Reading 3 (80-82, 88) Flashcards
The heart is a ____ that pushes _____ around the body. Blood enters the heart at a ______ pressure and leaves at a ____ pressure, providing the force to propel the blood through the _____ system.
The heart is a PUMP that pushes BLOOD around the body. Blood enters the heart at a LOW pressure and leaves at a HIGHER pressure, providing the force to propel the blood through the CIRCULATORY system.
Blood returning from the body is sent to the ____ side of the heart and then to the _____ to pick up ____ and release _____. The oxygenated blood is sent to the ____ of the heart and back to the _____, where ____ is released and _____ is collected.
Blood returning from the body is sent to the RIGHT side of the heart and then to the LUNGS to pick up OXYGEN and release CO2. The oxygenated blood is sent to the LEFT of the heart and back to the BODY, where O2 is released and CO2 is collected.
What does the complete division of the heart insures
No mixing of deoxygenated blood (in right side) and oxygenated blood (in left side)
What does it mean that the mammalian heart is auto rhythmic
Will continue to beat if removed from body (and kept at appropriate sln)
What are heart contractions dependent on
Rhythm comes from w/in heart itself (NOT BRAIN)
What is responsible for the pumping action of heart
Myocardium (large strong muscle fibers) and other cardiac muscle cells are weakly contractile and produce or conduct rhythm for rest of heart
How does the SA node act as the pacemaker for the heart? Describe the electrical
Cells in SA node rhythmically produce APs which spread via gap jxns to fibres to both atria -> resulting contraction pushes blood into ventricles -> electrical activity moves into AV node and AP spreads slowly thru AV node -> then AP spreads rapidly thru Bundle of His and Purkinje fibres to excite both ventricles
Where are the semilunar valves located
- btwn ventricle and main artery on each side of heart
When heart relaxed what happens to the semilunar valve and blood flow
- high arterial pressure shuts SV valves and prevents BF from artery back into ventricle
What happens when ventricular pressure is greater than arterial pressure
- ventricular contraction inc pressure of blood in ventricle. When ventricular pressure greater than arterial pressure, SV valves open and blood flows into arteries. then myocardium relaxes and ventricular pressure declines, and SV valves close
The cardiac cycle involves _____ of the atria and ventricles which are triggered by ____ in the myocardial cells
The cardiac cycle involves SEQUENTIAL CONTRACTIONS of the atria and ventricles which are triggered by APs in the myocardial cells
The combined electrical activity of myocardial cells produces electrical currents that spread thru _______
the body fluids
The regular pattern of signals produces by the heart is called _____
the electrocardiogram
The components of ECG are correlated to electrical activity in _____
atria and ventricles
P wave corresponds to
Atrial depolarization
QRS complex corresponds to
Atrial repolarization and ventricular depolarization