Homeostasis Flashcards
If internal environment within cells were not regulated, what would happen?
Would not be able to release waste (e.g CO2 and urea)
What are the two main concepts that drive the structure and function of multicellular organisms?
- Surface area to volume ratio (issue for larger organisms)
2. Rate of diffusion (main way in which cells exchange with environment)
What is the size of organisms limited by?
Limited unless exchange surfaces and transport systems evolve.
What is the rate of diffusion limited by?
Distance.
In order to keep inner cells healthy, what must be organised?
Cells of complex organisms are organised into functional units.
What are the functional units into which complex organisms are organised?
- cells of related types form tissues
- tissues function together to form organs
- organs work together in systems
- organisms are made up of multiple systems
Do all animals have the same major organ systems? Why or why not?
No. This is because the environment and animal type dictates the evolution of a particular system.
What are the four major types of tissue?
- connective tissue (e.g BLOOD, bone, cartilage)
- muscle (smooth which lines digestive tract and controls blood flow, cardiac, skeletal)
- epithelium (barriers/borders: protection, secretion, absorption. E.g skin)
- nervous tissue (nervous and glial cells)
What is the function of glial cells?
Part of nervous tissue. Acts as supporting, regulating network. Helps mediate neurons.
What type of tissue is blood?
Connective tissue.
Where do specialised cells come from?
They come from stem cells which are cells that have the potential to become specialised.
What is differentiation?
The process by which structure and function become specialised.
What are the two types of stem cells?
Some stem cells can become any cell type = totipotent
Adult stem cells are less flexible = multipotent. E.g bone marrow stem cells only produce red and white blood cells.
Define homeostasis.
The tendency to maintain a relatively stable internal environment.
What type of feedback do physiological mechanisms that maintain homeostasis rely on?
All rely on negative feedback which reduces the error signal that triggered the regulatory mechanism. (Minimises change)
List some examples of variables maintained by homeostasis,
- blood pressure
- water balance
What is the difference between negative and positive feedback?
Negative feedback = reduces change
Positive feedback = amplifies change
How is heat generated by the body?
Via cellular respiration. Therefore the more your cells respire, the more heat is produced.
Describe the relationship between thermal energy generation and loss for warm blooded and cold blooded animals.
Warm blooded: thermal energy loss = thermal energy generated, therefore constant temperature maintained.
Cold blooded;
Thermal energy loss < thermal energy produced, hotter
Thermal energy loss > thermal energy produced, cooler
What are the costs and benefits of homeostasis in general?
Costs:
- uses energy, very expensive in terms of metabolic costs
- risk of predation
Benefits:
- metabolic efficiency achieved
- less dependent on environment
What is the stimulus response model?
Stimulus > receptor > control centre (integratory system) > effector > response
What happens if the set point is drifted from in homeostasis?
Something physiological happens to bring back set point.
What are the costs and benefits involved in using homeostasis to maintain body temperature?
Costs:
- metabolically expensive to stay warm in cool environment
- water loss for cooling (e.g sweating, panting)
Benefits:
- high efficiency as enzymes are optimised for one temperature
- can remain active in cold, more time to forage, less risk of predation as they still have the energy to run away
- able to use wider range of environments
Describe what occurs with the homeostasis of blood gas (holding in breath) and name the type of feedback occurring.
- Holding in breath causes decrease in oxygen and increase in CO2.
- Increase in CO2 leads to increase in carbonic acid which is detected by the body as it measures pH which indirectly measures CO2.
- when the urge to breathe is too great, the concentration of blood CO2 is the highest and therefore deep breaths are taken to decrease the CO2 concentration (NEGATIVE FEEDBACK reduces stimulus).
- overshoot occurs and acts to correct via reduced breathing
