STUDENT INVESTIGATION 4.3

Background

When one body system is affected by an external stimulus (for example, a change in environment), all the other body systems play an interactive role in helping to maintain a stable condition in the body. In other words, each body system helps the other in the face of a challenge until all of the responses cascade down towards a new adaptive state. In the case of space flight, the human body moves from an "Earth-normal" condition to a "space-normal" condition. When the astronaut returns home, the body systems must again work together to reestablish that "Earth-normal" condition. The human body is truly amazing.

Procedure

A concept map is a flow diagram that illustrates the cascading nature lone leading to others, which lead to others, which lead to others, etc.) of a related set of responses for a particular phenomenon. It illustrates how the various systems react in response to a stimulus. In this case, we are interested in illustrating the flow of events that occurs in the human body as a result of space flight (Figure 10). The stimulus, which causes the flow of events to begin, is, in our case, the removal of gravity. The primary response from which all other responses follow is, in our case, the increase in volume the of fluids in the upper body (the headward fluid shift). We chose this as our starting point because by now, you are well familiar with this human response to space flight.

What follows from the primary response are the secondary responses in Figure 10.

Figure 10. Concept map illustrating the inter-relationships of the various body responses to the removal of gravity.

Your teacher will provide each of you with a copy of Figure 10. You are instructed to fill in the blank compartments for both the secondary responses and the subsequent responses with the appropriate statements, which are provided for you. Be aware that the statements which we have provided to you will all be used and they are not in order.

The following is the list of the secondary responses and the subsequent responses for your use in filling out the compartments on the concept map provided to you by your teacher. Use your logic and experience that you have gained through your use of this manual to complete the map.

SECONDARY RESPONSES

1. Increase in CVP, BP, HR, CO
2. Kidney stimulated to increase urine output
3. Body senses a "flood" in upper body
4. Change in physical characteristics: Puffy Face-Bird Legs Syndrome

5. Increased destruction of RBCs
6. Decrease in RBC production
7. Stabilization of CVP, BP, HR,CO
8. Initial increase in RBC concentration
9. Decrease in plasma volume
10. Heart shrinks in size because of decrease in workload
11. Decrease in body mass because of fluid loss
12. Altered hormone and electrolyte balance

CVP - Central Venous Pressure

RBC - Red Blood Cell

BP - Blood Pressure

HR - Heart Rate

CO - Cardiac Output