1/18: Homeostasis Flashcards
What is homeostasis?
Process of maintaining a relatively constant/stable internal environment (set point) in spite of changing external environments
What is homeostasis important for?
Cell functions
What is the external environment?
Outside the body
What is extracellular fluid?
Internal environment; inside body, outside cells
What are the two compartments of the ECF?
- Plasma
- Interstitial fluid
Where is plasma?
In blood vessels, fluid portion of blood
Where is interstitial fluid?
Outside blood vessels and cells
What is intracellular fluid?
Intracellular environment = inside cells
Where is the intracellular fluid?
Cytoplasm
What are examples of the body maintaining homeostasis?
BP, [Na+], [Glu], [K+], pH, body H2O, BT
When do homeostatic processes restore balance to the ECF?
Following a disturbance
ex: blood glucose levels increase after eating, return to their set point via homeostasis
What kind of process is homeostasis?
A dynamic, not a static process
Steady state (requires energy input) vs equilibrium
What is dynamic constancy?
Levels change over short periods of time, but remain relatively constant over long periods of time
What happens to the system when physiological variables change dramaticall over a 24-hr period?
The system is still in overall balance
What do we refer to when homeostasis is maintained?
Physiology
What do we refer to when homeostasis is not maintained?
Pathophysiology
What are the two levels that homeostasis can occur in?
Cellular homeostasis
Extracellular fluid
What are components of cellular homeostasis?
Function of each cell
Cytoplasm of single cell
Necessary for normal cell function
Relies on components of extracellular fluid
What are components of extracellular fluid?
Environment outside of the cell
Necessary for normal cell function
What are the two types of extracellular fluid?
Local
Systemic
What is local homeostasis restricted to?
One tissue space
What does local homeostasis utilize?
Paracrines and autocrines
What does local homeostasis maintain?
Function of tissue
What does systemic homeostasis involve?
Entire body
What does systemic homeostasis utilize?
Nervous system and endocrine system
What does systemic homeostasis maintain?
Function of heart and brain