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An 8 year-old boy with Duchenne muscular dystrophy (Problems that the…
An 8 year-old boy with Duchenne muscular dystrophy
Anatomy
Muscular System
Permits movement, maintains posture and circulates blood throughout the body
Organs
Cardiac Muscle
the wall of the heart
Responsible to pump blood throughout the body
Smooth Muscle
Internal organs
Movement of substances
Skeletal Muscle
Skeletal Muscles
Posture,Motion, Heat production
Cells
Myocytes
Cells that make up muscle tissue
Macromolecules
Proteins
Actin
Thin myofilament
I bands
Z discs
Troponin
Interacts with ion calcium
green dots
Myosin
Thick myofilaments
H zone
M line
Tropomyosin
"Wet Spagetti"
yellow lines
Muscle Tissue
Cardiac muscle tissue
Involuntary
intercalated discs
Striations
branched cells
Skeletal muscle tissue
Voluntary
lots of striations
myofibrils
Smooth muscle tissue
Nuclei
Spindle-shaped cells
Physiology
Skeletal Muscle process
Muscle contraction is active process that requires energy to occur
Fast ATPAse
enzymes liberate energy quickly & burns through ATP very fast
The energy of muscle contraction is ATP
ATPase enzymes can be fast-acting or slow-acting
2.
Slow ATPase
enzymes liberate energy more slowly & use ATP more slowly
ATPase: The enzyme in myosin that breaks down ATP to liberate energy
ATP for muscle contraction
Way #1- from glycolysis ( ONLY 2-4 molecules of ATP)
Breaks down of glucose
Muscle cells store glucose in form of glycogen ( attach a sugar molecule to another one
Primary mode of ATP is breaking down glycogen which fibers are
glycolytic
Way # 2- from the Electron Transport Chain (found in the mitochondria)
The ETC generates A LOT of ATP, but this process requires oxygen
Primary mode of ATP generation is the ETC, the fibers are
Oxidative
Bone Remodeling
the process in which old bone tissue broken down & new bone tissue is made
Bone remodeling occurs:
In response to Gravity
In response to physical activity/physical strains
In response to the body's mineral requirements
20% of all the bones is replaced every year
Compact bone it takes about 10 years to recycle
Spongy bone can be replace much more quickly
The Femur is the strongest & longest bone in the body
The cell membrane of muscle cell : Sarcolemma
Sarcomere: is the contractile unit of a muscle cell
T-tubules: Muscle Action potential : they are important because it allows charge to go through the whole muscle
Myofibrils: the part of muscle fiber that is MOST involved in the process of muscle contactions; BUNDLES OF CONTRACTILE PROTEINS
Endomysium: the sheet of connective tissue that surrounds each muscle cell
Sarcoplasmic reticulum: Calcium storage
Tendons: the structure that attaches muscle to bone & is composed of dense regular connective tissue
Mitochondria: make ATP
Cross bridge cycle
1- Cross bridge formation- energized head myosin head attaches to an action myofilament
2 -the power stoke-force is being produced as actin is pulled toward the M line making it bend forward
3-Cross Bridge detachment- myosin head detaches
4- Cocking the Myosin hea- to begin all over again
Proteins
Myosin- thick filament consist of many myosin molecules whose heads protude at opposite ends of the filament
Actin-thin filament consists of two strands of actin subunits twisted into a helix plus two types regulatory proteins
Proteins tropomyosin and troponin do not participate in contaction but can control whether or not it can occur
Tropomyosin -covers the myosin binding sites on actin; no muscle contraction
Troponin- keeps tropomyosin in place
Downstream Affects
There is no cure for this disease
Symptoms: affecting the proximal muscles those close to the core of the body
later affecting the limb muscles those close to the extremities
seemed to become clumsy
In children muscles in legs are usually some of the first affected
Quadriceps get affected
experience muscle cramps
usually can be treated with over-the-counter pain relievers
Upstream causes
Fracture (Direct Cause)
Broke his radius when he tripped climbing down the stairs
complains of muscle aches
The patient's Duchnne muscular dystrophy (Direct Cause)
A rare genetic disease
Primarly affects males
Mutation in the DMD gene which happens during birth and can be inherited
The muscles in the body become weak and damaged over time
Duchenne is caused by mutation to the dystrophin gene, x chromosome
Duchenne (Indirect cause)
Prevents the body from producing dystrophin
The dystrophin protein is needed for muscles to function properly.
Dystrophin is a protein found in muscle cells.
One of a group of proteins that work together to strengthen muscle fibers
Protein dystrophin protect individuals from injuries as muscle contract and relax
Without dystrophin, muscles cells become damaged and over time are being replaced with scar tissue and fat in a process fibrosis
Indirect cause
lifestyle factors
much less physically active
a changed in walking pattern in the last few months
Ability to do daily activities
Building proteins
Central Dogma
in transcription, a cell its DNA to make mRNA message
is the synthesis of an RNA copy of a segment of DNA
RNA is synthesized by the enzyme RNA polymerase
in translation, a cell translates the mRNA message into a protein
mRNA is a nucleic acid
Proteins are mede out amino acids
Problems that the patient could possibly faced
Mobility may be very limited
having a hard time standing up, walking, and climbing chairs
Person may have to receive proper treatment and therapy
Muscle weakness in internal organs which may lead to other complications such as the heart and lungs
Patient may possibly rely on assistive devices such as walker or wheelchairs to get around
muscle deterioration
The 8 year-old with DMD is at a stage of transitional phrase
cognitive disability
change in behavior
leading to learning problems
memory and emotional interaction
Verbal learning
Attention focusing
Cardiac muscle tissue
heart
lack of dystrophin can weaken the muscle layer in the heart (myocardium)
extensive scarring of the tissues
cause abnormalities in the heart
Respiratory function
the diaphram and other muscles that operate lungs may weaken
making lungs less affective
poor respiratory functions
mental dullness
difficulty concentrating
Headaches
respiratory infections
Involuntary