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What happens to our body when we drink water to maintain a dynamic "steady state"?
H2O in -->
Osmolality decreases in the blood-->
This decrease is sensed by osmoreceptors in the brain-->
Production of ADH-->
H2O out--->
Osmolality increase.
In the case of passive exchange, what is the amount dependent on?
– The gradients of the moving substance
– Permeability across the membranes of the substance
– Surface to volume ratio
Which internal factors need to be kept in homeostasis in order for an organism to function?
1. Gases: O2 and CO2
2. pH in the internal environment
3. Water, ions, and other osmolytes
4. Nutrients and waste products
5. Temperature
6. Volume and pressure of extra cellular fluids
What does it mean if something is a threat to homeostasis? What does an organism have to do in order to achieve homeostasis again?
Threats are stressors that will affect the balance of homeostasis and energy is required to maintain it.
For example:
* Change in partial pressure of O2 or CO2
* Change in pH
* Change in temperature
* Predation
* Injury
* Lack of food
When a threat to homeostasis occurs, reserved energy needs to be consumed in order to achieve homeostasis once again.
What is the difference between regulators and conformers?
Regulator:
* Possess a constant internal environment or homeostasis.
* Maintain their body temperature.
* The body fluids have a fixed osmotic concentration.
* Consume large amount of energy.
* Have a wide range of environmental distribution.
Conformer:
* Their body temperature changes according to that of environment.
* Osmotic concentration of body fluids varies according to that of external medium.
* They consume lesser amount of energy and are less active.
* They (in most cases) have a narrow range of environmental distribution.
What is feedback regulation when a stressor is affecting an organism?
What different kinds of feedback regulations are there and how does it work?
Feedback regulation is the main component of homeostasis.
A) On/Off system (a very rough system)
B) Proportional system (On/Off working at the same time in "tonus").
The mechanism:
1. A stressor will affect a variable
2. This variable triggers a sensory system in the body
3. The sensor sends signals to an effector
4. Effector acts to regulate and maintain homeostasis.
What is Allostasis?
The process of achieving homeostasis through physiological or behavioural responses.
What is developmental plasticity and phenotypic plasticity?
Developmental plasticity:
Changes in neural connections during development as a result of environmental interactions as well as neural changes induced by learning.
Phenotypic plasticity:
Short‐term changes in a character or trait to meet changes in the environment.
What are the roles of the cell membrane?
The cell membrane (also called plasma membrane) have the role of:
* Being a selective barrier
* Being a selective transporter
* Keeping up the membrane potential
* Keeping up cell volume
* Keeping intracellular homeostasis
* Being an anchoring place for receptors
* Being an anchoring place for cytoskeleton
* Being an anchoring place for some enzymes * Creating connections between cells
* Creating possibilities for communication
* Being a receiver of communication signals
What is the membrane potential? Is it positively or negatively charged? What is the membrane potential range in millivolts (mV)?
The difference in electric potential between the intracellular environment and the extracellular environment of a biological cell.
With respect to the exterior of the cell, typical values of membrane potential range from –40 mV to –80 mV. (Negatively charged)
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