15.1 - Principles of Homeostasis Flashcards
Define homeostasis
Homeostasis: The maintenance of a stable equilibrium in the conditions inside the body
What is negative feedback, how does it work & 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 is positive feedback and give 2 examples?
- 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)
Blood clotting
Childbirth
Explain positive feeback in blood clotting.
During blood clotting, platelets are attracted to the damaged blood vessel, they continue to be attracted until the clot is formed
Explain positive feedback during 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.
Why do plants and animals need communication system?
- 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
What is cell signalling?
Definition: Communication between cells involving the release of a signalling molecule binding to the receptor cell, causing a change within the recipient cell
- Exists for neuronal and endocrine systems
- Hormonal system uses blood stream
- Slower communications as hormones travel long distances to communicate between distant cell
- Neuronal system uses nervous system to travel between cells
- Fast communication as impulses are passed between adjacent cells
