pathology 2 - Pathology 2- Cell Injury, Adaptation and Cell...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Pathology 2- Cell Injury, Adaptation and Cell Death Clinical and experimental pathology still grounded in the beliefs of 19 th century German scientist and stateman Rudolf Virchow that disease arises, not in organs or tissues, but primarily in individual cells→ every cell comes from an identical pre- existing cell When the environment changes exceed the capacity of the cell to maintain homeostasis we recognize cell injury Agents that can cause injury or present damaging stimulus to the cell: Physical agents- trauma, radiation, extremes of temperature, changes in pressure Chemical agents- air pollulants, CO, pesticides, poisons, toxins, drugs Biological agents- microorganisms; biological toxins Nutritional or metabolic alterations- nutritional deficiencies, ischemia=lack of blood supply(no blood=no oxygen=doesn’t get rid of toxic metabolites), hypoxia=lack of oxygen (pneumonia, anemia, CO poisoning, anoxia=total absence of oxygen) **not all hypoxia is ischemic; ischemic cells will become hypoxic Immune reactions -allergens, autoimmune disease Genetic defects- single amino acid substitution such as sickle cell disease; chromosomal abnormalities such as trisomy 21 or Down syndrome Cellular aging ( loss of intrinsic repair mechanisms, repeated healing and repair following external injuries **reaction of the cell to a stress or damaging stimulus can range from a mild, completely reversible response to a long- term adaptive change in cell growth to irreversible damage and cell death Reversible to irreversible= point of no return=not well defined Response depends on severity of stimulus, time frame over which it is exposed to the stressor, and the individual cell type and its characteristics (rate of division, presence of protective mechanisms, its nutritional or metabolic state, its blood supply) Vulnerable cell components: cell membranes (critical for ionic and osmotic homeostasis), mitochondria (generation of energy), protein synthesis, and cellular DNA **and cytoskeleton Cellular Adaptation-all can be physiologic (happen normally in body) or pathologic Response to persistent sublethal injury (chemical or physical) reflects an adaptation of the cell to the environment achieving a new steady state and preserving cell viability Adaptive responses: regulation of cell receptors (up or down regulation) or changes in protein synthesis and turn over→adaptations include changes in cell size( atrophy or hypertrophy), number (hyperplasia) or organization (metaplasia, dysplasia) Atrophy= increased protein degredation and decreased protein synthesis= reduced demands leads to atrophy of organs= decrease in mass due to shrinkage of cell size=may have diminished function but ARE NOT dead; not cell # Due to diminished blood supply (ischemia) or diminished nutrional or trophic factors, a new steady state is reached in which a smaller cell is able to survive; decrease work load(immobilization), loss of innervations, decreased blood and nutrient
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 7

pathology 2 - Pathology 2- Cell Injury, Adaptation and Cell...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online