Costanzo Phys Flashcards
What part of the circulation is the most dynamic in size
Arterioles
What receptor found in arterioles causes them to constrict
α1 receptors
What receptor in arterioles causes them to relax
β2 receptors
What are the general category of chemicals that cause changes in arteriole size
Catecholamines
What is the volume of blood inside the arteries called
Stressed volume
What is the volume of blood inside veins called
Unstressed volume
How is blood flow to one area altered
- Increase CO
- Divert blood from other structures to it
- Combine 1 and 2
What is velocity of blood related to?
Flow/area
What is the major mechanism for changing blood flow in CV system
Increasing or decreasing arteriole resistance
The most susceptible variable in the resistance equation?
Radius
Stuff/(pi*r^4)
What is resistance to flow directly correlated to
Length of vessel (length inc = resistance inc)
Viscosity (hematocrit)
Which resistance system shows the system as a whole? Closed loop?
Parallel = system
-no decrease in pressure among organs
One loop = series (A->ariole->cap->vule->V)
-sum of pressures is sum of system
What are turbulent sounds of blood called
Kortokoff sounds
What are audible murmurs
Turbulent flow sounds caused by disruptions of laminar flow
Reynolds number less than what is laminar
2000
Anemia can cause what changes in blood flow
Decreased hematocrit means less viscosity means less resistance
Thrombi cause what relating to blood flow
Decreased diameter means increased velocity means more likely turbulent flow
At what part of a blood vessel is viscosity and blood cells lowest
Walls
Where is the largest pressure drop seen
Small A to arterioles
What causes the small dip in systolic pressure? (Dicrotic notch or incisura)
The aortic valve closing
Stroke volume is…
The volume ejected from the LV in one stroke
Why is pressure higher in large A than aorta
The pressure wave from the contraction travels faster than flow; the large A need to contract to keep the blood moving
Where is pulse pressure lost
Arterioles due to increased resistance and more compliant vessels
What changes do we see to BP in arteriosclerosis? Aortic stenosis? Aortic regurgitation?
- Hardened vessels are less compliant causing a larger change in pressure than normal
- Valve stenosis causes decreases pressure because less blood can leave the ventricle
- Same as stenosis
Which portion of cardiac conduction ensures that the ventricles have time to fill
Slow conduction through AV node
What are the components of normal sinus rhythm
SA node initiates, 60-100 bpm, correct sequence
What phase is the upstroke?
0
What is phase 1 of the cardiac AP
The initial repolarization
What is phase 2 of cardiac AP
The plateau (longer in vent)
What is phase 3 of cardiac cycle
Repolarization
What is phase 4 of cardiac AP
Rest
What ultimately controls the HR
The pacemaker cell with the fastest phase 4 depolarization
What causes a latent pacemaker to take over
- SA node inhibited by drugs or disease
- Signal from SA node cannot reach the heart
- Latent pacemaker cell becomes faster than SA node
