muscle
tissue
Muscle tissue is a
tissue that is formed by muscle fibers or myocytes. Comprised approximately 40%
and 45% of the mass of human beings and specializes in the contraction,
allowing them to move living things (Animal Kingdom).
As
muscle cells are highly specialized organelles need different names. The muscle
cell is generally known as muscle fiber sarcoplasm the cytoplasm, the smooth
endoplasmic reticulum, smooth sarcoplasmic reticulum, and sometimes
mitochondria, sarcosomes
The anatomical and
functional unit is called a sarcomere. Because muscle cells are much longer
than wide, often called muscle fibers, but this should not be confused with the
intercellular substance forms, ie collagen fibers, reticular and elastic, as
the latter are not alive, as the muscle cell.
The muscle fibers,
which are usually arranged in bundles or fascicles.
A rich capillary
network.
Supporting fibrous
connective tissue with fibroblasts and collagen and elastic fibers. It acts as
a mooring system and traction coupling of muscle cells so that they can act
together. Also leads the blood vessels and innervation of muscle fibers own
There are three types
of muscle tissue classified based on structural and functional factors.
Functionally, the muscle can be under mind control (voluntary muscle) or
pregnant (involuntary muscle). Structurally, it can display regular transverse
bands along the length of the fibers (striated muscle) or not to present
(non-striated or smooth muscle). Based on this the three types of muscle are:
Voluntary or skeletal
striated muscle: Inserted in cartilage or fascia, which is the serous portion
of the limbs and the body walls. It is composed of cells
"multinucleated" long (up to 12m) and cylindrical contract to facilitate
the movement of the body and its parts.
Their cells have
large numbers of mitochondria. The contractile proteins are arranged regularly
in dark bands (mainly myosin but also actin) and clear (actin)
Cardiac muscle: is
formed on the walls of the heart and is in the walls of major blood vessels of
the body. Mass derived from a strictly defined the splanchnic mesenchyme, the
mantle mioepicardico whose cells arise from the epicardium and myocardium. The
cells of this tissue have unique and central nuclei, are also highly
specialized junctions called terminal intercalated disks that facilitate the
conduction of nerve impulses.
Muscle function
Its main function is
the movement that can be of three types:
1. Is the movement of
all internal structures: it consists of smooth muscle tissue and vessels will
encounter, visceral walls and glands.
2. Outward movement,
characterized by manipulation and motion in our environment. It is
characterized by being composed of striated muscle.
3. Automatic
movement: it works by itself, is the heart muscle. Striated muscle tissue.
Muscle is a tissue
contrast and movement, is divided into striated, smooth and cardiac striatum is
voluntary and is in most of the body covering the long bones (such as the
femur), the smooth is visceral and involuntary and is in the viscera and other
internal organs, while the heart is the most important is in the heart wall and
consists of light and dark fibers in addition to being involuntary.
The function is to
maintain a tone of the viscera and blood vessels, keeping us in the right
position and obviously the movement.
The limb muscles
(skeletal muscle) and can contract and move the bones, causing flexors contract
to flex the limb extensors contract to the contrary.
The muscle of the
heart and arteries so that blood gets to be mobilized.
The muscles of the
intestines, stomach and esophagus contract harmoniously making the bolus
progresses through the digestive tract.
Diagnostic
a group of inherited
disorders characterized by weakness and atrophy of muscle tissue, with or
without degeneration of nerve tissue. There are nine types of muscular
dystrophy and they all occur with the eventual loss of strength, increasing
disability and sometimes deformity.
The best known of the
muscular dystrophies is Duchenne muscular dystrophy (DMD English acronym),
followed by Becker muscular dystrophy (BMD its acronym in English).
Here are nine
different types of muscular dystrophy. Each type differs in the affected
muscles, the age of onset and rate of progression. Some types are named after
the affected muscles, including the following:
Age of onset type
symptoms, progression rate and average life
Becker
Adolescence to early
adulthood Symptoms are almost identical to Duchenne but less severe, progresses
more slowly than Duchenne; survival into middle age. congenital
At birth Symptoms
include general muscle weakness and possible joint deformities; the disease
progresses slowly; short life.
Duchenne
Between 2 and 6 years
Symptoms include general weakness and wasting of muscles, affecting the pelvis,
upper arms and legs and eventually involves all voluntary muscles, survival
beyond age 20 is slightly frequent. distal
Between 40 and 60
Symptoms include weakness and wasting of the muscles of the hands, forearms and
lower legs, the progression is slow, rarely leads to total disability.
Emery-Dreifuss
Between childhood and
puberty Symptoms include weakness and wasting of the muscles of the shoulders,
upper arm andshin, are common joint deformities, the progression is slow, can
cause sudden death from cardiac problems.
facioscapulohumeral
From childhood to
early adults Symptoms include facial muscle weakness and deformity and degree
of atrophy of the shoulder and upper arm, the progression is slow, with periods
of rapid deterioration, the patient may live for several decades after of its
appearance.
Girdle
Between late
childhood and middle age Symptoms include weakness and wasting, affecting first
the shoulder girdle (shoulder) and pelvic progression is slow, death is usually
due to cardiopulmonary complications.
Girdle
Between late
childhood and middle age Symptoms include weakness and wasting, affecting first
the shoulder girdle (shoulder) and pelvic progression is slow, death is usually
due to cardiopulmonary complications.
myotonic
Between 20 and 40
Symptoms include weakness of all muscle groups accompanied by delayed
relaxation of muscles after contraction, affecting first the face, feet, hands
and neck, the progression is slow; sometimes spanning 50 to 60 years.
oculopharyngeal
Between 40 and 70
Symptoms affect muscles of eyelids and throat causing weakening of throat
muscles that, over time, causes inability to swallow and emaciation from lack
of food, the progression is slow.
muscular system
The system allows the
skeletal muscle to move, it is stable and shape of the body. In vertebrates is
controlled through the nervous system, although some muscles (such as the
heart) can operate autonomously. Approximately 40% of the human body consists
of muscles, namely that for every kg of total weight, 400 g corresponding to
muscle tissue.
Functions of the
muscular system
The muscular system
is responsible for:
Locomotion effect the
displacement of the blood and limb movement.
Motor activity of
internal organs: the muscular system is responsible for making all of our
organs perform their functions, helping other systems such as the
cardiovascular system.
Information on the
physiological state, eg renal colic causes strong contractions of smooth muscle
generating a sharp pain, a sign of colic own.
Mimicry: the set of
facial actions, also known as gestures, which serve to express what we feel and
perceive.
Stability: the
muscles together with the bones allow the body to be stable, while in active state.
Posture: position
control by the body at rest.
Heat production: to
produce muscle contractions causes heat energy.
Form: the muscles and
tendons are the typical appearance of the body.
Protection: the
muscular system serves to protect the proper functioning of the digestive
system to vital organs.
muscular system
components
The muscular system
consists of muscles and tendons.
Muscles
Muscle.
Skeletal muscles of
the arm during a contraction: biceps brachii-left, left-and right-triceps,
right. The first flex the arm and the second extends it. They are antagonistic
muscles.
The main function of
the muscle is contracted, to generate movement and perform vital functions.
There are three groups of muscles, as available:
Skeletal muscle
Smooth muscle
The heart muscle
striated muscle
(skeletal)
Striated muscle is a
type of muscle is the sarcomere fundamental unit, and having been to see him
through a microscope, grooves are formed by alternating light and dark bands of
the sarcomere. It consists of muscle fibers in bone shape, with ends very
refined, and shorter than the smooth muscle. It is responsible for movement of
the skeleton, the eyeball and tongue.
Smooth muscle
Smooth muscle, also
known as visceral or involuntary, is composed of bone-shaped cells that have a
core that resembles the shape of the cell containing it, though no transverse
grooves show slightly longitudinal grooves. The stimulus for the contraction of
smooth muscles is mediated by the autonomic nervous system. Smooth muscle is
located in the reproductive and excretory systems, blood vessels, skin and
internal organs.
There unitary smooth
muscles, which contract quickly (not triggered innervation) and multiunit
smooth muscles, in which the contractions are dependent on the nerve
stimulation. Are unitary smooth muscles such as the uterus, ureter,
gastrointestinal tract, and so on.; And multiunit smooth muscles are those
found in the iris.
Atrophy
The word comes from Greek àtrophos atrophy which means
"without nutrition." In biological terms is a significant decrease in
cell size and the body of which forms part, due to loss of cell mass. Atrophic
cells show a decrease in function but are not killed. With regard to the above
may require a perfect cellular metabolism depends not only on an efficient
delivery of nutrients, but also the correct usage of these, this is only
possible when the cells live in an ideal environment for morphological
structure and functional. The morphological structure of the cell is affected
by the environment in which they live, that is why the multiple forms of the
cells of our bodies respond to the adjustment of living matter to external
conditions well defined, cell differentiation is the externalization of a
latent adaptation, accumulated over millions of generations.
Types of atrophy
In the microscopic appearance are three main types of
atrophy: simple atrophy, degenerative atrophy and atrophy number.
Simple atrophy is a decrease in volume of the
components leads to muscle shrinkage or shrinking of the tissue and organ.
Atrophy is more common, affecting more differentiated cells. It can be seen
during the prolonged fast in almost all body tissues and mainly in muscle
tissue.
Atrophy numerical decrease in the number of cells,
usually affects tissues labile elements.
In degenerative atrophy can see big changes to the
cytoplasm and nuclei of cells and organ tissue. This process can lead to the
occurrence of necrosis.
In all cases of atrophy, the cytoplasm is the most
adversely affected, there is almost always a quantitative reduction of the
latter, until the point that, observing the atrophic tissue under a microscope,
densification can be distinguished one cell, caused by the uniform reduction
cell volume.
These changes are accompanied by profound alterations
cytoplasmic: turbidity, presence of pigment granules (pigmentation of wear) and
declining numbers of some organelles such as mitochondria.
pathological atrophy
According to the causes that produce can occur as
follows:
Atrophy of food shortages
Atrophy of circulatory failure
Atrophy by physical
functional atrophy
The nutritional deficiency leads to an overall loss in
body weight due to a generalized atrophy of all cells and specific functional.
In this case, there is a decrease in number, but especially cell volume, both
coming to destroy its own constituent material, apart from the reserve, to
satisfy the needs of energy metabolism, as an inability to synthesize materials
to regenerate the cytoplasm itself.
The loss is proportionately the same in all organs: in
fact an act of self-defense, the body tries to protect the elements that would
be affected by a phenomenon atrophic as above, to the detriment of those in
which no vital functions important and whose function would not be so upset by an
atrophic process, hence may have greater weight loss in the liver and
intestine, but less or no in the brain and heart.
neuromuscular disorders
"Muscular dystrophy" (the
acronym is MD) is a broad term that describes a genetic disorder (hereditary)
of the muscles. Muscular dystrophy causes the muscles of the body is very weak.
Over time, muscles degenerate and are replaced with fatty deposits.
Other health problems commonly associated with
muscular dystrophy include the following:
heart problems
scoliosis - lateral curvature and rotation (side to
side) of the spinal bones (vertebrae) that make a person seem inclined to one
side.
Obesity
Duchenne muscular dystrophy is a genetic disease that
is inherited. Our genes determine our traits, like eye color or blood type.
Genes are found within cells of the body, in a rod-shaped structures which are
called chromosomes. We normally have 23 pairs of chromosomes, ie a total of 46
chromosomes in each cell of the body. The first 22 chromosomes are present in
men and women, while the last pair determine gender, so it is called the sex
chromosome pair: females have two X chromosomes, while males have one X and one
Y chromosome .
Muscular dystrophy is usually seen in children before
the age of five, with weakness typically affecting the muscles of the shoulders
and pelvis as one of the initial symptoms. The following are the most common
symptoms of muscular dystrophy. However, each child may experience symptoms
differently. Symptoms may include:
awkwardly difficulty climbing stairs
frequently trips and falls
inability to jump or hop normally
tiptoe gait
leg pain
facial weakness
inability to close eyes or whistle
weakness in the shoulder and arm
myasthenia gravis
Myasthenia gravis (MG) is a complex autoimmune
disorder in which antibodies destroy neuromuscular connections, causing
problems with the nerves that communicate with muscles. MG affects the
voluntary muscles of the body, especially the eyes, mouth, throat and limbs.
Myasthenia gravis may be inherited as a rare genetic
disease, babies born to mothers with MG may acquire or is it also
possible that the disorder may develop spontaneously
later in childhood.
There are three types of MG in children, among which
include the following:
Congenital MG - MG is very rare non-immune that is
inherited as an autosomal recessive. This means that the disorder affects men
and women equally and that to suffer it, you need two copies of the gene, one
inherited from the father and one from the mother. Generally, symptoms of
congenital MG usually begin during the first year of baby's life and last a
lifetime.
Transient neonatal MG - between 10 and 15 percent of
babies born to mothers with MG may have a MG. It occurs when antibodies common
in MG cross the placenta to the developing fetus. Neonatal MG usually lasts
only a few weeks and babies are not at increased risk of developing
hypertension in later years.
Juvenile MG - this auto-immune disorder that usually
develops in adolescents, especially in Caucasian women (white), which lasts a
lifetime and you can get in and out of remission. About 10 percent of cases of
juvenile-onset MG.
spinal muscular atrophy
Spinal muscular atrophy (the acronym is SMA) is a
degenerative problem that affects the spinal cord and nerves resulting in
muscle wasting and weakness.
The SMA is an autosomal recessive, which means it can
equally affect both men and women and that it takes two copies of the gene, one
inherited from each parent, to develop the disorder.
It was discovered that a gene called survival motor neuron
(the acronym is SMN) have an abnormal area (either through the elimination or
an extra copy of a gene) in over 95 percent of cases of SMA. You can evaluate
symptomatic persons of all ages through DNA studies typically done from blood
samples.
When both parents are carriers, there is a 25 percent
(one in four) chance with each pregnancy of having a child with SMA. Carrier
testing in the general population are often difficult and usually are available
only if studies have been made to a previously affected child within the family.
Botulism
botulism
It is a rare but serious illness caused by the
bacterium Clostridium botulinum. Bacteria can enter the body through wounds or
food can live in improperly canned or preserved.
causes
Clostridium botulinum is found in soil and untreated
water throughout the world. It produces spores that survive in foods improperly
preserved or canned, where they produce toxin. When eaten, even tiny amounts of
this toxin can cause severe poisoning. Foods that tend to most frequently contaminated
home-canned vegetables, pork and ham cured, smoked or raw fish and honey or
corn syrup. Botulism may also occur if the organism enters through open wounds
and produces toxin there.
Infant botulism occurs when a baby ingests living bacteria
or its spores and they multiply in your GI tract. The most common cause infant
botulism is eating honey or corn syrup.
Clostridium botulinum also occurs normally in the
stool of some infants.
Each year, there are about 110 cases of botulism in
the United States and the majority are in infants.
Symptoms usually appear between 8 and 36 hours after
consuming contaminated food. No fever with this infection.
In adults, symptoms may include:
abdominal cramps
Difficulty breathing may lead to respiratory failure
Difficulty swallowing and speaking
double vision
Dry mouth
sickness
vomiting
Weakness with paralysis (same on both sides of the
body)
Symptoms in babies may include:
constipation
Poor feeding and weak sucking
Shortness of breath
weak cry
Weakness, loss of muscle tone
treatment
You will receive botulinum antitoxin.
For difficulty breathing, you must remain in the
hospital. The medical team a clear airway and provide treatment. You can insert
a tube through the nose or mouth into the trachea to provide an airway for
oxygen. You may also need a respirator.
Patients who have difficulty swallowing may receive
intravenous fluids. You may also enter a feeding tube.
Doctors report cases of botulism to State health
authorities or the Centers for Disease Control and Prevention (Centers for
Disease Control and Prevention, CDC) of the United States, in such a way as to
remove contaminated food from stores .
Some people receive antibiotics, but may not serve.
Tetanus
Tetanus
Tetanus or tetanus is a disease caused by potent
neurotoxins produced by bacteria that affect the nervous system and produces
violent muscle contractions.
The causative agent, Clostridium tetani is an
anaerobic bound, gram-positive, mobile, with a larger diameter terminal spore
giving it a drumstick appearance. The spores are stable in general atmospheric
conditions and may live for years, except that comes into contact with oxygen,
or sunlight (which destroys both the body as spores in a few hours). Are
resistant to certain disinfectants such as phenol, formaldehyde and ethanol,
but are destroyed by hydrogen peroxide, glutaraldehyde and heat sterilization.
symptoms
With Tetanus often begins with mild spasms in the jaw
muscles (lockjaw). The spasms can also affect the chest, neck, back and
abdominal muscles. The back muscle spasms often cause arching, called
opisthotonos.
Sometimes the spasms affect muscles that help with
breathing, which can lead to breathing problems.
Prolonged muscular action causes sudden, severe and
painful muscle groups, which is called tetany. These episodes can cause
fractures and muscle tears.
Other symptoms include:
drooling
excessive sweating
fever
Spasms of the hand or foot
irritability
Difficulty swallowing
Uncontrollable urination or defecation
Signs and tests
The doctor will perform a physical exam and ask
questions about your medical history. There is no specific laboratory test
available to determine the diagnosis of tetanus.
muscular dystrophy
It is a group of disorders that involve muscle
weakness and loss of muscle tissue, which worsen over time.
causes
Muscular dystrophies (MD) are a group of inherited
conditions, which means they are transmitted from parents to children. They can
appear in childhood or adulthood. There are many different types of muscular
dystrophy include:
Becker muscular dystrophy
Duchenne muscular dystrophy
Muscular Dystrophy Emery-Dreifuss
Facioscapulohumeral muscular dystrophy
Duchenne muscular girdle
myotonia congenita
myotonic dystrophy
symptoms
Symptoms vary with the different types of muscular
dystrophy.
All the muscles may be affected or only specific
groups of muscles such as those around the pelvis, shoulders or face. Muscular
dystrophy can affect adults, but severe forms tend to occur in early childhood.
Symptoms include:
Mental retardation (only present in some types of the
condition)
Muscle weakness that slowly gets worse
delayed development of muscle motor skills
Difficulty using one or more groups of muscles
drooling
drooping eyelid (ptosis)
frequent falls
loss of strength in a muscle or muscle group as an
adult
loss in muscle size
trouble walking (delayed walking)
Exams and Tests
A physical examination and medical history will help
the doctor determine the type of muscular dystrophy. Specific muscle groups are
affected by different types of muscular dystrophy.
The medical examination may show:
Abnormally curved spine (scoliosis)
Joint contractures (clubfoot, claw hand or other)
Low muscle tone (hypotonia)
