10 01 Mammalian Eye as a Sensory Organ

10. 01 Mammalian Eye as a Sensory Organ HKAL | Modern College

Session Objectives � Structure of Mammalian Eye � Functions vs. Structures � Accommodation � Next Session

Structure of Mammalian Eye

Structure of Mammalian Eye

Functions vs. Structures Structure 結構 Eyelid 眼瞼 Conjunctiva 結膜 Cornea 角膜 Function 功能 protects the cornea from mechanical and chemical damage and the retina from bright light by reflex action 保護角膜免受機械性或化學性損害，及透過反射動作保護視網膜 免受強光損害 thin transparent layer of cells protecting the cornea and continuous with the epithelium of eyelids 是透明的細胞薄層，保護角膜，與眼瞼的上皮相連 transparent front part of the sclera 是結膜的透明前部份 the curved surface acts as a main structure refracting (bending) light towards the retina 彎曲的表面作為主要結構以折射(扭曲)光線至視網膜 protect the front part of the eye 保護眼睛的前部份

Functions vs. Structures Structure 結構 Ciliary muscles & Suspensory ligament 睫狀肌及懸靭帶 Lens 晶體 Function 功能 contraction and relaxation of circular and radial muscles regulate the tension of the suspensory ligament which alters the shape of the lens 環肌及放射肌的收縮及放鬆會調節懸靭帶的張力，從而改變晶體 的形狀 transparent, elastic biconvex structure 是透明及富彈性的雙面凸透鏡結構 provides fine adjustment for focusing light on to the retina and separates the aqueous and vitreous humour 提供精確調節以聚焦光線至視網膜，以及分隔水狀液及玻璃狀液

Functions vs. Structures Structure 結構 Iris 虹膜 Pupil 瞳孔 Function 功能 circular muscle containing the pigment giving eye its color 是為環肌，載有色素，令眼睛有顏色 it separates the aqueous humour region into anterior and posterior chambers 分隔水狀液區域為前後間隔 controls the amount of light entering eye 控制進入眼睛的光線量 opening in iris, all light enters eye through this 虹膜的孔，光線經此進入眼睛

Functions vs. Structures Structure 結構 Choroid 脈絡膜 Retina 視網膜 Optic nerve 視神經 Blind spot 盲點 Fovea / yellow spot 黃點 Function 功能 rich in blood vessels supplying nutrient and oxygen to the retina 有大量血管以供應養份及氧氣予視網膜 covered with pigment cells preventing reflection of light within the eye 表面佈滿色素細胞，防止光線於眼睛內作反射 contains the photoreceptor cells, rods and cones 載有光感受器細胞，視桿細胞及視錐細胞 bundle of nerve fibers carrying impulses from the retina to the brain 神經纖維束，將視網膜的[神經]脈衝傳遞至腦部 point where the optic nerve leaves eye 是為視神經離開眼睛的點 there are no rods or cones here, therefore it is not light-sensitive 此處無視桿或視錐細胞，所以不對光線敏感 most sensitive part of retina, contains cones only 是為視網膜上最敏感的部份，只載有視錐細胞 most light rays are focused here 大部份光線均聚焦至此點

Functions vs. Structures Structure 結構 Aqueous humour 水狀液 Vitreous humour 玻璃狀液 Function 功能 clear solution of salts 清晰的鹽溶液 supply oxygen and nutrients to the conjunctiva, cornea and the lens 供應氧氣及養份至結膜，角膜及晶體 clear semi-solid substance 清晰的半固態物質 supporting the eyeball 支持眼球

Functions vs. Structures

Functions vs. Structures

Functions vs. Structures

Accommodation � It is a reflex mechanism by which light rays from an object are brought to focus on the retina 這是反射機制，可將來自物件的光束聚焦至視網膜上

Accommodation Light from Distant Object 來自遠方物件的光線 Light from Near Object 來自附近物件的光線 1) circular ciliary muscle relaxed 環睫狀肌鬆弛 2) suspensory ligament tauts (under tension) 懸靭帶蹦緊（張力） 1) circular ciliary muscle contracted 環睫狀肌收縮 2) suspensory ligament slacks 懸靭帶鬆弛 3) lens pulled out thin (less convex) 晶體拉緊變薄（凸出較少） 3) elastic lens restores its shape (more convex) 富彈性的晶體回復形狀（凸出較大） 4) light focused on retina 光線聚焦至視網膜 5) Divergence response 散開反應 Both eyes are directed at the distant object for better vision 兩眼會引導至遠方物件達致較佳視覺 4) light focused on retina 光線聚焦至視網膜 5) Convergence response 聚合反應 Both eyes are directed at the near object for better vision. 兩眼會引導至附近物件達致較佳視覺

Accommodation

Accommodation

Wrap Up

Next Session � Pupil Reflex � Vision � Day Vision � Light Vision � Night Blindness � Color Blindness � Other Eye Disorders