Pathophysiology

• #Schweitzer
• Pathophysiology at the paramedic level, as taught by #Schweitzer, is essentially a basic understanding of homeostasis. Homeostasis is the result of chemical processes in the body that keep the body in balance. When these processes do not work correctly, disease occurs
  • Factors that predispose someone to disease may be controllable—like lifestyle and environment—or they may be immutable—like age, sex, and genetics
    • These factors are known as the etiology of a disease. Etiology in turn are arranged to form a pathogenesis, the sequence of factors leading up to a disease
  • When a disease is called idiopathic, we are not sure what caused the disease. If a disease is Iatrogenic, it is the result of medical treatment for something else
• Disease at the Chemical Level
  • [[Atomic Bonding]]
  • All organic chemicals contain carbon*. If a chemical does not contain carbon, it is considered inorganic
  • Carbohydrates, like glucose, are the primary fuel source for the cell ([[Cellular Respiration]])
  • Proteins are nitrogen-based* compounds made of amino acids held together by peptide bonds
    • Enzymes are a kind of protein that bind to a substrate and speed up a chemical process. Enzymes' names often end in -ase.
  • Lipids (triglycerides, phospholipids, steroids) are chemicals that do not dissolve in water. Lipids perform long-term energy storage as well as assist in insulation, structure, and control
  • Buffer systems* serve to counter the body's natural acid production to keep the body's pH within the normal range of 7.35–7.45. At the paramedic level, the main buffer system studied will be the ((3drxnh0J6)).
• Disease at the Cellular Level
  • Cells have a membrane wall made of a phospholipid bilayer that provides a selectively permeable barrier between itself and the extracellular fluid. Proteins on and in the cell membrane serve as receptors, transporters, gates, and enzymes
  • The selective permeability of cell membranes highly important to pathophysiology. Chemicals can pass through cell membranes through three main methods: simple diffusion, facilitated diffusion, and active transport
    • Simple diffusion occurs as chemicals (think particles) move from an area of high concentration to one of low concentration. Cell membranes are generally resistant to simple diffusion, but it will slowly occur
      • Osmosis is the movement of water towards areas of low water concentration. Osmosis is really just a specific term for the simple diffusion of water
    • Facilitated diffusion occurs when a receptor site on the cell membrane opens channels that allow certain chemicals to diffuse into the cell without expending energy
    • Active transport occurs when proteins move chemicals against the diffusion gradient from an area of low concentration to an area of high concentration. Active transport requires energy expenditure
  • Water retention in the body happens through the balance of hydrostatic and oncotic pressure
    • Hydrostatic pressure in the capillaries, the pressure exerted by the contraction of the heart, results in a push of water through the capillary walls into the interstitial spaces.
    • When water is pushed out, proteins dissolved into the plasma cannot pass through, resulting in a higher concentration of protein inside the capillaries. Oncotic pressure (or osmotic pressure) caused by the higher concentration of protein inside the capillaries pulls water back into the capillaries
    • Edema may occur in a deficiency of proteins in the plasma failing to create sufficient oncotic pressure, or in cases of heightened hydrostatic pressure.
  • The Renin Angiotensin Aldosterone System
    • When blood pressure falls, the kidney releases renin into the bloodstream. Angiotensinogen is released by the liver into the bloodstream and reacts with renin to form angiotensin I. Angiontensin I reacts with Angiotensis-converting Enzyme (ACE) in the lungs to form Angiontensin II. Angiotensin II triggers the adrenal glands to release aldosterone, and the pituitary glands to release Anti-diuretic Hormone (ADH or vasopressin)
    • Aldosterone and vasopressin cause sodium* retention in the kidneys and potassium release through the urine
    • Increased sodium in the bloodstream results in a greater water content in the blood, resulting in greater blood volume and pressure. Increased pressure stops the release of renin, completing the cycle
  • Cell abnormalities can be benign or malignant, and come in many different forms
    • Hyperplasia is an increase in the number of cells in the tissue, which may be a hormonal response or a compensatory response to illness or injury
    • Hypertrophy is an increase in cell size, and may be a physiological response to increased demand or a pathological response to increased stress
    • Atrophy is a decrease in cell size and may be a hormonal response or a pathologic response
    • Metaplasia occurs when an adult cell reversibly changes into a different adult cell type to protect itself from stress
    • Dysplasia is an abnormal or disordered growth in a cell, and is a precursor to cancer
  • Cells can die either through necrosis or apoptosis
    • In necrosis, the cell suddenly dies resulting in an immediate release of the cell contents, leading to an inflammatory response
    • In apoptosis, whether normal or pathologic, the cell contents are broken down and recycled, with no resulting inflammatory response
• Disease at the Tissue Level
  • Carcinogenesis is the process of developing a malignant neoplasia. Neoplasia may be understood as dysplasia* at the tissue level.
    • Once cancer develops, it becomes invasive: spreading along tissue planes and attaching to various tissue types
• Disease at the Organ Level
  • {{[[TODO]]}} Add shock notes
  • {{[[TODO]]}} Add ARDS/MODS notes
  • Acute Respiratory Distress Syndrome
  • Multiple Organ Dysfunction Syndrome
  • Shock is the inadequate perfusion of body tissues, also known as hypoperfusion. Shock may be cardiogenic, distributive, hypovolemic, and possibly obstructive depending on which textbook you're reading
    • Cardiogenic shock is an issue of hypoperfusion originating in the heart. This may be a result of increased or decreased preload or afterload, decreased cardiac contractile force, or significantly altered heart rate
      • Blood pressure is maintained through baroreceptors in the aortic arch and carotid sinus through the RAAS* and natriutic peptide. A drop in blood pressure will also increase the heart rate leading to tachycardia
      • The presence of pulmonary edema separates it from other forms of shock due to severe left ventricle failure
      • This kind of shock may also result in an acute myocardial infarction due to the reduced blood flow to cardiac muscle
    • Distributive shock is an issue with the capacity of the veins and arteries delivering blood to the body. This is often the result of a massive drop in blood pressure, resulting in an inability to deliver oxygen and remove waste from the end tissues
      • Venous tone (degree of openness) is controlled by a balance of the sympathetic and parasympathetic nervous systems