eye Flashcards
what are sensory organs
specialised organs providing interrelation between CNS and external and internal environment
what does a sensory analyser consist of
sensory organ - peripheral part
nerves - intermediate part
brain - different centres for analysis
where is the eye ball located
- peripheral part of visual analyser located in bony orbit
what is the function of the eyeball
- protects and supports photoreceptors
- gather, focus and process light into precise images
what are the 3 layers of the eyeballl
- external/ tunica fibrosa - sclera and cornea
- middle/ tunica vasculosa - choroid, ciliary body and iris
- inner - pigment epithelium and retina propria
what is the sclera
- soberest posterior 5/6 of the eyeball and forms white dense connective tissue
- moderate amount of ground substance
- few fibroblasts
what are the layers of the sclera
- episclera
- stroma/ sclera proper
- suprachoroid lamina/ lamina fusca
describe the episclera
- loose connective tissue
- has fibroblasts, macrophages, lymphocytes and vessels
describe stroma/ sclera proper
- strong irregular collagen fibres
- sparse fibroblasts
- low vessel content
describe suprachoroid lamina/ lamina fusca
- connects sclera to choroid
- loose connective tissue and melanocytes
describe the cornea
- transparent and colourless
- avascular
- covers anterior 1/6 of eyeball
what are the layers of the cornea
- anterior epithelium - stratified non keratinised
- anterior elastic lamina - collagen fibres
- stroma - lamellae and collagen 1 and 5 fibres
- posterior elastic lamina - collagen 7 fibres
- endothelium - simple squamous or low cuboidal
describe the middle layer/ chorioid proper
- located in posterior 2/3 of eye
- loose connective tissue with numerous vessels and melanocytes forming black layer
what are the layers of the choroid proper
- suprachroidal lamina
- vascular lamina
- choriocapillary lamina
- basal lamina
describe the suprachoroidal lamina of chorioid proper
- loose connective tissue
- melanocytes and fibroblasts
describe the vascular lamina of the choroid proper
- arteries and veins
- collagen and elastic fibres
- fibroblasts and melanocytes
describe the choriocapillary lamina of the choroid proper
- small fenestrated capillaries that nourish the outer retinal layer
describe the basal lamina of the choroid proper
- eosinophilic layer
- separates choroid from retina
- elastic and collagen fibres
what are the contents of the ciliary body/ middle layer
- ciliary muscle
- ciliary processes
describe ciliary processes
covered by epithelium
secretes aqueous humour into posterior chamber
what are the 2 layers of the ciliary epithelium
- non pigmented epithelium
- pigmented epithelium
describe the ciliary stroma
- smooth muscle
- fenestrated capillaries
what are the 3 functional portions of the ciliary muscle
- outer longitudinal or meridional
- radial
- circular
why is the ciliary muscles important
contraction and relaxation alter the convexity of the lens which is required for focusing on near and far objects