Homeostasis 1 Flashcards
Tissues
Group 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 + waste
Define Homeostasis
Preventing disturbance in the system to maintain an optimum internal environment
What does homeostasis require?
- Integration of organ systems
- Regulation at cell tissues and system level
What does homeostasis mean?
Similar condition
What is the aim of homeostasis?
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 brought about in order to minimise change?
Through negative feedback control
What is the mechanism of negative feedback control?
- Receptors 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 too?
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 optimum conditions
What can homeothermic 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 does 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
What does diabetes associated hyperglycaemia cause?
- Loss of salt and H2O
- Acid/base disturbance
- 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 H20 balance?
- Input: thirst mechanism
- Output: regulation of urinary losses
