Physio Interaction B/t Heart And Circulation

Front 1

relationship between venous blood vloume, nevous return, ventricular filling, and cardiac output.

Back 1

-

Front 2

Vascular function curve vs. cardiac function curve

Back 2

-

Front 3

changes in vascular function curve when blood volume is increased and decreased and whe peripheral resistanceis changed

Back 3

-

Front 4

nature of interaction between cardiac fucntion curve and vascular function curve

Back 4

-

Front 5

1. central ventral compartment
2. venous return

Back 5

1. great veins in thorax and right atrium
2.
- flow (ml/min) returning to central venous compart. from peripheral venous compart.
- Venous return -> central venous compart -> cardiac output
- directly proportional to pressure gradient b/t
peripheral venous compartment and central venous compartment
- inversely proportional to venous resistance.

Front 6

Venous return relationships.

Back 6

Directly proportional to pressure gradient b/t peripheral venous compartment and central venous compartment.

Inversely proportional to venous resistance.

Front 7

blood volume in central venous compartment is affected by:

Back 7

- differences between VR (inflow) and CO (outflow)

Front 8

Central venous pressure (CVP) is determined by:

Back 8

Volume of blood in central venous compart.(CVC) and compliance of CVC.

C = V/P

Front 9

Venous resistance is determined by:

Back 9

- exogenous inputs to smooth muscle in walls (cause constriction/dilation)
- transmural pressure across walls.
- low compared to arterial pressure

Front 10

filling of right ventricle is determined by:

Back 10

Right atrium pressure, which is determined by CVP

Front 11

Filling of left ventricle

Back 11

Right ventricle -> pulmonary circulation -> left atrium (passive conduit, no reflex to affect flow) -> left ventricle

Determined by CVP since changes in R atrium is passed along passively to L atrium and then to L ventricular.

Determinants: CVP and atrial pressure

Front 12

CO and VR

Back 12

Steady state: CO = VR (flow is same in all compartments)


Mean circulating time: blood left from L ventricle to R atrium take 1 min.

Sudden change in CO/VR
-> transient imbalance b/t VR & CO
-> compliant system so changes in flow takes time to take effect

Front 13

What if the heart stops

Back 13

CO falls to 0, MAP 102, CVP 2
- flow remains from aterial to venous side until flow is same as CO (0) - equilibration takes time.

Continue blood flow to venous increases venous volume
-> increase CVP

Decreased arterial volume
-> decrease MAP

Flow stops when CVP = MAP

Mean circulatory pressure = pressure when no flow.

If compliance is same for arterial and venous side,

Mean circulatory pressure =
(CVP + MAP)/2

Front 14

Vascular Function Curve

Back 14

CVP as a function of CO

Slow heart, CVP rises
Accelerate heart, CVP falls

Slow heart has similar effect as stopping heart.

Front 15

1. Heart stops
2. Heart restarts

Back 15

1.
- Volume leaves arterial compartment and arterial pressure drops.
- Volume enters venous compartment and venous pressure rises.

2.
- volume is pumped out of venous compartment and venous pressure falls
- volume is pumped into arterial compartment and arterial pressure rises.

Front 16

What if the heart restarts?

Back 16

With same volume of blood transered from V to A compartment, MAP rises with increment 19 times greater than decrement in CVP (due to lower A compliance)

Pressure different rise until flow through system = CO.

Front 17

Why does congestive heart failure does edema?

Back 17

Decrease SV, decrease CO, increase venous P, increase mid-cap hydrostati P, increase filtration -> edema.

Front 18

What happens to vascular function curve during hemorrhage and transfusion?

Back 18

Decrease blood volume -> decrease mean circulatory pressure (pressure at which flow stops after heart stops)

Volume expansion and hemorrgahge are parallel lines shift upward or doward respectively.

When heart restarts after
1. hemorrhage: starting at lower mean circulatory pressure
2. transfusion: starting at higher mean circulatory pressure

Front 19

Peripheral Resistance effects on vascular function curve

Back 19

Arteriole contain small blood volume
-> arteriolar constriction or dilation will not change mean circulatory pressure.

Increase in resistance
-> increase volume to be transfer from V to A compart in order to achieve 1:19 pressure gradient.

***Vasoconstriction/dilation
-> change slope of vascular function without changing mean circulatory pressure

Front 20

Cardiac function curve

Back 20

CVP and CO relationship

Higher CVP -> higher preload -> higher SV -> higher CO.

Front 21

Cardiac function vs. Vascular function

Back 21

- Vary CVP and measure CO = cardiac function curve
(CVP increase, CO increase)
- Vary CO and measure CVP = vascular function curve.
(CO increase, CVP decrease)

Front 22

Equilibrium point

Back 22

CVP suddenly increases
-> CO increases
-> CVP decrease
-> CO decrease
= equilibrium pt

intersection between vascular and cardiac function curves.