Cardiorespiratory Mechanics :)

Question 1

what is laminar blood flow?

Answer 1

where velocity of the fluid is constant at any point, and flows in layers

Question 2

where is laminar blood flow the fastest?

Answer 2

closest to the lumen

Question 3

what is turbulent blood flow?

Answer 3

when blood flows erratically, forming eddys, and is prone to pooling

Question 4

what changes is turbulent blood flow linked to?

Answer 4

pathological changes to the endothelial lining of blood vessels

Question 5

what pressure differences causes inspiration?

Answer 5

Pressure of atmosphere > Pressure of alveoli

Question 6

what pressure differences causes expiration?

Answer 6

pressure of atmosphere < pressure of alveoli

Question 7

define compliance

Answer 7

tendency to distort under pressure

Question 8

define elastance

Answer 8

tendency to recoil to its original volume

Question 9

what is blood pressure the same as

Answer 9

mean arterial pressure

Question 10

state the equation for blood pressure

Answer 10

Blood pressure (MAP) = Cardiac Output x Resistance

Question 11

state the equation to calculate pulse pressure

Answer 11

pulse pressure = systolic blood presssure - diastolic blood pressure

Question 12

state the equation for cardiac output

Answer 12

cardiac output = stroke volume x heart rate

Question 13

state the equation for cardiac output

Answer 13

cardiac output = stroke volume x heart rate

Question 14

state the equation for mean arteriole pressure

Answer 14

diastolic blood pressure - 1/3 (pulse pressure)

Question 15

define airway transmural pressure

Answer 15

the pressure difference between the alveolar pressure and intrapleural pressure

Question 16

define intrapleural pressure

Answer 16

pressure within pleural cavity

Question 17

state the equation for compliance

Answer 17

Compliance = change in volume / change in pressure

Question 18

state the equation for elastance

Answer 18

Elastance = change in pressure / change in volume

Question 19

define perfusion

Answer 19

the passage of bodily fluids i.e blood through a system to an organ or tissue

Question 20

what is the 2 key elements of the Law of Leplace?

Answer 20

the tension on the wall of a sphere is the product of the pressure x radius of the chamber
tension inversely proportional to thickness of wall

Question 21

what initiates rapid ejection in the cardiac cycle

Answer 21

the opening of the aortic and pulmonary valves

Question 22

what does fluid and air flow according to?

Answer 22

pressure gradient

Question 23

state the poiseuille’s law equation

Answer 23

* N = fluid viscousity * L = length of the tube * R = inner radius of the tube

Question 24

if you half the radius in poiseuille’s law what happens to flow

Answer 24

flow decreases 16 times

Question 25

what is resistance inversely proportional to?

Answer 25

resistance => inversely proportional to r(to the power of 4)

Question 26

in what generation does resistance in the lung peak?

Answer 26

generation 4

Question 27

why does resistance begin to decrease after generation 4?

Answer 27

number of aiways start to cumulatively increase

Question 28

what happens do the airways as the lung volume increases?

Answer 28

airways dilate

Question 29

what increases the conductivity of airways

Answer 29

increasing lung volume

Question 30

what component of arteries and arterioles regulate diameters and resistance to blood flow?

Answer 30

smooth muscle in walls

Question 31

which out of arteries and veins acts as a reservoir for blood volume in body?

Answer 31

veins

Question 32

why do we see a fall in pressure across circulation?

Answer 32

falls due to viscous (frictional) pressure losses

Question 33

when arteries/arterioles are smaller, what happens to the resistance to flow?

Answer 33

resistance to flow increases

Question 34

why is pulmonary circulation at a lower blood pressure than systemic circulation?

Answer 34

pulmonary circuit has a smaller distance

Question 35

what does TPR stand for

Answer 35

total peripheral resistance

Question 36

Blood pressure (MAP) = Cardiac Output x Resistance: what are some assumptions for this equation? (3)

Answer 36

1. steady flow 2. rigid vessels 3. right arterial pressure is negligble

Question 37

how is the regulation of blood flow achieved?

Answer 37

through resistance variation in vessels with a constant blood pressure

Question 38

state 3 variables that increase resistance of a tube

Answer 38

1. fluid viscousity (n,eta) 2. the length of the tube (L) 3. inner radius of the tube (r)

Question 39

state the 2 types of blood flow

Answer 39

1. turbulent 2. laminar

Question 40

how does blood pressure cuff deflation lead us to hear blood flow?

Answer 40

slow deflation of cuff causes turbulent flow => can be heard by stethoscope

Question 41

at what speed does ventricular pressure fall when the aortic valve closes

Answer 41

rapidly

Question 42

at what speed does aortic pressure fall when the aortic valve closes

Answer 42

slowly

Question 43

why does aortic pressure fall slowly after the closing of the aortic valve?

Answer 43

the aorta and large arteries have elastic tissue = act as buffer to change pulse pressure

Question 44

why is the large extrapulmonary airways supported with cartilage?

Answer 44

prevents airway collapsing in the case of -ve transmural pressure

Question 45

state 2 structural properties of lung tissue

Answer 45

compliance elastance

Question 46

how does arterial compliance lead to continuous blood flow with controlled pressure? (stages)

Answer 46

blood enters artery => artery stretches => artery recoils in diastole but due to the stretch alongside aortic valve => artery becomes a reservoir for generating diastolic blood flow => continuous blood flow with controlled pressure

Question 47

what will a decrease in arterial pressure impact and what will happen to blood pressure?

Answer 47

impact on diastolic blood flow => increase in blood pressure

Question 48

what is a pulse?

Answer 48

the difference between systolic and diastolic blood pressure

Question 49

state 2 pumps essential for venous return

Answer 49

1. skeletal muscle pump 2. respiratory pump

Question 50

how does the skeletal muscle pump work in terms of venous return?

Answer 50

when muscles contract => squeezing veins due to valves it pushes blood upwards => when muscles relax it creates a negative pressure sucking blood forward

Question 51

how does the respiratory pump work in terms of venous return?

Answer 51

diaphragm pulls down (-ve intrathoracic pressure => air flow) => hypercompliant veins dilate in presence of negative pressure => helping suck blood back into chest from head neck and abdomen

Question 52

state 2 health problems that can impact venous return

Answer 52

1. incompetent valves => dilated superficial veins in leg => varicose veins 2. prolonged elevation of venous pressure = oedema

Question 53

what is the pathology of aneurysmal disease?

Answer 53

vascular aneurysms = increase vessel radius => the inward force exerted by muscular wall must increase => if elastic muscle fibres weakened => force needed not produced => aneurysm expands until it ruptures

Question 54

what happens to vessel walls over time

Answer 54

weaken

Question 55

what does compliance depend on

Answer 55

vessel elasticity

Question 56

at low pressure, which is higher venous or arterial compliance?

Answer 56

venous (as veins hold 70% of blood)

Question 57

what is the link between compliance, transmural pressure and vessel volume?

Answer 57

Compliance = relationship between transmural pressure and vessel volume

Question 58

how does venous compliance work and aid with storage of blood?

Answer 58

Increased smooth muscle contraction => decreased venous volume => increased venous pressure => changes in venous pressure distend (swell) veins and increase the volume of blood stored in them.

Question 59

where are the air pockets smaller in the lung?

Answer 59

at the apex

Question 60

does the apex of the lung need more or less air flow than the top of the lung

Answer 60

less

Question 61

are ventilation and perfusion greater at the top or bottom of the lung?

Answer 61

bottom

Question 62

why is there less ventilation at the top of the lung?

Answer 62

Pressure of the Pleural cavity = more -ve => greater transmural pressure gradient => also Alveoli are larger and less compliant => less ventilation

Question 63

why is there more ventilation at the apex of the lung?

Answer 63

Pressure of the Pleural cavity = less -ve => smaller transmural pressure gradient => alveoli are also smaller and more compliant => more ventilation

Question 64

why is perfusion lower at the top of the lung?

Answer 64

Lower intravascular pressure => less recruitment => greater resistance => lower flow rate

Question 65

why is perfusion greater at the apex of the lung?

Answer 65

Higher intravascular pressure (gravity effect) => more recruitment => higher flow rate

Question 66

why does the difference in ventilation between the apex and base of the lung vary more than perfusion?

Answer 66

perfusion involves liquid => heavily impacted by gravity

Question 67

where is the maximum efficiency on the ventilation-perfusion graph?

Answer 67

When ventilation-perfusion crosses => ventilation-perfusion = 1

Question 68

when there is no gravity, is there a preferred perfusion location?

Answer 68

no