Kidney ultrasound. Also called: renal ultrasound. A kidney ultrasound is used to determine the size, shape and location of the kidneys without cutting the skin. A kidney ultrasound makes it possible to see the kidneys from outside the body by using ultrasonic waves.
An early recognized function of astrocytes is the control of K + levels in the brain. Neuronal activity leads to an increase in K + concentration from a resting level of about 3 mM to a maximum of 10 - 12 mM under physiological conditions and to even higher values under pathological conditions.strocytes may also limit the number of synapses since astrocyte membranes can ensheath the neuronal processes and thus compete with synapses. Astroglial cells can also be involved in the elimination of synapses in the CNS, the process which underlies the final tuning and plasticity of the neuronal inputs.
Astrocytes comprise some 90% of all human brain cells, but because they lack the electrical activity of neurons, they were never really considered to participate in the process of long-term potentiation -- changes in synaptic strength thought to underlie learning and memory.he effect appeared to be localized, with synapses just 200 micrometers away from clamped astrocytes exhibiting normal LTP formation. But astrocytes extend only about 50 to 70 micrometers, Volterra said, suggesting that the effect was not entirely contained within the reach of the manipulated astrocyte.