6 Nervous Tissue Flashcards
-two categories of cells found in the nervous tissue.
-these require a chemically stable environment.
Neurons and Neuroglia
-have distinctive cell shapes with a membrane capable of generating electrical impulses. They transfer impulses from one ____ to the next via synapses
-have highly irregular shapes with one or more cellular processes extending from the cell body, also have a long lifespan and are generally considered amitotic (do not divide).
-make up only 10% of nervous tissue
Neurons
-the specialized contact areas between two neurons.
-Where the axon terminal meets another cell
synapses
-are the most abundant cells in nervous tissue (over 90%), filling essentially all the space in the nervous system not occupied by neurons and blood vessels. They provide structural, metabolic, and protective support for neurons.
-support, protect, and nourish neighboring neurons both in the CNS and PNS.
Neuroglia
parts of a neuron:
- Cell body or Soma or Perikaryon.
- Axon.
- Dendrites.
Part of a neuron that contains the same organelles found in other cells except for abundant endoplasmic reticulum and polysomes (Nissl substances) and lack of centrioles which are crucial in the process of cell division.
Cell body/Soma/Perikaryon.
*Part of a neuron
Each neuron has an ____
axon
-the area of the cell body where the axon arises
-also called the trigger zone because it is where action potentials are generated.
axon hillock
These are neuronal processes that serve as the receptive region of the neuron.
Dendrites.
Classification of Neurons Based on the Number of Cellular Processes
- Unipolar neurons or Primary sensory neurons.
- Bipolar neurons.
- Multipolar neurons.
These neurons have a single stem process that bifurcates to form processes (peripheral and central). They innervate peripheral tissues bringing somatic and visceral sensory information to the CNS.
Unipolar neurons or Primary sensory neurons
neurons that have two processes. These neurons are sensory neurons located in the retina of the eye, spiral ganglion of the cochlea, vestibular ganglion of the vestibular organ, and olfactory epithelium.
Bipolar neurons
Each neuron has numerous cell processes (one axon and many dendrites). These are the most prevalent type of neurons.
Multipolar neurons
Classification of Neurons Based on Function
- Sensory or afferent neurons.
- Motor or efferent neurons..
- Interneurons or association neurons.
neurons that respond to sensory stimuli and transmit that information to the nervous system, particularly to the CNS.
Sensory or afferent neurons
neurons that transmit signals from the brain or spinal cord to the muscles or glands.
Motor or efferent neurons
sometimes called association neurons, are the most numerous of all neuronal types. Mostly located in the brain and spinal cord, some are found in the autonomic ganglia. They function to distribute sensory information and coordinate motor activity.
Interneurons or association neurons
Classification of Neurons Based on Neurotransmitters
- Cholinergic neurons.
- Serotonergic neurons.
- Adrenergic neurons.