Cardiovascular system Flashcards
What are the two circuits that blood flows?
- pulmonary circuit and systemic circuit
What does the pulmonary circuit do?
carries deoxygenated blood to the lungs and oxygenated blood back to the heart
What does the systemic circuit do?
carried oxygenated blood to the body and deoxygenated blood back to the heart
Where is the heart positioned?
behind sternum and ribs for protection
Explain the left side of the cardiac muscle?
has thicker muscular wall which can contract with more force to circulate oxygenated blood from the lungs through the large systemic circuit to the muscles and organs
Explain the right side of the cardiac muscle?
contracts to circulate deoxygenated blood from the body through the pulmonary circuit to the lungs
What lies between the atria and ventricles?
atrio-ventricular valves
What lies between the ventricles and exiting blood vessels ?
lemi- lunar valves
Explain the path of blood through the left side of heart?
- blood is oxygenated at the lungs
- through pulmonary vein
- into left atria
- oxygenated blood through left bicuspid AV valve
- into left ventricle
- forced out of left side into aorta
- then to muscles and organs
Explain path of blood through right side of heart?
- deoxygenated blood from muscles and organs arrives through right atria through vena cava
- right atria to right AV valve (tricuspid) to right ventricle
- forced out right side of heart into pulmonary artery
- carries deoxygenated blood to lungs
What is the cardiac muscle?
myogenic
WHat does myogenic mean?
- has capacity to generate its own electrical impulses that through muscular walls forcing contraction
What is the conduction system?
set of five structures which pass the electrical impulse through the cardiac muscle in a coordianted fashion?
What are the five parts of the conduction system?
- sino- atrial node
- atrio- ventricular node
- bundle of His
- Bundle branches
- Purkyne Fibres
What is the sino atrial node?
- located on right atrial wall
- SA node generates the electrical impulse that fires through the atria walls causing them to contract
What is the atrioventricular node?
- collects impulses and delays it for 0.1 seconds to allow atria to finish contracting
- releases to bundle of His
What is the bundle of His?
- located in the Septum of heart
- splits impulses in two ready to be disturbed through each seperate ventricle
What are the bundle branches?
carry the impulse to base of each ventricle
What are the purkyne fibres?
- distribute the impulse through ventricle walls, causing them to contract
What happens when the electrical imoulses journey is complete?
atria and ventricles relax and heart refills with blood
What is the cardiac cycle?
refers to process of cardiac muscle contraction and movement of blood through its chambers
What are the two phases of the cardiac cycle?
- cardiac diastole and cardiac systole
What is cardiac diastole?
relaxation of the cardiac muscle, firstly of the atria then the ventricles
What is cardiac systole?
contraction of the cardiac muscle, firstly atria then ventricles
Explain diastole?
- atria and then ventricles relax, expanding drawing blood in atria
- pressure in atria increase opening AV valve
- blood passively enters ventricles
- SL valves are closed to prevent blood from leaving heart
Explain atrial systole?
- atria contract, forcing remaining blood into ventricles
Explain ventricular systole?
- ventricles contract, increasing pressure closing Av valves to prevent backflow in atria
- SL valves are forced open as blood is ejected from the ventricles into aorta and pulmonary artery
What is heart rate?
the number of times the heart beats per minute
WHat is stroke volume?
the volume of blood ejected from the left ventricle per beat
What is cardiac output?
the volume of blood ejected from the left ventricle per minute
What is bradycardia?
a resting heart rate below 60 bpm
Cardiac output formula?
heart rate x stroke volume
What is venous return?
the return of blood to the right atria through the veins