Homeostasis

Functions of Life

1. Maintaining Boundaries
2. Movement
3. Responsiveness
4. Digestion
5. Metabolism
6. Excretion
7. Reproduction
8. Growth and Development

Homeostasis

* processes carried out by all organ systems that create a dynamic state of equilibrium with the same amount of movement in and out of systems
* all organisms must maintain a constant internal environment to function properly

Body Fluid and Composition

* essential to maintain homeostasis and consists of intracellular fluid and extracellular fluid

Intracellular Fluid (ICF)

* found inside cells, tissues and organs
* makes of 2/3rds of the bodies fluids

Extracellular Fluid (ECF)

* found outside cells
* can be either interstitial fluid or plasma
* makes up 1/3rd of the bodies fluid

Receptor

* monitors the environment in a feedback system and responds to changes
* sends message to the control center

Control Center

* determines the set point, analyzes the input and determines a response which is sent to the effector

Effector

* acts upon information from the control center

Negative Feedback Mechanisms

* majority of the homeostatic processes which reverse an initial effect
* includes body temperature and blood sugar levels

Body Temperature

* type of negative feedback mechanism
* the body maintains a temperature of 37 which is important for many physiological processes

Blood Sugar Levels

* type of negative feedback mechanism
* when blood sugar drops, glucagon is released from the pancreas causing the liver to release glucose
* when blood sugar rises, insulin is released from the pancreas and fat cells absorb glucose

Positive Feedback Mechanisms

* amplify the initial effect and are not homeostatic
* includes labour contractions and blood clotting

Labour Contractions

* type of positive feedback mechanism
* the brain releases oxytocin, intensifying labour contractions which causes more oxytocin to be released

Blood Clotting

* type of positive feedback mechanism
* a break or tear occurs in the blood vessel wall and platelets adhere to the site releasing chemical that attract more platelets

Homeostatic Imbalances

* can cause diseases and be associated with other organisms
* increases with age

Diabetes

* example of homeostasis failing with an improper negative feedback loop
* results from a breakdown in the production/functioning of insulin in which blood sugar accumulates