22 year old male complaining of muscle loss and cramping
muscle is an organ, composed of muscle tissue, connective tissue, blood vessels and nerves
fascicle: skeletal muscle is arranged into bundles of muscle fibers called fascicle
cell/ muscle fiber: 80% of muscle fiber volume is made up of myofibrils, long cylindrical structures, approximately one or two micrometers in diameter that extend the length of each fiber
myofibril contains bundles of protein filaments called myofilaments, sarcomeres
filament: there are two types of myofilaments, thick and thin. thick filaments are comprised of bundles of 200-500 myosin protein molecules. Thin filaments are composed of two strands of actin protein.
Dense irregular connective tissue surrounds the entire skeletal muscle is called the epimysium. Dense irregular connective tissue containing an extensive network of blood vessels and nerves surrounding the fascicles is the perimysium. And the innermost areolar connective tissue layer that insulates each muscle fiber is called the endomysium
Cordlike structures composed of three layers of dense regular connective tissue which attach muscle to bone, skin, or another muscle are called tendons. Thin, flattened sheets of dense irregular tissue are called aponeuroses
Myosin (Thick) consists of two strands, with each strand having a head and a tail. Myosin heads serve as binding sites for actin (thin) and sites where ATP attaches and splits into ADP and phosphate by ATP to generate the energy for contraction.
Actin (Thin) Filamentous actin (f-actin) resembles two beaded necklaces intertwined, while globular actin (g-actin) resembles individual beads and contains a feature called a myosin binding site, where the myosin head attaches during muscle contraction
Skeletal muscle is connected to and controlled by motor neurons. Extending from the brain and spinal cord to muscle fibers are motor neurons, each having a long-branched extension at its terminal end called an axon or nerve fiber. Skeletal muscle contains neuromuscular junctions which exist between axons and muscle fibers and is considered voluntary muscle, as it is consciously controlled by the nervous system. Skeletal muscle composed of a network of blood vessels delivering both oxygen and a nutrient to muscle fibers while eliminating waste products is termed vascularized
Muscle contractions: Excitation. Acetylcholine form a synaptic vesicle is released and Ach binds to Ach receptors, which causes muscle fiber contraction. An action potential is triggered by the binding of Ach along the sarcolemma anf t-tubules to the sarcoplasmic reticulum, stimulating the release of calcium ions.
Cross bridge cycling involves calium ion binding to troponin, which triggers the sliding of thin filaments past thich and thus the shortening of sarcomeres and sucle contraction. a nerve signal is passed down a motor axon, triggering the entry of calcium ions into the synaptic knob, calcium ions then bind to proteins in the synaptic membrane, and this binding of calcium ions triggers the release of Ach into the synaptic cleft. Once Ach is released from the knob, Ach diffuses across the synaptic cleft in the motor end plate and is available to bind with Ach receptors
Binding of Ach to Ach receptors in the motor end plate triggers the opening of channels that allow for rapid diffusion of sodium into the muscle fiber and slow diffusion of potassium out of the channel. end plate potential is a reversal in polarity, whereby there is a reversal in electrical charge difference at the motor end plate. Action potential involves two events: depolarization, where an influx of sodium causes the sarcolemma to become more positive, and repolarization, where the flow of potassium of the sarcolemma returns the sarcolemma back to its original negative resting membrane potential of -95 milivolts. repolarization allows the muscle fiber to generate a new action potential time and time again when stimulated by a motor neuron.
When calcium is released from the sarcoplasmic reticulum and binds to globular troponin, is changes shape and the troponin-tropomyosin complex moves exposing the myosin binding sites of actin and thus cross bridge cycling is initiated. There are 4 steps:
- the process of myosin heads attaching to myosin binding sites and forming a cross bridge between thick and thin filaments called a cross bridge formation
- the process of myosin heads swiveling and pulling thin filaments past thick filaments toward the center of the sarcomere is called a power stroke
- binding of ATP to the ATP binding site of a myosin head resulting in the release of the myosin head form the actin binding site.
- the enzyme ATPase splitting ATP into ADP and phosphate, resulting in a release of energy which will serve to reset the myosin head in a cocked position.
Fuels and components: sodium, potassium, phosphate, ADP, ATP, protein, glycogen, glucose, creatine
Factors contributing to fatigue
inadequate release of calcium ions from the SR, resulting in a decline of Ca2+concentration in the sarcoplasm.
Depletion of creatine phosphate
insufficient oxygen
depletion of glycogen and other nutrients
buildup of lactic acid and ADP
failure of action potentials in the motor neuron to release enough acetylcholine
Intense weight-training program and running
Vegan diet consisting of only fruit juice, and does not eat soy.
Skips meals
Drinks a gallon of water every day but never any sports drinks.
He has no electrolytes in him and all that water is diluting the amount of sodium in his body
He is malnourished and is actually starving .He does not like soy but with a vegan diet, he has to rely on plant proteins or other sources and soy is an excellent source. And only doing a liquid fruit juice diet can lead to a dangerous calorie restriction which means he is not getting enough nutrients. This causes FATIGUE, hair loss, electrolyte imbalance, gallstones, constipation, anemia, menstrual problems, LOSS OF MUSCLE MASS, and heart damage,
Pros of a vegan diet: Promotes weight loss, reduced risk of serious illness, there are alternative sources of B-12, and it is environmentally sustainable
Cons of a vegan diet: excessive weight loss can become weight gain, lacks vital nutrients, bloating and discomfort, dehydration
When you skip meals, your body doesnt get energy from food and it looks for new sources of energy. Your metabolism starts converting fat into energy which can lead to health issues like FATIGUE, kidney stress, low blood pressure, constipation and nausea.. there are no pros to skipping meals
Epimysium is a layer of dense irregular connective tissue that surrounds the whole skeletal muscle. This fibrous tissue ensheathes the entire muscle to protect and support it like a tough leather sleeve.
Perimysium is a layer of dense irregular connective tissue around each fascicle. these tough, fibrous connective tissue sleeves also provide protection and support but to each bundle of muscle fibers.
Endomysium is composed of areolar connective tissue that surrounds each muscle fiber. these more delicate coverings function to electrically insulate the muscle fibers.
Could be developing a condition known as Rnhabdomylosis. This condition leads muscle tissue to break down and and release a harmful protein, myoglobin into the blood stream and damages the kidneys. Symptoms include: soreness, swelling and inability to bend and dark brown urine. Causes are:strenuous exercise such as spinning, P90X, CrossFit, weight lifting, and running.
His body requires energy but he is not eating, so the body will eat the muscles when there is nothing left.
Kidneys can shut down and patient would end up on dialysis. With kidney failure, the risk of an overload of potassium in the body can lead to abnormal heart rhythms and even death.
His cells could Hyper-polarize and die
Pros and cons: He is drinking water to stay hydrated, which is good, but he is drinking too much and not eating anything so he is creating imbalances in his body that result in fatigue and cramping
Malnutrition complications include: stunting growth, vision problems, diabetes, and heart disease
Protein deficiency can cause, fatty liver, swelling, skin degeneration and increase of infections.