Homeostasis Flashcards
Define homeostasis?
A set of processes by which the body tries to maintain a relatively constant internal environment.
What is homeostasis concerned with?
Keeping the levels of factors in the internal environment within narrow limits.
What does homeostasis mainly involve?
Regulation of the fluid that surrounds cells (extracellular fluid).
What are the 2 major elements of extracellular fluid?
1) . Interstitial fluid (tissue fluid) =
- fluid that leaves blood capillaries.
2) . Blood plasma =
- fluid that surrounds blood cells.
How much interstitial fluid leaves blood capillaries?
Approx. 12 litres.
How much blood plasma surrounds blood cells?
Approx. 3 litres.
List factors in the internal environment that are regulated within set limits?
- Core body temperature.
- Blood pressure.
- Blood gases.
- pH.
- Glucose.
- Calcium ions.
- Blood volume.
- Sodium ions.
What happens when the environment surrounding the cells is subjected to changes?
The cells take in (from internal environment) =
- CO2.
- Glucose.
- Amino acids.
- Vitamins.
- Minerals.
What happens to cellular waste products in the internal environment?
Raised levels (such as CO2 and ammonia).
How is the temperature of the internal environment changed?
Heat gained from muscle contraction and metabolism changes the temp.
Why do cells survive these challenges?
The composition of the internal environment is stabilised by;
- homeostatic regulation.
Why is it important to keep the surrounding cells within these narrow limits?
Chemicals within the cells may become subject to altered activity.
What are the homeostatic mechanisms in the body based around?
Feedback loop.
What are self-adjusting mechanisms?
Control process is built into the system =
- form a loop/cycle.
- usually reacts to change automatically.
What are the 3 factors of a feedback loop?
1). Receptor =
- stimulus received.
- converted into a signal.
2) . Controller =
- interprets signal.
3) . Effector =
- produce response.
