Regulation of Blood Pressure Flashcards
Regulation of blood pressure is split into short and long term regulation. Which methods are employed by the body for each of these to regulate blood pressure?
Short term = baroreceptor reflex
Long term = regulation of blood volume
Why is it important to keep the blood pressure high enough?
To perfume vital organs
Why is it important to keep the blood pressure low enough?
To stop damage to organs
Explain the steps of the baroreceptor reflex?
Include: the nerve fibres involved in each step and the locations of structures.
1) BP is monitored by baroreceptors (afferent nerve fibres) in the aortic arch and carotid sinus (“bulge” where common carotid bifurcated).
2) BP is relayed to the medulla (lowest part of the brain stem) where it is compared to a set point.
3) ANS efferents send correct impulses to cause a response in the heart and the vasculature to bring the BP closer to the set point.
Which area of the medulla in the brainstem do the baroreceptor afferent signals travel to?
The nucleus tractus solitarius
Describe the nerve pathway from the aortic arch to the nucleus tractus solitarius.
Aortic arch —-> aortic nerve —-> vagus nerve —-> nucleus tractus solitarius
Describe the nerve pathway from the carotid sinus to the nucleus tractus solitarius.
Carotid sinus —-> carotid sinus nerve —-> glossopharnygeal nerve —-> nucleus tractus solitarius
What does the PNS do to BP?
Decreases it.
What does the SNS do to BP?
Increases it.
Which receptors in the heart are the target for PNS outflow aiming to reduce the heart rate?
Muscarinic (M2) receptors (a subset of cholinergic receptors)
How does PNS stimulation decrease BP?
Which receptors are involved in this process?
Slows HR via M2 receptors, which decreases cardiac output and therefore heart rate.
Which receptors in the vasculature are the target for SNS outflow aiming to increase BP?
Alpha-1 adrenergic receptors.
Which receptors in the heart are the target for SNS outflow aiming to increase BP?
Beta-1 adrenergic receptors.
Which X2 areas of the CV system are targeted by the SNS to increase BP, and which receptors at each of these locations are responsible for this?
The vasculature = alpha-1 adrenergic receptors
The heart = beta-1 adrenergic receptors
What X2 ways does the SNS alter the vasculature to increase BP?
1) increases arterial tone = increases TPR = increases BP
2) increases venous tone = decreases venous capacitance = increases CVP/preload = increases stroke volume = increases cardiac output = increases BP