Short term control of blood pressure Flashcards
Why is regulating mean arterial pressure (MAP) important?
MAP ensures adequate blood flow to organs, particularly the brain and heart, preventing ischemia and organ failure.
Where are arterial baroreceptors located?
In the carotid sinus and aortic arch.
What is the function of arterial baroreceptors?
They detect changes in blood pressure and send signals to the medullary cardiovascular centers to adjust heart rate and vascular resistance.
What happens when blood pressure rises?
Baroreceptors increase firing rate → stimulate parasympathetic activity → decrease heart rate and vasodilation → lower BP.
What happens when blood pressure drops?
Baroreceptors decrease firing rate → increase sympathetic activity → increase heart rate and vasoconstriction → raise BP.
What other receptors provide input to the medullary cardiovascular centers besides arterial baroreceptors?
Cardiopulmonary baroreceptors (in atria & pulmonary vessels) detect blood volume changes.
Chemoreceptors (in carotid & aortic bodies) respond to O₂, CO₂, and pH levels.
Higher brain centers (e.g., hypothalamus, cortex) adjust BP in response to emotions, pain, or exercise.
what are the components of the arterial baroreceptor reflex?
Your baroreceptor reflex includes neurons and the nerve fibers that carry their messages about your blood pressure. It also includes the cardiovascular system that receives those messages and acts on that information. These include: Baroreceptors in your carotid arteries and aortic arch.
What is the equation relating MAP, cardiac output (CO), and total peripheral resistance (TPR)?
MAP = CO × TPR
What factors influence cardiac output (CO)?
Heart rate (HR) and stroke volume (SV), where CO = HR × SV.
How does TPR affect MAP?
Increased TPR (vasoconstriction) raises MAP, while decreased TPR (vasodilation) lowers MAP.
How does the cardiovascular system respond to exercise?
Increased sympathetic activity → increased HR, CO, and vasoconstriction in non-essential organs.
Vasodilation in active muscles to increase blood flow.
Mean arterial pressure increases slightly due to CO increase.
Why is the CVS response to excercise important?
It ensures oxygen and nutrients are delivered to active muscles while maintaining BP.
What happens when moving from lying down to standing up?
Blood pools in lower extremities due to gravity → decreases venous return → lowers stroke volume & CO → temporary drop in BP.
Baroreceptors detect drop in BP → increase sympathetic activity → increase HR & vasoconstriction to restore BP.
What condition can occur if this response is impaired?
Orthostatic hypotension – a sudden drop in BP causing dizziness or fainting.
What is the Valsalva manoeuvre?
A forced exhalation against a closed airway (e.g., holding breath while straining).
What are the cardiovascular effects of the Valsalva manoeuvre?
Phase 1: Increased intrathoracic pressure → compressed veins → increased BP.
Phase 2: Decreased venous return → decreased stroke volume & CO → BP drops.
Phase 3: Release of breath → venous return restored.
Phase 4: Overshoot in BP due to reflexive sympathetic activation.
