Final: Circulation 4 Flashcards
cardiac cycle (2)
- pumping action of the heart
- contains two phases: systole and diastole
cardiac cycle: systole (2)
- contraction/pressure-generating
- blood is forced out into the circulation
cardiac cycle: diastole (2)
- relaxation
- blood enters the heart
fish cardiac cycle (2)
- serial contractions of chambers
- valves are passive
fish cardiac cycle: valves (2)
- valves open and close according to pressure differences
- assure unidirectional flow of blood
fish cardiac cycle: bulbus arteriosus
- in teleosts, noncontractile bulbus arteriosus serves as volume and pressure reservoir
mammal cardiac cycle (2)
- atria and ventricles alternate systole and diastole
- maximizes stroke volume and therefore, cardiac output
mammal cardiac cycle steps (4)
- two atria contract simultaneously
- there is a slight pause
- two ventricles contract simultaneously
- atria and ventricles relax while the heart fills with blood
mammal cardiac cycle simplified (5)
- ventricular diastole 1
- atrial systole
- ventricular systole 1
- ventricular systole 2
- ventricular diastole 2
mammal cardiac cycle: ventricular diastole 1 (3)
- pressure in atria exceeds ventricular pressure
- AV valves open and the ventricles passively fill
- atria is in diastole
mammal cardiac cycle: atrial systole (2)
- atrial contraction forces additional blood into ventricles
- ventricles are in diastole
mammal cardiac cycle: ventricular systole 1 (3)
- isovolumetric contraction (volume remains the same)
- ventricular contraction pushes AV valves closed and increases pressure inside the ventricle
- atria are in diastole
mammal cardiac cycle: ventricular systole 2 (3)
- ventricular ejection
- increased ventricular pressure forces the semilunar valves open and blood is ejected
- atria are in diastole
mammal cardiac cycle: ventricular diastole 2 (3)
- as ventricles relax, pressure in arteries exceeds ventricular pressure
- semilunar valves close
- atria in diastole
birds/mammals: ventricular filling (2)
- fill passively during diastole due to venous pressure
- atrial contraction adds a little blood to the ventricles
fish/some amphibians: ventricular filling (2)
- ventricles actively filled by contraction of atrium
- they generate little passive ventricular filling due to low venous pressure after going through two capillary beds
left ventricular pressure
- contracts more forcefully and develops higher pressure to pump blood to body/systemic system
right ventricular pressure
- contracts less forcefully as less pressure is needed to pump blood through the lungs
characteristics of the pulmonary circuit system (2)
- resistance is low due to high capillary density in parallel
- large cross-sectional area
why is the pulmonary circuit a low pressure system (2)
- protects delicate blood vessels of lungs
- prevents edema that would be caused by fluids exiting the blood into the lungs
circuit blood flow
- systemic and pulmonary circuits have the same total blood flow
control of cardiac contraction (3)
- neurogenic pacemakers
- myogenic pacemakers
- artificial pacemakers
neurogenic pacemakers (2)
- rhythm generated in neurons
- present in some invertebrates
myogenic pacemakers (2)
- rhythm generated in myocytes
- present in vertebrates and some invertebrates