Pathological anatomy. It is the part of science that is responsible for the study of cell injuries, tissues, organs, their structural and functional consequences and therefore the repercussions on the organism. The special pathological anatomy is responsible for the study of the specific responses of each tissue or organ.
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- 1 Etymology
- 3 Pathological responses
- 4 Aspects of the disease
- 5 Historical evolution
- 6 Pathology of cells and interstitial spaces
- 1 Cell injury
- 7 Cell adaptation
- 8 cell death
- 9 Storage diseases: thesaurismosis
- 10 Causes of these processes
- 11 Diseases due to accumulation of substances
The word pathology comes from the Greek , and is the study (logos) of suffering or damage (pathos).
Pathological anatomy is one of the fundamental pillars of medicine and an essential basic discipline for doctors, veterinarians and other health professionals.
The interpretation of the symptoms of the different diseases or alterations that are found in the exploration of the patients requires the knowledge of the entire spectrum of lesions that appear in each one of the tissues or organs .
Pathological anatomy includes all aspects of the disease, fundamentally at the morphological level. These alterations are studied with various methods, ranging from molecular pathology to macroscopic pathology, going through all levels and techniques of observation and study, from histochemistry and immunohistochemistry to ultrastructure, optical microscopy or simple direct ocular vision ( macroscopic).
General pathological anatomy deals with the study of the foundations and development of basic pathological response processes, ranging from cellular adaptation to changes in the environment, cell injury and death, their causes and consequences, disorders of the growth of cells , tissues and organs, as well as the responses of the individual to the various injuries caused by external and internal agents and the mechanisms of repair of these injuries. According to the pathology there are three basic causes that originate the diseases that are:
- These are diseases that end in -itis, such as appendicitis.
- These are diseases that end in -osis, such as osteoarthritis.
- Uncontrolled cell growth. These are diseases that end in -oma, such as melanoma.
The four aspects of a disease, which form the core of pathology, are:
- Etiology: They are the causes of the disease.
- Pathogenesis: These are the mechanisms by which the disease develops.
- Morphological changes: These are the structural alterations that occur in the cells and
- Clinic: These are the functional consequences of morphological changes.
Pathologists or specialists in pathological anatomy are responsible above all for the study of the morphological changes of diseases.
There are sine matter diseases in which a clear morphological alteration cannot be observed, such as most psychiatric diseases and many functional disorders such as irritable bowel syndrome.
Hippocrates was the first to recognize that the pathology was based on an alteration of the humors and their relationship, based on the naturalistic philosophy of Empedocles who had already described those humors: blood, lymph, black bile and yellow bile. Galen kept the theories of Hippocrates current throughout medieval times, turning them into dogmas. Gradually, authors began to emerge who did not see Hippocrates’ theories as absolute truths. Vesalius based his study of the disease on morphological aspects, leaving aside the dogmatism imposed at the time.
Starting with the Renaissance, the first autopsies began to be carried out, a new current of authors began who believed only what they could see, definitively moving away from the dogmatic ideas that had prevailed up to that moment.
Thus, organicist anatomy was born, which directly relates morphology to the alterations and symptoms that accompany the disease.
The authors who were appearing at the time and who discovered how valuable the autopsy was for the study of medicine, such as Morgagni, understood that the observation and study of morphological alterations were the fundamental basis for understanding diseases.
At the end of the 18th century , Bichat introduced the concept of weaving. He tried to find simple units that make up the organs, the world of pathology entered in this way in the tissue era.
Already in the 19th century , and thanks to the development of the optical microscope , the cell theory was introduced, which provided a further level in the organization of living beings. Robert Hooke was the first to talk about cork cells. In Germany they began to relate cells and their alterations to pathologies. Claude Bernard also added that the physical and chemical characteristics of the cell and its alterations are also related to the disease
In recent times pathological anatomy has experienced an extraordinary development, thanks to advances in the field of technology, medicine, biology . Likewise, it can be affirmed that pathological anatomy is in continuous development.
Cellular pathology and interstitial spaces
- ischemia and hypoxia
- Chemical substances
- Infectious agents
- thermal variations
- Ionizing radiation
- immunological agents
- genetic alterations
- Nutritional imbalance
Faced with various stimuli, the cell undergoes changes that serve to adapt to the situation. These changes are:
- Atrophy: decrease in the size of the organ due to poor stimulation (this is what happens, for example, to the quadriceps when a patient is bedridden for a long period of time)
- Hypertrophy: opposite situation in which the size of the organ increases due to overstimulation. It derives from an increase in the size of the cells that make up the tissue and is not about an increase in their number. Hypertrophy can be physiological (muscles of a
athlete) or pathological
- Hyperplasia: in this case, the number of cells in the organ increases, causing its size to increase, it can also be the result of a hormonal physiological process (increase in the size
of the breasts during lactation), physiological compensatory (when a section of the liver is removed) or a pathological process (enlargement of the endometrium due to excessive hormonal stimulation derived from the existence of an ovarian tumor).
- Metaplasia: change of one tissue for another. It is generally the result of an aggression, it is worth noting the metaplasia of the respiratory epithelium by another type
Malpighian in smokers. The epithelial tissue changes to adapt to the aggression posed by smoke. The risk of metaplasia is that this tissue becomes much more susceptible to malignancy.
When all the adaptation and resistance mechanisms have been exhausted, cell death occurs. The cell can die in two different ways:
- Necrosis: it is produced by acute cell injury under pathological conditions, that is, derived from some non-physiological situation that produces cell death (it can
be called murder). Necrosis is characterized by its violence, the cell breaks to the outside releasing substances that are harmful to the tissue in which it is. The typical changes of a necrotic cell are: pyknosis, karyorrhexis and karyolysis. Depending on the mechanism of injury, there are several types of necrosis: Coagulative necrosis: occurs due to tissue ischemia that generates coagulation of intracellular proteins, making it unviable (this is what occurs, for example, in acute myocardial infarction ). The area of necrosis is replaced by fibrous tissue. fat necrosis
- Traumatic: it is not usual, it is produced by a traumatism that exceeds the capacities of
- Enzymatic: occurs when digestive enzymes(lipases, proteases, etc.) are released into the environment without control, or are activated in an unsuitable place. This occurs, for example, in pancreatitis , where the “stagnation” caused by obstruction of the Wirsung duct causes pancreatic digestive enzymes to activate within it.
- Caseating necrosis: it is the necrosis typically produced in tuberculosis.
- Apoptosis: programmed cell death. In this case a series of physiological or
pathological changes generate biochemical changes in the cell and it “decides” its own death, in an orderly manner, disintegrating into small vesicles that will be phagocytosed by macrophages and without major repercussions for the tissue in question (could be called suicide)
Storage diseases: thesaurismosis
It is the morphological expression of a metabolic disorder that generates an unusual accumulation of a certain substance inside the cell. The morphological lesion can be reversible or irreversible. Some of these disorders only have biochemical repercussions.
Causes of these processes
- Increased synthesis of said substance.
- Decrease in its catabolism.
- inability to degrade it.
Diseases due to accumulation of substances
- Thesaurismosis of triacylglycerides: They can be stored abnormally in the cells
parenchymatous of an organ (steatosis) or in the adipose tissue (lipomatosis).
Steatosis: will typically occur in cells of the liver, kidney, skeletal muscle and heart muscle. It is due to an increased supply (greater intake) of fats, a decrease in ß-oxidation, a decrease in proteins (thanks to proteins they can be transported through the blood, if they decrease it is not possible to mobilize them, remaining stored) or due to of some toxin. Among the steatosis are hepatic steatosis, renal steatosis (due to hypoxic processes such as heart failure or glomerulonephritis, muscular steatosis and Reye’s syndrome). Lipomatosis:it can be a generalized increase in adipose tissue (obesity) or local at the level of an organ. In organs that involute with age (thymus, bone marrow…) it is a normal process. If it occurs in another way, such as in skeletal muscle, it is a pathological process (myopathies and muscular dystrophies)
Cholesterol thesaurismosis: Cholesterol is the base molecule of steroids and bile acids, it also has a structural mission in cell membranes to which it gives flexibility. Under normal conditions it is not possible to see it by optical microscopy, the fact of seeing it is in itself pathological. When it accumulates it does so in the form of crystals and in inadequate quantities it is a great pro-inflammatory. The lymphocytes are ready to surround it and to achieve this they fuse to form foreign body multinucleated giant cells. If the process is slow, the macrophages phagocytize it, becoming multivesiculated or xanthomatous cells. Cholesterol has a yellowish color, they can be seen especially in skin, mucous membranes and joints