Cardiovascular System Flashcards
What is MAP?
Mean arterial pressure.
Perfusion pressure.
Average pressure in arteries during one cardiac cycle. Relationship between Cardiac output and systemic vascular resistance.
Normally between 70-110mmHg
Calculation - diastolic + 1/3(sys -diastolic)
Describe how heart works?
Deoxygenated blood from systemic circulation from inferior and superior vena cavas enters right atrium > thru tricuspid valve > into right ventricle > they pulmonary valve > into pulmonary circulation > into left atrium > thru bicuspid valve > into left ventricle > through aortic valve > into systemic circulation
What do arteries do?
Carry oxygenated blood from heart, except pulmonary and umbilical arteries.
Higher pressure.
What do veins do?
Carry deoxygenated blood thru systemic circulation back to heart, except pulmonary and umbilical veins. Closer to skin. Low pressure. Contain valves to help blood flow. Can collapse with no blood.
What do capillaries do?
Smallest of all vessels.
One layer of endothelial cells.
Contain arterioles and venules to help enable has exchange.
Lungs- O2 exchange for co2
Tissues- O2, co2, nutrients and waste
Kidneys- wastes eliminates
Intestines- nutrients picked up, waste released
What happens in the conduction system?
SA node sends electrical impulse to AV node > contraction of atria.
AV node sends impulse down bundle of HIS, down left/right bundle branches around thru purkinji fibres > contraction of ventricles.
What are cardiomyocytes?
High mitochondria density which allows quick production of ATP (adenosine triphosphate) making them highly resistant to fatigue.
They make up cardiac muscle.
What is a cardiac cycle?
AV valves close marking the beginning of cycle.
Systole-Ventricles contract ejecting blood into aortic and pulmonary valves into trunks.
Ventricles relax > semi lunar valves close > beginning of diastole
All valves closed
Diastole- Pressure in ventricles is lower than atria > atria contract and eject blood, filling relaxed ventricles
Calculation of cardiac output?
CO = HR x SV
Calculation of ejection fraction?
Amount of blood pumped out of ventricle / total amount of blood in ventricle = ejection fraction %
What are the 2 mechanisms to increase SV?
Increase in end diastolic volume (blood in ventricle prior to contraction)
Increase in sympathetic system activity
What is cardiac output?
Volume of blood pumped by heart per minute
What is frank starlings law?
Stroke volume of heart increases when volume of blood increases when filling the heart. Stretch factor triggers a more forceful contraction
What is ANP? ANH
Atrial natriuretic peptide/hormone
Senses increase bp when atria stretch.
Shuts off RAAS and stabilises
How is the heart perfused?
Collects oxygenated blood from left ventricle, supplying arteries covering myocardial cells and deoxygenated blood enters the right atrium via the coronary sinus