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Many axons are wrapped by an insulating substance called myelin, which is actually made from glial cells. Myelin acts as insulation much like the plastic or rubber that is used to insulate electrical wires. A key difference between myelin and the insulation on a wire is that there are gaps in the myelin covering of an axon. Each gap is called a node of Ranvier    and is important to the way that electrical signals travel down the axon. The length of the axon between each gap, which is wrapped in myelin, is referred to as an axon segment    . At the end of the axon is the axon terminal    , where there are usually several branches extending toward the target cell, each of which ends in an enlargement called a synaptic end bulb    . These bulbs are what make the connection with the target cell at the synapse.

Visit this site to learn about how nervous tissue is composed of neurons and glial cells. Neurons are dynamic cells with the ability to make a vast number of connections, to respond incredibly quickly to stimuli, and to initiate movements on the basis of those stimuli. They are the focus of intense research because failures in physiology can lead to devastating illnesses. Why are neurons only found in animals? Based on what this article says about neuron function, why wouldn't they be helpful for plants or microorganisms?

Types of neurons

There are many neurons in the nervous system—a number in the trillions. And there are many different types of neurons. They can be classified by many different criteria. The first way to classify them is by the number of processes attached to the cell body. Using the standard model of neurons, one of these processes is the axon, and the rest are dendrites. Because information flows through the neuron from dendrites or cell bodies toward the axon, these names are based on the neuron's polarity ( [link] ).

Neuron classification by shape

Three illustrations show some of the possible shapes that neurons can take. In the unipolar neuron, the dendrite enters from the left and merges with the axon into a common pathway, which is connected to the cell body. The axon leaves the cell body through the common pathway, the branches off to the right, in the opposite direction as the dendrite. Therefore, this neuron is T shaped. In the bipolar neuron, the dendrite enters into the left side of the cell body while the axon emerges from the opposite (right) side. In a multipolar neuron, multiple dendrites enter into the cell body. The only part of the cell body that does not have dendrites is the part that elongates into the axon.
Unipolar cells have one process that includes both the axon and dendrite. Bipolar cells have two processes, the axon and a dendrite. Multipolar cells have more than two processes, the axon and two or more dendrites.

Unipolar cells have only one process emerging from the cell. True unipolar cells are only found in invertebrate animals, so the unipolar cells in humans are more appropriately called “pseudo-unipolar” cells. Invertebrate unipolar cells do not have dendrites. Human unipolar cells have an axon that emerges from the cell body, but it splits so that the axon can extend along a very long distance. At one end of the axon are dendrites, and at the other end, the axon forms synaptic connections with a target. Unipolar cells are exclusively sensory neurons and have two unique characteristics. First, their dendrites are receiving sensory information, sometimes directly from the stimulus itself. Secondly, the cell bodies of unipolar neurons are always found in ganglia. Sensory reception is a peripheral function (those dendrites are in the periphery, perhaps in the skin) so the cell body is in the periphery, though closer to the CNS in a ganglion. The axon projects from the dendrite endings, past the cell body in a ganglion, and into the central nervous system.

Questions & Answers

to have a better understanding as to how our human bodies function. the knowledge we gain can improve our quality of life. Without our study of anatomy how could a doctor know what prescription to give us when our bodies is being attacked by a bacteria? We wouldn't!
Robin Reply
discuss nervers system in human being life.
Allen Reply
neuralgia what is other name of it
how are neurons adapted to their function
Namiyaba Reply
machenic support production of blood cells locomotion protection of delicate organs
Ackson Reply
what are hormones?
what is anatomy
Juma Reply
what are the functions of bones
To support and control the movements of the body
the study of human body is called anatomy
the study of human body is nt only anatomy but also physiology and histology
ooops lol I thought Michael was the one with the questions so sorry people. yes anatomy is the study of the body(structure)and it's physiology (functions).
what are the muscles of respiration?
Hi everyone, Why actyl choline decreases blood pressure although it affects adrenal gland leading it to secret adrenaline and noradrenaline which increase blood pressure?
cholinergic receptors are mostly under Parasympathetic response while adrenergic (norepinephrine) receptors are mostly sympathetic although they are cholinergic adrenergic receptors as well
vocal cords
MT Reply
musah was admitted to your ward yesterday with traumatic amputation of the right thump . he complained this morning that he has not passed enough urine. Questions. 1) will you consider his complain to be pathological or physiological?. 2) in less than three sentences, justify your opinion. 3) Apply your understanding of the renin- angiotensin-aldosterone system to explain the factors and mechanisms accounting for his complains.
Ellen Reply
the mineral salt which break up a large portion of bone tissue is
Aurora Reply
please I need help. musah was admitted to your ward yesterday with traumatic amputation of the right thump. he complained this morning that he has not passed enough urine. Questions. 1). will you consider his complain to be pathological or physiological?.
2). In less than three sentences, justify your opinion.
musah copmlan to be physiological because of:-
cholesterol and triglycerides in simplest terms are fats (lipid) found in blood
Roy Reply
calcium is important for bone density and development. it also helps for safe / normal blood clotting, blood circulation to and from the heart, and muscle movement
please undertand me action potential ?
minimum potential that must be overcomed to cause polarization and stimulate a neuronal response( generate impulse)
what is muscle tissue
Rifat Reply
the muscle tissue is one of the 4 basic tissues in our body and is responsible for movement of our body
What Is difference between Ovary and Ovum
ovary is female reproductive organ while ovum is a female gamete formed from ovary
Thank You
What Is Cholesterol and Triglycerides
the mineral salt which break up a large portion of bone tissue
in simple way muscle tissue is responsible for movement of our body.
Hi Be Home Be safe , how are things doing hope all is well
Natarajan Reply
3 longitudinal bands of smooth muscles found in large intestines
what's is sutures
Nimeshka Reply
what would I like to know
Roy Reply
anything u can tell me
anatomy mins
when two or more bones meet.
I am interested in learning but it is a little threatening corona virus covid 19
Samnang Reply
I don't know about Corona virus
what would you like to know?

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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