POI 201: Introduction To Medical Physiology And Blood PDF

# POI 201: Introduction to Medical Physiology and Blood ## Department of Human Physiology, Faculty of Allied Health Sciences, North-Eastern University Gombe By Dr Aliyu Muhammad ### Course Contents * Introduction and History of Physiology * Structure and Functions of Cell Membrane * Transport Pro...

# POI 201: Introduction to Medical Physiology and Blood ## Department of Human Physiology, Faculty of Allied Health Sciences, North-Eastern University Gombe By Dr Aliyu Muhammad ### Course Contents * Introduction and History of Physiology * Structure and Functions of Cell Membrane * Transport Process * Special Transport Mechanism in amphibian bladder, kidney, gall bladder, intestine, astrocyte and exocrine glands * Biophysical Principles * Homeostasis and Control Systems ## Introduction and History of Physiology: Introduction ### Definition and Scope of Physiology * Physiology is derived from the Greek words "physikos" (natural) and "logos" (study). * Medical physiology is the study of the functions and processes that occur within living organisms, particularly humans. * Helps us understand how the body works, from the molecular level to the entire organism. * Integrates biology, chemistry, physics, and mathematics. ### Scope Physiology encompasses various subfields, including: * Neurophysiology * Cardiovascular physiology * Respiratory physiology * Renal physiology * Gastrointestinal physiology * Endocrinology * Immunology * Molecular physiology ## Introduction and History of Physiology: History * The study of physiology dates back thousands of years, with significant contributions from ancient civilizations and scientists. ### Ancient Period (3000 BCE - 500 CE) * Egyptian Medicine: Ebers Papyrus (1550 BCE) describes physiological concepts. * Greek Medicine: Hippocrates (460-370 BCE) and Galen (129-216 CE) laid foundations * Ayurveda: Ancient Indian medicine (1500 BCE) emphasized balance and homeostasis. ### Middle Ages (500-1500 CE) * Galen's Dominance: Galen's teachings influenced physiology for centuries * Ibn Sina (Avicenna): Canon of Medicine (1025 CE) integrated Greek and Islamic knowledge ### Renaissance and Enlightenment (1500-1800 CE) * Andreas Vesalius: De humani corporis fabrica (1543 CE) revolutionized anatomy * William Harvey: De motu cordis (1628 CE) described blood circulation * René Descartes: Philosophical foundations for modern physiology ### Modern Era (1800-1900 CE) * Claude Bernard: Introduction à l'étude de la médecine expérimentale (1865 CE) * Rudolf Virchow: Cellular pathology (1858 CE) * Emil Adolf von Behring: Discovery of diphtheria antitoxin (1890 CE) ### 20th Century (1900-2000 CE) * Nobel Prizes: Physiology/Medicine awards recognized groundbreaking discoveries. * Molecular Biology: Understanding biological processes at molecular level. * Systems Physiology: Integrative approaches to studying complex systems. ### 21st Century (2000 CE - present) * Genomics and Proteomics: Advanced technologies for understanding biological processes. * Systems Biology: Integrating physiology with mathematics and engineering. * Translational Physiology: Applying basic research to clinical practice. ### Key Figures and Discoveries: * Hodgkin and Huxley (nerve impulse) * Frank and Starling (cardiac physiology) * Krebs and Cori (metabolic pathways) * Selye (stress and adaptation) * McCulloch and Pitts (neural networks) ### Physiology's Impact on Medicine: * Diagnosis and treatment of diseases * Development of therapeutic strategies * Understanding human development and aging * Improving healthcare outcomes ## 2. Structure and Functions of Cell Membranes * The cell is the structural and functional unit of living organism with all characteristics of life. * Bounded by a cell membrane, which maintains the homeostasis of the cell interior. * It contains various membrane-bound organelles or compartments within, which specialized functions are subserve. * These membrane-bound organelles are characteristic of all eukaryotic cells, including those in humans. ### Cell Membrane * Also known as plasma membrane or plasmalemma. * It is a protective covering or sheath, enveloping the human cell body, forming a dynamic interface between the intracellular and extracellular environments. * It is a semipermeable membrane that allows free exchange of certain substances between Extracellular Fluid (ECF) and Intracellular Fluid (ICF). ### Structure of Cell Membranes * The thickness of cell membranes ranges from 6-10 nm, and on the average about 7.5nm. * Structurally known as a unit membrane or a three-layered membrane. * The three layers of cell membrane are; one central electron-lucent layer and two electron-dense layers each placed on either side of the central layer. ### Composition of Cell Membrane * Primarily composed of a phospholipid bilayer, which includes: * **Phospholipids**: These molecules form the basic structure of the membrane, with hydrophilic (water-attracting) "heads" facing outward toward the water inside and outside the cell, and hydrophobic (water-repelling) "tails" facing inward, away from the water. * **Cholesterol**: Interspersed within the phospholipid bilayer, cholesterol molecules help to stabilize membrane fluidity. #### **Protein** * There are two main types: * **Integral proteins**: Embedded within the lipid bilayer and can span across it. They play roles in transport and communication. * Examples of integral proteins: Cell junction proteins, Cell adhesion proteins, Some carrier (transport) proteins, Channel proteins, Some hormone receptors, Antigens and Some enzymes. * **Peripheral proteins**: Attached to the exterior or interior surfaces of the membrane. They serve various functions, including signaling and maintaining the cell's shape. * Examples of peripheral proteins: Proteins of cytoskeleton, Some carrier (transport) proteins and Some enzymes #### **Carbohydrate** * Often attached to proteins (glycoproteins) or lipids (glycolipids), these molecules are involved in recognition and signaling processes. * Carbohydrates comprise 5%-10% of cell membranes. They consist of glycolipids and glycoproteins and form the glycocalyx coat on the surface of the plasma membrane. This layer is responsible for the immunological characteristics of the cell and carries surface receptors that are involved in molecular recognition. ## Functions of the Plasma Membrane * **A transport function**: This is brought about by selective permeability to ions and macromolecules, allowing the maintenance of cytosolic ionic composition, osmotic pressure and pH (around 7.2-7.4). * **The maintenance of cell shape and structure**: This is achieved by the presence of anchoring sites for cytoskeletal filaments and extracellular matrix components. * **Intercellular communication**: involving signal transduction, i.e. the detection of chemical signals (messengers) from other cells. These signals mediate nerve transmission, hormone release, muscle contraction and the stimulation of growth. * **Absorptive function**: Nutrients are absorbed into the cell through the cell membrane. * **Intercellular adhesion**: This is brought about by the fusion of the membrane with other cell membranes via specialized junctions. * **Directed cell movement**. * **Excretory function**: Metabolites and other waste products from the cell are excreted out through the cell membrane. * **Exchange of gases**: Oxygen enters the cell from the blood and carbon dioxide leaves the cell and enters the blood through the cell membrane. ### Clinical Physiology * Membrane permeability disorders. * Transport-related diseases (e.g., cystic fibrosis). * Signaling dysregulation (e.g., cancer). * Membrane structure-related diseases (e.g., muscular dystrophy). ## 3. Transport Process * Membrane transport mechanisms can be classified as: ### I. Passive Transport * Diffusion * Osmosis * Facilitated diffusion ### II. Active Transport * Pump-mediated transport (e.g., Na+/K+-ATPase) * Vesicular transport (endocytosis, exocytosis) *** * **Passive diffusion:** along an electrochemical gradient. * Diffusion refers to the random movement of particles in solution from an area of higher concentration to one of lower. * May involve either dissolution and diffusion in membrane lipid, or passage through ion channels. * Ion channels may be permanently open (non-gated, passive, or leakage) or be gated, i.e. can be opened or closed: e.g., voltage-gated; extracellular or intracellular ligand gated; mechanically gated (mechanical deformation); ion-gated; or gap junction activation.. * Voltage-gated channels are found in neurons and muscle cells. Mechanical gating is exemplified by the mechanical deformation of cilia of the hair cells of the inner ear brought about by sound waves. * **Facilitated transport**: aided by membrane transporters (carrier proteins) in the direction of the electrochemical gradient. * More rapid than simple diffusion. * Carriers must be able to recognize the substance transported, to permit translocation, followed by release of the substance with recovery of the carrier. * **Osmosis**: the passage of water from a region where its concentration is high, through a semipermeable membrane, into a region where its concentration is lower. * **Active transport**: an energy requiring process operating against an electrochemical gradient. Can be mediated by: * **Primary ATPases**: Nap/K+-ATPase; H+-ATPase; K+/H+-ATPase; Ca2+ ATPase: these transporters are known as pumps. * **Adenosine5-triphosphate (ATP)-binding cassette proteins**: which bind ATP and use the free energy from ATP hydrolysis to selectively transport materials, e.g. the cystic fibrosis transmembrane conductance regulator. * **Secondary mechanisms**: being coupled to Na+ or H+ transport. The mechanism can be either a co-transport (symport) or a counter-transport (antiport system):K+/ H+-ATPase or proton pump. * **Vesicular transport**: which can be classified as: * **Endocytosis:** * **Pinocytosis:** the plasma membrane forms vesicles that trap extracellular fluid; * **Phagocytosis:** Receptor-mediated endocytosis. * **Exocytosis**: fusion of membrane-bound vesicles with the plasma membrane, allowing their contents to be released into the extracellular space. ## 4. Special Transport Mechanism * **Amphibian Bladder:** * Water absorption (aquaporin-2) * Ion transport (Na+, K+, Cl-) * **Kidney:** * Glomerular filtration * Tubular reabsorption and secretion * **Gall Bladder:** * Water and electrolyte transport * **Intestine:** * Nutrient absorption (e.g., glucose, amino acids) * Electrolyte transport * **Astrocytes:** * Ion homeostasis (K+, Na+, Ca2+) * Water transport (aquaporin-4) * **Exocrine Glands:** * Secretion mechanisms (e.g., salivary, pancreatic) ## 5. Biophysical Principles This section contained a diagram depicting biophysical principles influencing MSC behavior which is not easily converted into markdown. It included illustrations pertaining to: * Elasticity * Pore size and porosity * Stress-relaxation * Topography * Growth factors and derivatives * Genetic regulators * Small bioactive molecules * Nucleus