuity. 行 路 度 路 路 率 A 兩 兩 路 B 度 不 A 兩 路 路 更 兩 路 異 了

13 (IV) Stimulus Duration 刺 Rapidly adapting receptors vs. Slowly adapting receptors vs.

14 (V) Central Control of Afferent Information Information coming into the nervous system is subject to control by both ascending and descending pathways. 行 行 路 行 路 (A) 來 (B) 來 行 路 (B) (A)

15 Section B Specific Sensory System

16 I. Somatic Sensation A () ( ) B ()( ) C 離 () D 狀 () ( 力 ) E 路 ()

17 狀

18 狀 ( )

19 不

20 (I) Touch-Pressure - Rapidly adapting receptors vibration, touch, movement Slowly adapting receptor pressure 力 (II) Sense of Posture and Movement A major receptor type responsible for the senses of posture and kinesthesia is the muscle-spindle stretch receptor.

21 (III) Temperature It is still unknown how heat or cold generate receptor potentials. 冷 不 (IV) Pain Tissue damage and immune cells release chemical agents that stimulate specific receptors that give rise to the sensation of pain. 泌 刺 The process of sensitization results in an increased sensitivity to painful stimuli (hyperalgesia). 刺 度 ()

22 Stimulation-produced analgesia, transcutaneous nerve stimulation (TENS) and acupuncture control pain by blocking transmission in the pain pathways. 刺 刺 路 來

23 II. Vision Visible spectrum 見 見 nm 不 不

24 (I) The Optics of Vision 狀 狀 狀

25 狀 a 狀 a 來 更 ( 離 )

26 The ciliary muscle, which is stimulated by parasympathetic nerves, draws nearer to the lens as it contracts, resulting in accommodation for viewing nearobjects. 狀 刺 狀

27 狀 狀

28 狀 狀 狀

29 The only lens cells that retain the capacity to divide are on the surface of the lens. With increasing age, the central part of the lens becomes denser and stiffer. The increasing stiffness makes accommodation for near vision difficult (presbyopia). 裂 力 年 狀 來 狀 老 來 老 An eyeball too long or too short relative to the focusing power of the lens causes nearsighted (myopic) or farsighted (hyperopic) vision, respectively. 狀 力

30 () ()

31 Stimulation of sympathetic nerves to the iris enlarges the pupil by causing the radially arranged muscle fibers to contract. 刺 列 The choroid prevents light reflection back to the photoreceptor cell.

32 (II) Photoreceptor Cells ( )

33 The photopigments of the rods and cones are made up of a protein component (opsin) and a chromophore (retinal). () ( ) The rods and each of the three cone types have different opsins, which make each of the four receptor types sensitive to different wavelengths of light. 不 不 不 不

34 When light falls upon the chromophore, the photic energy causes the chromophore to change shape, which triggers a cascade of events leading to hyperpolarization of the photoreceptors and decreased neurotransmitter release from them. 落 量 狀 連 串

35 ( ) ( ) 列 Light path 路 Light path 路 Light path 路

36 (III) Neural Pathways of Vision 路 刺 () 路 流 狀 路 聯

37 The optic-nerve fibers from half of each retina cross to the opposite side of the brain in the optic chiasm. 來 數 Coding in the visual system occurs along parallel pathways, in which different aspects of visual information, such as color, form, movement, and depth, are kept separate from each other. 路 行 不 例 狀 度 行

38 (IV) Color Vision Different wavelengths excite one of the three cone photopigments most strongly. 不 刺 類

39 (a) Some ganglion cells receive input from all three types of cones. (b) Opponent color ganglion cells are excited by input from one type of cone cell and inhibited by input from a different cone type. 來 若

40 藍 (a) 藍 刺 率 (b) 刺 (c) 藍 刺 不

41 (V) Eye Movement Six skeletal muscles control eye movement to scan the visual field for objects of interest, keep the fixation point focused on the fovea centralis despite movements of the object or the head, prevent adaptation of the photoreceptors, and move the eyes during accommodation. 六 論 了

42

43 III. Hearing (I) Sound The Freauencies audible to human beings extend from 20 to 20,000 Hz. 率 20 Hz. 20,000 Hz.

44 (II) Sound Transmission in the Ear 咽 () 廓 ( 卵 )

45 Because liquid is more difficult to move than air, the sound pressure transmitted to the inner ear must be amplified. 更 卵 力 力 卵 卵

46 卵

47 Each part of the basilar membrane vibrates maximally in response to one particular sound frequency. 不 率 卵

48 (III) Hair Cells of the Organ of Corti 立

49 (IV) Neural Pathways in Hearing 路 The different arrival times of low-frequency sounds and the difference in intensities of highfrequency sounds are used to determine the direction of the sound. 利 度

50 IV. Vestibular System

51 兩

52 (I) The Semicircular Canals The semicircular ducts detect angular acceleration during rotation of the head. 度 (a) (b) 狀

53 (a) (b) 了 率 (c) 率 () 刺 ( ) ( ) 率

54 (II) The Utricle and Saccule Otoliths in the gelatinous substance of the utricle and saccule move in response to changes in linear acceleration and the position of the head relative to gravity. 度 力

55 (III) Vestibular information amd Pathways (1)to control eye muscle (2) to maintain upright posture 立 (3) to provide conscious awareness of the position and acceleration of the body. 度

56 V. Chemical Senses (I) Taste

57 Different types of taste receptors operate by different mechanisms. 不 不 eg. Salt test ion channel Sweet test second-messenger 離

58 (II) Smell ( )

59 Odorant molecules bind to specific receptors (protein binding sites). Each olfactory receptor cell has one of the 1000 different receptor types. ( ) Olfactory pathways go to the limbic system. 路