Term
| ultimate goal of the cardiovascular system |
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Definition
| to perfuse the capillary beds of the body with blood, so that exchange of gases, nutrients & wastes can occur |
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Term
Cardiac output (CO)
(Know Equation) |
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Definition
- is the volume of blood pumped out of each ventricle in 1 minute
- = HR (beats/min.) x SV (ml/heartbeat)
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Term
Stroke Volumn
(Know Equation) |
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Definition
- Stroke volume (SV) is the volume of blood pumped by each ventricle during systole
- Stroke Volume (SV) = EDV – ESV.
- CO is maintained by increasing HR
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Term
| What is End-Diastolic Volume (EDV) |
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Definition
- How much blood fills the ventricles
- End-Diastolic Volume (EDV) is about 120 ml
- End-Systolic Volume (ESV) is about 60 ml
- Thus, with every beat the heart pumps about 60% of ventricular blood (or about 70 mL)
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Term
As you increase EDV, what happens to stroke volume and preload? |
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Definition
- Anything that increases EDV can increase SV.
- Anything that increases contractility can increase SV.
- that the critical factor controlling stroke volume is preload
- Preload is how stretched the ventricles are before they contract
- Preload depends on EDV. The greater the EDV, the more the ventricles are stretched.
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Term
What is a "positive chronotropic factor"? |
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Definition
- Factors that increase HR
- Factors that decrease HR are ‘negative chronotropic factors’.
- NE increases HR
- Ach decreases HR
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Term
What is the SA (sino-atrial) node? |
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Definition
| the impulse-generating (pacemaker) tissue located in the right atrium of the heart |
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Term
What is a pacemaker potential? |
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Definition
- a rhythmic and automatic depolarization that occurs in ‘autorhythmic’ or ‘pacemaker’ cells
- pacemaker depolarization occurs because ion channels that conduct Na+ or Ca2+ into the cell slowly open
- usually trigger an action potential
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Term
What does Starling's Law of the Heart (The Frank-Starling Mechanism) say? |
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Definition
- ‘The heart pumps all the blood that returns to it.’
- Starlings law states that the critical factor controlling stroke volume is preload
- The more the ventricles are stretched, the harder they contract
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Term
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Definition
- the amount of blood returning to the heart through the venous system
- The amount of blood in the ventricles (EDV) is determined by venous return
- A slow heart rate, exercise - anything that increases venous return or slows heart rate - increases EDV
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Term
In which vessels is the flow of blood SLOWEST? |
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Definition
| Velocity is slowest in the capillary beds because they have a greater cross-sectional area |
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Term
During strenous exercise, which two organs/tissues receive the highest volume of blood flow? |
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Definition
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Term
What is ejection fraction? (EF)
(Ratio) |
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Definition
- the ratio of SV-to-EDV (EF=SV/EDV)
- normally 50 - 75 % under resting conditions
- reflects the contractility of the ventricles
- Increased ventricular contractility increases EF
- Decreased contractility (from disease) decreases EF.
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Term
| What is 'Positive Ionotropic' factors? |
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Definition
factors that increase contractility
Increased by NE and E |
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