Cellular Processes, Mitosis, and Hematology Principles

Isotonic Solutions: Solute concentration inside and outside the cell is equal, maintaining stable cell volume.
Filtration: Movement of water and solute particles driven from high to low concentration gradients (e.g., in the kidneys).
Active vs. Passive Transport:
- Active Transport: Requires ATP energy (e.g., active pumps, endocytosis, exocytosis).
- Passive Transport: Does not require ATP energy (e.g., diffusion, osmosis, filtration).
Endocytosis: Active cellular uptake process.
- Phagocytosis: Ingestion of solid particles ("cell eating"), such as white blood cells engulfing pathogens.
- Pinocytosis: Ingestion of fluid solutions ("cell drinking"), such as uptake of glucose and water in the intestines.
Exocytosis: Energy-dependent expulsion of waste, hormones, and proteins out of the cell.

Mitotic Stages (IP-MAT):
- Interphase: The primary life phase of the cell.
- Prophase: Onset of DNA replication.
- Metaphase: Replicated DNA aligns along the cellular midline.
- Anaphase: Initial separation of replicated genetic material.
- Telophase: Complete separation resulting in two identical daughter cells.

Classification: Blood is classified as a liquid tissue.
Primary Functions: Transportation (oxygen, nutrients, waste), regulation (temperature, acid-base balance, fluid balance), and protection (infection defense, blood loss prevention).
Normal Blood pH: Ranges between $7.35$ and $7.45$ ( $< 7.35$ is acidic; $> 7.45$ is basic).
Blood Components:
- Plasma ( $55\%$ total volume): Liquid portion composed mainly of water, nutrients, and plasma proteins including albumin (maintains fluid distribution), globulins, antibodies, complement system, and clotting factors.
- Formed Elements: Includes red blood cells, white blood cells, and platelets.

Hematopoiesis: Formation of new blood cells within myeloid tissue (red bone marrow) and lymphoid tissue (lymph nodes, thymus, spleen).
Red Blood Cells (Erythrocytes):
- Contain hemoglobin ( $\text{HGB}$ ) for oxygen and carbon dioxide transport.
- Bi-concave disc shape lacking a nucleus or organelles.
- Lifespan: $80 - 120\,\text{days}$ ; destroyed primarily by the spleen and secondarily by the liver.
- Erythropoiesis Regulation: Kidneys detect low blood volume/oxygen and secrete erythropoietin ( $\text{EPO}$ ) to signal increased RBC production in bone marrow.
White Blood Cells (Leukocytes):
- Provide immune defense (normal count: 5,000 - 10,000\,\text{cells/\mu L}).
- First Responders: Neutrophils and Lymphocytes.
- Secondary Response / Cleanup: Eosinophils, Basophils, and Monocytes (macrophages performing phagocytosis).
Platelets (Thrombocytes): Cell fragments required for hemostasis.

Hemostasis Steps:
1. Vascular contraction (constriction).
2. Platelet plug formation.
3. Coagulation cascade ( $\text{Prothrombinase} \rightarrow \text{Prothrombin} \rightarrow \text{Thrombin} \rightarrow \text{Fibrinogen} \rightarrow \text{Fibrin}$ clot).
ABO Blood Typing System:
- Type A: A antigens, anti-B antibodies.
- Type B: B antigens, anti-A antibodies.
- Type AB: A and B antigens, no antibodies.
- Type O: No antigens, anti-A and anti-B antibodies.
Rh Factor:
- $\text{Rh}^+$ blood possesses the Rh antigen and can receive $\text{Rh}^+$ or $\text{Rh}^-$ blood.
- $\text{Rh}^-$ blood lacks the Rh antigen and can only receive $\text{Rh}^-$ blood.
Compatibility:
- Universal Donor: $O^{-}$ blood.
- Universal Recipient: $AB^{+}$ blood.
Transfusion Reaction (Agglutination): Clumping of blood caused by antibodies binding to mismatched antigens during incompatible transfusions, causing fever, tachycardia, shortness of breath, and pain.
Type and Crossmatch: Testing protocol performed to verify blood compatibility and prevent transfusion reactions.