M103 T3 L2 Flashcards
Where in the body is bp taken from?
from the brachial artery in the upper arm area
What is one kPa equal to in Newtons per square metre?
1000 N/m2
What is 1 torr proportional to?
1mm of mercury in height
What are the standard measurements of blood pressure?
120/75 mmHg
where 120 is systolic, 75 is diastolic
How does blood travel from the intestines to the liver when in the hepatic portal system?
blood leaves via the capillary beds in the walls of the gut
pass through the hepatic portal vein
reach the capillary beds in the liver
Which three factors can result in an increase of bp and which organs are responsible for their regulation?
cardiac output - heart
blood volume - kidney
peripheral resistance - blood vessels
How long does a single heart beat course last?
approx 1 sec
What happens to blood pressure during diastole and systole?
Diastole - heart relaxes - pressure decreases
Systole - heart suddently contracts - pressure sharply increases, then pressure slowly decreases as heart relaxes and aortic valve closes
What is the equaiton for pulse pressure?
Pulse Pressure = Systolic pressure - Diastolic pressure
How do you calculate the mean pressure from an arterial pressure graph?
it is 1/3 of the way up between the diastolic and the systolic pressure
How is the RR interval calculated?
60 / heart rate
What is the equation for cardiac output?
Cardiac output = Heart rate x stroke volume
What is the effect of atrial systole on ventricular blood volume capacity?
20-25% of the total that fills the ventricles
What is the equation for Stroke Volume?
Stroke volume = End Diastolic volume - End systolic volume
What is the equation for Ejection Volume?
Ejection volume = Stroke volume / End diastolic volume
What is the equation for Conductance?
g = 1 / R
What is the relationship between blood vessel radius and blood flow?
as the radius gets larger, the flow increases by x^4
What physical factors affect blood flow? (Rich Penguins Videotaped Lizards)
Blood vessel radius
Pressure
Viscosity
Length
What biological factors have an impact on blood vessel diameter?
Central regulation - the CNS
Local regulation of pressure
Immune system
Haemostasis
How does exercise affect cardiac output and systolic / diastolic pressure?
Cardiac output increases by four fold
Systolic increases, diastolic decreases
What happens when you stand up after a while?
all the blood that had been sitting around the backside area suddenly slides down to the legs, resulting in a huge pooling for a second or two of blood that will be in the lower extremity
Getting that blood out of the lower extremity and back to the rest of the body requires an increase in the heart’s work as well as some kind of exercise / movement to trigger the heart pump
What are the effects of standing?
peripheral vasoconstriction
vastly increased heart rate
diastolic pressure drops dramatically and systolic pressure is really low
Vasoconstriction occurs so that both pressures get back to normal
What are the overall bp changes from standing?
Diastolic pressure increases, systolic stays the same