Cardiopulmonary Physiology Flashcards
What is the normal pacemaker of the heart?
The SA node
How does a nerve impulse travel after being fired from the SA node?
- Impulse travels into the Atria and both atria contract (right then left)
- Impulse goes from Atria to the AV node
- Impulse enters Bundle of his before splitting into left and right bundle branches
- Impulse travels into purkinje fibers from bundle branches and contract ventricles
What are baroreceptors?
Where are they typically located in the circulatory system?
mechanoreceptors that detect changes in pressure
Carotid sinus, aortic arch and origin of the right subclavian artery
How does the baroreceptor reflex work to control blood pressure?
- baroreceptors (BRs) react to increased BP
- BRs send increased signals to CNS via cranial nerves 9 and 10
- CNS increases parasypathetic activity to heart and decreases sympathetic activity to the heart
- Both increased PNS activity and decreased SNS activity lower BP
What is the Bainbridge Reflex?
reflex to increase cardiac output via increased HR via inhibition of PNS system due to increased pressure in right atrium
How does the chemoreceptor Reflex control BP?
- Chemoreceptors in aorta and carotid arteries sense increases or decreases in pH via increased/decreased blood O2/ blood CO2
- In case of decreased O2, decreased CO2, and decreased pH the SNS activity is increased to increase cardiac output the PNS is also inhibited which further increases HR and cardiac output
What are the two main nerves which send information from the heart to the CNS?
Glossopharyngeal and Vagus
What is the difference between systole and diastole?
systole refers to a contraction of a heart segment which forces blood out of the segment
diastole refers to the relaxation of a heart segment when the segment is re-polarizing
What is cardiac pre-load?
the tension in the ventricular walls at the end of diastole which reflects the venous filling pressure that fills the left ventricle during diastole
What is cardiac afterload?
the forces that impede the flow of blood out of the heart, primarily the pressure in the peripheral vasculature, the compliance of the aorta, and the mass and viscosity of blood
What is stroke volume?
volume of blood ejected by each contraction of the left ventricle which normally ranges between 60-80 ml
What is cardiac output?
amount of blood pumped from the left ventricle per minute, it is the product of HR x SV and in adults males is normally between 4.5-5 L/min with females being slightly less
How much oxygen is usually dissolved in 100 mL of arterial blood?
~0.3 mL
How is 80-90% of CO2 transported in blood?
How is the other 10-20% transported?
as bicarbonate ions
5-10% is dissolved in blood
5-10% is in the form of carbamino compounds
What is Rate Pressure Product an index of? What does it provide?
myocardial oxygen consumption and coronary blood flow
Provides an easy to measure way to find causes of the onset of angina pectoris or the development of ECG abnormalities in patient’s with heart disease