Cardiovascular response Flashcards
What is normal intrathoracic pressure during inspiration and expiration?
- 7 inspire
- 2 expire
What is the respiratory pump?
More increase in venous return during inspiration because of increase negative pressure. (because of decrease in central venous pressure)
What does inspiration do the HR without the baroreceptor response?
Mechanoreceptors in lungs are stretched and inhibit tonic vagal activity of SA node and thus increase HR.
Opposite of what increase firing of baroreceptors does to the HR.
Influenced by RR, Depth and HR
What does Exercise do the respiratory pump?
Deep rapid breathing makes respiratory pump exaggerated leading to huge increase in venous return
What does yawning do to venous return?
Significant decrease in intrathoracic pressure especially with stretching that leads to huge increase in venous return.
What does coughing do to intrathoracic pressure and effects after that?
Decreases it significantly. If prolonged it can decrease venous return via compression of thoracic vessels enough to cause fainting.
How does a valsalva maneuver work?
Forced expiration against a closed glottis… several phases in this reaction.
- arterial pressure elevated
- fall of venous return and bp
- compensatory reflex increase in HR and peripheral vasoconstriction (see red face and distended peripheral veins high pressure)
- cessation of maneuver causes abrupt fall in pressure
- venous blood moves
- rapidly into central venous pool
- rapid increase in SV, CO, arterial pressure
- reflex bradycardia occurs
What is the net affect of standing?
higher HR and TRP
Needed for brain blood flow consequences of skeletal pump action
- otherwise we would pass out after 10-20 minutes
What are the net effects of exercise?
Increase HR, CO, MAP and PP
CVP stays the same
What are the net effects of pregnancy?
Decrease of TRP but to compensate we increase circulating blood volume otherwise MAP would tank.
Why are fetal HR faster?
Smaller hearts must work faster to do job.
Volume goes up ^3 for everything increase in length
What are the effects of estrogen on the CV system?
- Lower cardiac afterload (due to lower left ventricular mass to body ratio)
- Lower arterial blood pressure
- Greater aortic compliance
- Improved ability to induce vasodilatory mechanisms
