Cardiovascular System Flashcards
What is coronary circulation?
Supply of oxygen rich blood to the heart tissue
Which arteries supply the heart with blood?
- right coronary artery
- left coronary artery
Where do the coronary arteries branch from?
Aorta
What is the heart?
Muscular pump that keeps blood flowing through the vessels
What do vessels do?
Deliver blood to the body and then return it back to the heart
What is the pulmonary circuit?
- right side of the heart
- carries O2 poor blood to the lungs for gas exchange and then returns it to the heart
What is the systemic circuit?
- left side of the heart
- carries O2 rich blood to the body and returns O2 poor blood back to the heart
What is coronary circulation?
Hearts blood supply - O2
What are the three layers of the heart wall?
- endocardium
- myocardium
- epicardium
Endocardium
- innermost lining
- simple squamous epithelium overlying a thin layer of loose Ct
- continuous with the inner lining of blood vessels
Myocardium
- cardiac muscle
- thickest layer
Epicardium
- simple squamous epithelium overlying a thin layer of loose CT
What is systole?
Contraction
What is diastole?
Relaxation
What are the major branches off the aorta?
- brachioceohalic artery: right subclavian artery and right common carotid artery
- left common carotid artery
- left subclavian artery
Embryological development of the heart
- derived from mesoderm
- Heart bulge forms the heart: original near head but undergoes lateral folding to end up in correct position
When does the heart start beating?
Beginning of week 4
What are the three layers of blood vessels?
- tunica intima
- tunica media
- tunica adventitia
Characteristics of the tunica intima
- endothelium
- basement membrane
- loose CT
Characteristics of the tunica media
- smooth muscle
- collagen
- elastin (sometimes)
Characteristics of the tunica adventitia
- loose CT
- often interweaves itself with tissue of neighbouring structures/organs
What are the 4 valves of the heart?
- right atrioventricular valve (3 cusps)
- left atrioventricular valve (2 cusps)
- pulmonary valve (3 cusps)
- aortic valve (3 cusps)
What are the different circuits of the heart?
- pulmonary
- systemic
The walls of which ventricle is thicker?
Left
Action potential of the heart
- resting membrane potential of -90mV
- Na+ floods in - depolarisation
- Ca2+ prolongs depolarisation
- K+ channels open at end of plateau
Conduction in the heart
Sinoatrial node - atrioventricular node - atrioventricular bribers - branching fibres - purkinje fibres
What is systole?
Contraction
What is diastole?
Relaxation
What are the phases of the cardiac cycle?
- Ventricular filling
- Ventricular filling
- Isovolumetric contraction
- Ventricular ejection
- Isovolumetric relaxation
- Ventricular filling
What is the cardiac output formula?
CO= SV x HR
What is the average stroke volume at rest?
70mL
How is heart rate changed?
Change heart rate
Change stroke volume
- Ventricular filling (2/3)
- all chambers relaxed
- AV valves are open
- blood flows from atria to ventricles
- Ventricular filling (1/3)
- atrial systole
- completes the process of ventricular filling
- each ventricle contains and end diastolic volume
- Isovolumetric contraction
- ventricular contraction begins
- AV valves close as some blood is forced back
- pressure in ventricles increases but not enough to open semilunar valves
- Ventricular ejection
- ventricular systole continues
- when pressure of yeh ventricles exceeds the arteries the semilunar valves open
- ventricles eject blood
- Isovolumetric relaxation
- ventricular systole ends
- ventricular pressure drops
- semilunar valves close (AV valves are still closed)
- Ventricular filling
- all chambers relaxed again
- ventricular pressure drops below atrial pressure
- AV valves open
- blood accumulated in atria rushes into ventricles
Why does standing for a long time make someone faint?
- standing means that the muscles around the deep veins in the leg are not contracting
- therefore blood is not being forced back towards the heart and venous return is compromised
- this reduces cardiac output and results in insufficient blood supply reaching the brain, and hence fainting occurs
