The Physiological & Psychological Impact of Ageing

Part I Systemic Impact

Structure of Lecture

1. Cardiovascular system

2. Respiratory System

3. Musculo-skeletal system

4. Nervous system

1. Cardiovascular system

1. Cardiovascular system

Main functions in homeostasis:

• Transportation of materials around the body- useful products to cells- harmful by-products away

• Defence mechanisms- removal of dangerous chemicals

• Temperature control- dermal blood vessels

• Acid/Base Balance- optimal pH 7.35-7.45

The Heart

Deposits of collagen and fatty tissue Deposits of collagen and fatty tissue into heart muscle.into heart muscle.

Walls of arterioles = thicker with less Walls of arterioles = thicker with less elasticity.elasticity.

Longer time between diastole and Longer time between diastole and systole of heart muscles.systole of heart muscles.

Decreased cardiac output (1/3 less Decreased cardiac output (1/3 less Oxygen from 20-80 years).Oxygen from 20-80 years).

More difficult to do strenuous More difficult to do strenuous exercise.exercise.

Ageing changes of the Heart

Cardiac Output (CO) = Stoke Volume (SV) x Heart Rate (HR)

The Cardiac Cycle

Cardiac Cycle

Blood Pressure Changes Associated with Ageing

• 40% of the elderly have systolic pressure above thesafe maximum (160 mmHg)

• Systolic Blood Pressure

- ↑ 5-8 mmHg per decade after 40-50 yrs

- in females systolic BP stops rising after 70 yrs

• Diastolic Blood Pressure

- ↑ 1 mmHg per decade

Pulmonary Congestion

• Induced by blood remaining in the left ventricle after contraction.

• Inhibits blood flow from the lungs & raises bloodpressure in the lung capillaries which forces fluid out of the capillary walls

• This PULMONARY OEDEMA reduces respiratoryfunction and causes individuals to feel out of breathmore quickly.

Coronary Artery Disease

• The older heart requires more oxygen to pump the same amount of blood around the body as a youngheart.

• This is not important as long as the coronary arteriesremain normal.

• However, age changes cause deficiencies in the normal functioning of coronary arteries.

• ATHEROSCLEROSIS prevents adequate bloodsupply to the heart.

• This causes MYOCARDIAL INFARCTION

Coronary Arteries

Age Changes in Arteries

• Loss of elasticity- accumulation of calcium & lipids- breakage of elastic fibres

This loss of elasticity means that vessels are less able to be stretched by blood flow.

- ↑ systolic blood pressure

• Widening & Lengthening

At first this compensates for elasticity loss but fibres are eventually stretched until they stretch no more.

Each heart contraction causes a rapid and dramatic rise in systolic BP

This leads to increases in cardiac O2 demand

• Diminished Elastic Recoil

Causes slowing of blood flow through arteries

ATHEROSCLEROSIS

• Most common form of arterial disease forming oneof a group of arterial diseases known as ARTERIOSCLEROSIS.

• Causes the formation and enlargement of scar likematerial called PLAQUE in the walls of arteries.

• Plaque cases arteries to narrow and thus reduces blood flow.

• It also causes stiffening of the arteries reducing theirability to dilate when oxygen demands in crease.

Age Changes in Arteries

• Atherosclerosis also involves roughening of the inner lining of arteries and exposure of underlying collagen.

• Both of these factors promote the formation of clotswhich can impede and totally block blood flow.

• Atherosclerosis causes:

- heart attacks- strokes- aneurysms- kidney disease- muscle problems in the legs

Mechanisms Promoting Atherosclerosis

• Endothelial Dysfunction• Free Radicals

- formation of lipid peroxides

• Blood Low Density Lipoproteins (LDLs)- eg cholesterol & triglycerides

• Elastase- an enzyme that breaks down elastic fibres

• Glycation- the use of glucose to form cross links

between protein molecules

- produces age-related glycation end products(AGEs) and FRs

Risk Factors in Atherosclerosis

Smoking↑Blood pressureHigh blood LDLsDiabetes MellitusFamily historyAdvancing age

Age Changes in Capillaries

• Become narrower and irregular in shape

• Decrease in number

• Walls become thicker

• Decreased permeability

• Reduce the ability of the circulatory system toadjust quickly to changes in the demands of the body

Age Changes in Veins

• Thickening of the walls and valves

• Varicose veins

- ↑ vein diameter

- promotes clot formation

thrombus → embolus

2. The Respiratory System

Main functions for homeostasis:

• Gaseous exchange

- obtaining 02 & eliminating CO2

Ventilation (breathing)

Perfusion (pulmonary circulation)

Diffusion (02 in & CO2 out)

Age Changes Affecting Ventilation

• Narrowing of Bronchioles

• Decreased alveolar surface area

• Respiratory muscles become weaker

• Decrease in lung elasticity

Consequences:

↓Rate at which air can circulate through the system

Ventilation is made more difficult and this ↓ 02 supplyand ↑CO2 in the blood.

Ventilation

Minute Volume = Vol. Per breath x breaths per minute

Vital Capacity = Tidal Volume + Inspiratory Reserve Vol + Expiratory Reserve Vol.

VC = TV + IRV + ERV

Total Lung Capacity = TV + IRV + ERV + Residual Vol. (TLC) (RV)

6.0 litres

2.72.2

1.2

0

• Ageing does not affect the TLC but does affect thevolumes of air that can be moved.

• The loss in elasticity of the lungs leads to

↓ IRV & ERV

• Tidal volume increases and there are increases inresidual volume

• The vital capacity of the lungs decreases

• These volume changes have two effects:

1) decrease in maximum minute volume.

2) ↓ VC with ↑RV means less fresh air is inspired. This ↓ rate of diffusion.

Diseases of the Respiratory System

• Respiratory diseases (excluding lung cancer) arethe fourth leading cause of death in the elderly.

• Lung cancer

• Chronic Bronchitis- inflammation of the bronchioles- ↑ mucous production

↓ ventilation by making airways narrower

• Emphysema- destruction of parts of the the lungs

e.g. bronchioles & alveoli

• Pneumonia- inflammation of the lungs → infection

3. Musculo-Skeletal System

Main functions in homeostasis:

- movement - support- heat production- protection- mineral storage- blood cell production

Age changes in muscles

• ↓ nerve-muscle interactions

• ↓ muscle mass

• ↓ blood flow in muscles

Consequences

• ↑ Reaction Times (RTs)

• ↓ speed of movement

• ↓ endurance

Skeletal Age Changes

• Loss of bone matrix(more extensive in post menopausal females)OSTEOPOROSIS

• Stiffening of hyaline Cartilage between joints due to loss of H2O and Ca2+ deposition.OSTEOARTHRITIS

Consequences

• Generalised weakening of the bone(falls tend to cause more fractures in elderly)

• ↓ joint mobility

4. Nervous System

Main functions for homeostasis:

• monitoring

• communication

• stimulation

• memory

• information processing

Age Changes in the Nervous System

• Loss of brain volume

• ↓ neurotransmitters, slower

nerve conduction rate.

• ↓ numbers & changes in the

structure of synapses

• ↓ numbers of motor neurons

• slower reflexes

• memory loss

- ↓ short term memory (STM)

- greatest decline in STM is for information

presented verbally and quickly.

- long term memory is largely unaffected

• increase reaction time ( ↑accidents?)

• vocabulary & conversation

• sleep pattern changes.

• personality changes?

Diseases of the Nervous System

Cerebro-Vascular Accidents (CVAs) or Strokes

• third leading cause of death in the over 65 age

group

• occur when blood supply to the brain is disrupted

- common result of atherosclerosis

- hypertensive haemorrhagic stokes

• Effects depend upon the site of blockage/leakagein the brain:

- paralysis/paresis- loss of language skills- visual field defects

Dementias

A broad category of diseases which involve a serious decline in memory and a decline in at least one other major function.

- sufferers cannot carry out normal activities- difficulties must be experienced on a long term

basis- caused by an identifiable physical abnormality

• Number and rate of dementia cases are ↑

• Incidence rate rises exponentially with age

• Effects: ↓ STM, loss of motor function, personality changes

Alzheimer’s Disease (AD)

• Fifth leading cause of death in the US

• AD is becoming a more important factor of ageingas risks of heart disease & cancer decline

• Early onset or familial ADLate onset or senile dementia of the Alzheimer type

• Causes:Genetic abnormalities?Normal part of the ageing process ?

• Changes in the brain:senile plaques → beta amyloidneurofibrillar tangles → dead neuronslow levels of acetylcholine