Homeostasis Flashcards
Does not contain info on dilution principle
What is homeostasis?
Maintaining (relatively) constant internal environment
What feedback system is primarily responsible for our bodies maintaining homeostasis?
Negative feedback system
Describe the negative feedback system.
- Change in monitored variable (eg temperature)
- Fed back to integrating centre
- Signal sent to effector mechanism = response
- Corrects original change to normal value
What are homeotherms?
Organisms that maintain constant body temperature
Both feed forward systems and negative feedback systems can be used to regulate our temperature. How does a feed forward system work?
Additional receptors sense stimulus and activate effector mechanism before any internal change occurs
Basically predicts and anticipates a change
In terms of maintaining a constant internal environment, which is more effective, feed forward or negative feedback systems?
Feed forward
Can prevent the initial change from happening, whereas negative feedback only reacts to the change
However, it is harder to anticipate changes so negative feedback is a ‘safer’ option in a way
What is the effect of the positive feedback mechanism?
Reacts to initial stimulus/change by causing even greater disturbance
Escalates the change
Give an example of where positive feedback is used…
Nerve action potential
Ovulation
Other sexual behaviour
The body contains a lot of liquid
What is it more important for our body to maintain (homeostasis), the volume or the concentration?
Concentration
Maintaining the correct composition and concentration of the ECF especially, is fundamental to life
What three compartments is the water in our body found in?
Intracellular fluid
Interstitial fluid
Plasma
Plasma + interstitial = extracellular (ECF)
What is the ratio of extracellular fluid to intracellular fluid?
1:2
If a boi drinks 3L of water, how much will end up in his intracellular fluid?
2L into his Intracellular
1L into extracellular
Which compartment of body fluid do we measure?
for concentration etc
Plasma
Describe the permeability of the capillary walls.
Permeable to everything (Ions, glucose, H2O etc)
except plasma proteins
Describe the permeability of cell walls
Selectively permeable
Generally will take in what molecules/ions etc the cell needs and chucks out waste
