In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of ranvier. true or false

True

Explanation:

Node of Ranvier are gaps periodically located along the myelin on axons,  their function is to facilitate the conduction of nerve impulses, this can be achieved because these gaps are rich in ion channels (Na+, Cl-) that trigger the propagation of action potential. The conduction in these nodes has the particularity to "jump" thanks to the discontinuity it has (as you can see in the image I added).

I hope you find this information useful and interesting! Good luck!

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation:

the tricuspid valve is present between right atrium and right ventricle