Question

A 50-year-old man was admitted to the hospital with the diagnosis of chronic obstructive lung disease. On review of the chart, the nurse noted the patient is both hypoxic and has an elevated carbon dioxide level. When examining the patient, the nurse notes an increased respiratory effort and use of accessory muscles.

1. What is compliance, resistance, and residual volume as it relates to COPD.

2. In patients with chronic obstructive disease, there is a decreased surface area for diffusion. Explain how that will impact diffusion and how that relates to the hypoxia and elevated carbon dioxide.

3. Explain the difference between the function of the central and peripheral chemoreceptors.

answers in bulletin

Answer 1

1. In obstructive lung disease that has increased resistance and compliance. The compliance increases because the lung is destroyed resulting in it thinning. Thin walls means need little pressure to inflate, but since elastic recoil is low expiration is difficult (air is left behind as a result, hyperinflation). Results in leftward shift in pressure vs. volume curve.

Residual volume increases in COPD hence it increases the total lung capacity .

2. In COPD ,surface area for diffusion decreases hence the normal respiratory function is altered - Functions of the respiratory system

The function of the respiratory system is gas exchange

Oxygen from inspired air diffuses from alveoli in the lung into the blood in the pulmonary capillaries

Carbon dioxide produced during cell metabolism diffuses from the blood into the alveoli and is exhaled.

And as a complication hypoxia , hypoxemia , shortness of breath etc occur .

3. Difference between the function of the central and peripheral chemoreceptors :-

Central chemoreceptors :-

Chemoreceptors in medulla that sense changes in CO2 and pH levels in CSF or interstitial fluid in the brain. They surround the respiratory center (in medulla) and send signals to respiratory center

Peripheral chemoreceptors :-

Carotid and aortic body are a cluster of chemoreceptors made of glomus cells (neuron like) that sense systemic changes in O2, CO2 and pH and secrete neurotransmitters to nearby neurons that send signals to the respiratory center in the medulla. Carotid body sends info via CN9 and aortic body sends info via CN 10.