On these “Gold Standard Step 1 Facts” pages you will find Free:
- USMLE Audio Review files from our “Gold Standard USMLE Reviews”
- Transcriptions of those files
- And videos (as they become available)
The idea is that you can review for the USMLE online by:
- Listening to the Audio
- Following along with the transcription
- Or by watching the video (if available)
If you like what you here, you can purchase the entire Gold Standard Step 1 MP3 audio USMLE review for your iPhone, iPod, or computer here.
Let’s start our USMLE Review with Anatomy from the Gold Standard USMLE Step 1 Audio Review program.
Play USMLE Audio MP3 62 03 High Altitude Response Below
Begin 62 03 High Altitude Response Transcription
Now let’s talk about high altitude response.
When a person goes to a high altitude, what is the immediate effect on arterial oxygen tension?
- At high altitude, arterial oxygen tension decreases and the person becomes hypoxemic
This is directly a decrease due to a decrease in what other PO2?
- Alveolar PO2.
The body accommodates for high altitude in six ways. First, what happens to ventilation of the lungs?
- Ventilation increases, tidal volume increases.
An acute increase in ventilation would be how big?
- Ventilation may increase as much as two thirds over normal.
Second, what do kidneys produce more of in high altitudes? It starts with an E.
- At high altitude, the kidneys produce more erythropoietin
What does increased production erythropoietin directly lead to?
- More erythrocytes
And what does an increase in erythrocytes lead to?
- More hemoglobin
Third, an increase in what compound results in a shift to the right of the oxygen dissociation curve?
- 2,3 diphosphoglycerate
How does this effect hemoglobin?
- It decreases the affinity of hemoglobin for oxygen
And what does this facilitate?
- Unloading of oxygen in the tissues
Fourth, what condition will be increased in ventilation cause in the blood? It starts with RA
- Increased ventilation will cause respiratory alkalosis
And what will the kidneys do in response to this?
- The kidneys will excrete more bicarbonate
Fifth, how will the pulmonary vessels respond to hypoxemia?
- There will be pulmonary vasoconstriction which will raise the pulmonary vascular resistance.
What two effects will this have on the heart?
- There will be an increased work load for the right heart and hypertrophy of the right heart
And finally, sixth, what will the cells of the body create more of? It starts with an M
- The cells will create more mitochondria.
Student doctor, please pause the tape and summarize the six ways that the body responds to high altitude.
- Ventilation increases, erythropoietin increases, 2,3 diphosphoglycerate increases, respiratory alkalosis causes kidneys to excrete more bicarbonate, pulmonary vasoconstriction results in right heart hypertrophy and body cells create more mitochondria.
****END OF TRANSCRIPTION****
Want More USMLE Step 1 Review Facts?
- Download the complete 82 Hour Gold Standard USMLE Step 1 Audio Review Here
- Find the complete list of Gold Standard Step 1 USMLE Facts Here