8.1 Resp Many Points

Question 1

What is asthma? Sx? Causes?

Answer 1

“hyperreactive airway disease”, chronic inflammatory disorder that causes episodes of bronchial constriction
symptoms: wheezing, dyspnea, cough, chest tightness
many causes: genetic, allergy, chemical exposure
each episode causes permanent inflammatory changes in bronchioles

Question 2

What is COPD?

Answer 2

chronic bronchitis: excess mucus obstructs airflow oxygen diffusion is low (hypoxia) cyanosis
excessive mucus, fibrosis, remodeling due to inflammation
pulmonary vasoconstriction, pulmonary hypertension
hyperreactive airways: episodes of bronchoconstriction
narrowing
emphysema: overdistension of alveoli with trapped air obstructs airflow, loss of recoil  high residual volume left in lung
loss of elastic recoil, hyperinflation, “dead space” in lung

Question 3

What is the PO2 in the atmosphere, alveoli, and pulmonary capillaries?

Answer 3

Atmosphere: 160 mmHg
Alveoli: 100 mmHg
Capillary: 40 mmHg

Question 4

What is the PCO2 in Tissue, and at Alveoli?

Answer 4

Tissue: 46
Alveoli: 40

Question 5

What is ventilation/perfusion coupling?

Answer 5

Vasodilation and Vasoconstriction within the pulmonary capillaries can be adjusted alongside bronchoconstriction and bronchodilation to match local airflow and blood flow at the respiratory membrane

Question 6

What happens if perfusion if greater than blood flow?

Answer 6

gases don’t have time to exchange properly:
CO2 is high: causes bronchodilation, increases airflow
O2 is low: causes vasoconstriction of pulmonary capillaries, decreases blood flow

Question 7

What happens if perfusion is less than blood flow?

Answer 7

excess gas exchange may occur:
CO2 is low: causes bronchoconstriction, decreases airflow
O2 is high: causes vasodilation of pulmonary capillaries, increases blood flow

Question 8

How does O2 sat effect O2’s offloading from HgB?

Answer 8

Hemoglobin need to bind oxygen in order to carry it from the lungs to the systemic circulation, but also needs to unbind oxygen in order to deliver it from the systemic circulation to the tissues.
LOADING and UNLOADING of oxygen from hemoglobin is dues to PO2 gradients at each site

Low O2? Unload more

Question 9

What leads to increases in )2 unloading from HgB?

Answer 9

Increased Temperature
Increased CO2 levels
Increased H+ levels
Increased 2,3 BPG (metabolite)

Question 10

What is the Bohr effect on Hgb?

Answer 10

When Hb binds H+ or CO2, it changes the molecular structure of hemoglobin, weakens bonds and makes it more likely to unload O2
more O2 unloading with high H+ and CO2 levels

Question 11

What is the Haldane effect on HgB?

Answer 11

Hemoglobin can bind and buffer CO2 and H+, this will happen at the tissue level when O2 is unloaded and free to pick up other molecules
unloading of O2 increases the ability hemoglobin to bind to CO2 and H+

Question 12

What is the formula for CO2 transport?

Answer 12

CO2 + H20 H2CO3 HCO3- + H+

1st reaction uses carbonic anhydrase

Question 13

What is the chloride shift?

Answer 13

Bicarb in RBC replaced with Cl- (chloride shifts into cell to maintain charge)

Question 14

What is respiratory acidosis?

Answer 14

(low pH due to lack of adequate ventilation)

Decreased ventilation CO2 builds up

Question 15

What is respiratory alkalosis?

Answer 15

(high pH due to lack of adequate ventilation)

Increased ventilation  CO2 removed

Question 16

What is metabolic acidosis?

Answer 16

(low pH due to high cellular activity)

Increased activity  increased CO2 produced

Question 17

What is metabolic alkalosis?

Answer 17

(high pH due to low cellular activity)

Decreased activity  decreased CO2 produced

Question 18

What part of brainstem controls breathing?

Answer 18

Medulla

Question 19

What are the medullary respiratory centers? What do they control?

Answer 19

Ventral Respiratory Group (VRG) sets basic rhythm, inspiration and expiration
Dorsal Respiratory Group (DRG): inspiration

Question 20

How does the pons effect breathing?

Answer 20

works with medulla to fine-tune breathing
Pneumotaxic Center (Pons) inhibit inspiration to allow expiration
Apneustic Center (Pons) excites inspiration to enhance breathing, leads to “gasps”

Question 21

What are central chemoreceptors sensitive for?

Answer 21

Arterial PO2: no effect
Arterial PCO2: MAIN REGULATOR
Indirect due to H+ accumulation inside brain
very sensitive, will increase or decrease medulla activity based on need to remove CO2

Question 22

How do chemoreceptors on the aorta effect breathing?

Answer 22

Peripheral) chemoreceptors can stimulate or inhibit the medulla
mainly influenced by high H+ in the blood
BUT – can respond to low levels of oxygen if CO2 response is attenuated (ex: COPD)

Question 23

What is chronic hypoxia? What organs are particularly vulnerable?

Answer 23

lack of oxygen for extended period of time due to respiratory dysfunction
heart and brain – especially vulnerable

Question 24

What is hypoxemia?

Answer 24

low oxygen levels in blood
normally few symptoms because hemoglobin saturation is over 90% at levels of PO2 as low as 70mmHg
at PO2 = 60mmHg, severe hypoxemia
behavioral changes, loss of movement coordination, restlessness, impaired judgement delirium, stupor, coma

Question 25

What is the compensation for hypoxemia?

Answer 25

increased ventilation
pulmonary vasoconstriction –> pulmonary hypertension
increased workload right ventricle, RV heart failure –> cor pulmonale
erythropoietin (EPO) secretion by kidney RBC’s