2. definition
mmm
myoton
ia
myoton
ia
myasthen
ia
myastheni
a
M.H Physiology Presentation
Channelopathies : are diseases that is caused by
disturbed function
or dysregulation of ion channels . They may be congenital
(main reason mutations) or acquired (resulting from
autoimmune attack on ion channels) .
These diseases are usually associated with excitable cells ,
including
Muscles .
Examples in muscles :
1- myotonia
2- myasthenia
3- malignant hyperthermia
3. definitio
mmmmyoton
ia
myastheni
a
myastheni
a
M.H
myoton
ia
Physiology Presentation
Myotonia : neuromuscular disorder characterized by
delayed relaxation (prolonged contraction) of skeletal
muscle after voluntary contraction . All its forms share this
same symptom .
Cause : dysfunction of the channels that shape the
action potential
Which is caused by autosomal dominant mutation .
Types :
- Some of these mutations lead to overexpression of
K channels
- A variety of myotonias is associated with mutation in Na
channels :
* hyperkalemic periodic paralysis
* paramyotonia congenita
+
+
+
-
5. definitio
mmm
myoton
ia
myasthen
ia
myastheni
a
M.H
types
Physiology Presentation
Myasthenia : abnormal
muscle weakness or disease . It
can be also be related to loss of
ion channel function in muscle.
In congenital myasthenia the
patient has a group of inheritable
disorder of one of a group of ion
channels necessary for the
transmission of neuronal
signaling to muscle response.
6. definitio
mmm
myoton
ia
myasthen
ia
myasthenia
types
M.H Physiology Presentation
Mutation in Ca that allow for
neuronal transmitters release or in
the acetylcholine receptor
nonspecific cation channels ,
important in neuronal transmitters ,
have both been shown to cause
congenital myasthenia.
Alternations of channel functions can
also occur via autoimmune disease ,
such as that observed in myasthenia
gravis.
In this disease , the antibodies to the
nicotinic acetylcholine receptor can
reduce its functional presence at the
muscle membrane by 80% and thus
2+
7. definitio
mmm
myoton
ia
myasthen
ia
myasthenia
M.H
types
Physiology Presentation
therapy
ion
Malignant Hyperthermia
: it is resulted from mutations in
the Ca release channels in
muscle ( ryanodine receptors )
that amplify the Ca response
within cell .
Patients with this condition
display normal muscle function
under normal conditions.
However , certain anesthetic
agents ,or in rare cases
exposure to high environmental
heat or strenuous exercise, can
trigger abnormal release of Ca
from the sarcoplasmic reticulum
in the muscle cell ,resulting in
sustained muscle contraction
2+
2+
2+
8. definitio
mmm
myoton
ia
myasthen
ia
M.H
therapy
types
therapy
Physiology Presentation
Therapeutic Highlights :
Although the symptom associated with each individual
channelopathy may be similar , treatments for individual
diseases include a wide variety
of drugs that are targeted to defect the individual ion
channel (or proteins associated with ion channels ).
Appropriate drug therapy helps improve symptoms and
maintain acceptable muscle function .
Further interventions related to individual diseases are to
avoid muscle movements that exacerbate the disease.
9. definition
mmm
structur
al
therapy Physiology Presentation
structur
al
structur
al
metabolic Muscular dystrophy : it is a group of
diseases that cause progressive weakness and loss of
mass . They are about 50 such diseases haven been
described .
causes : mutations in genes (prominent cause)
symptoms :
Symptoms with of the most common variety begin in
childhood
mainly progressive muscle weakness . Specific signs
and symptoms
begin at different ages and indifferent muscle groups
, depending on the type of muscle dystrophy.
In childhood :
- Frequent falls - difficulty rising from sitting
10. definitio
mmm
therapy
structur
al
Physiology Presentation
structur
al
structur
al
metabolic The dystrophin gene is one
of the largest in the body ,
and mutations can occur at
many different parts of it .
Types :
1- Duchenne muscular
dystrophy : is a serious
form of dystrophy and it is
the most common form .
It is a X-linked disease and
usually fatal by the age of
30
In this case the dystrophin
protein is absent from the
muscle
11. definitio
mmm
structur
al
structural
metabolic
therapy
structur
al
Physiology Presentation
2- Becker muscular dystrophy : is a mild form of
the disease and slow in progress than the Duchenne .
Dystrophin is present ,but is altered or reduced in
amount.
3- limb-girdle muscular dystrophies of various
types are associated with mutation of the gene coding
for the sacroglycans or other components of the
dystrophin–glycoprotein complex . Hip and shoulder
muscles are usually the first to be affected . Patients
with this type may have difficulty in lifting the front part
of the foot.
Titin is also a target to mutations due to its enormous
size and structural role in the sarcomere. These
13. definitio
mmm
structur
al
structural
metabolic
structur
al
therapy Physiology Presentation
Metabolic myopathies :
Causes : mutation in the genes that
code for enzymes involved in the
metabolism of carbohydrates , lipids
, proteins to CO and H O to
produce ATP.
Symptoms :
- exercise intolerance the person
becomes tired very easily
- muscle weakness (primary
symptom)
- accumulation of toxic metabolites
like people with acid maltase
deficiency or debrancher enzyme
deficiency may eventually need a
wheel chair
Example :
McArdle syndrome (phosphorylase
2
2
14. definitio
mmm
structur
al
structural
metabolic
therapy
structur
al
Physiology Presentation
Therapeutic Highlights :
Although acute muscle pain and soreness can be
treated with anti-inflammatory drugs and rest . The
genetic dysfunctions described previously are not
easily addressed.
The overall goals are to slow muscle function
/structure loss and , when possible relieve symptoms
associated with the disease.
Extensive monitoring ,physical therapy , and
appropriate drugs including corticosteroids can aid
to slow disease progression . Assistive devices and
surgery are not uncommon as the disease progress.
