Cardiology Lectures 4-6: Blood Pressure Flashcards
What is blood pressure?
Blood Pressure is “the outwards (hydrostatic) pressure exerted by the blood on blood vessel walls”
What is the upper limit of systolic blood pressure?
140
What is the upper limit for diastolic BP?
90
What is the term for normal blood flow?
Laminar
What is the first Korotkoff sound?
Systolic BP
What is the fifth Korotkoff sound?
Diastolic Pressure is Recorded at the Fifth Korotkoff Sound (point at which sound disappears
What is the main driving force of the venous return to the heart?
MAP
What is MAP?
The average arterial blood pressure during a single cardiac cycle which involves contraction and relaxation of the heart
How do you calculate MAP?
(Diastolic x 2 + Systolic) divided by 3
What is the other way to calculate MAP?
BDP + 1/3 Pulse pressure
What is the normal range for MAP?
70-105
What is the lowest MAP that allows perfusion of coronary arteries, brain and kidney?
at least 60
What determines MAP?
CO and total peripheral resistance
What is total peripheral resistance?
Sum of resistance of all peripheral vasculature in the systemic circulation
What are the major resistance vessels?
Arterioles
Where are you baroreceptors?
Aortic arch
Carotid sinus
Which nerve signals to the medulla from the carotid sinus?
CN IX
Which nerve signals to the medulla from the aortic baroreceptors?
CN X
Why are baroreceptors important?
Short term BP regulations ie postural changes
What is postural hypotension?
Results from failure of Baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position
How is MAP controlled long term?
By hormones which control blood volume.
What two main factors control extracellular fluid volume?
Water
Sodium
What three mechanisms control long term blood pressure?
Rennin-Angiotensin-Aldosterone- System
Atrial Natriuretic Peptide
Antidiuretic hormone
Where is rennin released?
Kidneys
What does rennin do?
Stimulates the formation of angiotensin I