heart parts, layers, pathway Flashcards
what is the heart enclosed in?
- pericardium (double walled sack with 3 layers)
- 3 layers:
1. fibrous pericardium
2. parietal pericardium
3. visceral pericardium (epicardium)
1 and 2 are attached
3 is actually on the heart
2 and 3 are serous membranes for friction
pericardium
- serous
- parietal layer lines internal surface of the fibrous pericardium
- visceral layer (epicardium) on external surface of heart
- separated by fluid pericardinal cavity
layers of the heart wall
- epicardium: visceral layer of serous pericardium
- myocardium:
- spiral bundles of cardiac muscle cells (to make it more efficient at pushing fluid out)
- fibrous skeleton of the heart crisscrosses, interlacing layer of connective tissue (anchors, supports great vessels and valves, and limits spread of action potential to specific paths) - endocardium:
- continuous with endothelial lining of blood vessels, made of simple squamous
4 chambers of the heart: atria
2 atria:
- where blood enters FIRST
- separated internally y by interatrial septum
- coronary sulcus (atrioventricular groove) encircles the junction of the atria and ventricles
- auricles increase atrial volume
4 chambers of the heart: ventricles
2 ventricles:
- separated by interventricular septum (super thick wall of muscle)
- anterior and posterior interventricular sulci mark the position of septum externally
atria
- receiving chambers
- walls are ridged by pectinate muscles
- vessels entering right atrium: superior and inferior vena cavas
- vessels entering left atrium: right and left pulmonary veins
veins
low pressure, to the heart
arteries
high pressure, away from heart
ventricles
- discharging chambers
- walls are ridged by trabeculae carnae
- papillary muscles project into ventricular cavities
- vessel leaving right ventricle: pulmonary trunk
- vessel leaving left ventricle: aorta
pathway of blood through heart
- the heart= 2 side by side pumps
- RT side: pump for pulmonary circuit (vessels that carry blood to and from LUNGS)
- left side: pump for systemic circuit (vessels that carry blood to and from all body tissues)
equal volumes of blood are…
pumped to the pulmonary systemic circuits
pulmonary circuit
short, lower pressure
systemic circuit
blood encounters a lot of resistance in the long pathways, lots of pressure
(left ventricle thicker because of more pressure)
pathway of blood: steps
- RT ventricle
- passes through pulmonary semilunar valve
- into pulmonary trunk
- pulmonary arteries
- lungs
- back into heart through pulmonary veins
- left atrium
- atrial ventricular valve (bicuspid)
- left ventricle
- pumped past aortic semilunar valve
- aorta
- out to other systems of the body
- superior/inferior vena cava
- back to the right atrium
- right atrial ventricular valve (tricuspid)
- right ventricle (start)
coronary circulation
- blood supply to heart muscle itself
- arterial supply varies and contains many anastomoses (junctions) in branches
- collateral routes give more ways to deliver blood