Physiology

Question 1

The primary drive for the way we breath when exercising comes from what; explain metabolically and using cardiac physiology.

Answer 1

Increase of CO2 in the tissues according to the equation AV=VCO2/PaCO2 will increase ventilation and explain the breathing rate during exercise. Additionally, HR increases along with SV to insure adequate CO so that the job of removing CO2 from the tissues (and delivering O2 to the tissues) is accomplished quickly; avoiding hypoxia. These are both increased via efferent signals from the NTS stimulating cardiac acceleration via sympathetic nerves branching from the chain ganglion in the thoracic cavity which innervate the heart. This increases inotropic, chronotropic, and dromotropic effects in the heart.

Question 2

What’s going on with the V/Q ratio during a restrictive disease? Explain

Answer 2

V/Q will be normal or greater than 0.8. This is commonly the result of interstitial lung disease, in which there will be a decrease in DLCO because of an interstitial fibrosis which impairs diffusion across the alveoli (creating dead space) and creates an A-a gradient mismatch.

Question 3

What happens to the vascularization of your skin when you work out; initially, as well as, later in your work out?

Answer 3

Initially, the skin is cool b/c alpha 1 receptors in arteriovenous anastomosis stimulate vascoconstriction, shunting blood to more vital organs. Eventually, though the need to cool the body over-rides this response and the SNS input by these alpha 1 receptors is inhibited

Question 4

What’s the main problem with cardiogenic shock? What test should you order to confirm and how do you treat it?

Answer 4

Decreased in contractility of the heart due to damage of obstruction will decrease O2 delivery to tissues

serum lactate, ABG, CXR, EKG, Echocardiogram (US)

Treat- VIP ventilation, infusion, and pressors to increase SVR and Epi for contractility.