Midterm Review Quiz

Inflammatory Response

• Inflammation is a crucial component of the innate immune system, triggered by tissue injury.
• It's a rapid, non-specific process to contain damage, eliminate pathogens, and initiate healing.
• Key features include activation (seconds after injury), vascular changes (increased blood flow, redness, heat, swelling), and cellular events (leukocyte recruitment and destruction).
• Cytokines (signaling molecules) regulate the response, with pro-inflammatory cytokines amplifying and anti-inflammatory ones dampening the reaction.

Inflammatory Cell Characteristics

• Acute inflammation involves redness, swelling, heat, pain, and function loss.
• Processes include vasodilation, increased permeability, and leukocyte recruitment.
• Inflammation is protective, neutralising microorganisms and promoting tissue repair.
• The process starts within seconds and resolves within days of injury or microbial invasion.

Cytokines and Chemokines

• Cytokines are signaling molecules released by the immune system, regulating other cell activity.
• Chemokines are released by immune cells, recruiting additional immune cells to specific locations.

Chronic Inflammation

• Chronic inflammation results from unresolved acute inflammation or persistent triggers.
• It features lymphocyte and macrophage infiltration, fibroblast proliferation, connective tissue formation, and epithelial cell proliferation.
• These processes potentially cause scarring or polyp formation.

Cells Involved in Inflammation

• Mast cells release histamine and other mediators causing vasodilation.
• Macrophages engulf pathogens and debris, releasing pro-inflammatory cytokines, and presenting antigens to T helper cells.
• Neutrophils are abundant phagocytes, releasing enzymes and ROS to kill pathogens.
• Dendritic cells bridge the innate and adaptive immune systems, capturing antigens and presenting them to T cells.
• Eosinophils primarily fight parasites and regulate vascular mediators (released by mast cells).

Innate Immune System

• The innate system is the body's initial defense.
• It includes physical and biochemical barriers, the microbiome, and immune cells (mast cells, macrophages, dendritic cells).

Adaptive Immune System

• The adaptive immune system targets specific pathogens.
• T lymphocytes (T cells) mature in the thymus and differentiate into T helper (Th) cells and T cytotoxic (Tc) cells.
• B lymphocytes (B cells) mature in the bone marrow and differentiate into plasma cells (producing antibodies) and memory B cells.

Hypersensitivity Reactions

• Three major types of hypersensitivity reactions are allergy (environmental antigens), autoimmunity (self-antigens), and alloimmunity (tissues from another individual).
• Four major mechanisms (types I - IV) underlie these reactions.
• Type I (immediate/humoral) is mediated by IgE antibodies. Type II (tissue-specific) involves IgG or IgM antibodies, type III (immune complex-mediated) is mediated by IgG or IgM, and type IV (cell-mediated) reactions are mediated by T cells.

Antibody-Dependent Cellular Cytotoxicity

• Antibodies bind to target cells, marking them for destruction by immune cells (NK cells, macrophages, neutrophils).

Immune Complex-Mediated Hypersensitivity

• Immune complexes (antigen-antibody aggregates) activate the complement cascade.
• Neutrophils phagocytose complexes, leading to tissue damage, as in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).

Cell-Mediated Hypersensitivity

• T cells mediate delayed reactions, taking 24–72 hours to develop.
• Antigen presenting cells (APCs) present antigens to T cells.
• Activated T cells release cytokines and activate macrophages leading to tissue damage.

Cachexia

• Cachexia is a complex metabolic disorder characterized by the wasting of muscle tissue and atrophy of white adipose tissue.
• Key characteristics include an abnormal energy balance, where energy input may not meet the body's energy needs.

Human Immunodeficiency Virus (HIV)

• HIV is a retrovirus infecting and destroying CD4+ T helper cells of the adaptive immune system.
• It also infects macrophages, dendritic cells, NK cells, and cytotoxic T cells.

Infection Concepts

• Factors influencing a microorganism's ability to cause infection include communicability (spead from one person to another), infectivity (ability to invade and multiply), pathogenicity (ability to produce disease), mechanism of action (how the microorganism damages tissue), portal of entry (route of infection), toxigenicity, and virulence (capacity to cause severe disease).
• The ID50 (Infectious dose 50%) is determined in research models.

Skin Layers

• The epidermis is the outermost layer, primarily composed of keratinocytes which produce keratin (a protein giving strength and resilience).
• Melanocytes are cells producing melanin.
• The dermis lies beneath the epidermis, composed of connective tissue. Fibroblasts create collagen within this layer.
• The subcutaneous layer is comprised of fat tissue (adipocytes), and contains blood vessels, nerves, and hair follicles.

Viral Skin Infections

• These infections include herpes simplex virus (HSV), varicella zoster virus (VZV), human papillomavirus (HPV), measles virus, and rubella viruses.
• These viruses infect skin cells, causing cell death and an inflammatory response.

Fungal Skin Infections

• Dermatophytes (e.g., trichophyton, microsporum) are fungi causing superficial skin lesions, feeding on keratin.
• Mycoses (e.g., tinea infections) are classified according to location.
• Candidiasis (Candida albicans) affects skin and mucous membranes.

Skin Cancer

• Various types of skin cancer exist—basal cell carcinoma, squamous cell carcinoma and malignant melanoma.
• Risk factors include excessive sun exposure, fair skin, freckles, family history of skin cancer, and weakened immune systems.

Psoriasis

• Psoriasis is a chronic immune-mediated inflammatory skin disease.
• It involves epidermal cell turnover, causing red, elevated and scaly plaques, often on the scalp, elbows, or knees.
• Triggered by an immune response to an unknown antigen.
• Associated with Th1 and Th17 cells, activating cytokines such as IL-17, IFN-γ, and TNF-α.

Acute Coronary Syndromes

• Sudden blockage in a coronary artery (caused by thrombus formation).
• Two conditions exist : Unstable angina (transient ischemia) and myocardial infarction (sustained ischemia leading to cell death).

Chronic Obstructive Pulmonary Disease

• COPD is characterized by a progressive, usually irreversible, airflow limitation.
• Two major components are emphysema (destruction of alveolar walls) and chronic bronchitis (mucus hypersecretion and airway inflammation).

Asthma

• Asthma is an inflammatory disorder causing bronchoconstriction, airway hyperresponsiveness, and airway remodeling.
• Triggered by allergens and characterized by airway constriction, mucus hypersecretion, and inflammation mediated by Th2 cells, producing cytokines like IL-4, IL-5, IL-8 and IL-13.

Deep Vein Thrombosis

• Deep vein thrombosis (DVT) involves blood clot formation, usually in the deep veins of the leg.
• The Virchow's triad of risk factors for DVT include venous stasis, venous endothelial damage, and hypercoagulability.
• Venous stasis occurs with immobility; endothelial damage result from trauma; and hypercoagulability can stem from pregnancy, cancer, or medications.

Heart Failure

• Systolic heart failure (left-sided) occurs when the heart is unable to pump enough blood to meet the body's needs.
• Factors that trigger left-sided heart failure can include reduced contractility, increased preload (volume of blood before contraction), or increased afterload (resistance to blood flow).
• Right-sided heart failure is associated less commonly with lung diseases as cause, such as Chronic Obstructive Pulmonary Disease.

Urinary Tract Obstructions

• Kidney stones (nephrolithiasis) are a common cause of upper urinary tract obstructions.
• These crystals form when urine becomes supersaturated.
• Calculi lodge in the calyces, ureteropelvic junction, or ureterovesical junction.

Glomerulonephritis

• Inflammation of the glomeruli (kidney's filtering units) can be chronic or acute.
• Acute glomerulonephritis commonly arises from infections by bacteria such as Streptococcus.
• Chronic glomerulonephritis can stem from systemic conditions, such as diabetes and hypertension

Acute Kidney Injury

• Acute kidney injury (AKI) is a sudden decline in kidney function.
• It is commonly caused by reduced blood flow to the kidneys, direct damage to the kidneys, or blockage of the urinary tract.
• Risk factors include pre-existing kidney disease, diabetes, heart failure, liver failure, older age, and exposure to certain medications or toxins.

Chronic Kidney Disease

• Chronic kidney disease (CKD) is a progressive loss of kidney function over time.
• Common causes include diabetes, high blood pressure, glomerular diseases, and family history of kidney disease; older age and ethnicity may increase risk.

Hepatitis

• Viral hepatitis, typically caused by Hepatitis viruses A, B, C, D, E, G, Epstein Barr virus, varicella virus, alcohol abuse, drugs, and autoimmune disorders.
• Transmission varies depending on the hepatitis type (fecal-oral, blood-to-blood, or mother to child).
• Risk factors include poor sanitation, unprotected sex, sharing needles, contaminated blood transfusions before 1992, and contact with infected individuals.

Hypercapnia , Hypoxemia and V/Q Ratio

• Hypercapnia refers to increased carbon dioxide (CO2) level in blood. Hypoxemia refers to decreased oxygen (O2) level in blood. Both result from ventilation-perfusion (V/Q) mismatches.
• V/Q mismatches occur when the amount of air reaching the alveoli does not match the amount of blood flowing through the capillaries.