Cellular Adaptation, Injury, Death, and Fluid-Electrolyte Dynamics

Flashcards covering cellular adaptation mechanisms, types of cellular injury and death, fluid movement dynamics (edema, RAAS), and acid-base imbalances based on Unit 1 lecture notes.

Atrophy

A decrease in cell size.

Hypertrophy

An increase in cell size.

Hyperplasia

An increase in the number of normal cells.

Metaplasia

The replacement of mature cells by another mature cell type.

Dysplasia

Abnormal changes in the size, shape, and organization of mature cells; also referred to as atypical hyperplasia and not considered a true adaptive mechanism.

Reactive Oxygen Species (ROS)

Chemically reactive molecules containing oxygen, such as superoxide ($O_2^{\bullet-}$), hydrogen peroxide ($H_2O_2$), and hydroxyl radical ($^{\bullet}OH$), which are byproducts of cellular metabolism and can destroy cell membranes and structures.

Oxidative stress

A state that occurs when the production of reactive oxygen species overwhelms the body's antioxidant balance, leading to cellular injury.

Point of no return

The stage of irreversible cellular injury often marked by mitochondrial damage due to an increase of $Ca^{++}$ in the cell.

Hypoxia

A condition characterized by inadequate oxygen in the tissues, which can lead to decreased $ATP$ and subsequent cellular swelling.

Ischemia

A mechanism of cellular injury involving the obstruction or cessation of blood flow.

Ischemia-Reperfusion Injury (IRI)

Cellular damage caused by the restoration of blood flow and oxygen to ischemic tissues, leading to increased $ROS$, oxidative stress, mitochondrial calcium overload, and inflammation.

Major burn injury

A burn involving greater than $20\%$ Total Body Surface Area ($TBSA$), leading to increased capillary permeability, edema, hypovolemia, and a hypermetabolic response.

Leukocytosis

A clinical manifestation of cellular injury characterized by an increase in the White Blood Cell ($WBC$) count, typically indicating infection.

Necrosis

The sum of cellular changes after local cell death, characterized by cell swelling, rupture of organelles, and a slow, messy inflammatory response.

Apoptosis

Programmed cellular death of single cells involving nuclear and cytoplasmic shrinkage and phagocytosis, occurring without swelling or inflammation.

Coagulative Necrosis

A type of necrosis caused by protein denaturation (often from hypoxia) in the kidneys, heart, and adrenal glands.

Liquefactive Necrosis

Necrosis resulting from hydrolytic enzymes that lead to cyst formation, common in ischemic brain tissue or wet gangrene.

Caseous Necrosis

A combination of coagulative and liquefactive necrosis common in Tuberculosis ($TB$), often enclosed by a granulomatous inflammatory wall.

Fat Necrosis

Cell death occurring in the breast, pancreas, and abdomen where lipase action releases free fatty acids that undergo saponification.

Gangrenous Necrosis

Death of a large area of tissue due to hypoxia and bacterial invasion; classified as dry (coagulative), wet (liquefactive), or gas ($Clostridium$).

Osmotic Equilibrium

The state where water has moved across a membrane according to the osmotic gradient to balance concentrations between the Intracellular Fluid ($ICF$) and Extracellular Fluid ($ECF$).

Hydrostatic pressure

The mechanical force of water pushing against cellular or capillary membranes.

Oncotic pressure

The osmotic pressure exerted by plasma proteins that pulls water into the capillary.

Edema

The accumulation of fluid in the interstitial space, commonly caused by increased capillary hydrostatic pressure or decreased plasma albumin.

Renin-Angiotensin-Aldosterone System (RAAS)

A hormonal system triggered by low blood pressure or low serum sodium that leads to aldosterone release, causing sodium and water retention.

Natriuretic Peptides

Hormones including $ANP$ (atria), $BNP$ (ventricles), and Urodilatin (kidneys) that increase sodium and water excretion to lower blood pressure.

Antidiuretic Hormone (ADH)

A hormone released by the posterior pituitary that promotes renal water retention in response to increased plasma osmolality or decreased plasma volume.

Action Potential

The process of rapid depolarization (sodium entry) and repolarization (potassium exit) across a cell membrane.

Trousseau's Sign

A clinical test for hypocalcemia where carpopedal spasm is induced by inflating a blood pressure cuff on the arm.

Chvostek's Sign

A clinical test for hypocalcemia where tapping the facial nerve elicits twitching or spasms of the facial muscles.

Acidosis

A systemic increase in $H^+$ concentration, typically defined as an arterial blood $pH < 7.35$.

Alkalosis

A systemic decrease in $H^+$ concentration, typically defined as an arterial blood $pH > 7.45$.

Respiratory Acidosis

An acid-base imbalance caused by alveolar hypoventilation, resulting in an increase in $PaCO_2 > 44\,mm\,Hg$.

Respiratory Alkalosis

An acid-base imbalance caused by alveolar hyperventilation, resulting in a decrease in $PaCO_2 < 38\,mm\,Hg$.

Metabolic Acidosis

An acid-base imbalance characterized by a decrease in bicarbonate ($HCO_3^- < 22\,mEq/L$) or an increase in non-carbonic acids.

Metabolic Alkalosis

An acid-base imbalance characterized by an increase in bicarbonate ($HCO_3^- > 26\,mEq/L$) usually due to excessive loss of metabolic acids.