Answer:
Having considered how an appropriate primary immune response is mounted to pathogens in both the peripheral lymphoid system and the mucosa-associated lymphoid tissues, we now turn to immunological memory, which is a feature of both compartments. Perhaps the most important consequence of an adaptive immune response is the establishment of a state of immunological memory. Immunological memory is the ability of the immune system to respond more rapidly and effectively to pathogens that have been encountered previously, and reflects the preexistence of a clonally expanded population of antigen-specific lymphocytes. Memory responses, which are called secondary, tertiary, and so on, depending on the number of exposures to antigen, also differ qualitatively from primary responses. This is particularly clear in the case of the antibody response, where the characteristics of antibodies produced in secondary and subsequent responses are distinct from those produced in the primary response to the same antigen. Memory T-cell responses have been harder to study, but can also be distinguished from the responses of naive or effector T cells. The principal focus of this section will be the altered character of memory responses, although we will also discuss emerging explanations of how immunological memory persists after exposure to antigen. A long-standing debate about whether specific memory is maintained by distinct populations of long-lived memory cells that can persist without residual antigen, or by lymphocytes that are under perpetual stimulation by residual antigen, appears to have been settled in favor of the former hypothesis.
On sooory I send u answer in msg
<span>a. They have homologous structures because they have a common ancestor.
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Well a mutation is like a change in the DNA and so if there was a mutation in the antártica fish, something in their genes would change. If that mutation has a positive effect on it, then that mutation would be passed down to the generations of fish, helping that fish with its survival or something
Answer:
Cell
Explanation:
Glial cells and neurons are the two types of cells that make up the nervous system. Four tasks are carried out by glial cells, which make up the nervous system's supporting framework: Give the neurons structural support. protect the neurons. A neuron is a specialized, impulse-conducting cell that is the functional unit of the nervous system, consisting of the cell body and its processes, the axon and dendrites. Three components make up neurons (nerve cells), which perform the integration and communication processes. Axon terminals, dendrites, and axons. The cell body, also known as the soma, is their fourth component and is responsible for the fundamental functions of neurons. In the illustration to the right, a "typical" neuron is depicted. The neuron, a specialized cell created to send information to other nerve cells, muscle cells, or gland cells, is the basic functional unit of the brain. Neurons are nervous system cells that communicate information to other nerve, muscle, and gland cells. Axons, dendrites, and a cell body make up the majority of neurons.
