respiration - lecture 3

Question 1

describe pathway through heart

Answer 1

dexoy –> right heart –> right and left pulm arteries –> lungs –> left and right pulmonary veins –> left ventricle –> pumped to whole body via aorta and small amount goes to lungs

Question 2

compare pulmonary vs systemic circulation - right ventricle

Answer 2

right ventricle develops pressure of ~25mmhg during systole
- heart pushes blood - force - blood moves into circulation
F/A and pressure developed by right ventricle

compared to 120mmhg in right ventricle

Question 3

compare pulmonary vs systemic circulation - blood pressure

Answer 3

blood pressure in pulmon circ is lower than in systemic
heart at same level of lungs not hard to push blood to apex
but ex : heart to fingertips = systemic, high pressure system if lungs high pressure = could get breaks in alveoli, fluid into interstitium = increases thickness of alveolar capillary membrane and decreases diffusion rate = do not want high pressure system in lungs

Question 4

compare pulmonary vs systemic circulation - blood vessels

Answer 4

the blood vessels are thinner and have less smooth muscle than vessels in systemic circulation
offers less resistance against flow

Question 5

compare pulmonary vs systemic circulation - blood pressure diagram

Answer 5

pulmonary = mean 15, 25/8, 25% rv, ra 2, low pressure
systemic = mean 100, 120/80, 120% lv, 5 la, high pressure, 120 = systole, relax = 80 n
pulmonary = drop of 1/10th of pressure drop in systemic (pulm~100mmhg and syst = 10mmhg)
want same amount of blood in each side (volume, vol/time = flow, same co(cardiac output))

Question 6

what is flow

Answer 6

flow = pressure/resistance
need pressure for flow
big pipe = easy to flow fluid, small pipe = harder for same flow in same time, more resistance
blood flow in pulm = blood flow in systemic, co is equal

Question 7

describe flow

Answer 7

total pressure drop form pulm artery to left atrium = 10mmhg
pulmonary resistance ~1/10 of systemic

Question 8

describe low vascular resistance of pulm circ

Answer 8

low vascular resistance in pulm circ relies on thin walls of vascular system
low vascular resistance and high compliance of pulm circ allows lung to accept whole cardiac output at all times

Question 9

describe accommodation of pulmonary blood vessels - specific

Answer 9

starting to exercise = want to increase flow, so lower resistance but not pressure since leak
pulmonary circ has capacity to accommodate 2 to 3 fold increases in co without little change in pulm arterial pressure
not all blood vessels open

Question 10

describe accommodation of pulmonary blood vessels - gen

Answer 10

some closed at rest
does distension = wide so less resistance
and does recruitment= more blood vessels, recruit unopened ones = decreases resistance

Question 11

describe what serotonin, histamine and norepi do

Answer 11

cause contraction of smooth muscle
increase pulmonary vascular resistance in larger pulmonary arteries

Question 12

what do ach and isoproteranol do

Answer 12

relax smooth muscle
decreases pulmonary vascular resistance

Question 13

describe reflex vasoconstriction

Answer 13

in regions of lung that are poorly oxygenated

Question 14

what do nitric oxide do

Answer 14

produced by endothelial cells
relaxes vascular smooth muscle
leads to vasodilation

Question 15

describe effects of gravity on pulmonary blood flow - gen

Answer 15

test performed by injecting radioactive xenon in peripheral vein - blood goes to lungs and diffuses and can count = more blood flow at bottom
falls down bc gravity = bottom of lungs
supine = more homogenous, at bottom and back of lungs = higher, diff value from standing up

Question 16

describe starling resistor concept - top

Answer 16

arterial site = too low for any blood flow
squeezed so no blood flow
pressure much less
too low for any blood flow around alveoli
can be seen in disease situations

Question 17

describe starling resistor concept - middle

Answer 17

not high enough = so capillaries squeezed
high to entrance then squeezed then blood pushes and then flows, kind on and off
blood flow but not enough, pushes and squeezes on and off

Question 18

describe starling resistor concept - bottom

Answer 18

more pressure here
flows down pressure gradient
high more pressure then flows around alveoli = less pressure

Question 19

where do capillaries go

Answer 19

around alveoli
pressure on alveoli - can squeeze

Question 20

describe effects of gravity on pulmonary blood flow - zone 1

Answer 20

palv > p arter > p venous
so no blood flow
does not happen in healthy people

Question 21

describe effects of gravity on pulmonary blood flow - zone 2

Answer 21

p arter > p alv > p venous
squeezing effect
on outlet side then blood accumulates and pushes open and then restarts

Question 22

describe effects of gravity on pulmonary blood flow - zone 3

Answer 22

p art > p venous > p alv
blood flow increases as go down lungs

Question 23

describe effects of gravity on ventilation - gen

Answer 23

at rest = top alveoli more open than bottom = slinky effect
take breath = all open top all the same size = change of vol at bottom greater than at top - more fresh air goes to bottom then top
breathe radioactive xenon
change in vol greater at bottom

Question 24

describe effects of gravity on ventilation - specific

Answer 24

Gravity also affects the distribution of ventilation
In an upright lung at rest, in normal gravity, the alveoli at the top of the lungs are more opened than the bottom ones (think of a “Slinky” held in normal gravity)
the distribution of ventilation can be measured in a similar way as that of perfusion but with inhaled radioactive Xenon instead of infused in the blood.

Question 25

describe distribution of ventilation perfusion ratio in the lungs in normal gravity

Answer 25

ratio of ventilation/perfusion higher at top of lungs
point where ratio and ventilation and blood flow meet = equal to one
not one everywhere - we are not perfect but its normal
ex on space moon = will be much more uniform since less gravity = may not be perfect stills

Question 26

describe measuring pulmonary blood flow using ficks principle

Answer 26

O2 consumption per minute (VO2) is equal to the O2 taken up by the blood in the lungs in one minute, The [O2] in the blood entering the lungs is CVO2 and that leaving is CaO2. It then follows that:

VO2= Q (CaO2 - CVO2)
or
Q= VO2/ (CaO2 – CVO2)

where:
VO2: measured by comparing [O2] in the expired gas collected in a large spirometer and [O2] in inspired gas;
CaO2: measured from an artery;
CVO2: measured via a catheter from the pulmonary artery.

Question 27

describe o2 consumed vs o2 inhaled in alveoli

Answer 27

equal
stays equal on right and left sides of heart
ex = cells use more o2, so p02 decreases - 30mmhg, what happens = greater pressure gradient so will diffuse more oxygen from lungs into capillary to restore equilibrium