DMD Flashcards
ACE inhibitors
ACE inhibitors block the action of the enzyme ACE in the blood. ACE converts angiotensin 1 to angiotensin 2 which encourages blood vessels to constrict. The absence of them encourages dilation. ACE inhibitors block the formation of angiotensin 2.
Vasodilators
A drug that widens blood vessels. They are most predominantly used to reduce blood pressure and narrowed vessels. Therefore they improve blood flow, increasing oxygen supply and put less strain on the heart. Vasodilators dilate the blood vessel by relaxing the muscle around the vessel, by ACE inhibitors or by angiotensin 2 blockers.
Why does vasodilators affect DMD?
DMD can lead to cardiomyopathy (disease to the heart wall) that is caused by mutations in the DMD gene. The heart becomes weakened so doesn’t pump blood as efficiently. Vasodilators prevent tightening of muscles and narrowing vessel walls which helps improve blood flow.
Beta blockers function
They block the adrenal gland so they interrupt the transmission of stimuli through the beta receptors in the body. Signals from the sympathetic nervous system are carried by noradrenaline, a neurotransmitter produced by the adrenal gland and at the end of sympathetic nerve fibres. Beta blockers stop this transmission.
Beta blockers treat…
Arrhythmias, hypertension, tachycardia so slows down the heart and dilated the blood vessel. They can also be prescribed to improve heart wall function or to reduce symptoms of an overactive thyroid gland.
Beta blockers side affects
They are the same shape to fit the beta receptors in the lungs which can lead to breathing difficulties. The slower heart rate can reduce circulation leading to cold hands and feet.
How do beta blockers help DMD?
They allow the heart to beat slower with less force which leads to blood vessel dilation. This helps to lower the blood pressure and put less strain on the heart. This helps to increase the time at which the body can cope with cardiomyopathy.
DMD
A type of muscular dystrophy. A genetic disease causing muscle wastage and weakness. Suffers have a fault (mutation) on their dystrophin gene. This leads to dystrophin not being produced which is a protein that protects muscles.
Dystrophin
It is within muscles as part of a group of proteins that strengthens muscle fibres. This helps to protect you from injury as muscles contract and relax.
Cardiomyopathy
A general term for diseases of the heart muscle. The walls of the chambers become stretched, thickened or stiff. This affects the heart ability to pump blood around the body.
Recessive
To have it two faulty genes need to be present in female and one in male. Lower case marker. Effects the x chromosome.
Homozygous
Both are the same eg. Both dominant or both recessive
Heterozygous
One of each eg. One dominant one recessive
Phenotype
Characteristic caused by genotype
Eg. Healthy or affected
Alleles
Alternate versions of the same gene (one per gene)
Gamete
One from each parent. A circle denotes it is a gamete
Genotype
The combination of alleles an individual has.
Full blood count
Full blood count also known as a haematology profile examines the components of the blood. Often highly automated and uses special equipment in a lab. It involves measuring: erythrocyte, leukocyte and thrombocyte count per mm of blood. The size of the erythrocyte, mean size in a sample, the proportion of the blood made up by erythrocytes (haematocrit) and the amount of haemoglobin in erythrocytes. The amount of different types of leukocytes can be calculated to look at the bodies ability to fight infection. Thrombocyte count can show the bodies ability to clot blood.
Testing for creatine kinase
Full blood count
An enzyme catalyzing the conversion of ATP to ADP to release energy. High levels show signs of dmd. It leaks out damaged muscles into the blood.
Echocardiogram
A type of ultrasound that looks at the heart and the blood vessels nearby. Small probes send out high frequency sound waves that create echoes when they bounce off different parts of the body. These echoes are picked up off probes and turned into moving image on a monitor while the scan is carried out. Cardiomyopathy can be detected.
EMG - electrical test on nerves and muscles
Records electrical impulses that the muscle produces and the speed it travels along a nerve. Sensors are placed on the skin. DMD don’t respond well to EMG impulses.
Muscle biopsy
Minor surgical procedure removing a small but of muscle to be examined. Helps to rules out inflammation or other diseases.
Steroids
Strengthen muscles, lower inflammation and reduces immune activity. E.g. Strengthen muscles.
PCR
Used to amplify DNA. The sample is heated to 95 degrees (denaturation). Hydrogen bonds break between complementary bases. This separates the two strands and exposed the bases. Cool the sample to 55 degrees and add primer DNA polymerase, nucleotides and buffer (correct condition for DNA polymerase). This is the primer bonding stage. Primers will bond to complementary sequences on a single strand forming hydrogen bonds. Next is extension were the temperature is increased to 72 degrees activating taq polymerase which activates DNA polymerase. Taq binds to the primer adding nucleotides. This restores the original strand.
3 steps of pcr
Denaturation, primer bonding and extension.
3 main joints
Fibrous (fixed joint e.g. Teeth skull)
Cartilagenous (semi mobile e.g. Spine)
Synovial (Very freely moveable e.g. Hip socket knee)
Cartilage
Reduces friction and prevents bones from rubbing
Synovial fluid
Contained by synovial membrane. The cavity is for cushioning and protecting cartilage.
Ligaments
Connects bones together
Tendons
Attach muscle to bone
Smooth muscle
Makes up walls of organs and an involuntary muscle
Cardiac muscle
Heart muscle and an involuntary muscle
Skeletal muscle
Pulls in bones for movement and posture e.g. Tendons
Spine
Made up of small bones called vetebrays. It has cartilage between the bones for cushioning and protection. The spine protects the spinal cord (CNS)
Sliding filament theory
Actin is thin and myosin is thick. Myosin pulls actin inwards causing more overlap and the z band to get shorter. This creates a more thick appearance. As more filaments contract, it causes the whole muscle to contract. When the muscle relaxes the myosin releases the actin so they slide back over each other.
Myofibrils
Runs down muscles and is the site of contraction so contains lots of atp
Sinoatrial node
In the right atria wall and initiates the heart cycle as the pacemaker. It sends an electrical impulse across the atria causing atria systole.
Atrioventricular node to the end of the heart contraction
Received the impulse from the av node. Located in the septum. The impulse moves along the septum in the bundles of His. The impulse then moved through the purkinje fibres at the base of the heart. This causes the ventricle to contact (ventricular systole).
Diastole
The minimum atrial pressure when the heart is at rest and refilling.
Systole
The highest atrial pressure when the heart is contracting.
Vena cava
Deoxygenated blood enters the heart through this vessel on the right side. The heart is in diastole.
Pulmonary vein
Left side of the heart where oxygenated blood enters. The heart is in diastole.
Atrioventricular valves
Bicuspid left valve and tricuspid right valve. They open when atria starts to get quite full. Heart is in atria systole.
Semilunar valves
The valves as blood exists the heart. They open when the ventricle contract in ventricular systole.
Pulmonary artery
Blood leaves the right side of the heart through this and is deoxygenated. Under ventricular systole.
Aorta
Oxygenated blood is transported to the body through this vessel on the left side of the heart under ventricular systole.
Myogenic
Initiates its own contractions
ECG
Electrocardiogram. Measures the electrical pulse of the heart by sensors/electrodes on the chest.
P wave
Atrial systole the depolarization phase. The end of the wave is were the AV valve opens.
Depolarization
It is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell.
Repolarisation
It is the return of the ions to their previous resting state, which corresponds with relaxation of the myocardial muscle
QRS complex
Ventricular systole and at the end of the wave atrial diastole. At the peak of the Q wave the AV valve shuts.
T wave
Ventricular diastole and repolarization of the heart muscle.
Atrial pressure
Least change in pressure. Always quite low because the walls are thin so can’t exert a huge pressure. As the atria fills with blood there is a slight increase.
Ventricular pressure
Starts low but has a huge pressure change. The AV valve shuts and the pressure rises due to the thick muscular walls. The semilunar valve opens and the pressure lowers as blood leaves the heart.
When do the semi lunar valves open?
When the ventricular pressure is higher than the aortic pressure.
When do they AV valves open?
When the atrial pressure is higher than the ventricular pressure.
