The Biology of Ageing Flashcards
what is the average life expectancy worldwide?
67.2
women live more
why do women live longer than men on average
- women have high levels of oestrogen so less likely to get cardiovascular disease
- women have lower iron levels than men due to menstruation.iron forms damaging free radicals
- young men engage in risky
behaviour. testosterone.
-one x chromosome for men so dangerous mutations expressed.
what happens toyou halth as you get older?
get more sick
why do e not live longer than 100 yrs?
- cell division mitosis decreases
- DNA is damaged by environment
- breakdown in the accuracy of protein synthesis
- decline in immune function.
As we age what are the cellular/morphological changes?
- cell loss in amitotic tissue such as corneal endothelium
- skeletal and smooth muscle loss (wasting of iris dilator)
- changes in cellular organelles (mitochondria and endoplasmic reticulum)
- accumulation of lipofusein.
- accumulation of advanced glycation end products (AGEs)
- irreversible DNA damage
What does AGEs cause in crystalline lens?
cross-linking between crystallines is associated with cataract.
what is a telomere?
repetitive nucleotide sequence at each end of chromosome.
non coding.
what happens to the telomeres as the cell divides?
ends of the chromosome are lost
what are the coding parts of the DNA protected by?
telomeres
how does the elastic tissue change?
wrinkles and loss of arterial elasticity which leads to increase in blood pressure with age.
what happens to enzymes as connective tissue changes?
enzymes that destroy collagen upregulated (ptosis)
what happens to cartilage as connective tissue changes?
osteoarthrosis
what happen to bones as connective tissue changes?
osteoporosis
what happens to hair as connective tissue changes?
hairloss and pigment goes
what happens to the reproductive system of females due to ageing?
menopause
what is multisensory deterioration?
taste,smell
hearing (presbycusis)
what happens as the immune system declines?
elderly more prone to cancer.
what is the proximate cause?
immediate trigger.
what is the ultimate cause?
evolutionary explanation
adaptive
What is antagonistic pleiotrophy?
genes beneficial early in life but dangerous effects i old age
what is neoplasia?
excessive cellular proliferation producing a tumour.
uncoordinated growth
what are oncogenes?
promote cell growth
what are tumour supressor genes?
inhibit cell division
what triggers neoplasia?
- viruses
- hereditary factors
- failure of immune system
- chemical carcinogens
- uv or x-ray radiation
what are benign tumours?
- don’t move from the site they arose
- slow rate growth
- capsulated
- cells resemble normal tissue
what are malignant tumours?
- invade other tissues
- rapid rate of growth
- encapsulated
- does not resemble normal tissue
what is the cell of origin of tumour?
e.g neuroma (neural)
what is the most common ocular tumour?
melanoma
where is melanoma found?
choroid
cilliary body
iris
what are intercranial tumours?
affect any point in the visual pathway ,as well as other areas of he brain associated with visual reflexes.
where do intercranial in adults come from?
in adults dont come from neuromas
come from :
10%meningiomas
65% gliomas
what is an Acoustic neuroma?
- survive
- 10%
- 4th and 5th decade of life
- arises from schwann cell on the vestibular part of 8th cranial nerve
- originates in internal acoustic meatus.
what does a large tumour do?
squashes cerebellum
what are the symptoms of acoustic neuroma?
- loss of hearing (8th)
- disturbances of balances (8th)
- facial palsy (7th)
- disturbances of taste (7th)
- odd facial sensation(5th)
- difficulty swallowing (10th)
- Ataxia (cerebellum) uncoordinated movements.
- intracranial pressure goes up (pressure on the optic nerve)
how does intracranial pressure build up?
cerebrous spinal fluid builds up and isn’t drained off.
what are the ocular symptoms of acoustic neuroma?
-inability to close eyelids due to the disruption of 7th nerve innervation of orbicularis oculi.
-reduced tear secretion (7th)
-loss of corneal sensation (5th)
loss of stability of surface of cornea(5th)
-affect on lateral rectus (6th)
how to alleviate symptoms of lack of eyelid closure?
- ointment,taping at night.
- surgical tarsorrhaphy
- botulinum toxin tarsorrhaphy
- insertion of weight into upper eyelid.
what is ectropian?
symptom of acoustic neuroma
lower eyelid droops down
what is epiphora?
watering of the eye
what should you do about a non functional 7th nerve?
- facial nerves usually regenerate
- Nerve graft to connect functional 7th nerve on non-functional side
- Facelifts (including gold weight in eyelid,Teflon plate in lower lid.)
where is the pituitary located/
below the Optic Chiasm
how does the pituitary tumour grow?
grows upwards impacting the chiasm.
pituitary tumours will compress which fibres first?
fibres originating from the nasal inferior retina of both retinae.causes bitemporal field defect.
what does compressing fibres on the ventral surface of the chiasm cause?
bilateral superior scotomas.
