Lecture 18

Question 1

External respiration

Answer 1

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

Question 2

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

Answer 2

Independently

Question 3

Deoxygenated blood from right side goes in lungs to get

Answer 3

oxygenated and go back to heart by left side

Question 4

P of a specific gas in a mixture is called

Answer 4

Partial P

Question 5

Po2 (partial pressure of o2) and Pco2 in atm

Answer 5

Po2: 159 mmHg
Pco2: 0.3mmHg

Question 6

The greater the diff in partial pressure

Answer 6

The faster the rate of diffusion

Question 7

External respiration occurs in

Answer 7

Lungs

Question 8

Po2 and pco2 in alveolar air

Answer 8

Po2: 105 mmHg
Pco2: 40 mmHg

Question 9

Diffusion of o2 in external respiration

Answer 9

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

Question 10

Diffusion of co2 in external respiration

Answer 10

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

Question 11

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

Answer 11

105 mmHg (like alveolar air)

Question 12

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 =

Answer 12

100 mmHg

Question 13

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

Answer 13

40mmHg

Question 14

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

Answer 14

Lower due to increase use of o2

Question 15

3 factors influence external respiration

Answer 15

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

Question 16

Co2 is ___x more soluble than oxygen

Answer 16

20x

Question 17

The greater the surface area, the

Answer 17

More efficient gas exchange

Question 18

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

Answer 18

Rapid diffusion of gases

Question 19

Thickness of respiratory membrane increases with

Answer 19

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

Question 20

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

Answer 20

Match rate of perfusion (blood flow in pulmonary capillaries)

Question 21

Ventilation-perfusion coupling is the process that

Answer 21

Coordinates respiratory and cardiovascular systems to deliver o2 to body tissues

Question 22

Body responds to changes in ventilation by

Answer 22

Adjusting blood flow (airflow increases, blood flow too)

Question 23

Internal respiration

Answer 23

Exchange of gases between systemic capillaries and tissue cells

Question 24

Po2 in tissue cells

Answer 24

40 mmHg

Question 25

Po2 in systemic capillaries

Answer 25

100 mmHg

Question 26

Pco2 in tissue cells

Answer 26

45 mmHg

Question 27

Pco2 in systemic capillaries

Answer 27

40 mmHg

Question 28

Why is pco2 higher in tissue cells than in capillaries

Answer 28

Bc co2 is product of ATP

Question 29

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

Answer 29

Dissolved in plasma of blood

Question 30

98-98.5% of o2 is

Answer 30

Bound to Hb in RBC

Question 31

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

Answer 31

4 o2 atoms

Question 32

Hemoglobin is what type of molecule

Answer 32

Protein

Question 33

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

Answer 33

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

Question 34

O2 sat =

Answer 34

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

Question 35

When o2 binds to heme group it causes a

Answer 35

Confirmational change (increases affinity of 3 other o2 molecules )

Question 36

Once o2 unloads, all other o2 molecules

Answer 36

Loose affinity for heme groups

Question 37

Po2 bet 60-100 mmHg Hb is

Answer 37

90% or more saturated with o2

Question 38

Affinity of Hb yo o2 is affected by

Answer 38

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

Question 39

In Hb graph: green red and blue curves mean

Answer 39

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)

Question 40

Temperature on Hb graph

Answer 40

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

Question 41

Ph on Hb graph

Answer 41

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

Question 42

Pck2 and ph are related bc

Answer 42

Low blood ph results from high pco2

Question 43

As pco2 rises, Hb affinity

Answer 43

Decreases (releases o2)

Question 44

Why does co2 lower ph

Answer 44

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

Question 45

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

Answer 45

Decreases ph

Question 46

DPG (substance found in RBC) increases, Hb affinity

Answer 46

Decreases bc Hb binds o2 less tightly when combined with DPG

Question 47

After entering the bloodstream, a co2 molecule

Answer 47

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

Question 48

Co2 that dissolves in plasma dies what when reaching lungs

Answer 48

Diffuses into alveolar air and is exhaled

Question 49

When co2 binds to hb it makes

Answer 49

Carbaminohemoglobin on rbc

Question 50

Co2 binds where on hb

Answer 50

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

Question 51

Pco2 is high in systemic capillaries which promotes formation of

Answer 51

Carbaminohemoglobin

Question 52

Co2 in Carbaminohemoglobin exits body how

Answer 52

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

Question 53

Enzyme turning co2 in carbonic acid

Answer 53

Anhydrase

Question 54

How co2 that transforms into carbonic acid exit body

Answer 54

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

Question 55

Co poisoning how

Answer 55

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%.