Final Exam Review Flashcards
What is the purpose of arterial baroreflex?
to regulate blood pressure and maintain circulation to brain and other organs.
How do you rearrange Ohm’s law to understand blood pressure regulation?
Q = ∆P / R
to
MAP = Q x TPR
Blood pressure rises with exercise to satisfy Ohm’s law. To ensure a linear increase in blood flow to active muscle during exercise___________
the sympathetic nervous system causes vasoconstriction to increase blood pressure and drive blood flow
To control MAP, you regulate the _______ and the _________
heart; vasculature
What roles does the sympathetic nervous system play in heart rate, vasoconstriction and TPR?
Increases heart rate (increase Q), cause vasoconstriction to increase TPR
What is parasympathetic nervous system responsible for?
Decreasing heart rate
To regulate blood pressure you can either change/regulate the _____ or the ________
Pump (heart) or blood (resistance)
What is reflex cardiovascular control?
built in pathways that are responsible for monitoring change, send signals to brain to make changes to sympathetic or parasympathetic neurons.
What do baroreceptors do when you stand up?
baroreceptors will detect change in blood pressure and send signal to central environment (brain, brain stem). Change behaviour to correct problem and get everything back to normal
Feedback regulation of room temperature can be compared to the arterial baroreflex. Explain this concept.
o Air conditioning made room to cold, furnace turns on to correct the problem in the loop.
o Negative feedback reflex. Room temperature dropped so it was brought back up to correct the problem.
o Idea of sensitivity. Room temp dropped to 18, thermometer stopped working. We don’t detect the problem. Not until minutes later, sensor starts to work and initiates process to bring temp back to 21. Less sensitive system. Such as when system gets older and parts start to fail.
What is the mechanism that governs blood pressure under ALL physiological conditions? (whether we are exercising or not)
The Arterial Baroreflex
Explain how impaired baroreflex function can be seen using a head up tilt.
Table slowly head up tilt (stimulated standing movement).
o Healthy individual maintains steady and well-regulated blood pressure throughout entire protocol.
o In someone who doesn’t have a working arterial baroreflex, blood pressure will plumet when the head up tilt is initiated. Insufficient blood pressure and can’t drive blood to the brain. Which causes fainting. These people have issues with daily life.
Effect of head tilt on sympathetic nervous system activity?
increase
Effect of head tilt on blood pressure?
mean pressure maintained, therefore no change.
Effect of head tilt on femoral artery blood flow?
decreased
Effect of head tilt on stroke volume?
decrease
Effect of head tilt on calf circumference?
increase
Effect of head tilt on heart rate?
increase
Why do these neural and hemodynamic changes occur during head up tilt? Use baroreflex in response
o Arterial baroreflex will detect these changes. Elicits changes. Increased sympathetic activity which causes vasoconstriction in blood vessels. This results in an increase in TPR. All of this results in the mean pressure maintained (no change). Not changed throughout the stimulated standing or on our own.
What are the sensory components of the baroreflex?
baroreceptors and sensory neurons
What are the central components of the baroreflex?
brain and brainstem
What is the efferent component of the baroreflex?
autonomic nervous system
Explain the stretch responses in baroreflex
o Blood vessels will stretch and reflex dependant on what blood pressure is. If blood pressure is high, vessels will stretch. If falls, vessels get smaller and will detect less stretch. Stretch is caused by changes in pressure. First step of the arterial baroreflex, stretch receptors, sensors, monitors.
Do baroreceptors know exactly what the blood pressure is?
o Baroreceptors don’t know exactly what blood pressure is but they detect stretch to “infer” what it is.