communication, homeostasis and energy Flashcards
(27 cards)
What are 4 conditions that must be maintained within cells to ensure the survival of that cell?
-pH
-water concentration
-temperature
-prevent toxins build-up (e.g. CO2)
What is cell signalling
the communication process that governs the basic activities of cells and coordinates multiple cell actions within multicellular organism
What are some things cells might need to communicate about?
-carbon dioxide
-water concentration levels
-threats in the environment
-presentation of antigens
-release of cytokines
-temperature
nervous system (neuronal)
if the response needs to be rapid because the stimulus changes quickly or is an immediate threat- the nervous system is used as neurons are able to conduct electrical impulses much faster) hormones travel in the blood
-responses are faster but only short-term
endocrine system (hormonal)
the hormonal (endocrine) system uses the blood to carry chemical messengers
-slower but longer-lasting effects
Peptide hormones with examples
types of hormones that have to bind to receptors on the cell membrane of their target tissues- e.g. binding of adrenaline to the liver cells
-e.g. glucagon, adrenaline and ADH are peptide hormones
Steroid hormones with examples
do not bind to the cell but instead pass directly through the bilayer of the plasma membrane and any other membranes inside the cell
-able to do this as they are small and non-polar
-e.g. oestrogen
Blood glucose concentration range
4-7 mmoL/L
Body temperature
36-37.5 degrees C
pH of blood
7.35-7.45 pH
What is homeostasis?
the maintenance of a state of dynamic equilibrium and homeostatic control systems using the principle of negative feedback to maintain systems within narrow limits
What is negative feedback?
in a homeostatic control system, the combination of the physiological responses of the effectors brings the aspect back towards the optimum and therefore reverses the original change (the stimulus).
What is positive feedback?
involves a response that increases the original change
What are sensory receptors?
detect stimuli
What is a coordination centre?
receives and processes sensory input to coordinate a response
What are effectors?
brings about a response
-muscles or glands
Why is having a high blood water concentration dangerous?
-water moves from the blood into the cells by osmosis
-Due to the steep water potential gradient, lots of water moves into the cells by osmosis, causing those cells to swell
-Cells do not consist of a cell wall and the support that that would provide and so bursts (cytolysed)
Why is having a low blood water concentration dangerous?
-water moves from cell into the blood by osmosis
-Water potential gradient lots of water moves out of the cells, mouse mouses, causing the cell to shrivel and shrink
-No cell wall so cell becomes crenated
-this reduces the surface area and the cells ability to perform its specific function
-The decrease in the amount of cytoplasm also causes a decrease in chemical reactions
What is an ectotherm?
organisms that rely on external sources of heat and their body temperature fluctuates with external temperature
What is an endotherm?
organisms that use heat from metabolic reactions to maintain their body temperature and are largely independent of external temperatures
Behavioural responses of an ectotherm when body temperature is lower than it should be
-move to a sunny area to bask
-expose as much of their surface area to the Sun as possible
ectotherms rely almost exclusively on a range of these behavioural responses about endotherm‘s use, behavioural and physiological responses such as increased sweating to try to restore optimum levels
Why may some ectotherms stay in burrows?
borrows have more stable temperatures than the air, so it may be cooler in the burrow at the hottest part of the day, but it may be warmer than air at night
Advantages of ectotherms
-can use a greater proportion of energy from food to grow as energy is not needed to maintain body temperature
-Can survive for longer periods without food, as have lower metabolic demands/ need to eat this food
Why is it more beneficial to have ectotherms than endotherms in the food chain?
as ectotherms do not use energy from metabolic reactions to control their temperature, less energy is lost meaning more is available for growth (forming biomass) and this will be passed onto the consumer
