Questions
3–5 questions per university paper
Difficulty
Medium
Importance
Core foundation for physiology and pharmacology
Overview
Cell and General Physiology forms the fundamental basis of biological sciences, covering the structural architecture of cells and the internal balance of the human body. Mastery of this topic is critical for understanding systemic pathology and pharmacology in higher-level exams. Aspirants must focus on organelle functions and the mechanics of fluid dynamics between body compartments.
Cell Structure and Organelles
The cell is the basic functional unit of life, characterized by a complex endomembrane system that compartmentalizes biochemical reactions. Each organelle plays a specialized role in protein synthesis, energy production, or waste degradation to maintain cellular homeostasis.
- Nucleus: Contains genetic material and regulates gene expression.
- Mitochondria: Powerhouse of the cell, site of oxidative phosphorylation.
- Ribosomes: Protein synthesis machinery located on RER or free in cytoplasm.
- Lysosomes: Digestive centers containing acid hydrolases.
- Golgi Apparatus: Packaging and post-translational modification of proteins.
- Cell Membrane: Fluid mosaic model consisting of phospholipid bilayer and proteins.
Homeostasis
Homeostasis is the physiological process of maintaining a stable internal environment despite external fluctuations. It relies on feedback loops that sense changes, process information via a control center, and trigger effector responses.
- Negative feedback: Primary mechanism to reverse a deviation from the set point.
- Positive feedback: Amplifies a change, such as oxytocin release during labor.
- Set point: The target physiological value maintained by the body.
- Receptor: Sensory organ that detects changes in internal environment.
- Effector: Muscles or glands that execute the corrective response.
Body Fluid Compartments
Total body water is distributed across two primary compartments separated by cellular membranes: intracellular fluid (ICF) and extracellular fluid (ECF). Understanding the electrolyte balance and osmotic pressure between these compartments is essential for clinical fluid management.
- Intracellular Fluid (ICF): Comprises approximately 2/3 of total body water.
- Extracellular Fluid (ECF): Divided into plasma and interstitial fluid.
- Plasma: The fluid portion of blood, roughly 1/4 of ECF.
- Interstitial Fluid: Fluid surrounding cells, representing 3/4 of ECF.
- Osmolality: Number of solute particles per kg of solvent, key to water movement.
Exam Tip
Always draw a labeled diagram of the Cell Membrane Fluid Mosaic Model or a Feedback Loop, as diagrams often carry 30% of the marks in long-answer questions.
Common Mistakes
- Confusing the specific roles of Rough ER and Smooth ER in protein versus lipid synthesis.
- Misinterpreting positive feedback as a mechanism for homeostasis instead of a biological amplification process.
- Failing to clearly distinguish between interstitial fluid and plasma in the ECF compartment breakdown.
More Revision Notes
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