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Science for Med Revision > Homeostasis > Flashcards

Flashcards in Homeostasis Deck (21):
1

% of ECF is ISF?

80%

2

% of ECF that is plasma?

20%

3

What happens if capillary perfusion fails and plasma proteins enter the tissue?

Gangrene

4

What ratio of TBW is ECF?

1/3

5

What ratio of TBW is ICF?

2/3

6

Why do females have less TBW on average?

- Higher proportion of body fat

7

What % of muscle is water?

70%

8

What percentage of fat is water?

10%

9

Define homeostasis?

The body's ability to maintain a constant internal environment

10

What is the process negative feedback control?

- Change detected as a stimulus by a receptor
- Information sent to an integrating centre
- Integrating centre compares the stimulus to a reference level
- Magnitude of difference sent to an effector as an ERROR signal
- Effector responds equally opposite to fix

11

Feedforward control?

- Body "predicts" a change before it happens
- Pre-emptive

12

Positive feedback?

- Initial change from reference leads to even greater disturbance
- Think like exponentials

13

What is the dilution principle?

c=m/v

14

What does the dilution principle allow you to calculate in the body?

Volume of distribution

15

What must be taken into account before using the dilution principle?

- Volume that has been excreted

16

What 3 water compartments can be measured DIRECTLY?

- Plasma
- ECF
- TBW

17

How do you measure plasma?

Attach radioactive labels to plasma proteins

18

Why is plasma volume able to be measured this way?

Plasma proteins can't move out of the plasma

19

What radioactive dye could you use?

Evans blue

20

What do you use to measure ECF?

Sucrose

21

What do you use to calculate TBW?

Radioactive water