Physiology of Ageing Flashcards
What are the two broad groups of Ageing theories?
Programmed Theories and
Error Theory
What Programmed Theories are there?
Programmed Senescence Theory - Telemeres
Endocrine Theory
Immunology Theory
What Error theories are there?
Wear and Tear Theory
Rate-of-Living Theory
Cross-linking Theory
Free Radical Theory
Error Catastrophe Theory
Somatic Mutation Theory
What happens to the liver in ageing?
Liver size decreases by 45% with reduction in blood flow too (enzyme activity not affected).
Reduced production of albumin, clotting factors etc and
Impaired glucose metabolism.
What happens to the kidney in ageing?
Reduction in renal mass
Decreased cortical thickness
Diminished glomeruli and glomerular lobulation
Glomerular and vascular sclerosis
Tubular atrophy and fibrosis
Greater GBM permeability
ADH resistance
Impaired RA vasodilation ability
Creatinine levels are lower (lower muscle mass) therefore lower rises in creatinine are more significant (look at trends)
More likely to have urinary system problem
CVS changes in ageing?
Increase smooth muscle tone
Increase systolic vascular resistance / after load (isolated systolic hypertension)
Myocyte hypertrophy, lengthen contraction time
Increase left atrial size with age (AF)
Decrease in atrial pacemaker cells - conduction and rhythm disturbance
Venous stiffening
CNS changes in ageing?
30% reduction in brain mass by 80
Reduced production of catecholamine / serotonin / acetylcholine
Deplation of DA upatake site and depletion of cortical serotenergic / GABAnergic binding sites
Cognitive decline
PNS changes in ageing?
Loss of motor, sensory and autonomic fibres
Reduction in afferent and efferent conduction velocities
Number of muscle cells innervated bu each axon falls leading to denervation and muscle atrophy
ANS changes in ageing?
Increased sympathetic tone and reduced parasympathetic tone.
Reduced beta-adrenergic response as well
This leads to up-regulation of catecholamines giving high circulating levels
Reduced ability for aortic arch and carotid baroreceptors to respond to changes in arterial pressure.
GI tract changes in ageing?
Changing to involuntary stages of swallowing
Decreased secretion HCL and associated small rise in gastric pH
Decline in absorption of substances that use active transport eg B12
Prolonged transit time can cause constipation.
Resp changes in ageing?
Decline in elastic support of airways causing increased collapse of alveoli and small airways (harder work of breathing too)
Normal arterial O2 may be lower
Loss of muscle mass and weakening of muscles of respiration
Decrease in central nervous system responsiveness eg to CO2 and O2
Increased partial obstruction on inspiration (snoring) and sleep apnoea (OSA.)
Immune changes in ageing?
Macrophage function impaired
B cell and T cell function affected
Complement pathway is affected
reduced capacity to generate important mediator including TNF alpha, IL1 and NO
Increased auti-immunity with increased frequency of auto-antibodies against organ-specific and non-organ specific antigens.
Skin changes in ageing?
Reduced epidermal cell turnover,
Reduced vascular network
Increased fibrosis and skin atrophy
Reduction in vit D synthesis
Increased susceptibility to skin injuries including pressure ulcers and skin tears
Increased vulnerability to infections and neoplasia die to impaired immunity
Impaired thermoregulation
MSK changes in ageing?
Sarcopenia - age related loss of muscle strength
Loss of type 2 fibres (like in thighs)
Reduced force of contraction
Change in structure of collagen fibres within joints contribute to loss of elasticity
Loss of bone mineral density causing ostooporisis and increased risk of fracture
Osteoarthtirits
