Innate Immunity Cells, Hematopoiesis, and Key Mechanisms
Characteristics of Innate Immunity
Innate Immunity: Rapid response (minutes to hours), non-specific (broad target recognition), with no immunological memory (reacts identically upon repeat exposure). Primary soluble factors include cytokines, chemokines, complement proteins, and acute-phase proteins.
Hematopoietic Lineage of Innate Cells
- Pluripotent Hematopoietic Stem Cell (Bone Marrow)
- Myeloid Progenitor
- Neutrophils
- Eosinophils
- Basophils
- Monocytes
- Macrophages
- Dendritic Cells
- Lymphoid Progenitor
- Natural Killer
- Myeloid Progenitor
Tumor Pathology: Growth Patterns, Structure, and Atypism
I. Types of Tumor Growth
- Expansile Growth: The tumor grows as a cohesive mass, pushing aside adjacent tissues. It forms a capsule, demarcating it from normal tissue (e.g., fibroadenoma).
- Infiltrative (Invasive) Growth: Tumor cells invade and destroy surrounding tissues without clear boundaries. This is a hallmark of malignant neoplasms.
- Exophytic Growth: Grows outward from an epithelial surface into a free space (e.g., lumen of the stomach, colon, or bronchus).
- Endophytic (Ulcerative) Growth: The tumor
Thymic Positive Selection and Adaptive Immune Activation Mechanisms
Positive Selection in the Thymus
Positive selection occurs in the corticomedullary area of the thymus to select T lymphocytes capable of recognizing self HLA molecules.
Stages:
- Epithelial cells in this area are antigen-presenting cells (APCs) and express abundant HLA-I and HLA-II with their own peptides.
- The new T cells, with their T cell receptor (TCR), examine the APC.
- If the TCR of the T cell binds to the HLA molecule of the APC, the T cell survives because it receives survival signals.
- If the TCR
Neurological Conditions: Bell’s Palsy to Subarachnoid Hemorrhage
Bell’s Palsy Etiology
Idiopathic; commonly associated with HSV-1, VZV. Autoimmune inflammation or ischemia is suspected. Sporadic outbreaks are reported.
Clinical Features
- Mastoid/ear pain precedes weakness by 1–2 days.
- Rapid onset facial weakness within 48 hours.
- Loss of forehead wrinkling and eye closure.
- Impaired taste (anterior 2/3 of the tongue).
- Hyperacusis (stapedius paralysis).
- Decreased salivation; lacrimation is usually preserved.
- Bell’s phenomenon (upward/outward eye movement on attempted
Key Obstetric and Gynecological Conditions: Diagnosis and Management
Analgesia for Labour
Labour pain in the first stage is visceral, arising from cervical dilatation and uterine contractions, transmitted via T10–L1. In the second stage, it becomes somatic due to stretching of the vagina and perineum, transmitted via S2–S4.
Methods for pain relief include:
- Non-pharmacological: Reassurance, breathing techniques, massage, warm baths, and TENS (Transcutaneous Electrical Nerve Stimulation).
- Pharmacological (Systemic): Opioids such as pethidine or fentanyl, which may
Intracranial Pathology: Brain Tumors, ICP, and Abscess Management
Increased Intracranial Pressure (ICP)
The skull is a rigid compartment. Any added volume (tumor, blood, edema, or CSF) raises the Intracranial Pressure (ICP). ICP is considered elevated when it is greater than 20 mmHg (normal is typically less than 15 mmHg).
The relationship between ICP and Cerebral Perfusion Pressure (CPP) is critical: CPP = MAP − ICP. A rising ICP reduces CPP, leading to cerebral ischemia.
Causes of Elevated ICP
- Intracranial mass (tumor, hematoma, large infarct)
- Cerebral edema
- Hydrocephalus