the cardiovascular system 2 Flashcards
the part of the heart that causes it
blood pressure is generated by?
ventricular contraction
formula for pulse pressure
Systolic pressure- Diastolic pressure
in terms of vavles, aorta, arteries , ventricles…
describe what happens in ventricular contraction
ventricles contract
semi-lunar valves open
aorta and arteries expand and store pressure in the elastic walls
describe what happens in ventricular relaxation
ventricles relax
semi-lunar valves shut
elastic recoil of arteries sends blood forward to the rest of the circulatory system
factors that affect blood pressure
Cardiac Output
Peripheral Vascular resistance
Volume
involves pulse and diastolic pressure
formula for the mean arterial pressure(MAP)
Diastolic + 1/3 Pulse Pressure
involves heart rate and stroke volume
formula for cardiac output
Stroke Volume x Heart Rate
involves Cardiac output and peripheral vascular resistance
formula for MAP
CO (Cardiac Output) x PVR (Peripheral Vascular Resistance)
the PVR is aka
systemic vascular resistance
involves EDV and ESV
formula for stroke volume
EDV-ESV
factors that affect the HR
autonomic innervation
hormones
fitness levels
age
factors that affect stroke volume
heart size
fitness levels
gender
contractility
duration of contraction
preload(EDV)
afterload(resistance)
factors that affect CO
HR and SV
preload
the initial stretching or tension of the cardiac muscle fibers in the ventricles just before they contract
afterload
the pressure against which theheart must work to eject blood during systole
factors that affect blood vessel resistance
vessel diameter
vessel length
blood viscosity
viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate
how does a decrease in radius affect blood vessel resistance
if the radius decreases be one half, the resistance decreases by 16 fold(2^4). so simply, a small change in radius results to a high change in resistance of the blood vessel
Hypervolaemia
increased blood volume
Hypovolaemia
decreased blood volume
factors affecting blood volume
Oedema = accumulation fluid in interstitial space
Disruption in fluid exchange between blood and tissues
Hormonal Regulation
Kidney Function
think about how blood volume affects cardiac output and therefore BP
how does blood volume affect blood pressure
Increase in Blood Volume:
If blood volume increases, there is more blood circulating in the vascular system.
The increased volume leads to an increase in cardiac output, the amount of blood pumped by the heart per minute.
An increase in cardiac output results in an increase in blood pressure.
Decrease in Blood Volume:
If blood volume decreases, there is less blood in circulation.
The decreased volume leads to a decrease in cardiac output.
A decrease in cardiac output results in a decrease in blood pressure
factors affecting osmotic balance in the blood
Increased hydrostatic pressure – eg heart failure – back pressure2. Decreased plasma protein concentration – osmotic balance disrupted
Increase in interstitial proteins
involves contraction and dilation
vascular tone
balance between contraction and dilatation in a vessel
contraction and dilation of a blood vessel depends on?
Composition of the vessels
Local factors like N.O and Endothelin
Mechanical factors like stretch
Metabolic factors like CO2 and O2 availability
Temperature
