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
What happens to SV of moderate or untrained people when exercise intensity is great?
SV does not increase as greated intensities
What happens to HR of moderate or untrained people with cardiac output up to maximal workloads?
HR increases
What is a good indicator of training intensity?
HR
What happens to EDV as percent peak oxygen consumption increases to 100 percent?
Increases slightly and declines slightly near 100%
What happens to ESV as percent peak oxygen consumption increases to 100 percent?
Remains constant and decreases slightly approaching 100%
What happens to Stroke Volume as percent peak oxygen consumption increases to 100 percent?
Increases and levels off near 50%
What happens to Cardiac Output as percent peak oxygen consumption increases to 100 percent?
Increases steadily
What happens to Heart Rate as percent peak oxygen consumption increases to 100 percent?
Increases steadily
How does blood flow?
From area of high pressure to area of lower pressure
What is rate of flow proportional to?
the pressure difference between 2 ends of a vessel or between 2 chambers
Increases in pressure differences _______ flow
increases
How is blood flow calculated?
Change in pressure/resistance to flow
Decreases resistance _____ flow
Increases
Increase in radius of vessel ______ flow
Increases
When does highest blood pressure occur? Lowest?
Highest pressure occurs during systole and lowest occurs during diastole
What does increasing cardiac output (like in exercise) do to BP?
Increases
What does increasing capacitance do to BP?
decreases
What does aerobic and weight training do to resting BP?
reduce
What is plasma composed of?
90% water
7% plasma proteins
3% other
What portion of total blood volume is made up by plasma?
55-60%
What happens to plasma volume during intense physical activity?
may decrease in volume as much as 10%
What does adaptation to training do to plasma volume?
can increase as much as 10% at rest
What portion of blood is made up by formed elements?
40-45% of blood
What are formed elements made up of?
99% red blood cells, 1% white blood cells and platelets
What do platelets do?
Important for blood clotting and contribute to heart attack and stroke (plaque buildup)
What is hematocrit?
the percentage of total blood volume composed of formed elements
What is a normal level of WBCs?
3,500-10,500?
What level of WBCs should be concerning?
below 1,000
What is a normal level of hemoglobin for men?
13.5-17.5
What is a normal level of hemoglobin for women?
12-15.5
What is a concerning level of hemoglobin?
below 8
What is a normal level of platelets?
150,000-450,000
What platelet level is concerning?
below 20,000
What do red blood cells do?
transport oxygen via hemoglobin
What is hemoglobin composed of and what is it necessary for?
protein (globin) & iron-containing pigment (heme)… necessary for binding oxygen
Where is hemoglobin produced in adults?
bone marrow of long bones
Why can’t RBCs repair themselves?
Nuclei are removed from RBCs when produced
What is the lifespan of a RBC?
4 months
What is the acute effect of onset of aerobic or weight training on plasma volume?
Substantial reduction of plasma volume
What is the acute effect of onset of aerobic or weight training on RBCs?
increase number of RBCs and increase oxygen-carrying capacity
What is the effect of prolonged aerobic exercise on plasma volume?
decreases 10-20%
What is the acute effect of weight training on plasma volume?
decreases 0-22%
What is the chronic effect of long-tern aerobic training on plasma volume?
Increases 10-20%
What are the main adaptations at rest for endurance training?
- increase cardiac output during activity
- increased oxygen delivery to skeletal muscle
- increased endurance performance
What are the main adaptations at rest for weight training
- increased ability to maintain cardiac output against increased BP during weight training
What is arterial-venous oxygen difference (a-v O2 diff)?
the amount of oxygen per 100 mL of arterial blood entering a tissue minus that leaving the tissue
What happens to a-v O2 during exercise?
Increases
What is normal a-v O2 at rest?
5mL O2 per 100 mL of blood
What is normal a-v O2 during exercise?
Increases to 15 mL O2 per 100 mL of blood
What is the Fick equation?
Oxygen delivery = blood flow x a-v O2 diff
VO2 = Q x a-v O2 diff
What can increase VO2 for the whole body?
Increases either Q or a-vO2 diff
At rest, _______% of cardiac output goes to skeletal muscle.
15-20%
During maximal exercise, ______% of cardiac output goes to skeletal muscle
80-85%
What are precapillary sphincters?
muscular rings at the entrance of capillary beds
What factors affect redistribution of blood?
- parallel circuitry
- vasodilation
- vasoconstriction
- precapillary sphincters
What causes vasoconstriction?
release of norepinephrine by sympathetic nerves
What causes vasodilation?
release of epinephrine by sympathetic nerves (can also cause vasoconstriction)
Explain autoregulation
changes in skeletal muscle during exercise that stimulate muscle chemoreceptors and increase vasodilation
What increases venous return?
- venoconstriction
- muscle pump
- respiratory pump
How does venoconstriction increase venous return?
constriction of veins via sympathetic stimulation is effective in tissues other than skeletal muscle
How does muscle pump increase venous return?
rythmic muscle contractions propelling blood to the heart through one way valves
How does the respiratory pump increase venous return?
changes in intrathoracic pressure during expiration and inspiration, forcing blood toward the heart
