The physiology of ageing Flashcards
What are the effects of ageing?
Increased reliance of homeostatic reserves
Variable reduction in most organ function
Loss of functional reserve
Reduction in repair mechanisms
Increased prevalence of systemic disease
What are the theories of ageing?
Error theory
Free radical theory
Immune theory
Programmed theory of ageing – changes in cell replication
Neuroendrocrine theory
How is the cardiovascular system affected with age?
Artery stiffening -> Increased systolic arterial pressure
What are the consequences of increased systolic arterial pressure?
Increased systemic vascular resistance -> increased cardiac afterload -> increase left atrial size -> delayed relaxation and diastolic dysfunction (drdd) [drdd -> myocyte hypertrophy -> prolonged contraction -> drdd]
Systolic hypertension -> LVH
Changes result in decreased stroke volume
Attenuated increase in cardiac output during exercise
Reduced atrial pacemaker cells
How is the nervous system affected with age?
30% brain mass loss by age 80
Reduced production of neurotransmitters
Loss of motor, sensory and autonomic fibres
Slowing of conduction velocities/signal transduction rates
Reduced innervation in some myocytes
Increased sympathetic tone
Loss of vascular baroreceptor sensitivity
How is the cochlea affected with age?
Loss of hair cells
Loss of ganglion cells
Reduced fibres in cochlea nerve
=> presbyacusis = high frequency sounds
How are the eyes affected with age?
Astigmatism = flatter cornea
Lens and iris harden
Reduced ciliary muscle response -> impaired near vision
Vitreous humour floaters
Skin and muscle changes (enopthlamos, ptosis)
Small pupil
Sluggish light response
How is the renal system affected with age?
Reduction in cortical mass Tubular atrophy and fibrosis Reduced GFR (Sclerosis+loss of glomerular, lobulation reduction) Increased basement membrane permeability Decreased renal blood flow
Increased susceptibility to acute kidney injury
Reduced creatinine clearance
Effect on drug metabolism
How is the bladder affected with age?
Increased incidence of trabeculation and pseudodiverticula
Urethral epithelium becomes stratified squamous
Submucosa vascularisation is altered
Bladder capacity declines
Increased risk of UTI
Prostate enlargement (in some men)
How is the respiratory system affected with age?
Reduction in glandular epithelial cells, mucosa, and infection protection
Less elasticity of bony thorax
Muscle weakening and reduced mass
Reduced surface area of alveolar gas exchange
Reduced CNS responsiveness
Ventillation-perfusion mismatch and reduced arterial oxygen tension
How is the mouth affected with age?
Reduced saliva production Impaired muscles of mastication Tooth loss Decrease in taste buds and therefore sensation Decline in sense of smell Tongue enlargement Atrophic changes in jaw
All cause reduced food intake, impaired mastication
How is the upper GI tract affected with age?
Pharyngeal muscle weakness and abnormal relaxation of cricopharyngeal muscle
Reduced oesophageal peristalsis
Impaired relaxation of lower oesophageal sphincter
Desynchronisation causes impaired swallow safety
Increased incidence of achlorhydria with age caused by chronic atrophic gastritis
Malabsorption
How is the small bowel affected with age?
Shortening and broadening of villi
Impaired absorption/decreased efficiency in absorption
Reduced lipase production from pancreas
How is the large bowel affected with age?
Atrophy of mucosa and muscle layer
Cell infiltration of lamina propria and mucosa
Hypertrophy of lamina muscularis mucosa
Increase in connective tissue
Impaired motility with increased transit time with tendency for constipation
How is your immune system affected with age?
Impaired macrophage function Slowing and reduction in complement pathway Reduced B and T cell function Cytokine dysfunction Reduced production of TNFα/IL-1/NO Increased autoimmune response
