Feedback Control with cardiovascular system Flashcards
What is blood pressure? (general)
Blood pressure is the outwards (hydrostatic) pressure exerted by the blood on blood vessel walls.
What is pulse pressure?
The difference between systolic and diastolic blood pressure.
What is the systolic blood pressure?
The pressure exerted by the blood on the walls of the aorta and the systemic arteries when the heart contracts.
What is the diastolic blood pressure?
The pressure exerted by the blood on the walls of the aorta and the systemic arteries when the heart relaxes.
What is the mean arterial blood pressure? (MAP)
The average arterial blood pressure during a single cardiac cycle which involves contraction and relaxation of the heart.
Why does MAP need to be tightly regulated?
To ensure the blood pressure is high enough to perfuse vital organs but not too high that it would damage blood vessels or cause strain on the heart and other organs.
What is the baroreceptor reflex?
A short-term regulatory mechanism of the mean arterial blood pressure via negative feedback.
What are the sensors called in the negative feedback control of MAP?
baroreceptors
What is the control centre called in the negative feedback control of MAP?
Medulla
What are the effectors called in the negative feedback control of MAP?
Heart and blood vessels
What are the two main types of baroreceptors?
Carotid baroreceptors and aortic baroreceptors
Why can’t MAP be calculated by averaging the systolic and diastolic pressures?
The diastolic period is twice as long as the systolic portion.
What happens to the firing rate of baroreceptors if MAP is increased/decreased?
If the MAP increases, the firing rate of baroreceptors afferent neurons increases.
If the MAP decreases, the firing rate of baroreceptors afferent neurons decreases.
Define cardiac output (CO).
The volume of blood pumped by each ventricle of heart per minute
Define stroke volume (SV).
The volume of blood pumped by each ventricle per heart beat.
Define systemic vascular resistance (SVR).
The sum of resistance of all vasculature in the systemic circulation.
What is the formula/relationship between MAP, cardiac output and systemic vascular resistance?
MAP= CO X SVR
What is the formula/relationship between MAP, stroke volume and heart rate?
MAP= SV X HR
MAP can be regulating by regulating…
Heart rate , stroke volume and
systemic vascular resistance
What is vasomotor tone?
Vascular smooth muscles have a tonic supply of sympathetic nerves meaning they are partially constricted at rest.
What are the two formulas for calculating MAP from systolic and diastolic blood pressure?
Formula 1:
MAP= [ (2x diastolic) + systolic] divided by 3
Formula 2:
MAP= Diastolic blood pressure + 1/3 pulse pressure
What does the Nucleus tractus solitarius (NTS) do?
It is the first synapse site for all CVS afferents in the medulla.
It relays info to other regions in the brain e.g. hypothalamus.
It also modulates the activity of the autonomic nervous system.
What does autorhythmicity mean?
The ability of creating its own rhythm i.e. the heart beating rhythmically in the absence of the external stimuli.
What will decreasing or increasing the sympathetic discharge do to the vasomotor tone?
Decreasing sympathetic discharge will decrease vasomotor tone.
Increasing sympathetic discharge will increase the vasomotor tone.
