Lecture 18 Flashcards

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1
Q

External respiration

A

Diffusion of o2 from alveoli into blood in pulmonary capillaries + diffusion of co2 in opposite direction

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2
Q

In pulmonary gas exchange (external respiration), each gas diffuses

A

Independently

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3
Q

Deoxygenated blood from right side goes in lungs to get

A

oxygenated and go back to heart by left side

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4
Q

P of a specific gas in a mixture is called

A

Partial P

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5
Q

Po2 (partial pressure of o2) and Pco2 in atm

A

Po2: 159 mmHg
Pco2: 0.3mmHg

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6
Q

The greater the diff in partial pressure

A

The faster the rate of diffusion

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7
Q

External respiration occurs in

A

Lungs

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8
Q

Po2 and pco2 in alveolar air

A

Po2: 105 mmHg
Pco2: 40 mmHg

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9
Q

Diffusion of o2 in external respiration

A

From alveolar air (105 mmHg) to blood in pulmonary capillaries (40 mmHg)

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10
Q

Diffusion of co2 in external respiration

A

From deoxygenated blood (45 mmHg) to alveoli (40mmHg)

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11
Q

Diffusion of o2 in blood occurs until pulmonary capillary blood Po2 is

A

105 mmHg (like alveolar air)

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12
Q

Blood at 105 mmHg (after diffusion to equalize) mixes with blood supply to lung so that po2 in pulmonary veins returning to left side of heart =

A

100 mmHg

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13
Q

Pco2 45 mmHg of deox blood diffuses into alveoli until 40 mmHg in both so that oxy blood going back to left side of heart has pco2 of

A

40mmHg

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14
Q

During exercise, is the po2 in pulmonary capillaries higher or lower than 40 mmHg

A

Lower due to increase use of o2

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15
Q

3 factors influence external respiration

A
  1. Partial P gradient and gas solubilities
  2. Thickness and surface area of respiratory membranes
  3. Ventilation-perfusion coupling
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16
Q

Co2 is ___x more soluble than oxygen

A

20x

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17
Q

The greater the surface area, the

A

More efficient gas exchange

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18
Q

Respiratory membrane is very tuin (0,5 um) so it allows

A

Rapid diffusion of gases

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19
Q

Thickness of respiratory membrane increases with

A

Edema, pneumonia, heart failure (slows rate if gas exchange)

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20
Q

For optimal gas exchange, rate of ventilation (gas reaching alveoli) must

A

Match rate of perfusion (blood flow in pulmonary capillaries)

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21
Q

Ventilation-perfusion coupling is the process that

A

Coordinates respiratory and cardiovascular systems to deliver o2 to body tissues

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22
Q

Body responds to changes in ventilation by

A

Adjusting blood flow (airflow increases, blood flow too)

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23
Q

Internal respiration

A

Exchange of gases between systemic capillaries and tissue cells

24
Q

Po2 in tissue cells

A

40 mmHg

25
Q

Po2 in systemic capillaries

A

100 mmHg

26
Q

Pco2 in tissue cells

A

45 mmHg

27
Q

Pco2 in systemic capillaries

A

40 mmHg

28
Q

Why is pco2 higher in tissue cells than in capillaries

A

Bc co2 is product of ATP

29
Q

O2 doesn’t dissolve well in water so only 1,5-2% is

A

Dissolved in plasma of blood

30
Q

98-98.5% of o2 is

A

Bound to Hb in RBC

31
Q

Hb composed of four subunits with each a heme group and can carry

A

4 o2 atoms

32
Q

Hemoglobin is what type of molecule

A

Protein

33
Q

Each heme group (on every globin protein chain) has an iron atom at the center that binds with

A

1 o2 molecule.
1 RBC contains ~ 1 billion hb molecules

34
Q

O2 sat =

A

Amount of o2 bound/max that could bind X100 = __%

35
Q

When o2 binds to heme group it causes a

A

Confirmational change (increases affinity of 3 other o2 molecules )

36
Q

Once o2 unloads, all other o2 molecules

A

Loose affinity for heme groups

37
Q

Po2 bet 60-100 mmHg Hb is

A

90% or more saturated with o2

38
Q

Affinity of Hb yo o2 is affected by

A
  1. Temperature
  2. PH
  3. Pco2 and co
  4. 2,3- diphosphoglycerate (2,3-DPG)
39
Q

In Hb graph: green red and blue curves mean

A

Green: higher Hb affinity (po2 of 50 = 90%)
Red: normal (po2 50 = 83%)
Blue: reduced affinity (po2 50 = 73%), Hb is letting go of o2 (usually in tissues)

40
Q

Temperature on Hb graph

A

T increases, affinity decreases. Heat is product of metabolic reactions, metabolically active cells need more o2

41
Q

Ph on Hb graph

A

Decrease in ph = decrease in affinity.
H+ ions bind to Hb (protein) so alters structure slightly -> decrease o2 carrying capacity. More o2 available for tissue cells

42
Q

Pck2 and ph are related bc

A

Low blood ph results from high pco2

43
Q

As pco2 rises, Hb affinity

A

Decreases (releases o2)

44
Q

Why does co2 lower ph

A

Bc when entering blood most is temporarily converted to carbonic acid -> unstable and dissociates in H+ and bicarbonate-> [H+] increases

45
Q

During exercise, lactic acid (byproduct of anaerobic metabolism within muscles) does what to blood ph

A

Decreases ph

46
Q

DPG (substance found in RBC) increases, Hb affinity

A

Decreases bc Hb binds o2 less tightly when combined with DPG

47
Q

After entering the bloodstream, a co2 molecule

A
  1. Dissolves in plasma (7%)
  2. Binds to hb within rbc (23%)
  3. Converted to carbonic acid (70%)
48
Q

Co2 that dissolves in plasma dies what when reaching lungs

A

Diffuses into alveolar air and is exhaled

49
Q

When co2 binds to hb it makes

A

Carbaminohemoglobin on rbc

50
Q

Co2 binds where on hb

A

Globin proteins (doesn’t compete with o2 bc not same place)

51
Q

Pco2 is high in systemic capillaries which promotes formation of

A

Carbaminohemoglobin

52
Q

Co2 in Carbaminohemoglobin exits body how

A

In pulmonary capillaries, pco2 is low so Hb releases co2 that enters alveoli but diffusion

53
Q

Enzyme turning co2 in carbonic acid

A

Anhydrase

54
Q

How co2 that transforms into carbonic acid exit body

A

Carbonic acid dissociates into h+ and bicarbonate ions (either peed out or kept in buffer system) and reenters rbc, leaves it and diffuses out

55
Q

Co poisoning how

A

Co combines to heme group too but binding is 200x stronger than o2 so can’t be released as well. At [0,1%] of CO, half available Hb are bound with it so o2 carrying capacity is reduce by 50%.