cardiovascular System

Question 1

myocardium changes with age

Answer 1

reduced myocyte numner
increase LV wall thickness
increased fibrous component
increased cardiac muscle contraction and relaxation time
amyloid fat deposits

Question 2

myocyte number

Answer 2

• myocytes enlarge and reduce in number, through apoptosis and necrosis- due to lack of o2
• myocardium valves being replaced by fibrous/calcified tissue
• partially compensated by hypertrophy of remaining myocutes

Question 3

LV wall thickness

Answer 3

may increase by ~30%
heart is pumping against higher pressure– reduced ventricular dimensions but some pathologies may result in ventricular atrophy

Question 4

increased fibrous component

Answer 4

fibrous componentincreased collagen in tissue, cross linking= myocardial fibrosis (less contractile and functional)
myofilament binding to ca2+ combines with fibrous alterations of heart to increase myocardial stiffening which prlongs early diastolic filling.

Question 5

amyloid deposits

Answer 5

amyloid deposits found in atria and ventricles (endocardium and pericardium)- produce inflammatory markers. Senule amylouidosis associated with atrophied myocardial fibres- results in arrythmia.

Question 6

ageing of valves and aorta

Answer 6

• Collagen crosslinking (made of fibrous tissue)
• Reduced elastin – stiffer and less elastic
• Increases inflammatory markers reduced elasticity + stiffening of the valves
• Less effective closing of valves- leaky valves (backflow of blood)

Question 7

arterial stiffness

Answer 7

reduced ability of an artery to expand and contract in response to pressure changes
.Independent predictor of mortality after CV event. AS may contribute to resetting baroreceptor response in carotid arteries increasing systolic pressure. AS increases in post menopausal women on HRT.

Question 8

pulse wave velocity

Answer 8

Pulse wave velocity- in younger people the aorta will bounce back when blood enters causing another pulse of pressure but with ageing there is an increase in pressure which can’t be absorbed by the enlargement of the arteries.
- therefore greater peaks in blood pressure and slower contractions means it takes longer to reach peak blood pressure

Question 9

conducting system ageing

Answer 9

SA node, electrical impulses by AV node- coordinating the contraction of the heart
- Decrease in number of SA node pacemaker cells- slightly less sympathetic response
- Increases chances of arrythmia- irregular heartbeat
- Axonal degeneration- compromises sympathetic innervation

Question 10

innervation of heart and ageing

Answer 10

s§ympathetic- releases NE (norepinephrine) + heart rate increases (in response to stimulation)
Parasympathetic- releases Ach + heart rate slows (at rest)
- Sympathetic stimulation declines
- Response to stimulation declines- lowers HR in response to stimulation

Question 11

changes in ventricular function with age

Answer 11

Heart rate- resting is maimtaind but maximal is consistently lower with age
- HRmax= 220-age
- HRmax=210-(0.65xage)- more accurate
Stroke volume
- Maintained (rest) or may increase to compensate reduced heart rate during submaximal exercise
Cardiac output
- Submaximal cardiac output maintained but maximal is reduced as max HR is reduced

Question 12

SV and contributing factors

Answer 12

• Ventricular relaxed during diastole= filling
• Preload- how much blood enters heart depends on how quickly the ventricles stretch
• EDV- how much blood is in the heart at its maximum
• ESV- amount of blood left in heart after a beat

Question 13

SV with ageing

Answer 13

Reduced early diastolic filling
- Sustained Ca2+ activation (to compensate for reduced contractile function) causes residual Ca2+ activation from previous contraction
- Delayed ventricular relaxation – slower relaxation will result in slower filling of the ventricles
- Increased late diastolic filling in men – makes up for the loss of early filling
- Maintained end diastolic volume
- Maintained dist fraction in healthy people (Frank starling principle)- more stretching of ventricles stimulates greater contraction

Question 14

baroreceptors reflexes

Answer 14

• Baroreceptor sensitivity declines- partly due to reduced arterial compliance + less sensitivity
• Neural transmission time increases- postural (orthostatic) hypotension (feeling dizzy when you stand up due to lower blood pressure)
• Responses are slower to change in sensation

Question 15

changes in blood vessels with age

Answer 15

muscle fibre numbers
collagen content and cross linkage
fat deposition
increased wall thickness due to calcification of vessel walls
reduced number of b adregernic receptors
endothelial becomes flatter

Question 16

smooth musle fibre

Answer 16

number and strength declines
reduced ability for vasoconstriction

Question 17

collagen

Answer 17

cross linkage- degradation of elastin= reduced elasticity
blood vessel walls become stiffer and more prone to damage

Question 18

fat deposition

Answer 18

lumen of blood vessels- vessel Xsection reduced- reducing blood flow and increasing blood pressure

Question 19

B adrenergic receptors

Answer 19

reduced number in response to sympathetic stimulation
reduced vasodilation in response to catecholamines

Question 20

endothelial cells

Answer 20

become flatter and less continuous, reduced proliferation and metabolism
contributes to atherosclerosis

Question 21

consequences of changes to blood vessels

Answer 21

• Reduced compliance; pulse wave returns in systole rather than diastole
• Increased large vessel and peripheral resistance
• Increased blood pressure
• Increased risk of damage to blood vessel walls

Question 22

development of atherosclerosis

Answer 22

• Fat building up on inside of blood vessels – less continuous endothelium with macrophages building up and causing foam cells
• Foam cells- activity contributes to fibrous cap + atheroma
• Plaque can break off and travel around the blood vessels, which can block / narrow the whole blood vessel

Question 23

effects of atheroscelrotic plaque

Answer 23

• Provides less blood to the heart which in turn will provide less oxygen to heart contributing to certain diseases

Question 24

consequences of atherosclerotic plaque

Answer 24

depends on the location of the affected vessels
- Brain- stroke – death of brain tissue, loss of speech/movement
- Coronary circulation- angina pectoris (pain in heart on exertion- due to lack of o2), myocardial infarction – heart attack
- Major arteries- aneurism – stretching of blood vessels which is weaker and may give way, leading to a large loss of blood
- Peripheral circulation- gangrene – localised death and decomposition of body tissue due to obstructed circulation

Question 25

factors infleuncing variability

Answer 25

• Telomere length
• Sex steroids (HRT)- linked with increased risk of CVD
• Inactivity- can accelerate negative effects of CVD/exercise- can help to treat and prevent
• Smoking
• Nutrition- has a large effect on atherosclerosis - fat, fish oils, fruit and vegetables
• Obesity (particularly abdominal)
• Disease – T2D and other chronic disease

Question 26

CVD diseases and ageing

Answer 26

congestive heart failure
- systolic dysfunction- heart doesn’t eject enough blood so will get a backup
- diastolic dysfunction – effects filling of the heart
- Fluid may build up in lungs or tissues, reduction in function
Arrythmias- irregular heart rate, due to loss of SA node cells
malignant disease eg acute leukaemia