Cpm Lecture 8

Front 1

8.1

arterial blood pressures

Back 1

- two numbers: 120/80
- higher number = systolic pressure, which is the high pressure in the arteries while the heart is pumping blood into the arteries.
- lower number = diastolic pressure, low pressure in the arteries while the ventricle is relaxing and there is no more blood being pumped.

Front 2

8.2

mean arterial pressure (MAP)

Back 2

- heart spends more time in diastole than in systole
- MAP is not the average of diastolic and systolic pressures
- MAP tends to be more like the diastolic pressure than the systolic.

MAP = diastolic pressure + 1/3 pulse pressure

Front 3

8.3

pulse pressure (PP)

Back 3

- difference between systolic and diastolic pressure

PP = systolic pressure - diastolic pressure

Front 4

8.4

cardiac output

Back 4

- the volume pumped by one side of the heart per unit time.
- both sides of the heart eject the same amount of blood during each cycle of systole
- CO on either side of the heart is equal

CO (flow) = heart rate * stroke volume

Front 5

8.5

stroke volume

cardiac index

Back 5

- how much blood volume of blood the heart is ejecting in one beat
- 70ml

cardiac index: cardiac output normalized to body area

Front 6

8.6

blood flow (Q)

Back 6

- analogous to Ohm's law
- potential difference (pressure gradient) divided by resistance to flow measured in mmHg per ml per min
Q = delta P/R

Front 7

8.7

diastole

Back 7

- blood returns to the heart during diastole
- during diastole (2/3 of the time), the heart is resting and passively filling with blood

Front 8

8.8

systole

Back 8

- heart is contracting and is ejecting blood, pumping out a stroke volume of 70 mL on each side

Front 9

8.9

right side of the heart

Back 9

- receives deoxygenated blood from the systemic side circulation (the whole body)
- systemic circulation -> RA -> RV (which is filling)

Front 10

8.10

left side of the heart

Back 10

- filling with oxygenated blood coming from the lungs (pumonary veins) -> LA -> LV (heart is filling)
- towards the end of diastole, the atria contract to affect the final filling of the ventricles

Front 11

8.11

4 valves

Back 11

- 2 AV vales and 2 valves leading to the aorta and pumonary artery
- left side of the heart, mitral valve and aortic valve
- right side: tricuspid and pulmonic valve

Front 12

8.12

SA node

Back 12

- in the right atrium is the pacemaker
- it has an inherent rate that is modulated by the autonomic nervous system.
- it initiates electrical depolarization that passes over internodal tracks eventually reaching the AV node, where there is a pause in the conduction

Front 13

8.13

rapid conduction through the HIS purkinje system to the Purkinje fibers ensues:

Back 13

and then ventricular depolarization occurs, followed by contraction.
- Atrial contraction precedes ventricular contraction precedes ventricular contraction allowing for filling of the heart.
- Rapid depolarization of the ventricles of the heart is necessary for an organized forceful contraction of the muscle.
- electric events precede the mechanical events

Front 14

8.14

pulmonary veins

Back 14

- carry oxygenated blood back to the left side of the heart, to the left atrium and than left ventricle

Front 15

8.15

heart, lungs and systemic circulation are a series circulation

Back 15

- all of the blood goes sequentially through the systemic and pulmonary circuits

Front 16

8.16

systemic circulation

Back 16

- blood flow through the entire body except the lungs
- 100% of the right side of the heart cardiac output goes to the lungs (5L/min)
- on the left side, the same cardiac output, 5L/min returns from the lungs, and is distributed between various regional circulations.
- high pressure and high ersistance circulation
- blood pressure in systemic arteries is 120/80 mmHg

Front 17

8.17

parallel circulation

Back 17

- despite the fact that you have a series circulation as a whole, within the systemic circulation, there are regional circulations in the various organs of the systemic circulation that are in parallel

Front 18

8.18

arteries

Back 18

- conduit/distributing vessels
- b/c they act as pipes that carry blood down to the capillaries. There is no exchange taking place in the arteries.
- small arteries, especially the arterioles have highest resistance: arterioles are the resistance vessels and then you get to the capillaries which are the exchange vessels.

Front 19

8.19

capillary

Back 19

- all of the exchange of gas, nutrients, and wastes take place across the capillary walls.
- once the blood passes the capillaries, it is then collected back into the venous system, which returns it to the heart.

Front 20

8.20

veins

Back 20

- called capacitance vessels b/c they hold a great deal of the blood in the system. They have the capacity for accommodating large volumes of blood.
- veins are capacitance vessels that can act as a reservoir of blood.

Front 21

8.21

pulmonary circulation

Back 21

- is a low pressure and low resistance circulation.
- vessels are shorter than those in the systemic circulation with not a lot of resistance
- blood just has to pump to the lungs and then back to the left heart unlike the blood that proceed into the systemic circulation (gives up O2 to tissues than returns to the right side of the heart and to the lungs)

Front 22

8.22

oxygenated blood

Back 22

- goes back to the left heart. All of the oxygenated blood goes to the systemic circulation, is deoxygenated, returns to the right heart and goes back to the lungs and is re-oxygenated

Front 23

8.23

biggest pulse pressure

Back 23

- in the left ventricle between 120 and 0
- left ventricle has the highest pressures and the lowest pressures because it needs high pressures in order to pump into the high resistance arteriole circulation, and it needs low pressures to fill from the venous system

Front 24

8.24

blood pressure in arteries

Back 24

- pulsing between 120 and 80.
- as you get into arterioles, which are the main resistance vessels, these high pressures fall off and there is the biggest drop across the arterioles.
- then there is a relatively low pressure gradient leading back to the right side where these pressure patterns are repeated but at a much lower pressure
- pulmonic circulation is a low pressure circulation

Front 25

8.25

right ventricular pressure

Back 25

- 25/0 mmHg

Front 26

8.26

pulmonary arterial pressure

Back 26

- approximately 25/10 mmHg, which is about 1/6 of the systemic arterial pressures

Front 27

8.27

sphygmomanometer (blood pressure cuff)

Back 27

- most common way to measure systemic arterial pressure indirectly
- works by inflating a cuff on your arms until no sound is heard, meaning that this point of pressure is above the systolic arterial blood pressure, a pressure that stops the flow of arterial blood into your arm
- starts letting up on the pressure from the cuff gradually, until the first pulsing sound of blood is heard. = when cuff pressure falls below the systolic pressure
- this is the measurement of the systolic pressure when there is blood going through the cuff and you hear this sound all the way until the cuff falls below the diastolic pressure b/c at that point, the flow is continuous and the cuff is not occluding any blood flow

Front 28

8.28

measure blood pressure directly in different places in the cardiovascular system

catheter

Back 28

- place a catheter into a large vessel and hooking it up to a transducer and an electronic recording device to measure pressure
- arterial catheter is placed into a large artery and advanced in a retrograde direction thru the large artery pulsing b/w 120 and 80 until it gets into the left ventricle through the aortic valve.
- this is about as far as you can go because you can't pass a catheter backward from left ventricle to the left atrium.
- not possible to go against arterial blood flow with a stiff catheter.
- measurements of pressure can be taken in the arteries, aorta, and left ventricle.

Front 29

8.29

swan-ganz catheter

Back 29

- directly measure venous and pulm. blood pressures
- catheter has a balloon around the outside of the catheter tip
- balloon is used to help float the catheter downstream antegrade with flow and the pressures are measured as you go.
- catheter is placed into a vein and guided downstream with the help of the balloon.
- goes into the vena cava and the catheter can travel all the way into the RA and the RV into a branch of the pulmonary artery.
- in the RA and large veins you do not see big pulse pressures, but after you pass through the tricuspid valve, in the RV, there is big regular 25/0 mmHg pulse pressures
- when catheter is floated into the pulmonary artery, a pulmonary pressure of 25/10 mmHg is seen

Front 30

8.30

pulmonary capillary wedge pressure

Back 30

learn it from the MNTS notes

Front 31

8.31

fick principle

Back 31

- to measure the rate at which an organ adds or removes a substance from the bloodstream is equal to the blood flow through that organ multiplied by the arterial-venous concentration difference of the substance that is being added or removed.
Q = organ flow*[a-v]

- flow through an organ or a system is equal to the rate at which some substance if added or removed in that organ or system, divided by the av concentration difference
Organ flow = Q/[a-v]

Front 32

8.32

cardiac output

Back 32

- flow through the lungs
CO = oxygen consumption/[a-v]

Front 33

8.33

arterial oxygen concentration

Back 33

- can be measured in any systemic artery because they are distributing vessels and no exchange is taking place

Front 34

8.34

venous oxygen concentration

Back 34

- must be measured in the pulmonary artery b/c this is the point when all the venous blood has been mixed and will have the same oxygen concentration.

Front 35

8.35

indicator dilution method

Back 35

learn from MNTS notes