15.1 The principles of homeostasis Flashcards
Define homeostasis
The maintainance of a dynamic equilibrium over a narrow range of conditions inside the body
What is negative feedback how does it work and give an example
Negative feedback systems work by the body noticing a change from ideal conditions, negative feedback systems work to reverse the stimulus to ideal conditions.
E.g. control of blood glucose levels (insulin & glucagon)
What’s positive feedback and give an example
Only a few positive feedback systems in the body
Change in internal environment is detected, positive feedback system works to exacerbate the change (increasing the response)
Eg. Blood clotting
Why do plants and animals need cell communication systems
Organisms must maintain a stable internal environment for cells to function
So any chages must be monitored
To do this, cells must be able to communicate by cell signalling
E.g. via the nervous system, endocrine system
How does positive feedback in blood clotting work
During blood clotting, platelets are attracted to the damaged blood vessel, they continue to be attracted until the clot is formed
How does positive feedback work in childbirth
Another example is during childbirth, the baby’s head pressing against the cervix, oxytocin stimulate the uterus contraction pushing the head of baby further against the cervix, more oxytocin is produced until the body is born.
What’s cell signalling
Communication between cells involving the release of a signalling molecule binding to the receptor cell, causing a change within the recipient cell
How does the endocrine (hormonal) system use cell signalling
Hormonal system uses blood stream
Slower communications as hormones travel long distances to communicate between distant cell
How does the neuronal system use cell signalling
Neuronal system uses nervous system to travel between cells
Fast communication as impulses are passed between adjacent cells
