Pathological anatomy

Pathological anatomy. It is the part of science that is in charge of studying cell, tissue and organ injuries, their structural and functional consequences, and therefore the repercussions on the body. The special pathological anatomy is in charge of studying the specific responses of each tissue or organ.

Summary

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  • 1 Etymology
  • 2 Concept
  • 3 Pathological responses
  • 4 Aspects of the disease
  • 5 Historical evolution
  • 6 Cellular and interstitial spaces pathology
    • 1 Cell injury
  • 7 Cell adaptation
  • 8 Cell death
  • 9 Deposit diseases: thesaurisms
  • 10 Causes of these processes
  • 11 Diseases due to accumulation of substances
  • 12 Source

Etymology

The word pathology comes from the Greek , and is the study (logos) of suffering or damage (pathos).

Concept

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 found in the examination of patients requires knowledge of the full spectrum of injuries that occur in each of the tissues or organs .

The 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, through all levels and techniques of observation and study, from histochemistry and immunohistochemistry to ultrastructure, light microscopy or simple direct eye vision ( macroscopic).

Pathological responses

General pathological anatomy deals with the study of the foundations and the development of basic pathological response processes, ranging from cellular adaptation to environmental modifications, cell injury and death, its 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 repair mechanisms of those injuries. According to the pathology, there are three basic causes of the diseases that are:

  • They are diseases that end in -itis, such as appendicitis.
  • They are diseases that end in -osis, such as osteoarthritis.
  • Uncontrolled cell growth. They are diseases that end in -oma, such as melanoma.

Aspects of the disease

The four aspects of a disease, which form the core of pathology are:

  • Etiology: They are the causes of the disease.
  • Pathogenesis: They are the mechanisms by which the disease develops.
  • Morphological changes: They are the structural alterations that occur in cells and

organs.

  • Clinic: They are the functional consequences of morphological changes.

Pathologists or specialists in pathological anatomy are mainly in charge of studying the morphological changes of diseases.

There are diseases without matter in which a clear morphological alteration cannot be objectified, as are the majority of psychiatric diseases and many functional disorders such as irritable colon.

Historical evolution

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 that had already described these humors: blood, lymph, black bile and yellow bile. Galen kept Hippocrates’ theories in force throughout the medieval period, 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.

From the Renaissance on, the first autopsies began to be carried out, a new stream of authors began who believed only what they could see, definitively moving away from the dogmatic ideas that until then prevailed.

Thus the organic anatomy is born, which directly relates the morphology with 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, came to understand 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. Trying to find simple units that make up the organs, the world of pathology thus entered the tissue age.

Already in the 19th century , and thanks to the development of the optical microscope , cell theory was introduced, which brought a further level to the organization of living things. Robert Hooke was the first to speak of 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 equally related to the disease

In recent times pathological anatomy has undergone extraordinary development, thanks to advances in the field of technology, medicine, biology . Likewise, it can be affirmed that the pathological anatomy is in continuous development.

Cellular and interstitial spaces pathology

Cell injury

  • Ischemia and hypoxia
  • Trauma
  • Chemical substances
  • Infectious agents
  • Thermal variations
  • Ionizing radiation
  • Immunologic agents
  • Genetic alterations
  • Nutritional imbalance

Cell adaptation

Faced with various stimuli, the cell undergoes changes that serve to adapt to the situation. These changes are:

  • Atrophy: decreased organ size 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: contrary situation in which the size of the organ increases due to overstimulation. It stems from an increase in the size of the cells that make up the tissue and is not a matter of increasing their number. Hypertrophy can be physiological (muscles of a

athlete) or pathological

  • Hyperplasia: in this case the number of cells in the organ does increase, causing it to increase in size, it may also be the result of a hormonal physiological process (increase in size

breastfeeding during lactation), physiological compensatory (when a section of the liver is removed) or a pathological process (increase 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 attack, it is worth noting the metaplasia of the respiratory epithelium by another of type

malpigian in smokers. The epithelial tissue changes to adapt to the aggression caused by smoke. The risk of metaplasia is that this tissue becomes much more susceptible to malignancy.

Cell death

When all adaptation and resistance mechanisms have been exhausted, cell death occurs. The cell can die in two different ways:

  • Necrosis: it occurs due to acute cell injury in pathological conditions, that is, derived from some non-physiological situation that causes cell death (can

called murder). Necrosis is characterized by its violence, the cell breaks to the outside releasing substances that are harmful to the tissue it is in. The typical changes of a necrotic cell are: picnosis, karyoxis and karyolysis. Depending on the injury mechanism, there are several types of necrosis: Coagulative necrosis: it occurs due to tissue ischemia that generates a coagulation of intracellular proteins, making it unfeasible (this is what occurs, for example, in acute myocardial infarction ). The necrosis area is replaced by fibrous tissue. Fat necrosis

  • Traumatic: it is not habitual, it is produced by a trauma that exceeds the capacities of

cellular adaptation

  • Enzymatic: occurs when digestive enzymes (lipases, proteases, etc.) are released to 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 the pancreatic digestive enzymes to activate within it.
  • Caseifying necrosis: is the necrosis typically produced in tuberculosis .
  • Apoptosis: programmed cell death. In this case a series of physiological events or

pathological pathways generate biochemical changes in the cell and the cell “decides” its own death, in an orderly manner, breaking up into small vesicles that will be phagocytosed by macrophages and without major repercussions for the tissue in question (could be called suicide)

Deposit diseases: thesaurisms

It is the morphological expression of a metabolic disorder that generates an unusual accumulation of a certain substance within the cell. Morphological injury can be reversible or irreversible. Some of these disorders only have a biochemical impact.

Causes of these processes

  • Increased synthesis of said substance.
  • Decreased catabolism.
  • Inability to degrade it.

Substance accumulation diseases

  • Thesaurisms of triacylglycerides: May be stored abnormally in cells

parenchyma of an organ (steatosis) or in adipose tissue (lipomatosis).

Steatosis: will typically occur in the cells of the liver, kidney, skeletal muscle, and heart muscle. It is due to an increase in the contribution (greater intake) of fats, a decrease in the ß-oxidation, a decrease in proteins (thanks to the proteins they can be transported through the blood, if they decrease it is not possible to mobilize them, being stored) or because of of some toxic. Steatosis includes hepatic steatosis, renal steatosis (due to hypoxic processes such as heart failure or glomerulonephritis, muscle 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 the organs that involve with age (thymus, bone marrow …) it is a normal process. If it occurs in another way, such as in skeletal muscle, there is a pathological process (myopathies and muscular dystrophies)

Thesaurisms of cholesterol: Cholesterol is the base molecule of steroids and bile acids, and it also has a structural mission in cell membranes, which gives it flexibility. Under normal conditions it is not possible to see it by light microscopy, the fact of seeing it is inherently pathological. When it accumulates it does so in the form of crystals and in inadequate amounts it is a great pro-inflammatory. The lymphocytes are arranged to surround it and to achieve this they fuse to form multinucleated giant foreign body cells. If the process is slow, macrophages phagocytize it, turning into multivesiculated or xanthomatous cells. Cholesterol has a yellowish color, can be seen especially on skin, mucosa and joints

 

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