How is the mammalian eye adapted to its functions? (20M)

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Presence of 
🔷 Sclera/sclerotic  layer; made of tough white  fibrous  layer;  made  up  of  thick rigid  connective  tissue;  protects  the  eye; maintains  shape  of  eyeball to prevent distortion of the image; Opaque to prevent light penetration. 
🔷Cornea;  transparent;  curved/disc-shaped  layer;  that  allows  light  to  enter  the eye;  refracts  light  towards  the  retina for proper image formation;
🔷Conjunctiva;  delicate  membrane;  lining  the  inside  of  the eyelid; consists of relatively tough unkeratinized, both stratified squamous and stratified columnar epithelium, with interspersed goblet cells; the epithelial layer contains blood vessels, fibrous tissue, and lymphatic channels; protects  the  cornea/eye; releases mucus and tears to lubricate and clean the eye. 
 🔷Eyelids  and  eye  lashes;  thin  muscle  with  hairs;  protects  the cornea/eye  from  mechanical/chemical  damage/protects  the  eye  from  entry  of  foreign  particles; protects  retina  from  bright  light;
🔷Choroid;  dark  pigmented  and  membranous  layer;  that  prevents light  reflection  within  the  eye/absorbs  light;  to  prevent  distortion  of  the  image;  has  blood vessels;  that  nourish  eye/retina/supply  oxygen/remove  Carbon  (IV) Oxide  and  wastes;  extends to  form  the  ciliary  body  and  iris;
🔷Ciliary  muscles;  have  elastic  muscles  that  contract  and  relax; to  alter  shape/curvature  of  lens  during  accommodation;
🔷Ciliary  body;  thickened  front  edge  of the  choroid layer;  that  produces  aqueous  humour;
🔷Suspensory  ligaments;  made  up  of  elastic connective  tissue  whose  contraction  and  relaxation adjusts  the  shape  of  lens  during accommodation/holds  lens  in  position;
🔷Lens;  transparent;  biconvex;  balloon-like;  it  refracts light  rays/focus  light  onto  the  retina;
🔷Vitreous  humour;  nourishes  cornea/lens;  refraction  of light;  maintains  eyeball  shape;
🔷Iris;  thin  circular  ring;  with  circular  and  radial  muscles;  it  gives eye  colour/absorbs  light;  controls  the  amount  of  light  entering  the  eye/adjusts  size  of  pupil;
🔷Pupil;  an  aperture  through  which  light  enters  the  eye;
🔷Retina;  has  photoreceptor cells/rods/cones  for  image  formation;  generates  impulses  to  the  brain  for  interpretation;
🔷Fovea/Yellow  spot;  with  only  cones;  for  high  visual  acuity/most  sensitive  part  of  the  retina.
🔷Blind  spot;  point  where  nerve  fibres  emerge  from  the  optic  nerve/where  optic  nerve  leaves eye/point  where  nerve  fibres  and  blood  vessels  enter the  eye;
🔷Optic  nerve;  transmits  impulses to  the  brain;
🔷Muscles;  inferior  and  superior  oblique  muscles;  move  eye  from  left  to  right; superior  and  inferior  rectus  muscles;  move  the  eye  up  and  down;  external  and  internal  rectus muscles  steady  the  eye  in  its  up  and  down  movement; 
🔷Lachrymal  glands;  secrete  a  watery and    saline  fluid  containing  lysozymes/lytic  enzymes/is  antiseptic  (tears);  that  moisten  the conjunctiva  and  cornea;  washes  away  dust  and  other  foreign  objects;  kills  microorganisms entering  the  eye;  Max.  20  mks 

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