2: Cardiovascular System Flashcards
Where is blood pressure highest?
Aorta (also very high in arteries supplying the heart)
What is an anastomosis?
intercommunication between 2 arteries ensuring blood flow to an are even if one artery is blocked
What is systole?
Contraction phase (blood is pumped out of the chamber)
What is diastole?
Relaxation phase (blood fills the chamber)
What are the factors of intrinsic control of the heart?
- Autorhythmaticity
- SA node
- AV node
- Purkinje fibers
What is autorhymaticity?
the ability to initiate impulse for contraction at regular intervals
What does the SA Node do?
it is the pacemaker of cardiac contraction
What does the AV node do?
delays impulses by 1/10 of a second, allowing the atria to contract before the ventricles
What do the Purkinje fibers do?
rapidly spread the impulse to contract throughout ventricles
What are the factors of extrinsic control of the heart?
- Parasympathetic nerve fibers
- Sympathetic nerve fibers
- Endocrine glands
- Bradycardia
What do parasympathetic nerve fibers do?
decrease the heart rate
What do sympathetic nerve fibers do?
increase the heart rate
What are some features of cardiac muscle (myocardium)?
- Capable of contraction and force generation (like skeletal muscle)
- Autorhythmaticity
- Intercalated discs that spread impulses to contract
- Synctial conraction
What is Syncytial contraction?
fibers contract simultaneously
What are the features of the fibers of the myocardium?
- Have high mitochondrial density
- Have extensive capillary network
- Use aerobic energy for contraction
What is the correlation between cardiac wall thickness and force generation?
The thicker the wall of the cardiac chamber, the greater the force
Which wall is the thickest?
Left ventricle (supplies the whole body)
What does regular physical training do to wall thickness?
Thickens the L ventricle wall and increases L ventricular mass
What does chronic hypertension do to wall thickness?
Thickens the L ventricle wall and increases L ventricular mass
How does training affect the wall thickness in the atria and right ventricle?
no increase
Which portion of the electrocardiogram correlates with the P wave?
atrial depolarization
Which portion of the electrocardiogram correlates with the QRS interval?
ventricular depolarization
Which portion of the electrocradiogram correlates with the ST segment and T wave?
ventricular repolarization
What is cardiac output?
amount of blood pumped per minute
How is cardiac output determined?
Q= HR x SV
What is the stroke volume?
amount of blood pumped per contraction of the ventricles
What is a typical cardiac output for men?
5 L/min
What is a typical cardiac output for women?
4.5 L/min
How does resting cardaic output between trained and untrained people compare?
About the same
How does training affect HR?
lowers
How does training affect SV?
higher
How is stroke volume determined?
SV= EDV - ESV
What is the end-diastolic volume (EDV)?
The blood left in the ventricles at the end of diastole
What is the end-systolic volume (ESV)?
The blood left in ventricles at the end of systole
What is the ejection fraction (EF)?
the ratio of available blood to pumped blood
How is ejection fraction (EF) determined?
EF = (SV/EDV) x 100
How does endurance training affect EDV?
increases
How does endurance training affect SV?
increases
How does endurance training affect HR?
decreases
What happens to SV of moderate or untrained people when exercise intensity increases up to 40-50% of peak oxygen consumption?
SV increases