Heart and Circulation Flashcards
What is the arterial system?
The conductance vessels that carry blood around the body
What occurs during microcirculation?
Transfer of nutrients, waste and water
What is the venous system?
The capacity vessels, which can swell to accompany a large volume of blood, that store and return blood to the heart
What is the composition of the pericaridal sac?
Fibrous tissue, lined by serous membrane which secretes a minuscule amount of lubricating fluid
What is the purpose of the pericardial sac?
To help prevent obstruction and pressure on the heart
What is the anterior surface of the heart known as?
The sternocostal surface
Explain the circulation of blood from the body to the lungs
De-oxygenated blood from the body is returned by veins to the right atrium, through the tricuspid valve to the right ventricle. Blood is then pumped to the pulmonary trunk, divides into left and right pulmonary arteries to the lungs where the blood is oxygenated
Explain the circulation of blood from the lungs to the body
Oxygenated blood returns from the lungs in the left and right, superior and inferior pulmonary veins to the left atrium. This blood is then passed through the mitral valve to the left ventricle which pumps blood into the aorta which conducts it into the body
Why are all blood vessels lined with endothelial cells?
To create a friction free surface for blood to flow across and regulates function
What could damage/absence of endothelial cells in blood vessels result in?
Blood clotting
Purpose of superior and inferior vena cava?
Drains blood into the heart
Function of coronary sinus?
Drains venous blood back into the right atrium for it to be oxygenated again
What is the pacemaker of the heart?
The sinoatrial node
Purpose of the sinoatrial node?
Generates spontaneous electrical pulses to set the rate of the heart and the speed that it contracts, part of the cardiac conduction system. Can be sped up or slowed down by ANS
What is the atrioventricular node?
The single point of electrical conductivity between the atria and the ventricles, coordinates electrical activity and contraction, part of the cardiac conduction system
What is the fossa ovalis?
The site of what was the foramen ovale in the embryo
What is the foramen ovale?
An opening from the right to the left atrium that allowed oxygenated blood from the mother to by-pass the foetal lungs to baby
Purpose of tricuspid valve?
Where blood leaves the right atrium
Composition of mitral valve in ventricle
Bicuspid. 2 flaps where blood drains from the atrium, connected with capillary muscles and tendons at the chordae tendineae
Purpose of capillary muscles, tendons and chordae tendineae in ventricle?
Contract to prevent inversion of valves during ventricular contraction
Structure of aortic valve in ventricle
Tricuspid, allows movement of oxygenated blood collected in left ventricle flow throughout body during ventricular contraction, and closes as the ventricles relax to prevent backflow of blood to the heart
What is the opening of the mitral and tricuspid valves in the ventricles dependent on?
The pressure of blood
What is the purpose of the papillary muscles and tendinous cords in the ventricles
Prevent cusp eversion into the atrium during ventricular contraction
Purpose of a smooth ventricular wall towards outflow?
To create a laminar (normal) flow of blood into the pulmonary trunk and aorta
What is the origin of the left coronary artery?
arises from the aortic sinuses just above the valve cusps
Distinguishing feature of pulmonary and aortic valves?
semi-lunar cusps
What occurs in the pulmonary and aortic valves during systole?
Blood passes through the valve, forcing the cusps against the vessel wall
What occurs in the pulmonary and aortic valves during diastole?
Elastic recoil in the pulmonary trunk and aorta forces blood between the cusps and the vessel wall resulting in the cusps meeting in the centre of each vessel
How is angina caused?
When the heart spends too much time in systole, so the heart cannot meet the energy demands of the body, reduced blood flow
Purpose of internodal tracks
Speed highways that take the signal from SA node to the AV node
Explain electrical conduction pathways of the heart
Wave of conduction passes from SA to AV node through the atria. Conduction passes from AV by the bundle of His.
What is blood volume regulated by?
The kidneys
Some functions of the cardiovascular system
temperature regulation
host defence
homeostasis
Why are the forces greater on the left side of the heart?
It has a greater distance to carry blood due to systemic circulation
What is the apex of the heart?
Left ventricle
What is the base of the heart?
Left atrium
What are the common arteries of the aortic arch?
Brachiocephalic trunk
left common carotid
left subclavian
