Pulmonary blood flow

Question 1

where do alveolar capillaries recieve blood from?

what is its oxygen and CO2 content?

how does its blood return to heart?

? blood gas in vein?

function?

Answer 1

from right ventricle thru pulmonary artery

low O2/ high CO2

pulmonary vein

high PaO2/ low PaCO2

gas exchange in alveoli

Question 2

where do extra-alveolar capillaries recieve blood from?

what is their gas content?

where do they deilver blood?

how does its blood return to heart?

function?

blood gas in vein?

Answer 2

left ventricle thru aorta

high O2/ low CO2

to tissue of lungs

pulmonary veins (venous admixutre)- reduces O2 content of pulmonary veins and increases CO2

provides nutrients to and removes waste from airways

low PaO2/ high PaCo2

Question 3

what is the equation for pulmonary blood pressure?

Answer 3

PBP= CO* PVR

PVR= pulmonry vascular resistance

Question 4

how was PVR compare to the rest of the body?

Answer 4

way lower because the same amount of blood that comes from heart (CO= 5L/mon) has to go to lungs that has way lower blood pressure (25/15 vs 120/80 in body)

(think about equation if this doesnt make sense)

Question 5

what things is PVR determined by?

Answer 5

1. high number of capillaries
2. how many capillaries open at given moment
3. lung volume- at low or very high volumes resistance increases because of the stretch or compression of caps (diameter decreases)

** sympathetic tone has way less influence than the bronchial branch (vasoconstriction)

Question 6

how does PVR respond to exercise?

Answer 6

PVR drops because more pulmonary capillaries open to accomodate increased CO

Question 7

what lung dieases lead to an increase in resistance?

Answer 7

COPD, interstitial lung disease, sleep disorderd breathing—> all lead to caps being destroyed and increase in resistance

Question 8

how does the PVR normal value, BP, and BV compare to that TPR?

Answer 8

lower

lower

equal

Question 9

when someone locks their knees, why is it they pass out?

Answer 9

gravity pulls their blood to their legs—>

their skeletal muscles cant pump the blood back up to thorax—>

causing less blood returns to heart (and then brain)

Question 10

what are the blood flow, alveoli size and blood pressure in the apex of lung?

Answer 10

little blood flow

expanded- high alveolar pressure

reduced- above level of heart

Question 11

what are the blood flow, alveoli size and blood pressure in the middle of lung?

Answer 11

normal

average

a little higher- at level of heart?

Question 12

what are the blood flow, alveoli size and blood pressure in base of lung?

Answer 12

lots of blood

smaller- low alveolar pressure

higher-below heart

Question 13

what is the role of nitric oxide?

Answer 13

made by endothelium when sheer forces—> causes smooth muscle relaxation/vasodilation—> plays big role in normal pulmonary blood flow by slowing down blood to get more ox to tissues and dont damage capillaries?

Question 14

what are some chemical modulators of blood flow that arent normally present (unless in disease)?

what do they (msybe) play role in?

Answer 14

endothelin 1- vasocontrictor made in lungs

thromboxane A2- ditto

pulmonary arterial hypertension and left-sded heart dysfunction

Question 15

why do we want to keep the alveoli “dry”?

Answer 15

O2 is not very water soluble—> if caps leaked water into alveoli it would impair O2 to get into blood

Question 16

what controls how much fluid moves from caps to lung?

Answer 16

Starling forces–> two main components:

1. hydrostatic pressures of the caps and tissues
2. oncotic pressures of caps and tissues

Question 17

what direction does cap hydorstatic pressure (Pc) send blood in the lung?

Answer 17

push fluid into alveoli

Question 18

what direction does tissue hydrostatic pressure (Pt) send blood in the body?

Answer 18

pushes fluid into cap in the rest of body

Question 19

what direction does Pt want to send blood in the lung?

Answer 19

from cap into alveolus

due to negative hydrostatic pressure in tissues as a result of same forces causing negatvie IPP (chest wall wanting to expand and lungs wanting to shrink… increase in IP volume)

Question 20

what direction does cap oncotic pressue (πc) move blood?

Answer 20

pulls water into cap

Question 21

what direction does blood flow in tissue oncotic pressure (πt) in alveoli?

Answer 21

pulls water into alveolus

Question 22

what are all of the forces moving water from cap to alveolus? which is greatest?

Answer 22

Pc, πt, Pt

Pc is the greatest

Question 23

what are the forces moving water from alveolus to cap?

Answer 23

only πc

Question 24

what is the equation for the sum of forces of fluid movement in lungs?

what is result?

Answer 24

(Pc+πt+Pt)- πc

Starling forces favor fluid filtatration along lenght of pulmonary cap and and move fluid into alveoli

Question 25

what do we rely on to remove fluid from alveoli?

Answer 25

lymphatics!!

Question 26

what diease causes the inability to remove water from alveoli?

Answer 26

congestive heart failure—> leads to pulmonary edema

Question 27

what major pathway do lungs take part in?

Answer 27

renin converts angiotensinogen (made by liver)—> angiotensin 1

ACE converts angiotensin 1–> angiotension 2 in the lungs

ACE alos inactivates bradykinin (can cause cough for people on ACE inhibitors)

Question 28

what is another lung enzyme that plays role in immune system activation have?

Answer 28

arachnoid acid metabolism—> leukotrienes and prostaglandins/thromboxane A2

prostaglandin E2 and F2aplha and leukotrienes are later removed from circulation i_n lungs_