Ageing

Osteoporosis, loss of calcium from bones, rate of cell replacement decreases, less protein made as DNA becomes defective

Fall in metabolic rate

Loss of brain cells causes slower responses & learning ability, loss of memory

Lower rate of nervous conduction reduces reaction time

Cartilage on joints > reduction in ease of movement

Arteriosclerosis/atherosclerosis reduce efficiency of circulatory system

Reduced vital capacity of lungs > become more breathless on exertion

Faulty copying of DNA and a lifetime of exposure to mutagens > faulty proteins may be made

Cross-linking of proteins such as collagen in connective tissue, causes connective tissue to stiffen e.g. in heart, affecting resting cardiac output

Other effect, e.g. wrinkling of skin/reduced renal filtration rate/slower circulation of blood

Body’s immune system produces antibodies against its own cells as the immune system deteriorates with age. Which also allows abnormal cells to proliferatea