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Bmsc 208 > Respiratory 5 > Flashcards

Respiratory 5 Flashcards

1
Q

What exists between alveoli and pulmonary capillaries at all time

A

Partial pressure gradient for O2 and CO2

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2
Q

What determines the O2 and CO2 diffusion rate between alveoli and capillaries

A

Gas composition in alveoli

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3
Q

In alveoli what remains relatively constant during quiet respiration assuming perfusion is normal

A

PO2 and PCO2

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4
Q

What is perfusion

A

Blood flow

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5
Q

O2 entering alveoli is equal to what

A

O2 uptake from pulmonary capillaries

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6
Q

What can alter partial pressures of O2 and CO2 and alter diffusion

A

Alterations in ventilation rate independent of changes in CV system
Ex) hyperventilation or hypoventilation

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7
Q

What can cause hypoventilation

A

Alcohol, drugs

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8
Q

What happens during hypoventilation

A

Slow breathing
- increased PCO2, not ventilating as much CO2 out
- decreased PO2 bringing in less O2

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9
Q

What happens during hyperventilation

A

Breathing rapidly, deeply
- bringing in more O2 than being taken up by capillaries
- O2 builds up in alveoli, alveolar PO2 increases
- exhaling CO2 faster then being brought to pulmonary capillaries, PCO2 decreases
- increased diffusion of O2 and CO2

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10
Q

What must happen so one organ system does not work harder then it needs to

A

Ventilation and alveolar blood flow (perfusion) must match

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11
Q

What must happen for external respiration

A
  1. Bringing O2 from atmosphere into alveoli
  2. Blood flow must be high enough to pick up available O2
  3. Matched ventilation/perfusion
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12
Q

What is local regional control to match perfusion and ventilation in lungs?

A

Gravity

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13
Q

How does gravity affect blood flow in lungs

A
  • blood flow is higher at base of lung and decreases up to apex during rest
  • low pressure circuit and right ventricle doesn’t create enough pressure to go against gravity
  • pressure of pumping and downward pressure causes perfusion in base
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14
Q

How does gravity affect ventilation

A
  • highest at base and decreases as move up
  • entire lung not -3 mmHg, more positive at base
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15
Q

Why is the intrapleural pressure more negative at the apex

A

Bigger space between the pleura because gravity

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16
Q

What does a more negative intrapleural pressure do to the alveoli at the apex

A

Partially open and filled with air even at rest and therefore do not take much air during ventilation

17
Q

What does not innervate the pulmonary arterioles like it does the systemic arterioles

A

Autonomic innervation

18
Q

What are the two local controls for smaller areas of the lungs

A

Pulmonary arterioles influenced by O2
Bronchioles sensitive to CO2

19
Q

What can affect blood flow in pulmonary arterioles

A

Decreasing O2 levels around
Decrease causes constriction

20
Q

Why do the pulmonary arterioles constrict in response to low O2

A

Increases resistance so blood flow can be diverted to ventilated arterioles that have adequate O2

21
Q

What causes constriction to low O2 in pulmonary arterioles

A

O2 sensitive K+ channels close

22
Q

What affects air flow in bronchioles

A

Increase CO2 causes dilation, reduces resistance so more CO2 exhaled
Decrease CO2 causes constriction, not over ventilating and no excessive removal of CO2

23
Q

What happens when one alveoli is blocked and air cannot move in

A
  • at first blood will continue to flow by, from CO2 and CO2 will increase in alveoli and region
  • O2 will decrease, no fresh O2 and everything in alveoli picked up
  • increase CO2 causes dilation of bronchiole
  • decrease O2 will cause arterioles to constrict
  • blood will take path of least resistance
24
Q

What are 3 local control of arterioles and bronchioles

A

PCO2 increases - bronchioles dilate
PCO2 decreases - bronchioles constrict
PO2 decreases - pulmonary arteries constrict

25
Q

What happens during a blockage in a pulmonary vessel (blood clot) in alveoli

A

Alveolar PO2 increases (fresh O2 being brought not picked up)
Alveolar PCO2 decreases (continuing to ventilate removing CO2 but no perfusion with new)

26
Q

What happens in region when there’s a vessel blockage

A

Tissue PO2 increases
Tissue PCO2 decreases
Bronchiole smooth muscle constricts diverting flow

27
Q

What is hypoxia

A

Too little oxygen

28
Q

What causes hypoxia

A

Impaired diffusion from alveoli to blood or impaired blood transport
- inadequate amounts of O2 reaching alveoli

29
Q

What is hypoxia often paired with

A

Hypercapnia
- excess CO2
- low levels ventilation or improper diffusion

30
Q

What do the sensors in the arterial blood to avoid hypoxia and hypercapnia respond to

A
  1. Oxygen - ATP production
  2. Carbon dioxide - CNS depressant/ acid precursor
  3. PH - denaturing of protein
31
Q

What is normal PO2 in arterial and venous blood

A

95 and 40 mmHg

32
Q

What is normal PCO2 in arterial and venous blood

A

40 and 46 mmHg

33
Q

What is normal pH in arterial and venous blood

A

7.4 and 7.37 (CO2 causes slight drop)

34
Q

What direction do gases diffuse

A

Down partial pressure gradients

35
Q

When does O2 and CO2 diffuse until

A

Equilibrium
Ex) PO2 cells 40 mmHg = venous 40 mmHg blood

36
Q

What 3 things is alveolar gas exchange influenced by

A
  1. O2 reaching the alveoli
  2. Gas diffusion between alveoli and blood
  3. Adequate perfusion of alveoli
37
Q

Two causes of low alveolar PO2 assuming perfusion remains constant

A
  1. Inspired air has low O2 content
  2. Alveolar ventilation
38
Q

When is inspired air low in O2

A

As increase elevation, PO2 decreases
- PO2 at sea level is ~160 mmHg, in Denver (1600m above) PO2 132 mmHg

39
Q

When does alveolar ventilation cause low alveolar PO2

A
  • Ventilation issue (hypoventilation)
  • increase airway resistance, decrease lung compliance, or CNS issue decrease rate or depth of breathing

Bmsc 208 (33 decks)

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