Tilt test overview
As occurs during acute blood loss, standing or tilting causes a reduction in central blood volume resulting in a reduction of central venous pressure and venous return.
In this simulation you will explore the resultant effects of gravity on the circulation during 60° and 80° postural tilt. To do this you will examine the effect tilt has on mean arterial pressure, heart rate, cardiac output, stroke volume and total peripheral resistance.
Watch the video below for an overview of the procedure followed to perform this experiment in a laboratory.
Please note that the video has been edited for brevity. In reality, the pooling of blood is progressive, and takes several minutes to stabilise.
Tilt table simulation
Choose the desired inclination and press the "Start recording" button. The first five minutes of the recording will correspond to baseline, or horizontal (0°) tilt. From minutes 5 to 10, the table will be tilted to the inclination you chose. The last 5 minutes will show the recovery.
Fill the table with the mean values for baseline and each tilt. Hover the mouse on the graph for a horizontal line to appear with the corresponding y-value for that mouse position, which will help you estimate the mean for each period.
Note: Record the initial response (first 5-10 seconds) to each tilt in the boxes below the table.
Initial MAP response:
Interactive activity
When a healthy person is subjected to head up tilt, is the initial MAP response (first 5-10 seconds) anincrease or decreaserelative to baseline? Enter the correct answer under "Start" in the "Arterial pressure" box of the diagram, and work your way through the rest of the drop-down boxes to explain the reflex response that followed that initial response.
Click this button when you're ready to submit your response:
For each of the newly appeared drop-down boxes, choose the correct neurotransmitter that is being released at that site. For your reference:
- NA = Noradrenaline
- ACh = Acetylcholine
- GABA = Gamma amino butyric acid
- EAA = Excitatory amino acid
Click this button when you're ready to submit your response:
