Human Physiology Master Reference Cheat Sheet
This guide provides a high-yield overview of human physiology across all major body systems, focusing on organ-specific functions, cellular mechanisms, and key regulatory pathways essential for exam preparation.
Core Principles
- Digestive System: Sequential breakdown and absorption of nutrients, with specialized roles for each organ from mouth to large intestine.
- Nervous System: Action potentials and synaptic transmission are fundamental to neural communication, with distinct sympathetic and parasympathetic pathways.
- Cardiovascular System: Cardiac pacemaker potential and excitation-contraction coupling drive the heart's rhythm and output.
- Respiratory System: Ventilation mechanics and gas exchange are governed by pressure gradients and surface tension dynamics.
- Renal System: Kidney tubules precisely reabsorb and secrete electrolytes and water to maintain homeostasis, with specific transporters and hormonal controls.
- Endocrine System: Hormonal axes (HPA, RAAS) and feedback loops regulate physiological processes.
- Musculoskeletal System: Muscle contraction relies on calcium-mediated interactions between actin and myosin, with distinct mechanisms in skeletal and smooth muscle.
- Immune System: Innate and adaptive immunity utilize specific receptors and antigen presentation (MHC) for pathogen defense.
- Integumentary System: The skin regulates thermoregulation and synthesizes Vitamin D.
- Reproductive System: Hormonal axes (HPG) and specific cellular interactions drive gametogenesis and the menstrual cycle.
Action Steps
- Review organ-by-organ functions of the digestive system, noting key secretions and absorption sites.
- Understand the cellular mechanisms of gastric acid secretion, including the H+/K+ ATPase and carbonic anhydrase.
- Trace the zymogen cascade in pancreatic secretion and the regulation by Secretin and CCK.
- Diagram nutrient absorption mechanisms for carbohydrates, proteins, and lipids across the enterocyte.
- Memorize the phases of an action potential and the ion channel dynamics involved.
- Differentiate the structural and functional roles of sympathetic and parasympathetic nervous systems.
- Analyze cardiac pacemaker potential and excitation-contraction coupling mechanisms.
- Explain the mechanics of inspiration and expiration, and the role of surfactant via Laplace's Law.
- Identify the specific transporters and hormonal controls (Aldosterone, ADH, PTH) in each segment of the renal tubule.
- Map out the major endocrine axes (HPA, RAAS) and their feedback loops.
- Compare and contrast skeletal and smooth muscle contraction mechanisms.
- Distinguish between MHC Class I and Class II antigen presentation and their respective T-cell interactions.
- Outline the Vitamin D synthesis pathway and its regulation.
- Describe the hormonal control of the male HPG axis and the female menstrual cycle.
Key Terms
- Mastication: The mechanical breakdown of food by chewing in the mouth.
- Peristalsis: Wave-like muscle contractions that move food through the digestive tract.
- Chyme: The semi-fluid mass of partially digested food expelled by the stomach into the duodenum.
- Zymogens: Inactive precursor forms of digestive enzymes secreted by the pancreas.
- Micelles: Aggregates of bile salts, fatty acids, and monoglycerides that aid in lipid absorption.
- Action Potential: A rapid change in membrane potential that travels along an axon, involving Na+ influx and K+ efflux.
- Excitation-Contraction Coupling: The process linking muscle action potentials to muscle contraction via calcium release.
- Surfactant: A substance (dipalmitoylphosphatidylcholine) that reduces surface tension in alveoli, preventing collapse.
- Clearance: The volume of plasma from which a substance is completely removed per unit time by the kidneys.
- HPA Axis: Hypothalamic-Pituitary-Adrenal axis, a major neuroendocrine system regulating stress response.
- MHC Class I: Surface molecules on nucleated cells presenting endogenous antigens to CD8+ T-cells.
- Calcitriol: The active form of Vitamin D (1,25-(OH)2D3), crucial for calcium absorption.
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