Homeostasis 1 Flashcards
Tissues
Groups of cells that share the same characteristics or specialisations
Organs
Collections of tissues, usually of several different types, that synchronise to perform a particular function
What is the equation of life?
Nutrients +O2 =Energy (ATP) + CO2 + Wastes
Homeostasis
Preventing disturbance in the system to maintain an optimum internal environment
What does homeostasis require?
Integration of organ systems
Regulation at cell, tissue and system level
What does homeostasis mean?
Similar condition
What does homeostasis aim to do?
Maintain a constant internal environment
What are examples of homeostasis in action?
Cooling down when hot
Heating up when cold
What are 3 common everyday challenges to our internal environment?
External temperatures
Diet
Exercise
What do external temperatures, diet and exercise impact on?
Body fluid composition
Energy stores
Body temperature
What happens to homeostasis at extremes?
It becomes less effective
How is the regulation of tissues and organ systems in order to minimise change brought about?
Through negative feedback control
What is the mechanism of negative feedback control?
- Receptor senses change (stimulus)
- Information sent to integrating centre
- Compared to reference level
- Signal generated and sent to effector
- Response produced
What is the magnitude of the generated signal in proportion to?
The magnitude of difference from normal and the magnitude of response
What is the aim of negative feedback control?
To restore the internal environment to optimal conditions
What can homeotherms do?
Maintain a constant temperature over a wide range of external temperatures
What are the characteristics of negative feedback systems?
- There is oscillation around the set point
- Restore the regulated variable after its initial displacement but cannot prevent it happening.
What happens in feed forward control?
Additional receptors permit system to anticipate change and therefore activate response earlier
What is an example of feed forward control?
Temperature receptors in our skin detect external temperature and activate response before any significant change in core temperature occurs
What doe positive feedback do?
An initial disturbance sets off a chain of events that lead to an even greater disturbance
What does positive feedback control lead to?
Instability
When does positive feedback control occur?
In the nerve action potential
Ovulation
What occurs during positive feedback control?
Self Amplification
What happens when the muscle and liver cells are unable to take up glucose from the blood in diabetes?
The body thinks it is starving. In response the liver releases glucose from its stores which increases the already high blood glucose levels
What does diabetes associated hyperglycaemia cause?
Loss of salt and H2O and acid/base disturbances
Blindness
Neural dysfunction
Kidney damage
How is the integration of systems coordinated?
Endocrine and nervous systems
What are homeostatic mechanisms represented by?
Reflexes
What can reflexes be/
Neural and/or hormonal
Simple or complex
How much of our body weight is made up of water?
60%
What processes are regulated in order to maintain H2O balance?
Input: thirst mechanism
Output: regulation of urinary losses
