Cardiovascular System Design

Question 1

The pulmonary and cardiovascular systems are in series/ parallel?

Answer 1

Series

Question 2

Flow in the systemic =circulation is divided between different tissues in series/ parallel?

Answer 2

Parallel

Question 3

How much volume does the interstitial compartement hold?

Answer 3

12L

Question 4

How much fluid is in the circulating plasma compartment?

Answer 4

3L

Question 5

How much fluid is in the intraccellular compartment?

Answer 5

30L

Question 6

In what two organs does flow most differ from oxygen consumption?

Answer 6

The Brain and the Kidney. More O2 use than flow in the brain. More Flow than O2 use in the kidney

Question 7

What percent of the blood is in the heart, lungs, and systemic circulation?

Answer 7

7% in the heart. 9% in the pulmonary system. 84% in the systemic system with more than 50% in the veins (~60%)

Question 8

Cardiac function means efficient ventricular pumping. What are the requirements for this?

Answer 8

Synchronized and regular intervals of cadiac cell contraction. Valves must fully open. Valves must not leak. Forceful contraction. Adequate ventricular filling.

Question 9

What is cardiac output? What is it equal to?

Answer 9

Defined as the quantity of blood per unit time pumped into the aorta by the heart. It equalss the quantity of blood per unit time that flows through the circulation

Question 10

How do you calculate cardiac output?

Answer 10

CO mL/min = SV (mL) x HR beats/min. Typically it is 5L/min at rest

Question 11

What is Starling’s Law? What determines the rate of Cardiac output?

Answer 11

Stroke volume increases as end-diastole volume increases (other things being constant). It is one of the primary regulators of CO. Venous return determines CO almost entirely.

Question 12

What happens to peripheral resistance with arteriole vasoconstriction?

Answer 12

An increase in peripheral resistance

Question 13

What effect does venous vasoconstriction have on CO and venous volume?

Answer 13

A reduced venous volume and increase in cardiac output via Starling’s law.

Question 14

Does the heart act as a generator of constant pressure or constant flow?

Answer 14

Constant pressure

Question 15

Where is flow velocity the greatest? Where is resistance the greatest? Where is volume the greatest?

Answer 15

Arteries. Arterioles. Venules and veins.

Question 16

What is mean arterial pressure? What is the formula to solve for it?

Answer 16

It is the average pressure over the entire cardiace cycle. It is estimated from diastolic pressure and pulse pressure. MAP=DP+1/3 (SP-DP). Normal is about 93mmHG

Question 17

What is pulse pressure?

Answer 17

The difference between systolic and diastolic presures. PP=SP-DP. PP=Stroke volume/ Compliance. SV=80mL Compliance=2mL/mmHg

Question 18

What is the dichrotic notch (or incisura)?

Answer 18

It is a small dip caused by the backfilling of the aortic valve as it closes.

Question 19

How is arterial pressure measured directly?

Answer 19

For pressures in the arteries, aorta and left ventricle a catheter is passed in a retrograde fashion (against blood flow)

Question 20

How is venous pressure directly measured?

Answer 20

A cather is passed antegrade (with flow). For veins right atrium and right ventricle.

Question 21

Is it possible to measure pulmonary venous and left atrial pressures directly?

Answer 21

NOT possible. Use pulmonary vapillary wedge pressure.

Question 22

What determines MAP?

Answer 22

Cardiac output and total peripheral resistance. MAP=CO x TPR

Question 23

How is short-term MAP control is primarily controlled?

Answer 23

Altering CO and peripheral resistance (neuronal and hormonal control). Altering peripheral resistance counteracts most moment-to-moment fluctuations of MAP

Question 24

How are most short-term alterations in MAP countered?

Answer 24

Via the baroreceptor reflex

Question 25

How is Long-term control of MAP achieved?

Answer 25

Primarily by altering blood volume via the kidneys.