Physiology - Death Flashcards
Life span
the potential maximum to which a species can live
Life expectancy
the avg no. years a person may live from a given age
Healthy life expectancy
Avg no. years a person may live in good health from a given age
Why is there a faster increase in life expectancy in males
Reduced smoking and improved treatments for cardiovascular disease as well as less hazardous working environments
Age-related changes must …
Be deleterious
Be progressive
Be intrinsic
Be universal
Do we all age at same rate
How we live and the environment in which we live can have a dramatic effect on the way in which we age
Sun exposure and smoking speeds age related changes in the skin
General changes seen in ageing
Loss of height
Loss of fat free and lean body mass
Gain and redistribution of adipose tissue
Grey hair
Why do we lose height when ageing
Disc degeneration but can be reduced by 50% with exercise
What is the effect of losing lean body was
Metabolically active so decreases basal metabolic rate and strength
Why does hair turn grey
Failure of melanocytes
Effects of aging on skin
Wrinkles Blotchiness Thinning epidermis Slowing of keratinocyte generation Loss of elasticity in dermis due to changes in collagen and elastin Lumps & bumps Dry – loss of oil secreting glands
Skin pathology when ageing
Ulcers
Skin cancers - BCC, SCC
Sun damage/ photo-ageing
Solar elastosis
Solar lentigines
Melasma
Actiniic keratoses
Solar elastosis
UV radiation breaks down elastic tissue in skin
Solar Lentigines
Dark brown spots that appear with age
Melasma
Dark patches of skin usually on the face and related to female hormones
Actinic keratoses
Rough scaly area of skin
Precancerous
UVB rays and ageing
Can cause DNA mutation, directly by creating compounds that affect pyrimidine bases
UVA rays and ageing
Penetrate dermis and damage leads to smaller dermis and damage to blood vessels
Damage DNA directly through production of Reactive Oxygen Species (ROS)
What can lead to free radical generation
UV
Infl
Production of cytokines
What can cause vitamin A deficiency in the skin
UV rays
Langerhans cells and ageing
Reduce as we ages
Langerhans cells and skin infections
The local Langerhans cells will take up and process microbial antigens to become fully functional antigen-presenting cells
BCC
Basal cell carcinomas
Most common in UK
Invasive but rarely metastasizes - related to sun damage
Increases cross-linking
SCC
Squamous cell carcinomas
Occurs wherever there is squamous epithelium, so cervix usually an SCC
On skin related to sun exposure
Seborrheic keratosis
Keratocytes in epidermis, etiology unsure
Reparing damaged skin
Retinoids, related to vit A, can alter structure of skin partly reversing or slowing process of photoaging
CO2 lasers, resurfaces skin by causing collagen production
Sarcopenia
Loss of skeletal muscle with age due to Inactivity and loss of motor neurons innervation
Loss of muscle mass and strength in ageing
Reduction in baseline protein production rate
- Activity related
- Fat infiltrating muscle plays a role
- Infl
- Innervation
- Multifactorial
Ageing and CVD
Stiffening due to increased collagen, widening of large arteries
Reduced ability to contract & dilate smaller arteries
Cardiomegaly
Reduced responsiveness to exercise
Postural hypotension
Cardiovascular pathology when ageing
Arteriosclerosis
Atherosclerosis
Coronary heart disease
Arteriosclerosis
Hardening of arteries
Thickening of muscle
Calcification
Can be caused by high bp
Atherosclerosis
Atheroma plaque, cholesterol, and macrophages
Ability of aorta to expand under pressure
Reduces with age
If aorta cannot stretch, then bp higher as being forced through a non-compliant rigid pipe
BP changes with age
Mean BP doesn’t change much with age
Systolic pressure increases with age
Reduced aortic compliance
Baroreceptor sensitivity in those >75
Reduced - reacts to changes in bp so reduces ability to compensate for sudden change in bp
Effects of aging on respiratory system
Intercostal and diaphragm muscles
Lung tissue becomes less elastic
Reduced ciliary function
Impaired ventilation
Respiratory system pathology when ageing
Lung cancer
Bronchitis
Maximum ventilation volume
Maximum amount of air breathed in a minute
Maximum O2 uptake
Maximum amount of oxygen taken in a minute (exercise)
Accumulative lung damage
Gradual increase of carbon deposits over time, emphysema
Effects of ageing on GI system
Reduced absorption of some vitamins D & B12
Reduced mucus secretion – increases risk of trauma and infection
Reduced motility
Reduced hepatocytes
Constipation
GI system pathology ehern ageing
Diverticulosis
Gallstones
Cancer
Effects of ageing of GU system
GFR decreases with age Adaptability to change slower Reduced ability to postpose bladder voiding Cannot completely void bladder contents Prostatic hypertrophy
GU pathology when ageing
Urinary incontinence
Prostate hyperplasia
Prostatic cancer
How does ageing affect drug clearing by kidneys
Atherosclerosis and stenosis of renal arteries leads to high bp and reduced GFR by as much as 50% by 80yrs
Excretion of sodium ions and drugs
Drug regimens and timings may need to be altered
Presbyopia
Age related long sighted, 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 —> less blood gets through.
You may also have heart disease, high bp or diabetes
Causes of presbycusis
Exposure to noise over the years. Exposure to stress over the years. Exposure to drugs or chemicals over the years. Smoking. Being overweight. Hereditary
30 dB
~ sound of quiet whisper
60 dB
~ sound of normal speech
Theories of ageing
Gene regulation
Free radical theory
Neuroendocrine
Free radicals
Any independently existing molecular species that contains an unpaired electron
Many are unstable and highly reactive
ROS
Atom with unpaired electron so highly reactive
Relates to O2 consumption
When are free radicals formed
During cellular reactions
Protection from ROS
Resistance of oxidative stress
- SIRT1, infl
- SIRT2 – metabolism
ROS and longevity
Some evidence that ROS can increase longevity by activation of SIRT3
Complex interaction between ROS and antioxidants that may be dose dependent
Decreased neurodegeneration
Gene theory
Telomeres shortened with each cell division which leads to cellular damage each time the cell divides
Cells cease replication once telomeres reach a certain length and cell goes into senescence
Telomerase can replace and repair telomeres ends of DNA being recognized as breaks, and triggering repair mechanisms
Where is telomerase found
Germ and cancer cells
What are shorter telomeres associated with
Increased disease risk
What can rate of telomere shortening be influenced by
Age Smoking Exercise Body weight Genetics (but not sex) Stress
Homeostatic (neuroendocrine) theory of ageing
Hypothalamus becomes less sensitive (no clear mechanism)
Loss of fine hormonal control
Cortisol increases (damages hypothalamus?)
Cortisol role in fat production/storage
Decreases bone formation
Health ageing
Diet Sleep UV exposure Activity Smoking Stress Fluids
