dendrites

Examples of dendrites in the following topics:

• Structural Diversity of Neurons

  • A typical neuron consists of a cell body and neuronal processes such as dendrites and axon.
  • The dendrites are short, tapering extensions that are the receptive regions and help in conveying incoming messages towards the cell body.
  • Bipolar neurons have two processes, an axon and a dendrite, that extend from opposite ends of the soma.
  • Multipolar neurons, the most common type, have one axon and two or more dendrites.
  • A signal propagating down an axon to the cell body and dendrites of the next cell

• Phagocytes

  • The main types of phagocytes are monocytes, macrophages, neutrophils, tissue dendritic cells, and mast cells.
  • Most monocytes leave the blood stream after 20–40 hours to travel to tissues and organs; during this process, they differentiate into macrophages or dendritic cells depending on the signals they receive.
  • Dendritic cells are specialized antigen-presenting cells that have long outgrowths called dendrites, which help to engulf microbes and other invaders.
  • Dendritic cells are present in the tissues that are in contact with the external environment, mainly the skin, the inner lining of the nose, the lungs, the stomach, and the intestines.
  • Monocytes differentiate into dendritic cells and macrophages, while mast cells and neutrophils are in a separate group of PMN granuolcytes as well.

• Characteristics of Nervous Tissue

  • A typical neuron consists of dendrites, the cell body, and an axon.
  • Dendrites are responsible for responding to stimuli; they receive incoming signals towards the cell body.
  • The dendrites receive incoming signals while axons propagate signals away from the neuron cell body.

• The Synapse

  • Synapses between axon endings of one neuron and a dendrite is called axodendritic synapse.
  • Synapses between 2 axons is called axoaxonal and between 2 dendrites is called dendrodendritic and between dendrites and cell body is somatodendritic.
  • Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may also follow graded electrical potentials found in dendrites.

• Types of Nervous Tissue

  • The two types of neuron processes are called dendrites and axons.
  • Dendrites are motor neurons that are short and have a large surface area for receiving signals from other neurons.
  • Dendrites convey incoming messages towards the cell body and are therefore called the receptive input region.

• Antigen-Presenting Cells

  • Antigen presentation is a process in the body's immune system by which macrophages, dendritic cells and other cell types capture antigens, then enable their recognition by T-cells.
  • Dendritic cells, B cells and macrophages play a major role in the innate response, also acting as professional antigen-presenting cells (APC).
  • Dendritic cells (DCs) phagocytose exogenous pathogens such as bacteria, parasites, and toxins in the tissues and then migrate, via chemotactic signals, to T cell-enriched lymph nodes.
  • High levels of Class II are found on dendritic cells, but can also be observed on activated macrophages, B cells, and several other host cell types in inflammatory conditions.

• Spinal Cord Grey Matter and Spinal Roots

  • The grey matter of the spinal cord contains neuronal cell bodies, dendrites, axons, and nerve synapeses.
  • The dendrite receives information from another neuron's axon at the synapse, and the axon sends information to the next neuron's dendrites.

• Lymph Nodes

  • Lymph nodes are repositories of B cells, T cells, and other immune system cells, such as dendritic cells and macrophages.
  • The cortex is mainly composed of clusters of B cells in the outer layers and T cells in the inner layers, and may also contain antigen-presenting dendritic cells.
  • There, antigen-presenting cells called dendritic cells present the antigen molecule to naive B and T lymphocytes.
  • The lymph node is also arranged in such a way that the chance of B and T lymphocytes encountering dendritic cells is quite high, to facilitate antigen presentation.

• WBC Function

  • This process is performed primarily by neutrophils, macrophages, and dendritic cells, but most other leukocytes can do it as well.
  • This process is primarily performed by macrophages and dendritic cells.

• Cytokine Therapy

  • The key transmitters of the signals are dendritic cells.
  • These cytokines induce the chemotaxis to the site of infection in its target cells (e.g., neutrophils, dendritic cells and macrophages).