Homeostasis Flashcards
Define external environment
The factors that are occuring and changing, OUTSIDE the body.
Define internal environment
Inside the human body, in this case it is liquid inside humans.
Defintion of homeostasis
Processes that are responsible for maintaining a relatively constant environment.
Define extra cellular fluid
Fluids that are located on the outside of the cell such as tissue fluid and plasma
Define infra cellular fluid
Fluid that is located on the inside of the cell, this is known as the cytosol
What separates the extra cellular fluids
Thin flat cells that form the walls of the capillaries
What separates extra cellular fluids and intra cellular fluids
Cell membranes
Is there exchanges between fluids
There are continous exchanges between fluids
- Nutrients
- Waste product
- Other subtacnes ie glucose
What is a stimulus??
A change, plural stimuli
Explain the stimulus response model
- Stimulus occurs
- Receptors detect stimulus
- Message then gets sent to the control centre
- Then from the control centre either nerves or hormones send a message to the effectors.
- A response is made
What can be control centres in the stimulus response model?
CNS
or single organs (like the pancreas)
Name the four types of receptors and what they recept
Chemorecptors (Chemicals)
Mechanorecptors (Pressure and movement)
Photorecetors (Detect Light)
Thermoreceptors (Temperaure)
Explain negative feedback
Same as stimulus response model however this means that the response that the effector produces counteracts the intial stimulus hence trying to bring back the levels to narrow limits.
Explain positive feedback
effector reinforces stimulus
-Effector produces the same response as stimulus, e.g blood clotting or ATP production in labour
What variables are subject to homeostasis?
Nutrient Concentration Temperature Water Ion Concentration pH Volume and Pressure of Blood Oxygen and Carbon Dioxide Concentration Red Blood Cells
