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Flashcards in Communication & Homeostasis Deck (20):

Maintaining internal conditions of the cells

- Enviroment - bathed in tissue fluid
- tissue fluid maintained by blood - excess diffuse into blood and are excreted
- the blood concentrations measured closely


A good communication system

- cover the whole body
- enable cells to communicate with each other + can be specific + rapid
- enable both short and long term responses


Cell signalling - The neuronal system

System of neurobes communicate across synapses
- very quick signal+ response to a quickly changing stimuli


Cell signalling - The hormonal system

- blood transports endocrine hormones to target cells around the body
- longer term responses



Keeping the internal enviroment constant despite external changes
- body temperature/blood pressure/ CO2 concentration/blood glucose concentration


Negative feedback

Process that brings about a reversal in a change of conditions that has been detected, back to the normal state to be maintained


Process of negative feedback

- change away from optimun
- sensory receptors detect change
-passes through a communication system ie nervous system
- effector cells ie liver/muscles reverse the change


Positive feedback

- the response increases the original change
- dangerous ie breathing in CO, caused u to breathe in more CO
- helpful- dialation of the cervix releases oxytocin, dilates more releases more oxytocin



An organism that relies on external sources of heat to regulate its body temperature


Advantages of being an ectotherm

- use less of their food in respiration
- means they have to eat less food
- greater proportion of energy can be used for growth


Disadvantages of being an ectotherm

- less active in cooler temperatures (increased risk from predators)
- may hibernate so need energy stores


Temperature regulation in ectotherms

To warm up
- bask
- some anatomical ie expanding rib cage for a larger surface area
To cool down
-hide in burrow from sun
- increase breathing rate more evaporation



An organism that can use internal sources of heat ie metabolic reactions to maintain its body temperature


Advantages of being an endotherm

- fairly constant internal temperature no matter what the external temperature
- activites possible no matter is winter/night
- inhabit colder parts of the world


Disadvantages if being an endotherm

- larger amount of energy intake used to maintain body temperature
- more food required
- less energy used for growth


Temperature regulation in endotherms
( anatomical)

- sweat glands- evaporation latent heat
- panting - evaporation
- hairs - insulation from convection/radiation
- vasoconstriction/dialation
- rate of metabolism
- skeletal muscles (spontaneous contractions) respiration = atp


Temperature regulation in endotherms (behavioural)

- shade/sunlight
- large surface area to the sun/ small SA
-inactive+ large surface area/ active + small surface area


Temperature regulation process

Thermoregulatory system detects change- nervous+ hormonal system carrying signals to target cells- effect to reverse the change


Peripheral temperature receptors

In the skin monitor the temperature in the extremities- to the thermoregulatory centre - can put in place behavioural mechanisms


Optimum conditions for enzymes

- suitable temperature
- suitable PH
- (aq) conditions so substrates+ products are in solution
- free from toxins plus excess inhibitors