MODULE 2 Flashcards
What is the purpose of the cardiovascular system?
to provide adequate blood flow to all tissues/organs
The base of the heart is located… and is the…
near the anterior chest wall, entry and exit to the heart
The apex of the heart is located…
inferior tip, points towards the left hip, 12-14cm from base
The heart sits in a cavity called the
anterior mediastinum
Size of the heart
12-14cm long, 9cm wide
The pericardium is… and contains
a double walled sac, an outer parietal pericardium and an inner visceral pericardium/epicardium
3 layers of the heart wall are
epicardium, myocardium, endocardium
Epicardium
covers the heart (visceral pericardium)
Myocardium
the thickest layer, muscular wall consisting of cardiac muscle cells, blood vessels, nerves and connective tissue
Endocardium
endothelium (epithelium) covers the inner surfaces of the heart, including heart valves. Forms smooth inner lining which reduces friction so blood can move through easily
External structures of the heart: 2 superior atria that are…
thin-walled, receiving chambers, expandable regions called auricles, externally separated from ventricles by the coronary sulcus
External structures of the heart: 2 inferior ventricles that are…
thick-walled chambers, discharging chambers, externally separated from each other by an interventricular sulcus (anterior and posterior)
Right atria receives… from…
deoxygenated blood, from the superior vena cava, inferior vena cava and coronary sinus
Left atria receives… from…
oxygenated blood, from right and left pulmonary veins from the lungs
Pulmonary trunk
takes blood from the ventricles and delivers to the lungs for oxygen collection
Aorta/aortic arch
takes blood from the ventricles and delivers to the body (for oxygen delivery)
Internal structures of the heart: atria (right atrium)
the right atrium receives coronary blood (deoxygenated blood) from the superior and inferior venae carvae and coronary sinus
Internal structures of the heart: ventricles are…
separated from the atria via atrioventricular valves (AV) which are anchored via chordae tendinae attached to papillary muscles
Right (tricuspid valve)
Left (bicuspid/mitral valve)
Trabelculae carnae are
muscular ridges, less likely for walls to stick together, blood moves through easily
Blood exits the ventricles via
semilunar (SL) valves:
Right pulmonary semilunar valve
Left aortic semilunar valve
Right ventricle
thinner than the left as it does not have to work as hard (5mm thick)
Left ventricle
(15mm thick) thick muscles, generates 4-6 x more force than the right ventricle. Contracts from bottom (apex) upwards and constricts diameter. Pushes blood into the systemic circuit therefore requires a lot of force
Function of atrioventricular valves (AV)
prevent backflow of blood into the atria when ventricles contract. Chordae tendinae tense, via contraction of the papillary muscles, preventing the AV valves everting into the atria
Function of semilunar valves (SL)
pocket-like crescent shaped cusps, forced open when ventricles contract, close when ventricles relax and blood in the arteries tries to flow backwards
Valves open or close in response to
pressure changes
Valves ensure the
one-way flow of blood through the heart
When AV valves open:
atrial pressure > ventricular pressure. As ventricles contract and intraventricular pressure rises, blood is pushed up against SL valves, forcing them to open.
Sequence of events once AV valves open
- blood returning to the heart fills the atria, putting pressure against AV valves, AV valves are forced open. 2. as ventricles fill, AV valve flaps limply into ventricles. 3. atria contract, forcing additional blood into ventricles
When AV valves close:
atrial pressure < ventricular pressure. As ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of SL valves and forcing them to close.
Sequence of events once AV valves close
- ventricles contract, forcing blood against AV valve cusps. 2. AV valves close. 3. papillary muscles contract, and chordae tendinae tighten, preventing valve flaps from everting into atria.
What is coronary circulation?
coronary circulation supplies blood to he myocardium. Left and right coronary arteries arise from the base of the aorta and circle the heart in the coronary sulcus.
Coronary circulation: left coronary artery gives rise to…
the anterior inter-ventricular artery - supplies anterior ventricles
Coronary circulation: right coronary artery gives rise to…
the posterior inter-ventricular artery - supplies posterior ventricles
Blood moves into the coronary arteries when…
the ventricles relax and blood in the aorta attempts to move backwards towards the heart i.e. in between heart beats
Function of the great cardiac vein
drains the anterior regions supplies by the anterior inter-ventricular artery
Function of the middle cardiac vein
drains the posterior regions supplies by the posterior inter-ventricular artery
All veins drain into the…
coronary sinus (then drains into the right atrium)