<< Chapter < Page Chapter >> Page >
By the end of this section, you will be able to:
  • Identify the classes of cells that make up nervous tissue
  • Discuss how nervous tissue mediates perception and response

Nervous tissue is characterized as being excitable and capable of sending and receiving electrochemical signals that provide the body with information. Two main classes of cells make up nervous tissue: the neuron    and neuroglia    ( [link] ). Neurons propagate information via electrochemical impulses, called action potentials, which are biochemically linked to the release of chemical signals. Neuroglia play an essential role in supporting neurons and modulating their information propagation.

The neuron

This figure shows a diagram of a neuron and a micrograph showing two neuron cells. The body of the neuron contains a single, purple nucleus. The cell is irregularly shaped, having many projections emerging from its surface. Six sets of dendrites project from the top, right, and bottom edges of the cell. The dendrites are yellow and branch many times after leaving the cell, taking on the appearance of tiny trees. The axon projects from the left edge of the cell. The axon is a long cable like structure that branches into several finger like projections at its end. This is where the neuron makes contact with other cells. A label also notes that the area where the axon emerges from the cell body contains microfibrils and microtubules. The micrograph is considerably less magnified than the diagram. The neurons stain darkly and their nuclei are clearly visible. Their irregular cell body is also visible, along with the beginning of the axons.
The cell body of a neuron, also called the soma, contains the nucleus and mitochondria. The dendrites transfer the nerve impulse to the soma. The axon carries the action potential away to another excitable cell. LM × 1600. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

Follow this link to learn more about nervous tissue. What are the main parts of a nerve cell?

Neurons display distinctive morphology, well suited to their role as conducting cells, with three main parts. The cell body includes most of the cytoplasm, the organelles, and the nucleus. Dendrites branch off the cell body and appear as thin extensions. A long “tail,” the axon, extends from the neuron body and can be wrapped in an insulating layer known as myelin    , which is formed by accessory cells. The synapse is the gap between nerve cells, or between a nerve cell and its target, for example, a muscle or a gland, across which the impulse is transmitted by chemical compounds known as neurotransmitters. Neurons categorized as multipolar neurons have several dendrites and a single prominent axon. Bipolar neurons possess a single dendrite and axon with the cell body, while unipolar neurons have only a single process extending out from the cell body, which divides into a functional dendrite and into a functional axon. When a neuron is sufficiently stimulated, it generates an action potential that propagates down the axon towards the synapse. If enough neurotransmitters are released at the synapse to stimulate the next neuron or target, a response is generated.

The second class of neural cells comprises the neuroglia or glial cells, which have been characterized as having a simple support role. The word “glia” comes from the Greek word for glue. Recent research is shedding light on the more complex role of neuroglia in the function of the brain and nervous system. Astrocyte cells, named for their distinctive star shape, are abundant in the central nervous system. The astrocytes have many functions, including regulation of ion concentration in the intercellular space, uptake and/or breakdown of some neurotransmitters, and formation of the blood-brain barrier, the membrane that separates the circulatory system from the brain. Microglia protect the nervous system against infection but are not nervous tissue because they are related to macrophages. Oligodendrocyte cells produce myelin in the central nervous system (brain and spinal cord) while the Schwann cell    produces myelin in the peripheral nervous system ( [link] ).

Nervous tissue

Part A of this diagram shows various types of nerve cells. The largest cell is a neuron. The central body of the neuron contains a single nucleus. Six sets of dendrites project from the top, left and right, edges of the neuron. The dendrites are yellow and branch many times after leaving the cell, taking on the appearance of tiny trees. The axon projects from the bottom edge of the cell and is covered with purple sheaths labeled the myelin sheath. The sheath is not continuous, but instead is a series of equally spaced segments along the axon. Another cell, called an oligodendrocyte, is spider like in appearance, with its leg-like projections each connecting to a segment of the neuron’s myelin sheath. Above the neuron are three astrocytes. They are much smaller than the neuron and have no axons, and are also irregularly shaped cells with many dendrites projecting from the central body. Finally, a microglial cell is shown above the neuron. It is the smallest of the cells in this figure and is an elongated cell with many fine, tentacle-like projections. The projections are concentrated at the two ends of the cell, with the middle area lacking any projections. The micrograph of the neural tissue shows that this tissue is very heterogenous, with both large and small cells embedded in the matrix. Much of the space between the cells is occupied by threadlike nerve fibers.
Nervous tissue is made up of neurons and neuroglia. The cells of nervous tissue are specialized to transmit and receive impulses. LM × 872. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

Chapter review

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.

Follow this link to learn more about nervous tissue. What are the main parts of a nerve cell?

Dendrites, cell body, and the axon.

Got questions? Get instant answers now!

References

Stern, P. Focus issue: getting excited about glia. Science [Internet]. 2010 [cited 2012 Dec 4]; 3(147):330-773. Available from:

(External Link)

Ming GL, Song H. Adult neurogenesis in the mammalian central nervous system. Annu. Rev. Neurosci. 2005 [cited 2012 Dec 4]; 28:223–250.

Questions & Answers

plzzz explain cardiac cycle
Piya Reply
what is anatomy
Gifty Reply
is the study of body structure
Amos
What are some of first questions are expected in anatomy and physiology course
Milner Reply
what is pacemaker
mekfira
its a device that is put into the heart to make sure it beats properly
Michelle
SA node produces impulse is called pacemaker
Piya
hi piya
Khubaib
hi Everyone
Hayat
hi everyone
Hong
hey
Edrick
hello
Damien
what's up
Damien
hlo
Lost
which of the following is the epithelial tissue that lines the interior of blood vessels?
Firomsa Reply
endothelial tissues
Osaki
Endothelial tissue
mabast
why are the questions only 3
Chisom Reply
you too can ask
Addo
what is the treatment of herpes simplex virus?
riad Reply
the long bone with two primary center's of ossification for shaft is ________
Aarambam
medulla
Addo
good
Ravi
ha moj ha
Hani
doctor and nurse
Ravi
y 're the questions only 3
Chisom
women are much likely to be pregnant at which stage?
Fatoumatta Reply
There are only six days during any cycle when a woman can get pregnant - the five days leading up to ovulation and the 24 hours after ovulation. This is because sperm can live for up to 5 days in a woman's body, and the ovum lives for only 12-24 hours.
THE
right
Adil
does this apply to women close to menopose
Kuria
what's reason the reason for BP growing ?
Adil
when after they have intercourse
AJ
what is andropause
William Reply
It's the men version of menopause!
Catia
The testosterone levels decrease
Catia
what would happen if the sugar lever drops below the normal level
Marvin Reply
If our blood sugar drops below 70 mg/dL, we may have symptoms, such as feeling tired, weak, or shaky, become confused or drowsy or even lose consciousness and possibly die.
Dhanya
symptoms of hypoglycemia include: shakiness, dizziness, headache, confusion, rapid pulse rate, sweating, Hunger, etc.
EMERIBE
you right
Khubaib
You become dizzy and weak
evans
Is there any way to disable this chat feature or at least mute notifications? Also, does every textbook app from this creator have the chat function?
Atone Reply
I don't think you can disable chat and yes it is on every app
AJ
what is homeostasis
Nikky Reply
what is respiratory
Nikky
Respiratory is breathing
Atone
respiration is an exchange of gases (O2 & CO2) between the body and outside environment.
joey
homeostasis is internal balance.
Ali
Respiratory is system where the body takes in oxygen n releases carbondioxide
Hassan
respiratory system is a system where exhalation and inhalation takes place
Kom
1)inhalation: active diaphragm & external intercoastal muscles 2)exhalation: passive (allow muscle group to relax)
Shoukat
mantaince of body is called homeostasis
Komal
hi komal
Khubaib
how are you komal?
Khubaib
hi
Komal
hey nikki
Khubaib
hii komal
Rinku
where you from kamal?
Khubaib
nice meet you
Rinku
oye rinku kya ha yahan kya kar rha ha
Khubaib
karachi
Komal
but I'm from lahore
Khubaib
friendship ho jay? komal
Khubaib
never
Komal
0309
Khubaib
khubaib arooj tu aa sakta h to me q nhi aa sakta
Rinku
4291248
Khubaib
waw komal
Rinku
where you from?rinku
Khubaib
what is medical coding
Antony
waw komal
Rinku
yar rinku kahan se ho ap
Khubaib
I am from dausa,Rajasthan
Rinku
yar hum to pakistan se hain humy baat karny do
Khubaib
hoe r u alll
SARFARAJ
komal jha?
Khubaib
answer me please...What is basic concept or Acidosis?
Khalid
hiii komal
SARFARAJ
al hamd.o.lillah muslim
Khubaib
or aap
Khubaib
Allah ka shukr ha
SARFARAJ
aby tu b india chala ja un ko zarorat ha foji logon ki
Khubaib
beshak
Khubaib
myself Khalid Shabbir.Doctor of Anesthesia from PIMS Hospital.& belongs to Capital IslamAbad(Pakistan).
Khalid
yar sarfraz ap india se kab ay
Khubaib
tell me abt ethmoid bone
Sakshi
bro am all ready indian
SARFARAJ
okkk
SARFARAJ
hii sakshi how are you?
Khubaib
m gd..plz tell me the answer of it..
Sakshi
Face ki he ethmoid bone
Rakesh
ethmoid bone. Irregularly shaped bone anterior to the solenoid. Forms the roof of the nasal cavity, upper nasal septum, and part of the medial orbit walls.
LaKecia
Its unpaired bone of skull that saprate the nasal cavity from the brain it's located at the roof of the nose between the two orbits it's bone is one of the bones that make up the orbit of eye.
SARFARAJ
sphenoid I meant
LaKecia
wrist joint ka dusra name kya he
Rakesh
till me fast my ans
Rakesh
Also included in the ethmoid bone is the crista galli and the cribriform plates. The plates help form the roof of the nasal cavity and the floor of the anterior cranial fossa.
LaKecia
the outer most covering of the brain ( the dura mater) attached to the crista galli and helps secure the brain in the cranial cavity
LaKecia
Sakshi Mishra. I hope that helped!
LaKecia
thnks fo tellng😊
Sakshi
yup
Sakshi
yw
LaKecia
ye kya
Dr
hi
Dr
oh welcome sakshi
Khubaib
synovial joint will have present in wrist
sk
what's the smallest blood vessal in the body?
sk
respiration is the process of inspiration an expiration
Bel
first fall give me ans plz
sk
The protection of internal envirnment from the harm of external envirnmen is called as homeostasis.
Rana
Because stem cells have the unique ability to develop into any cell, stem cell therapy is being considered for treatment of kidney damage. What are your thoughts on stem cell treatment? Give at least three reasons for or against the treatment.
Samira Reply
to know the structure of the human body. to study the region of the human body. to understand the circulation of blood in the human body.
Angelashimakela Reply
what do CNS stand for
Angelashimakela Reply
central nervous system
Dustin
What does that mean
Shafiw
what does what mean
Larita
It means the system of brain and spinal cord! Sensory system of body!
rashid
is it where we find sensory gland?
Angelashimakela
glands are not a part of CNS! but sensory receptors are a part of peripheral nervous system!
rashid
PNS
rashid
👏
Angelashimakela
Ask what u want to?
rashid
structure, function and results
Dustin Reply

Get the best Anatomy & Physiology course in your pocket!





Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Anatomy & Physiology' conversation and receive update notifications?

Ask