Pathophysiology and General Concepts of Disease

Vocabulary flashcards covering acid-base balance, general concepts of disease, diagnostic testing, adaptive immunity, hypersensitivity, HIV/AIDS, fluid and electrolyte disorders, and COVID-19 pathophysiology.

Arterial Blood Gas (ABG) Normal Values

Standard clinical reference ranges for arterial blood: pH of $7.35 - 7.45$, PaCO2 of $35 - 45\,mm\,Hg$, PaO2 of $80 - 100\,mm\,Hg$, HCO3- of $22 - 26\,mEq/L$, and SaO2 of $> 95\%$

Respiratory Acidosis

An acid-base imbalance caused by decreased alveolar ventilation, leading to CO2 retention and an arterial pH below $7.35$

Respiratory Alkalosis

An acid-base imbalance caused by increased alveolar ventilation (hyperventilation), leading to excessive CO2 excretion and an arterial pH above $7.45$

Metabolic Acidosis

An acid-base imbalance caused by a depression of HCO3- or an accumulation of noncarbonic acids, resulting in an arterial pH below $7.35$

Metabolic Alkalosis

An acid-base imbalance caused by an elevation of HCO3- or excessive loss of metabolic acids (such as through severe vomiting), resulting in an arterial pH above $7.45$

Disease

A disturbance of body structure or function, or an alteration in organ or tissue functioning, often associated with well-defined clinical characteristics

Etiology

The underlying cause or reason why a specific disease or disorder occurs

Clinical Manifestations

The objective signs and subjective symptoms (such as pain, coughing, dyspnea, or swelling) that denote the presence of a disease

Specific Treatment

A targeted medical treatment aimed specifically at curing or favorably altering the basic course of a disease (e.g., administering antibiotics for a bacterial infection or insulin for diabetes)

Symptomatic Treatment

A medical treatment aimed at alleviating patient symptoms to increase comfort without influencing the course of the underlying disease

Computed Tomography (CT)

A diagnostic imaging test that produces cross-sectional images of the body by rotating an X-ray tube around the patient at various levels

Magnetic Resonance Imaging (MRI)

A diagnostic imaging technique similar to CT scanning that constructs detailed images based on tissue density using ionizing/radiofrequency principles

Positron Emission Tomography (PET)

A diagnostic procedure involving the injection of a biochemical compound into a patient to evaluate organ function by measuring its distribution, metabolism, and emitted radiation

Endoscopy

A diagnostic procedure involving the insertion of a fiber-optic scope instrument to examine the interior of body cavities or organs

Active Acquired Immunity

Immunity obtained when the body is exposed to an antigen through contracting a disease or via a vaccine, requiring the individual to synthesize their own specific immunoglobulins

Passive Immunity

Immunity acquired by receiving pre-formed ready-made antibodies from an external source, such as maternal antibody transfer via the placenta or injection of hyperimmune serum

Helper T Cells (CD4 Cells)

T lymphocytes that stimulate and turn on the immune system by activating other immune cells; they serve as the primary target cell destroyed by HIV

Cytotoxic T Cells (CD8 Cells)

T lymphocytes that directly destroy non-self or abnormal cells, including cancer cells, virus-infected cells, and transplanted or grafted tissues

Type 1 Immediate Hypersensitivity

An IgE-mediated allergic reaction triggering histamine release, leading to bronchiole smooth muscle constriction and mucosal edema

Type 2 Cytotoxic Hypersensitivity

An immediate reaction mediated by IgG or IgM antibodies directed against cell-bound antigens, resulting in cell lysis or hemolysis (e.g., blood transfusion reactions, Rh incompatibility)

Type 3 Immune Complex Hypersensitivity

An immune reaction where IgG or IgM antigen-antibody complexes form and deposit in vessel walls, joints, or organs, triggering localized inflammation (e.g., serum sickness)

Type 4 Delayed Hypersensitivity

A cell-mediated immune response that manifests $24 - 48\,hours$ after exposure to an antigen (e.g., contact dermatitis, tuberculin skin test, graft rejection)

Seroconversion

The transition of an HIV-infected patient from an antibody-negative status to an antibody-positive status, typically occurring between $2\,weeks$ and $6\,months$ post-exposure

Acquired Immune Deficiency Syndrome (AIDS)

The advanced stage of HIV infection diagnosed when a patient's CD4 T-cell count drops below $200\,cells/\mu L$ or when specific opportunistic infections develop

Hydrostatic Pressure

The mechanical pushing force exerted by fluid against vessel walls that tends to drive fluid out of capillaries and into the interstitial space

Oncotic Pressure

The osmotic pulling force exerted by plasma proteins (such as albumin) that draws water from the interstitial space back into the vascular compartment

Edema

An abnormal accumulation of fluid within the interstitial spaces, resulting from increased capillary hydrostatic pressure, decreased plasma oncotic pressure, increased capillary permeability, or lymphatic obstruction

Hypernatremia

An elevated serum sodium concentration above $147\,mEq/L$, most commonly caused by a water deficit (dehydration) or sodium retention

Hyponatremia

A abnormally low serum sodium concentration below $135\,mEq/L$, caused by excess fluid volume diluting serum sodium or by excessive sodium loss

Hypokalemia

A serum potassium level below $3.5\,mEq/L$, causing decreased neuromuscular excitability, muscle weakness, and characteristic ECG changes like ST depression and shallow T waves

Hyperkalemia Electrocardiogram (ECG) Changes

ECG alterations associated with elevated serum potassium ($> 5.5\,mEq/L$), including tall peaked T waves, widened QRS complexes, prolonged PR intervals, and depressed ST segments

Carbonic Acid-Bicarbonate Buffer Pair

The body's primary extracellular buffer system, maintaining normal blood pH at a strict $20:1$ ratio of bicarbonate ($HCO_3^-$) to carbonic acid ($H_2CO_3$)

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)

An enveloped betacoronavirus carrying single-stranded messenger RNA (mRNA) that binds ACE2 receptors to cause COVID-19

Angiotensin-Converting Enzyme 2 (ACE2) Receptor

The host cell surface receptor utilized by SARS-CoV-2 for cell entry, located on lung epithelial cells, vascular endothelium, and other tissues

COVID-19 Transmission Routes

Mechanisms by which SARS-CoV-2 spreads between individuals, primarily via direct person-to-person respiratory droplets and contact, as well as indirect surface contact and aerosolized droplet nuclei

Acute Respiratory Distress Syndrome (ARDS)

A severe pulmonary complication seen in critical COVID-19 cases characterized by non-compliant ('stiff') lungs, diffuse alveolar damage, and acute severe hypoxemia ($SpO_2 < 92\%$)

Prone Positioning

An inpatient therapeutic intervention for COVID-19 patients where the patient is positioned face down on their abdomen to improve peripheral oxygen saturation

Extracorporeal Membrane Oxygenation (ECMO)

An advanced inpatient life-support technique that pumps and oxygenates a patient's blood outside the body, allowing severely compromised heart and lungs to rest