The most prominent cell of the nervous tissue, the neuron, is characterized mainly by its ability to receive stimuli and respond by generating an electrical signal, known as an action potential, which can travel rapidly over great distances in the body. A typical neuron displays a distinctive morphology: a large cell body branches out into short extensions called dendrites, which receive chemical signals from other neurons, and a long tail called an axon, which relays signals away from the cell to other neurons, muscles, or glands. Many axons are wrapped by a myelin sheath, a lipid derivative that acts as an insulator and speeds up the transmission of the action potential. Other cells in the nervous tissue, the neuroglia, include the astrocytes, microglia, oligodendrocytes, and Schwann cells.
Nervous tissue controls and coordinates the activities of the body. Two types of nerve cells:
Neurons - conducting cells receive stimuli and generate action potential; distinctive structure comprises:
large cell body with a nucleus
extensions of the cell body called dendrites
a long axon with insulating myelin and nerve endings, relay signals to other neurons, muscles, glands
Neuroglia - supporting and protecting cells
astrocytes - forms blood brain barrier in brain and regulates metabolism
oligodendrocytes - produce myelin in brain
Schwann cells - produce myelin in peripheral nerves
microglia - immune function
astrocyte
star-shaped cell in the central nervous system that regulates ions and uptake and/or breakdown of some neurotransmitters and contributes to the formation of the blood-brain barrier
myelin
layer of lipid inside some neuroglial cells that wraps around the axons of some neurons
neuroglia
supportive neural cells
neuron
excitable neural cell that transfer nerve impulses
oligodendrocyte
neuroglial cell that produces myelin in the brain
Schwann cell
neuroglial cell that produces myelin in the peripheral nervous system
Dendrites, cell body, and the axon.
1. The cells responsible for the transmission of the nerve impulse are ________.
A) neurons
B) oligodendrocytes
C) astrocytes
D) microglia
A
2. The nerve impulse travels down a(n) ________, away from the cell body.
A) dendrite
B) axon
C) microglia
D) collagen fiber
B
3. Which of the following central nervous system cells regulate ions, regulate the uptake and/or breakdown of some neurotransmitters, and contribute to the formation of the blood-brain barrier?
A) microglia
B) neuroglia
C) oligodendrocytes
D) astrocytes
D
1. Which morphological adaptations of neurons make them suitable for the transmission of nerve impulse?
Neurons are well suited for the transmission of nerve impulses because short extensions, dendrites, receive impulses from other neurons, while a long tail extension, an axon, carries electrical impulses away from the cell to other neurons.
2. What are the functions of astrocytes?
Astrocytes regulate ions and uptake and/or breakdown of some neurotransmitters and contribute to the formation of the blood-brain-barrier.