To determine the severity of a cancer, clinicians use the TNM Staging System, which evaluates the size of the primary Tumor, the involvement of nearby lymph Nodes, and the presence of distant Metastasis.
Diagnosis and Detection
Early detection is vital for improving prognosis. Clinicians often look for the "CAUTION" warning signs, which include changes in bowel/bladder habits, unusual bleeding, or the appearance of a new lump. While screening tests (like mammograms or colonoscopies) are essential for prevention, a biopsy is the only procedure that provides a definitive diagnosis. Biopsy methods include:
- Needle biopsy: A minimally invasive method using a thin needle.
- Endoscopic biopsy: Using an endoscope to view and sample internal organs.
- Surgical biopsy: The removal of part or all of a tumor; this is more invasive than other methods.
Exam Tip: If a question asks which diagnostic procedure provides a definitive diagnosis for cancer, the answer is always a biopsy, not imaging or blood tests.
Anemia: Deficiencies in Oxygen Transport
Anemia is a condition characterized by a deficiency in red blood cells (RBCs) or hemoglobin, which results in decreased oxygen transport to the body's tissues. This deficiency can stem from decreased RBC production (due to bone marrow damage or vitamin deficiencies like B12 or folate) or increased RBC destruction (due to blood loss or autoimmune conditions).
Classification by MCV
Anemia is clinically classified using the Mean Corpuscular Volume (MCV), which measures the average size of the RBCs:
| Type | MCV Value | Common Examples |
|---|
| Microcytic | $MCV < 80$ | Iron deficiency anemia |
| Normocytic | 80≤MCV≤100 | Chronic disease, acute blood loss |
| Macrocytic | $MCV > 100$ | B12 or folate deficiency (Pernicious anemia) |
Specific Manifestations and Sickle Cell Disease
General manifestations of anemia include fatigue, pallor (paleness), dyspnea (shortness of breath), tachycardia (increased heart rate), dizziness, and confusion.
A specific genetic form is Sickle Cell Anemia, a recessive condition where RBCs deoxygenate and change into a "sickle" shape. These sickled cells have a short lifespan and tend to stick together, obstructing blood vessels and causing severe complications in the central nervous system, heart, and kidneys.
Inflammation: The Body's Defense Mechanism
Inflammation is an immunologic defense mechanism designed to protect the body against invading pathogens and tissue trauma. While often necessary for healing, it can become pathological if it becomes chronic.
Acute vs. Chronic Inflammation
The distinction between acute and chronic inflammation is critical for understanding clinical presentation:
Acute Inflammation
This is an immediate, short-duration response to injury. When tissue is injured, bradykinin is released, activating pain receptors. This triggers mast cells and basophils to release histamine, which causes vasodilation and increased capillary permeability.
- Local Manifestations: Redness (erythema), swelling (edema), warmth, pain, and loss of function.
- Systemic Manifestations: Pyrexia (fever), malaise, fatigue, headache, and anorexia.
- Key Cells: Neutrophils and macrophages.
Chronic Inflammation
This is a slow-developing, long-duration process. It can result from persistent foreign substances, autoimmune conditions, or prolonged acute inflammation.
- Key Features: Characterized by the presence of lymphocytes, macrophages, and fibroblasts.
- Complications: Unlike acute inflammation, chronic inflammation often leads to significant tissue destruction and the production of collagen, resulting in the formation of fibrous scar tissue.
The Healing Process
Following an injury, the body moves through several phases to restore integrity:
- Inflammatory Phase: The immediate response to injury.
- Proliferative Phase: The stage where new tissue is built.
- Remodeling Phase: The final stage where the tissue is strengthened.
Healing can occur through resolution (minimal damage), regeneration (restoring the same cell type via mitosis), or replacement (forming scar tissue in areas that cannot regenerate).
Clinical Note: Factors such as adequate hemoglobin (to provide oxygen), good nutrition, and effective circulation promote healing. Conversely, anemia, diabetes, infection, and advanced age can significantly delay the healing process.
