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surface area/volume ratio
rapport m surface/volume

The ratio of surface area to volume is:

Surface area (m x ) / Volume (h)
Or surface area/weight

It has its significance for living organisms in many ways. It is difficult to measure the surface area and volume of a plant or animal, but the importance of this ratio appears through the use of cubes as model organisms.

In these models, as an object becomes larger its surface area (relative to volume) becomes smaller. This is also true for living organisms and is significant
Especially regarding heat and water loss.

(a) Volume/surface area and heat loss: They lose heat more quickly than small animals because their relatively larger surface area allows easier loss of heat escaping into the air, with the following results:

(1) Small mammals, such as mice, eat more food
Relatively large mammals eat to generate energy to replace the high heat loss.

(2) Birds and very small mammals have limits
Warm climates.

(3) Birds and mammals in cold habitats are usually larger than the same species in warm climates.

(b) Volume/surface area and water loss: Small organisms have larger evaporation surfaces, relative to their volume, and thus a greater tendency to lose water. This is important, given that many animals and plants suffer from problems of excessive water loss, and this problem becomes more severe the smaller the membership.


suspensory ligaments
Ligaments mpl suspenseurs

Suspension straps. Structures that hold the lens in place inside the eye of a vertebrate animal. See eye accommodation.


symbiosis
symbiose f

Solidarity. A relationship between organisms of different species for the purpose of nutrition. Examples of symbiosis include: parasitism and mutualism, the expression of which is limited to commensalism, with sometimes mutualism.


synapse
synapse f

Synapse. A microscopic gap between the dendrite of one axon and the axon of another neuron through which a nerve impulse must pass. Nerve impulses arriving at a synapse cause the diffusion of a chemical substance that crosses the gap and releases nerve impulses in the next nerve cell.


synovial membrane
membrane f synoviale

Synovial membrane is a connective tissue membrane that lines a mobile joint capsule in a vertebrate animal and is attached to the bones on both sides of the joint.
The synovial membrane secretes a synovial fluid that moistens the joint cavity, lubricates the joint when the bones move, and forms an anti-concussion cushion. See joint.


systole
system f

contraction. See heartbeat.