The Anatomy And Physiology Of Heart Flashcards
Describe location of heart in chest and formation
The location of heart is the bottom of heart (apex) is at the cross section of the fifth intercostal space and the midclavicular line.
Right atrium forms right border, right ventricle forms inferior border and most of anterior surface. Left atrium forms superior border, left ventricle forms left border and apex.
Describe the layers of pericardium and the heart.
Outside is fibrous pericardium, then parietal layer of serous pericardium, then pericardial space that contains fluid then visceral pericardium. Then you have myocardium (the cardiac muscle) then endocardium this thin membrane lines the chambers and valves of the heart consists of single layer of flat epithelial cells.
Explain the cardiac cycle and how valves control blood
- Deoxygenated blood enters through superior and inferior bean cava and enters right atrium
- Tricuspid valve forced open due to pressure and enters right ventricle
- Ventricle contracts and blood flows out of heart via pulmonary artery to lung
Oxygenated blood enters via pulmonary vein into left atrium
Bicuspid valve forced open blood enters left ventricle - Ventricle contracts and blood pushed to the body via aorta branches and to lower body via thoracic aorta.
Describe how contraction of the heart is initiated
Electrical impulse generated by sinoatrial node depolarising atria causing them to contract, depolarisation is spread through atria to atrioventricular node. At the avn the impulse is delayed slightly to allow ventricles to relax and fill with blood. Impulse travels down bundle of his where conducting pathways divide into two left and right bundle branches, the impulse spreads to the inner walls of the ventricles via purkinje fibres and travels from ventricles to atria. The rapid and controlled spread of impulse through ventricles stimulates muscle cells in ventricles to contract and pump blood to body.
