Gas Transport and Respiratory Disease

Question 1

Molecular O2 is carried in blood in 2 forms

Answer 1

• 1.5% is dissolved in plasma
• 98.5% is loosely bound to the Fe of Hemoglobin (Hgb) in RBCs

Question 2

How many molecules of O2 can be carried per Hgb

Answer 2

4 molecules of O2

Question 3

O2 is loaded/unloaded by changes in the shape of Hgb

Answer 3

• As O2 binds, Hgb affinity for O2 increases - efficient loading
• As O2 is released, Hgb affinity for O2 decreases - efficient unloading

Question 4

a fully saturated Hgb molecule has how many heme groups bound to O2

Answer 4

4 heme groups

Question 5

a partially saturated Hgb molecule has how many heme groups bound to O2

Answer 5

1-3 heme groups

Question 6

the rate of loading/unloading is regulated by

Answer 6

pO2, temperature, blood pH, and pCO2

Question 7

under normal, resting conditions arterial blood Hgb is how saturated

Answer 7

98%

Question 8

under normal, resting condition venous blood Hgb is how saturated

Answer 8

75%

Question 9

Venous Reserve

Answer 9

substantial amounts of O2, still available in venous blood

Question 10

What does the amount of O2 carried by Hgb depends on

Answer 10

pO2

Question 11

more O2 is present…

Answer 11

more O2 is bound to Hgb

Question 12

Safety Margin

Answer 12

at a high pO2, Hgb stays almost fully saturated seven with a large change in pO2

Question 13

Efficiency

Answer 13

at a low pO2, Hgb experiences sharp decreases In saturation with similar changes in pO2

Question 14

active body cells produce about how much CO2/minute

Answer 14

200mL of CO2/minute

Question 15

CO2 is transported in blood in 3 forms

Answer 15

• 7-10% dissolved in plasma
• 20% bound to globin of Hemoglobin (carbaminohemoglobin)
• 70% as bicarbonate ions in plasma

Question 16

carbonic amhydrase

Answer 16

enzyme found in RBCs that catalyzes the reactions

Question 17

exchange of CO2 slide 6+7

Question 18

Bohr effect

Answer 18

• O2 unloading from Hgb is enhanced by an increased pCO2
• enhances O2 delivery where it is most needed

ex. an exercising thigh muscle

Question 19

Haldane effect

Answer 19

• CO2 unloading from Hgb is enhanced by and increased pO2
• enhances CO2 delivery for expiration

ex. pulmonary circulation

Question 20

bicarbonate buffer system

Answer 20

important for resisting shift in blood pH
- if H+ concentration increases, H+ is removed by forming H2CO3
- if H+ concentration decreases, H2CO3 dissociates into H+

Question 21

respiratory acidosis

Answer 21

slow, shallow breathing allows CO2 to accumulate – carbonic acid forms, and pH drops

Question 22

respiratory alkalosis

Answer 22

rapid, deep breathing depletes CO2 - carbonic acid is reduced, and pH rises

Question 23

hypoxia

Answer 23

inadequate delivery of O2 to the body’s tissues

symptom: cyanosis when Hbg saturation dips below 75%

Question 24

Anemic hypoxia

Answer 24

too few RBCs or abnormal RBCs

Question 25

ischemia hypoxia

Answer 25

impaired/blocked blood circulation

Question 26

histotoxic hypoxia

Answer 26

body cells are unable to use delivered O2

Question 27

hypoxemic hypoxia

Answer 27

reduced arterial pO2

Question 28

CO poisoning

Answer 28

CO outcompetes O2 for heme binding sites

Question 29

Medulla Respiratory centers (2)

Answer 29

1. Ventral Respiratory Group (VRG) 2. Dorsal Respiratory group (DRG)

Question 30

Ventral Respiratory Group (VRG)

Answer 30

- impulses for inspiration travel along the phrenic and intercostal nerves - eupneic respiratory rate of 12-16 breaths/minute

Question 31

Dorsal Respiratory Greoup (DRG)

Answer 31

- integrates inputs from stretch and chemoreceptors and communications them to the VRG

Question 32

What determines the depth of ventilation?

Answer 32

the intensity of the stimulation to the inspiratory muscles

Question 33

chemoreceptors

Answer 33

receptors responding to chemical fluctuations in the blood - the amount of H+, CO2, O2

Question 34

what increases the rate + depth of respiration

Answer 34

a rise in CO2 triggers

Question 35

hyperventilation

Answer 35

an increase in the rate + depth of breathing - exceeds the body's need to remove CO2 - happens involuntarily during stress and anxiety

Question 36

what happens when we are hyperventilating

Answer 36

- leads to reduced levels of CO2 in the blood and vascular constriction

Question 37

symptoms of hyperventilation

Answer 37

decreased perfusion, tingling/numbness, dizziness, fainting

Question 38

hypothalamic controls

Answer 38

strong emotions and pain send signals to the respiratory centers - responses are mediated though the limbic system and the hypothalamus ex. gasping in shock, breath holding in anger, hyperventilation in excitement

Question 39

cortical controls

Answer 39

taking conscious control of respiratory rate - direct impulses from the cerebral motor cortex - medullary control are bypassed ex. voluntary breath holding -- the VRG will be automatically reinitiated when CO2 concentrations reach critical levels

Question 40

exercise

Answer 40

- working muscles consume O2 and produce CO2 - ventilation will increase 10-20 fold

Question 41

hyperpnea

Answer 41

increased ventilation in response to metabolic needs

Question 42

high altitude

Answer 42

- in increased altitudes, pO2 is lower - demands are met despite lower situation of arterial blood

Question 43

acute mountain sickness

Answer 43

headaches, SOB, nausea, dizziness

Question 44

Emphysema

Answer 44

permanent enlargement of the alveoli and pulmonary capillaries, use of accessory muscles, hyperinflation of the lungs

Question 45

chronic bronchitis

Answer 45

chronic and excessive mucus production, inflamed lower respiratory tract, obstructed airways, impaired ventilation

Question 46

dyspnea

Answer 46

labored breathing

Question 47

Asthma

Answer 47

- short term or reversible COPD symptoms: coughing, dyspnea, wheezing and chest tightness

Question 48

obstructive sleep apnea

Answer 48

collapse of the upper airways, musculature of the pharynx relaxes during sleep

Question 49

central sleep apnea

Answer 49

reduced drive from the brain's respiratory centers