Blood Pressure Feedback Mechanisms Flashcards
What is blood pressure?
The hydrostatic pressure exerted by the blood on blood vessel walls.
What is systolic arterial blood pressure?
The pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart contracts
What is systolic arterial blood pressure usually?
<140 mm/Hg
What is diastolic arterial blood pressure?
Is the pressure exerted by the blood on the walls of the aorta and systemic arteries when the heart relaxes
What is the diastolic pressure normally?
<90 mm/Hg
What is hypertension defined as?
Clinic blood pressure of 140/90 mmHg or higher and day time average of 135/85 mmHg or higher
What is pulse pressure?
The difference between systolic and diastolic blood pressures
What is MAP?
The average arterial blood pressure during a single cardiac cycle, which involves contraction and relaxation of the heart
What is twice as long as what?
Diastolic portion is to systolic.
How do you calculate MAP?
MAP = [(2x Diastolic) + Systolic] divided by 3
How do you calculate MAP?
MAP = DBP + 1/3 difference between SBP and DBP
What is the normal range for MAP?
70 - 105
What is the lowest value of MAP needed to perfuse the brain, heart and kidneys?
60
Why is a very high pressure not wanted?
It damages blood vessels and puts extra strain on the heart.
Why is a very low pressure not wanted?
Not enough perfusion of internal organs.
Where are the baroreceptors?
In the aortic arch and carotid sinus.
What nerve links the aortic baroreceptors to the brain?
Herings nerve.
What nerve links the carotid baroreceptors to the brain?
Vagus.
What is the control centre for blood pressure regulation?
Medulla (brain stem).
What kind of receptors are baroreceptors?
Mechanoreceptors.
What are mechanoreceptors sensitive to?
Stretch.
What happens to the firing rate of the baroreceptors when the MAP increases?
Increases
What happens to the firing rate of the baroreceptors when the MAP decreases?
Decreases
MAP=?
CO x SVR
