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Clinical cases are available! The best answer will be posted giving due credit. Send via       or by contacts!

 

1 - A man in his 60s came to emergency with chest pain and angina was diagnosed. In preliminary tests, electrocardiogram showed normal pattern and blood test showed Creatine kinase (CK-MB) increased. Discuss the possible causes that could lead to this clinical picture and their pathogenesis, injuries and possible consequences.

 

" The enzyme creatine kinase ( CK-MB ) is specific of cardiac muscle cells . Increasing this enzyme in blood test is indicative of leakage of intracellular enzymes into the peripheral circulation , an important marker of cell death , a framework considered irreversible. Extravasation of intracellular enzymes occurs as a result of damage to the cell membranes consistituted of phospholipids , suggesting a clinical diagnosis of ischemia ( reduced blood flow ) . Ischemia causes progressive impairment of various cellular biochemical pathways , which leads to reduction of the quantity and synthesis ATP ; increase in intracellular calcium that activates phospholipase enzymes, proteases, ATPase , endonucleases , amongst other. Phospholipases degrade the phospholipids of membranes causing an increase in plasma membrane permeability , which affect the intracellular osmolarity and, then,  intracellular enzymes pass into the peripheral circulation , increasing its concentration in blood. Another consequence of ischemia is hypoxia (low oxygen available to the tissues) that cause damage resulting in mitochondrial oxidative phosphorylation. To a certain extent the damage can be repaired, it is reversible. The cells can regain homeostasis if blood flow and oxygenation are restored . At this clinical picture we can say that the damage is irreversible due to the profound changes in cell membrane function .The cell lesions described are characteristic of necrosis, because it has already occurred autolysis (destruction of cells by their own enzymes) identified by the presence of CK-MB in the blood test. The clinical picture above is characteristic of infarct, which is defined as ischemia followed by cell death (necrosis), which can lead the patient to death. "

 

Dilliane da P. R. Almeida - student of Biomedicine / 4 period / UFF

 

" The increased level of creatine kinase in the blood indicates tissue injury. As the patient had angina - characteristic pain from the heart, this difference in levels just showing us that there was damage to the heart muscle. Probably , the patient suffered an ischemic (decreased blood flow to a tissue ) , plus hypoxia , subsequently coagulation necrosis , culminating in myocardial infarct. When ischemia happened , the whole machinery of ATP production was affected . With ischemia , came the hypoxia ( reduced oxygen to the tissues ) . Consequently, all dependent cellular mechanisms of energy ceased, including cardiac contraction , since the contraction needs energy to happen. This is because the respiratory chain ( one of these cellular mechanisms ) there is a need for a molecule of oxygen to form ATP. Thus , in a first stage , reversible lesions are normal. But if the lack of oxygen persists , an irreversible injury can happen - coagulation necrosis , where there will be an intense level of protein denaturation . This necrosiscombined with ischemia generates infarct , which may or may not lead the patient to death. "

 

João Figueira Scarini - Dentistry student / 2 period / UFF

 

 

2 - A group of soccer players was for a tournament in the Swiss Alps during winter. Most of these players during competition had difficulty breathing, dizziness, excessive fatigue, being diagnosed with hypoxia. Explain the pathogenesis of this hypoxia and possible consequences.

 

" Hypoxia by definition is a reduction or absence of oxygen. As athletes are at altitude , the gas pressure is lower which hinders gas exchange at the alveolar - capillary membrane. This process results in poor oxygen supply to the tissues. Hypoxia and aerobic respiration affects the capacity to generate ATP. The ATP becomes to be generated by glycolysis (anaerobic and inefficient ) and oxidative phosphorylation in the mitochondria (aerobic and efficient) . The lack of oxygen leads to increased anaerobic glycolysis with reduced glycogen to a greater production of lactic acid and intracellular acidosis. The decreased synthesis of ATP causes loss of cellular functions energy dependent such as membrane transport and maintaining ion gradients and protein synthesis. Hypoxia is a reversible lesion, ie, when the supply of oxygen to tissues is restored cells return to homeostasis. The duration of hypoxia and type of tissue is critical for the progression of injury, when it becomes causes irreversible cell death. "

 

Dilliane da P. R. Almeida - student of Biomedicine / 4 period / UFF

 

"Hypoxia is characterized by a reduction in oxygen supply to the tissues. In the Swiss Alps, due to the altitude, the oxygen ends up getting rarefied, ie, the air we breathe, the amount of oxygen is diminished. Thus, the lower the level oxygen entering, lower will be the level of oxygen that can reach the tissues - hypoxia. The lack of oxygen can change the respiratory chain, which will produce less and less energy (ATP). Less energy means changes in cellular mechanisms dependents of ATP. Another contributing factor to this situation of hypoxia is the addition of the winter. It contributes to this situation, since hypoxia may be caused by vasoconstriction, very common at low temperatures. Thus, players can adapt or undergo reversible lesions that, if not properly diagnosed and treated, can lead to irreversible damage, which consequently can lead to death. "

 

 

João Figueira Scarini - Dentistry student / 2period / UFF