Respiratory Physiology Flashcards

Question

Oxygen uptake in pulmonary capillaries

Answer 1

Blood enters with pO2 of 40 mmHg | Alveolar pO2 is 100 mmHg --> O2 moves from alveoli to capillary (saturated in .25 sec)

Answer 2

use CO because its not perfusion limited | Diffusion capacity = Vco/(P1-P2)

Answer 3

Takes 0.2 sec for O2 to combine with RBC | R = (P1-P2)/V

Answer 4

pressures are relatively low (25/8 mmHg) low resistance pulmonary capillaries surrounded by alveoli (pressure on capillaries from alveoli)

Answer 5

Recruitment of additional capillaries Distention of capillaries conducting blood Expansion of lung also reduces resistance NE, 5-HT, histamine --> increase resistance ACh, Iso, prostacyclin --> reduce resistance

Answer 6

O2 consumption = CO x (CAo2 - CVo2) | CO = VO2 / (CAo2 - CVo2)

Answer 7

PA > Pa > Pv doesn't occur naturally --> but during hemorrhage or PPB *alveoli "crushes" arteriole Apex of lung

Answer 8

Pa > PA > Pv blood flow is determined by pressure differential between arteries and alveoli (venous doesn't influence) Apical regions of lungs

Answer 9

Pa > Pv > PA flow is dependent on arterial/venous pressure difference (normal situation) occurs in midregion/base of lungs

Answer 10

Alveolar hypoxia --> constriction of blood vessels perfusing that hypoxic region of lung Independent of nerves Involves inhibiting VG K+ channels --> depolarize membrane potential Causes increase in [Ca] leading to vasoconstriction

Answer 11

(Pcap – P int) – ∂ (πcap – πint) | - too much fluid movement out --> alveolar edema --> shortness of breath

Answer 12

Reservoir for blood | Filter blood -> clots (PE)

Answer 13

Ang I --> Ang II by ACE ACE inactivates bradykinin (side effect of ACE inhibitors in increased bradykinin and cough) Synthesizes PGE and leukotrienes

Answer 14

hypoventilation diffusion limitation R --> L shunt ventilation-perfusion mismatch

Answer 15

If O2 is not replenished fast enough, alveolar PO2 declines

Answer 16

PAo2 = PIo2 - [PAco2/R]

Answer 17

reducing area available for gas exchange or increasing the distance can cause hypoxia

Answer 18

Occurs when not fully oxygenated blood mixes with fully oxygenated blood --> if you give 100% oxygen, it won't correct the shunt because you will still have mixing

Answer 19

Major cause of hypoxia in lung disease PE = Tons of ventilation and no perfusion (V/Q = infinity) --> will equilibrate to room air Airway obstruction = tons of perfusion but no ventilation (V/Q = 0) --> will equilibrate to blood gas

Answer 20

``` Apex = high V/Q Base = low V/Q ```

Answer 21

2 forms 1. dissolved in blood (0.3 ml/dL at Po2 of 100 mmHg) 2. Hemoglobin (20 ml/dL at Po2 of 100 mmHg)

Answer 22

``` EXERCISE 1. Decreased pH 2. Increased O2 3. Increased temp 4. Increased 2,3-BPG O2 is released easier at the tissues ```

Answer 23

3 Forms 1. Dissolved in blood (much more soluble than O2) 2. Bicarbonate (involves CA) Major form 3. Carbamino compounds (hemoglobin)

Answer 24

much more linear than O2 curve, O2 curve affects CO2 curve

Answer 25

diaphragm contracts down and intercostals contract bringing ribs and sternum out --> increases intrathoracic volume

Answer 26

``` typically passive (elastic recoil of lungs) active expiration --> abdominals and intercostals pull ribs downward ```

Answer 27

inflation of lung occurs when pressure around lung becomes subatmospheric Pressure differential is greater to inflate lung than to deflate it = hysteresis Lung volume is never 0

Answer 28

Lungs are very compliant Fibrotic disease --> reduced compliance Emphysema --> increased compliance

Answer 29

surfactant greatly reduces surface tension of lungs | - without it, smaller alveoli would empty into larger one and collapse

Answer 30

intrapleural pressure is less at base than apex (less negative) --> weight of lung is pressing against the chest wall

Answer 31

Increased pressure associated with exhalation can result in collapse of airways --> occurs at low lung volumes Airway disease patients --> purse lips to create back pressure to keep airways open so they don't trap air

Answer 32

at functional residual capacity

Answer 33

Smallest at large lung volumes, greatest at small lung volumes determined by radius of airways --> resistance decreases in smaller airways because total cross-sectional area is greater than large airways Medium-sized bronchi are main source of resistance

Answer 34

increases because ACh binds muscarinic receptors causing contraction

Answer 35

decreases because Epi binds beta-2 receptors causing dilation

Answer 36

Rate of flow during expiration is rapid initially then falls Drop in flow caused by compression of airway when thoracic volume is decreased to expel air Flow determined by alveolar pressure - pleural pressure

Answer 37

``` central controller (pons and medulla) peripheral sensors (chemoreceptors) efferent mechanisms (nerves and muscles) ```

Answer 38

pons and medulla (cortex can override to increase/decrease breathing) - respond to pH --> H+ stimulates respiration, alkalosis suppresses respiration - H+ cannot cross BBB, so CO2 diffuses across and is converted by ca to H and HCO3

Answer 39

carotid bodies and aortic arch sense hypoxia (increased firing rate as Po2 decreases) carotids respond to decrease in pH both carotid and aortic respond to hypercapnia (but not as much as central)

Answer 40

CO2 --> each 1 mmHg increase in Pco2 causes 2-3 L increase in ventilation if O2 held constant

Answer 41

If CO2 is held constant, most individuals don't respond to hypoxia until Po2 drops below 50 mmHg EXCEPTIONS --> high altitude, COPD

Answer 42

low pH stimulates ventilation when Pco2 and Po2 are constant (sensed by carotid bodies)

Answer 43

typically observe fall in Pco2 and rise in Po2 --> pH is stable during exercise until very intense levels