CV- Blood pressure Flashcards
What is the definition of blood pressure?
Pressure exerted by the blood on the wall of a blood vessel (in mmHg).
What is systolic blood pressure?
This is the highest pressure and is measured when left ventricle contracting and expelling blood into aorta.
What is diastolic blood pressure?
This is the lowest pressure and is measured when left ventricle relaxing and blood flowing to peripheral blood vessels.
What is pulse pressure?
This is the difference between systolic and diastolic blood pressure.
For example, if blood pressure is 120/80-> 120-80= 40mmHg
Impact of smaller lumen size for blood pressure?
This will result in higher blood pressure as the heart is having to force blood through a smaller space.
What is mean arterial pressure?
This is the pressure that propels blood through the tissues and is equivalent to: diastolic blood pressure+ 1/3 of pulse pressure.
Equation for cardiac output (CO)?
Cardiac output= heart rate× stroke volume.
More blood your heart pumps out, higher blood pressure (vice versa).
What is peripheral resistance?
Peripheral Resistance= vessel diameter and length.
Vasoconstriction and increased length increases blood pressure.
Why does vasodilation decrease blood pressure?
There is a larger space for blood to flow.
What causes increased length of vessels?
In obesity, there is more tissue so you grow more blood vessels and therefore they are longer.
How is blood pressure controlled?
1) Stimulus- blood pressure falls
2) Baroreceptors in carotid sinuses and aortic arch inhibited
3) Impulses from baroreceptors stimulate cardioacceleratory centre and inhibit cardioinhibitory centre
4) increase sympathetic impulses to heart causing increased heart rate, increased contractility and increased cardiac output
5) increased cardiac output and increased peripheral resistance return blood pressure to normal.
What is Marey’s Law?
There is an inverse relationship between blood pressure and heart rate (if blood pressure too high, heart rate will decrease to balance out).
What is the Bainbridge Reflex?
When blood returns to the heart, enters right atrium and it contains stretch receptors that detect increased atrial filling. Stretched atrial walls initiate this reflex.
This reflex results in increase in heart rate to ‘clear’ extra blood.
What is Frank Starling’s Law of the Heart?
When blood enters the ventricles from the atria, the ventricles are filling more and ventricular muscles are being stretched.
Greater stretch, greater force of contraction. Greater force of contraction, greater stroke volume.
What is the end diastolic volume (EDV)?
This is the amount of blood in the ventricle at the end of diastole (relaxation and filling of ventricle).
