9.1 Maintaining Internal Balance Flashcards
Homeostasis
The physiological state of the body in which internal physical and chemical conditions are kept within a range that’s suitable for life processes
Interstitial fluid
The fluid that surrounds the body cells
Internal environment
Extracellular fluid, which consists of fluid that surrounds the cells and tissues in the body and the plasma portion of the blood
Homeostatic mechanism
A system that monitors internal and external conditions and changes bodily functions to maintain homeostasis
Negative feedback
The response of a system that acts to maintain equilibrium by compensating for any changes made to the system
Sensor
The element of a feedback system that detects changes in the environment
Integrator
The element of feedback system that compares existing conditions with ideal conditions
Effector
The element (or elements) of a feedback system that acts to return the system to its optimal state
Positive feedback
The response of a system that acts to increase the effect of any changes made to the system
Maintaining an Internal Balance
- Homeostasis refers to body’s attempt to adjust to the fluctuating external environment
- Body tries to maintain a stable internal environment
- Many diff systems working together within body to maintain internal balance
Internal environment
- Refers to extracellular fluid, consists of interstitial fluid (btwn cells/tissues) and blood plasma
- Volume, temp, and chemical composition of internal environment can change quickly
- Body uses many systems to regulate its internal conditions
All organ systems
- Take in, process/distribute nutrients/other chemicals; also dispose of wastes
- synthesize nutrients/other molecules essential for cellular function
- respond to changes in environment
- Protect body from injury/reproduce
Set point
The optimal value for a given variable of a system
Homeostasis/feedback mechanisms
Involve “detection” and “correction”
- Both positive/negative feedback mechanisms
Stimulus
environmental change
3 main components of homeostatic control
1) Sensor (ex. sensory neuron)
2) Integrator (ex. brain)
3) Effector (ex. muscle or gland)
Negative feedback
- Primary mechanism of homeostasis
- Stimulus triggers a response that compensates for the change
Sensor
(ex. free nerve ending in the skin)
Integrator
the brain
Effector
A muscle or a gland
Response
System’s output
In the negative feedback mechanism,
the response of the system cancels or counteracts the effect of the original environmental change
Sensor
Gathers info and sends to the integrator
The integrator compares
to set points (optimal functioning conditions)
Integrator activates
Effector
Positive feedback systems
Reinforces changes which are occuring.
- Therefore, the variable is moved farther away from the steady state
Ex. Childbirth (uterine contractions)
