Lecture 8 Flashcards
What are the key principles of the mammalian cardiovascular system?
Four chambered pump
Unidirectional blood flow
Arterial blood flows away from heart
Venous blood flows towards heart
General physiology of the heart?
Two pumps that lie in series, with equal flow through the two circuits
What is the order of contraction?
Relaxation - Atria contract (right snd left side contract simultaneously) - Ventricles contract - relaxation
What valves control flow between the atria and ventricles ?
Tricuspid valves and mitral valves
What valves control flow from ventricles out to the circulatory vessels?
Aortic and Pulmonary valves
What are the valves doing during the filling phase?
AV valves are open and relaxed, and SL valves are closed.
What are the valves doing during atrial contraction?
AV valves are shut and SL valves are open
What are the valves doing during ventricular contraction
AV valves snap shut, building pressure so SL valves open.
What are the valves doing during the pumping phase?
SL valves are closed.
What is actin?
Thin filament - structural element that runs up and down the cell
What is Myosin?
Thick filament - Parallel to actin, the. motor
What is the role of calcium in cardiac contraction?
At rest calcium levels are low, calcium movement signals to the heart to contract
How does calcium signal to the heart?
Calcium interacts with actin and myosin, actin and myosin form a cross bridge which causes the cell to shorten and creates muscle contraction. (each cardiomyocyte is activated during each beat.)
What makes cardiac contraction stronger?
Increasing cytotoxic calcium levels and More cross bridge formation
What allows relaxation to occur?
calcium being pumped back into the sarcoplasmic reticulum lowering cytotoxic calcium levels and reducing the amount of cross bridges.
