CVRS ICA
Cardiovascular system-
Lecture 1 (Introduction)
- Cardiac output- CO
CO refers to volume of blood pumped/minute = 5L/min
Determined by:
1. Stroke volume (SV): volume ejected per contraction
2. Heart rate (HR)
CO= SV x HR
Left CO = Right CO
- Pulse pressure
It’s the difference between systolic and diastolic blood pressure.
Represents the force that the heart generates every time it
contracts
, Pressure falls as blood moves through the system. This is
because there is resistance to flow.
- Flow
Flow = pressure/resistance
Pressure = flow x resistance
ABP = CO x Total Peripheral Resistance (TPR)
ABP = CO x TPR
TPR is the resistance to flow offered by all systemic vasculatures
EXCLUDING pulmonary circulation
- Resistance
Vasodilation and vasoconstriction can change resistances.
Dilation increases flow and constriction decreases flow.
Note- any imbalance between VR (venous return) and CO leads to a
coordinated response so that ABP is maintained
Blood flows from RA > Lungs > aorta > CO > VR > RA
Lecture 2- cardiac cycle
, - Blood flow within the heart
Deoxygenated blood flows from the body through superior and
inferior vena cava to the right atrium and then right ventricle and
then through the pulmonary artery to the lungs. The valve
between right atrium and ventricle is called the tricuspid valve.
After being oxygenated in the lungs, the blood flows to the
pulmonary vein to reach left atrium, and then through the
bicuspid/mitral valve to the left ventricle and out for systemic
distribution through the aorta.
- Cardiac cycle
2 main phases- Diastole (relaxing) and Systole (contracting)
- Basic concepts
Valves open and close due to pressure differences across them,
blood flows down energy gradient, when a muscle surrounding a
chamber contracts, pressure increases and when it relaxes, it
decreases.
CO = SV + HR
- Cardiac cycle
When the patrial is greater than pventricular (pressure), then the
tri and bicuspid valves open, happens in ventricular diastole
(atria is unaffected too, this just refers to filling of ventricular
chamber), around 90% filled
When pventricular is greater than paortic, and when atrial
systole occurs, the atrial chambers contract, account for the rest
of the 10%
In ventricular systoles, isovolumetric contraction occurs where
basically ALL valves are closed to prevent backflow, and the
ventricular chambers start contracting increasing the pressure,
while this is happening, the atrial systole ends and diastole
starts, and starts to fill up again WITHOUT letting the blood into
the ventricular chambers
In the next phase of ventricular systole, ventricular ejection
occurs, where the aortic valves open (like the pathway to
pulmonary artery and aorta), and due to high pressure due to
ventricular contraction causes rapid ejection of blood through
those 2 places.
Cardiovascular system-
Lecture 1 (Introduction)
- Cardiac output- CO
CO refers to volume of blood pumped/minute = 5L/min
Determined by:
1. Stroke volume (SV): volume ejected per contraction
2. Heart rate (HR)
CO= SV x HR
Left CO = Right CO
- Pulse pressure
It’s the difference between systolic and diastolic blood pressure.
Represents the force that the heart generates every time it
contracts
, Pressure falls as blood moves through the system. This is
because there is resistance to flow.
- Flow
Flow = pressure/resistance
Pressure = flow x resistance
ABP = CO x Total Peripheral Resistance (TPR)
ABP = CO x TPR
TPR is the resistance to flow offered by all systemic vasculatures
EXCLUDING pulmonary circulation
- Resistance
Vasodilation and vasoconstriction can change resistances.
Dilation increases flow and constriction decreases flow.
Note- any imbalance between VR (venous return) and CO leads to a
coordinated response so that ABP is maintained
Blood flows from RA > Lungs > aorta > CO > VR > RA
Lecture 2- cardiac cycle
, - Blood flow within the heart
Deoxygenated blood flows from the body through superior and
inferior vena cava to the right atrium and then right ventricle and
then through the pulmonary artery to the lungs. The valve
between right atrium and ventricle is called the tricuspid valve.
After being oxygenated in the lungs, the blood flows to the
pulmonary vein to reach left atrium, and then through the
bicuspid/mitral valve to the left ventricle and out for systemic
distribution through the aorta.
- Cardiac cycle
2 main phases- Diastole (relaxing) and Systole (contracting)
- Basic concepts
Valves open and close due to pressure differences across them,
blood flows down energy gradient, when a muscle surrounding a
chamber contracts, pressure increases and when it relaxes, it
decreases.
CO = SV + HR
- Cardiac cycle
When the patrial is greater than pventricular (pressure), then the
tri and bicuspid valves open, happens in ventricular diastole
(atria is unaffected too, this just refers to filling of ventricular
chamber), around 90% filled
When pventricular is greater than paortic, and when atrial
systole occurs, the atrial chambers contract, account for the rest
of the 10%
In ventricular systoles, isovolumetric contraction occurs where
basically ALL valves are closed to prevent backflow, and the
ventricular chambers start contracting increasing the pressure,
while this is happening, the atrial systole ends and diastole
starts, and starts to fill up again WITHOUT letting the blood into
the ventricular chambers
In the next phase of ventricular systole, ventricular ejection
occurs, where the aortic valves open (like the pathway to
pulmonary artery and aorta), and due to high pressure due to
ventricular contraction causes rapid ejection of blood through
those 2 places.
