Somatic hypermutation

(noun)

a cellular mechanism by which the immune system adapts to the new foreign elements that confront it (for example, microbes). A major component of the process of affinity maturation, SHM diversifies B cell receptors used to recognize foreign elements (antigens) and allows the immune system to adapt its response to new threats during the lifetime of an organism.

Related Terms

Examples of Somatic hypermutation in the following topics:

  • Antibodies: Classes and Affinity Maturation

    • Antibodies undergo class switching, somatic hypermutation, and affinity maturation to improve their effectiveness to specific pathogens.
    • In these rapidly dividing cells, the genes encoding the variable domains of the heavy and light chains undergo a high rate of point mutation by a process called somatic hypermutation (SHM).

  • Antibody Genes and Diversity

    • The first stage is called somatic, or V(D)J, which stands for variable, diverse, and joining regions recombination.
    • In these rapidly dividing cells, the genes encoding the variable domains of the heavy and light chains undergo a high rate of point mutation, by a process called somatic hypermutation (SHM).
    • Somatic hypermutation involves a programmed process of mutation affecting the variable regions of immunoglobulin genes.
    • Outline the two stages which result in antibody diversity: somatic (V(D)J) and recombination stages

  • Maturation of B Cells

    • The B cell may either become one of these cell types directly or it may undergo an intermediate differentiation step, the germinal center reaction, where the B cell will hypermutate the variable region of its immunoglobulin gene ("somatic hypermutation") and possibly undergo class switching.

  • Somatic Symptom Disorders

    • Somatic symptom disorders involve physical symptoms but lack physical evidence of illness or injury.
    • A somatic symptom disorder, formerly known as a somatoform disorder, is a category of mental disorder included in a number of diagnostic schemes of mental illness, including the recent DSM-5 section Somatic Symptom and Related Disorders.
    • Those that do not pass the diagnostic criteria for a somatic symptom disorder but still present physical symptoms are usually referred to as having "somatic preoccupation".
    • Their replacement, somatic symptom disorder, has the following criteria for diagnosis:
    • Somatic symptom disorder is a controversial diagnosis.

  • Comparing the Somatic and Autonomic Nervous Systems

    • The peripheral nervous system includes both a voluntary, somatic branch and an involuntary branch that regulates visceral functions.
    • The peripheral nervous system (PNS) is divided into the somatic nervous system and the autonomic nervous system.
    • The somatic nervous system (SoNS) is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles.
    • The somatic nervous system controls all voluntary muscular systems within the body, and also mediates involuntary reflex arcs.
    • The somatic nervous system consists of three parts:

  • Localization of Pain

    • Localization of pain is determined by whether the pain is superficial somatic, visceral, or deep somatic.
    • Nociceptive pain may also be divided into visceral, deep somatic, and superficial somatic pain.
    • Deep somatic pain is initiated by the stimulation of nociceptors in ligaments, tendons, bones, blood vessels, fasciae, and muscles, and is a dull, aching, poorly localized pain.
    • Examples of injuries that produce superficial somatic pain include minor wounds and minor (first degree) burns.

  • Sensory-Somatic Nervous System

    • The sensory-somatic nervous system transmits sensory information from the body to the brain and motor movements from the brain to the body.
    • The sensory-somatic nervous system is composed of cranial and spinal nerves and contains both sensory and motor neurons.
    • Without its sensory-somatic nervous system, an animal would be unable to process any information about its environment (what it sees, feels, hears, etc. ) and could not control motor movements.
    • Explain the role of the cranial and spinal nerves in the sensory-somatic nervous system

  • Mutation

    • They can also be induced by the organism itself, through cellular processes such as hypermutation.

  • The Role of the Cell Cycle

    • While there are a few cells in the body that do not undergo cell division, most somatic cells divide regularly.
    • A somatic cell is a general term for a body cell: all human cells, except for the cells that produce eggs and sperm (which are referred to as germ cells), are somatic cells.
    • Somatic cells contain two copies of each of their chromosomes (one copy received from each parent).

  • Autonomic Reflexes

    • In these cases, the body will interpret the afferent pain stimulus as somatic.
    • If the peritoneal cavity becomes inflamed or if the bowel is suddenly distended, the body will interpret the afferent pain stimulus as somatic in origin.
    • This schematic (but not anatomically correct) depiction of a typical spinal nerve indicates (1) somatic efferent fibers, (2) somatic afferent fibers, (3 to 5) sympathetic efferent fibers, and (6 and 7) sympathetic afferent fibers.