Physiology Course Outline PDF

**Course Outline: Introduction and history of physiology. Structure and functions of cell membranes. Transport process. Special transport mechanism in amphibian bladder, kidney, gall bladder, intestine, astrocytes and exocrine glands. Biophysical principles. Homeostasis and control systems including...

**Course Outline: Introduction and history of physiology. Structure and functions of cell membranes. Transport process. Special transport mechanism in amphibian bladder, kidney, gall bladder, intestine, astrocytes and exocrine glands. Biophysical principles. Homeostasis and control systems including temperature regulation** **Introduction and History of Physiology** - **Definition**: Physiology is the branch of biology that studies the functions and mechanisms in living organisms. It focuses on how organs, tissues, cells, and molecules work together to maintain life. - **Historical Background**: - **Ancient Beginnings**: The study of physiology dates back to ancient civilizations. Greek physicians like Hippocrates (460--370 BC) proposed that the human body operates through natural laws. Aristotle (384--322 BC) also contributed to early physiological thought, describing vital processes. - **Galen**: The Roman physician Galen (129--200 AD) made significant contributions by dissecting animals to understand body systems, though many of his theories were inaccurate by modern standards. - **17th--18th Centuries**: William Harvey\'s discovery of blood circulation in the 17th century marked a turning point. Physiology developed further with the establishment of experimental methods. - **19th Century**: Physiology became more experimental, with figures like Claude Bernard, who introduced the concept of the \"internal environment\" and homeostasis. - **20th Century to Present**: Physiology expanded into molecular and cellular physiology, with advances in technology enabling precise examination of cellular processes. Today, physiology integrates with biochemistry, genetics, and biophysics. **Structure and Functions of Cell Membranes** - **Structure**: The cell membrane, also known as the plasma membrane, is primarily composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates. - **Phospholipid Bilayer**: Phospholipids have hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails, creating a semi-permeable barrier. - **Proteins**: Integral and peripheral proteins in the membrane assist in transport, signal transduction, and cellular interactions. - **Cholesterol**: Provides membrane stability and fluidity, particularly in animal cells. - **Carbohydrates**: Attached to proteins or lipids, they play roles in cell recognition and signaling. - **Functions**: - **Selective Permeability**: Controls the entry and exit of substances, allowing nutrients in and waste out. - **Signal Transduction**: Membrane proteins act as receptors for hormones and other signals. - **Cell Communication**: Carbohydrate molecules aid in cell-cell recognition. - **Structural Support**: Membrane proteins help attach the cell to the extracellular matrix or neighboring cells. **Transport Processes** - **Types of Transport**: - **Passive Transport**: Movement of molecules across the membrane without energy input, along the concentration gradient. - **Diffusion**: Movement of small or non-polar molecules (like oxygen) across the membrane. - **Facilitated Diffusion**: Transport of larger or polar molecules via carrier or channel proteins. - **Osmosis**: Diffusion of water across a semi-permeable membrane. - **Active Transport**: Requires energy (ATP) to move molecules against their concentration gradient. - **Primary Active Transport**: Directly uses ATP, as seen in the sodium-potassium pump. - **Secondary Active Transport**: Uses energy from an ion gradient created by primary active transport to move other substances. **Special Transport Mechanisms in Specific Organs and Tissues** - **Amphibian Bladder**: Exhibits water reabsorption and ion transport to maintain osmotic balance, a key survival feature in fluctuating environments. - **Kidney**: Uses specialized structures (nephrons) for filtration, reabsorption, and secretion to regulate water, electrolytes, and waste. - **Gall Bladder**: Absorbs ions and water to concentrate bile for fat digestion. - **Intestine**: Nutrient absorption through specialized transporters for glucose (via sodium-glucose transport proteins), amino acids, and lipids. - **Astrocytes**: Glial cells in the brain, astrocytes regulate ion balance, remove neurotransmitters, and maintain the blood-brain barrier. - **Exocrine Glands**: Secrete enzymes and other products via ducts; require active transport and vesicle-mediated transport for substance release. **Biophysical Principles** - **Diffusion**: The process by which molecules spread from an area of high concentration to low concentration. It is a passive process driven by thermal energy. - **Osmosis**: The movement of water through a semi-permeable membrane toward a higher solute concentration. - **Electrochemical Gradients**: Differences in ion concentration and electric charge across membranes drive ion movement, essential in nerve and muscle cell function. - **Membrane Potential**: Voltage difference across the cell membrane due to the distribution of ions, critical for nerve impulse transmission. - **Thermodynamics**: Cellular reactions obey the laws of thermodynamics, specifically in ATP generation and energy transfer within cells. **Homeostasis and Control Systems** - **Homeostasis**: The body's ability to maintain a stable internal environment despite external changes. Key variables include temperature, pH, glucose, and ion concentrations. - **Control Systems**: - **Feedback Mechanisms**: Most homeostatic control systems work through feedback, either: - **Negative Feedback**: A mechanism where the response counteracts the stimulus, helping stabilize conditions (e.g., blood glucose regulation). - **Positive Feedback**: Enhances the original stimulus, used in processes like childbirth. - **Regulators**: The nervous and endocrine systems are primary regulators of homeostasis. The nervous system provides rapid, short-term responses, while the endocrine system is slower but has longer-lasting effects. **Temperature Regulation** - **Thermoregulation**: Maintains body temperature within a narrow range, a crucial aspect of homeostasis. - **Heat Production**: Metabolic activities, especially in muscles, generate heat. - **Heat Loss Mechanisms**: - **Radiation**: Loss of heat in the form of infrared rays. - **Conduction and Convection**: Direct heat transfer to objects or air. - **Evaporation**: Loss of heat through sweating, especially effective in humans. - **Regulation by Hypothalamus**: The hypothalamus acts as the body's thermostat, detecting temperature changes and initiating responses like shivering (to generate heat) or sweating (to cool down). - **Adaptations**: - **Behavioral Responses**: Seeking shade, drinking water, or changing clothing. - **Physiological Responses**: Vasoconstriction to conserve heat or vasodilation to dissipate heat.