Homeostasis Flashcards
Define homeostasis
Process that keeps internal environment of the body constant to optimises physiological and biochemical processes that support life.
Why is it important to maintain constancy of the internal environment?
The body operates within normal ranges of different parameters and as long as we’re within those normal ranges then everything is okay but when we move out of that normal range that is when we can get unwell.
What are examples of body ranges that are controlled via homeostasis?
Regulation of temperature, maintaining healthy blood pressure, blood glucose regulation and regulating water levels.
Describe negative feedback
- Homeostatically regulated condition shifts
- Signal generated - endocrine or nervous
- Response produced (shivering or sweating)
- Original disturbance corrected, regulated condition back to normal range
Describe feed-forward control feedback
When the body anticipates and responds to changes in the environment before they have an effect.
While it cannot prevent dehydration, it can stop it from getting worse.
Kidney pre-empts dehydration is coming and acts to prevent it from getting worse until a point where negative feedback can restore that condition to normal.
Describe positive feedback
Encourages and intensifies a change in the body’s physiological condition, actually driving it farther out of the normal range.
Makes it worse.
EG - action potential
What is the key mechanism that homeostasis is controlled by?
Negative feedback
What is the daily water balance in an average healthy man?
It is equal
Whatever you gain you must lose
EG if total water consumption is 2.5L then total water loss is 2.5L
What are the three compartments water is stored in?
Intercellular fluid (fluid inside cells)
Interstitial fluid (fluid between cells but outside of blood vessels)
Plasma (fluid component of blood)
What makes up extracellular fluid?
Plasma and interstitial fluid
What is the main component of fluid?
Water
How does water move between the three compartments in which it is stored?
Water can move freely between these components (no barriers) although movement is subject to forces such as osmosis.
What is the difference between plasma and interstitial fluid?
Plasma and interstitial fluid have an almost identical composition - the only difference is that proteins and blood cells can be found in plasma but not in the interstitial fluid.
How is the component of the intracellular fluid different compared to that of the extracellular fluid?
The components of the intracellular fluid are very different to the composition of the extracellular fluid because the cell membrane that separates those two compartments is selectively-permeable but it allows water to cross it feely - no barrier. Barriers are things to ions and proteins.
What is the equation used in the dilution principle?
Concentration = mass/volume which is rearranged to Volume = mass/concentration
