AED - Cell Injury II - Week 1 Flashcards
Define hypoxia.
Lack of sufficient oxygen to maintain normal cell function.
Define anoxia.
Total lack of oxygen
What is the most common cause of cell injury?
Hypoxia
List 4 causes of hypoxia.
Reduced atmospheric oxygen (altitude)
Relatively less RBCs in the bloodstream (leukaemia)
Abnormal haemoglobin (sickle cell disease)
Reduced blood supply (ischaemia)p
What is the most common cause of hypoxia?
Ischaemia
List 4 cellular consequences of ischaemic hypoxia.
Severe vacuolisation of mitochondria
Membrane damage
Nuclear chromatin clumping
Release of lysosomal enzymes
What are the three main ocular structures affected by hypoxia in the eye?
Cornea
Retina
Optic nerve
What are retinal and optic nerve hypoxia usually related to?
Ischaemia or other blood disorders.
Where does the cornea get its nutrients from?
Largely from the aqueous humour
Where does the cornea get its oxygen from (2)?
Atmosphere and aqueous humour
What are the two most common causes of corneal hypoxia?
Lid closure from sleep (very mild) and contact lens wear
Is restoration of normal oxygen levels to hypoxic tissue generally good? Explain the consequences (2).
Generally is good but:
-Restoration of oxygen to a tissue that contains dead or dying cells means that oxygen is initially used more vigorously by mitochondria
–Increases generation of free radicals and reduces antioxidant efficiency
-Contents of dead cells may have secondary toxic/excitotoxic effects on recovering cells leading to secondary apoptosis
List 7 symptoms of contact lens related hypoxia.
Reduced VA
Corneal oedema
Epithelial erosion (SPK)
Epithelial microcysts
Endothelial blebs
Stromal striae
Limbal neovascularisation
What happens to the corneal epithelium with corneal hypoxia?
It shrinks, despite the cornea overall swelling
What happens to cell-cell junctions of the corneal epithelium with hypoxia? What does this lead to?
They are reduced, leading to loss of cells from the surface - desquamation