Cardiovascular system and the effects of ageing Flashcards
The cardiac cycle consists of?
A full sequence of contraction (systole) and relaxation (diastole) of the heart
What is the sequence of electrical activity?
Sinoatrial node, atrioventricular node, bundle of his, left and right bundle branches and purkinje fibres,
What is end diastolic volume (EDV)?
VOlume of blood at the end of ventricular filling
What is stroke volume?
Amount of blood ejected from each ventricle during systole
What is End-systolic volume (ESV)?
AMount of blood remaining in the ventricles after the end of contraction
Ejection Fraction (EF) is?
The percentage of EDV pumped from the ventricles
Cardiac Output (Q) is?
The bvolume of blood pumped by each ventricle per minute
What are physiological factors influencing stroke volume?
Filling Pressure, Stroke volume, Arterial pressure opposing ejection, contractility, energy of contraction and total peripheral resistance.
As we age the heart…
Increases in mass with age
What are 3 factors the slow down the contraction of the myocardium in older adults?
Slower calcium reuptake by sarcoplasmic reticulum, changes in myosin heavy chain compositions of myocytes, and prolonged action potential.
Blood pressure is a product of?
Cardiac output and peripheral resistance
What exerts primary influence over vascular resistance in the arterial system?
Small arterioles
What are the two primary factors for adequate blood delivery?
Pressure driving the blood, and state of the resistance in the arteries and arterioles.
The three structures are arteries and arterioles
Tunica intima (endo), tunica media (smooth muscle cells), and tunica adventitia (collagen fibres)
Two factors that influence major conduit arteries (aorta) to get stiffer and longer with age?
Thickening of the structural materials that make up vessel walls and Increase in sympathetic tone of smooth muscle
What is the key mechanism of Vascular endothelial dysfunction responsible for increase risk of CVD in ageing.
Reduced bioavailability of nitric oxide.
High levels of sympathetic nerve activity result in…
Increases in peripheral vascular resistance and ultimately hypertension.
Arterial stiffness affects blood pressure by?
Elevating pulse wave velocity, Reducing the ability to absorb energy during systole and Elevated systolic BP
Elevated Sympathetic nerve activity affects BP by?
More vasoconstriction, Greater vascular resistance and Elevated blood pressure
Maintenance of arterial BP at a constant level allows each organ to…
Control its own Perfusion to help sufficiently meet its own metabolic needs.
Exercise capacity falls with age (VO2max dropping 10% per decade from 25) due to?
Decreased cardiac output, Decreased a-vO2 diff and loss of muscle mass.
Blood flow in ageing limbs at rest is reduced with age, what factors influence this?
Often elevated MSNA (increasing vascular tone), fewer blood vessels available and/or inability to dilate blood vessels, and POTENTIAL physical INactivity.
