Death - Physiology Flashcards
Describe the difference between life span and life expectancy
Life span is the potential maximum to which a species can live and life expectanancy is the average number of years a person may live from a given age
Describe the general changes of ageing
- Loss of height due to disc degeneration
- Loss of fat free and lean body mass
- Gain and redistribution of adipose tissue
- Grey hair due to failure of melanocytes
Describe the effects of ageing on the skin
- Wrinkles
- Blotchiness
- Thinning epidermis
- Slowing of keratinocyte generation
- Loss of elasticity in dermis due to changes in collagen and elastin
- Lumps and bumps
- Dryness - loss of oil secreting (sebaceous) glands
- Ulcers
- Sun damage/photo aging e.g., solar elastoss, solar lentigines, melasma, acitinic keratose/solar aging
- Skin cancers - basal cell carcinoma, squamous cell carcinoma
Describe the role of UV, UVA and UVB on ageing, also known as solar ageing
UV
- Leads to inflammation, and production of cytokines, that attract neutrophils and can lead to free radical generation
- UV can lead to vit A deficiency in the skin
UVA
- UVA, penetrate dermis and damage leads to smaller dermis and damage to blood vessels.
- UVA can damage DNA directly through the productions of ROS (reactive oxygen species)
UVB
- UVB can cause DNA mutation, directly by creating compounds that affect pyrimidine bases
Describe the role of langerhans (dendrititc) cells as we age
Reduce as we age
How can we repair damaged skin?
- Retinoids - related to vit A, can alter structure of skin partly reversing or slowing process of photochanging
- Carbon dioxide lasers - resurfaces skin by causing collagen production
Describe the effects of ageing on the MSK system
- Sarcopenia, loss of skeletal msucle with age
- Bone resorption begins to exceed bone formation - can lead to osteoporosis
- Change in physical properties of cartilage
- Reduction in baseline protein production rate - loss of muscle mass and strength
Describe the effects ageing on the cardiovascular system including the pathology
- Stiffening (due to increased collagen) and widening of larger arteries
- Reduced abiliity to contract and dilate smaller arteries
- Cardiomegaly (enlarged heart)
- Reduced responsiveness to excercise
- Postural hypotension
- BP - Increased systolic blood pressure, reduced aortic compliance, reduced barorecpeotr sensitivity
- Pathology - arteriosclerosis, atherosclerosis, coronary heart disease
Describe the effects of aging on the respiratory system, including ageing
- Intercostal and diaphragm muscles weaken
- Lung tissue becomes less elastic
- Reduced ciliary function
- Impaired ventilation
- Pathology- lung cancer, bronchitis
Describe the effects of ageing on the pulmonary system, including the pathology
- Maximum ventilation volume (maximum amount of air breathed ina minute) deecreases
- Maximum O2 uptake (maximum amount of oxygen taken in a minute) decreases
- Pathology - accumlative lung damage
Describe the effects of ageing on the GI system, including the pathology
- Reduced absorption of some vitamins e.g., D and B12
- Reduced mcuus secretion - increased risk of trauma and infection
- Reduced motility
- Reduced hepatocytes
- Constipation
- Pathology - Diverticulosis, gallstones, cancer
Describe the effects of ageing on the genitourinary system, including the pathology
- Glomerular filtration rate (GFR) decreases with age
- Adaptability to change slower
- Reduced ability to postpone bladder voiding
- Cannot completely void bladder contents
- Prostatic hypertrophy
- Pathology - urinary incontinence, prostate hyperplasia, prostatic cancer
Describe the effects of ageing on hearing and site
- Presbyopia - age related long sightedness, can’t focus on things as close up, may be related to loss of ability to change shape
- Presbycusis - hardening and narrowing of the blood vessels that supply blood to cochlea so less blood get through. May have heart disease, high bp or diabetes
Describe the effects of ageing on telomeres
- Shorten with age
- Shorter length associated with increased disease risk
- Rate of shortening can be influenced by: age, smoking, excercise, body weight, genetics (not sex), stress
Describe the effects of aging on the homeostatic (neuroendocrine) theory
- Hypothalamus becomes less sensitive (no clear mechanism)
- Loss of fine hormone control
- Cortisol increases
- Cortisol role in fat production/storage
- Decreases bone formation
