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Water Balance in-the-Human-Body.pptx
- 1. Water Balance inthe Human Body
- 2. Water: The Essenceof Life Water is the most abundant substance in the human body, comprising approximately 60% of total body weight in an average adult. For a 70 kg person, this translates to about 42 liters of water distributed throughout various compartments. This vital substance serves as the foundation for nearly every biological process, from the smallest cellular reactions to complex organ systems.
- 3. Functions of Water:More Than Just Hydration Nutrient & Oxygen Transport Acts as the primary carrier of nutrients and oxygen through blood plasma, delivering essential compounds to every cell while removing carbon dioxide and metabolic waste products. Bodily Fluid Component Serves as the major component of all bodily fluids including blood, lymph, urine, saliva, digestive juices, and sweat, enabling communication between organ systems. Acts as Lubricant Provides cushioning for joints and protects delicate organs such as the brain, heart, and lungs. Cerebrospinal fluid and synovial fluid prevent mechanical damage during movement. Thermoregulation Maintains optimal body temperature through sweat evaporation, respiration, and blood flow distribution. High heat capacity allows water to absorb and dissipate excess heat efficiently.
- 4. The 60-40-20 Rule 1 TotalBody Water ~60% body weight 2 Intracellular Fluid (ICF) Upto 40% body weight | 28 L 3 Extracellular Fluid (ECF) Upto 20% body weight | 14 L This simple rule provides a framework for understanding how water is partitioned throughout the body. The intracellular compartment contains twice as much water as the extracellular space, reflecting water's critical role in cellular metabolism. 42L Total Water Volume In a 70 kg adult 28L Inside Cells Intracellular fluid 14L Outside Cells Extracellular fluid
- 5. The Dynamic FluidCompartments Water doesn't remain static—it constantly moves between compartments to maintain homeostasis and support cellular function. Intracellular Fluid (ICF) The fluid inside cells represents the largest water reservoir in the body. It contains high concentrations of potassium, magnesium, and phosphate, creating the perfect environment for cellular metabolism, protein synthesis, and energy production. • Houses cellular organelles and genetic material • Site of most metabolic reactions • Maintains cell structure and volume Interstitial Fluid This fluid surrounds and bathes individual cells, acting as a medium for nutrient delivery and waste removal. It serves as the critical interface between blood capillaries and cells. • Facilitates gas exchange (O₂ and CO₂) • Transports hormones to target cells • Removes cellular waste products Plasma The fluid portion of blood, plasma is rich in proteins, electrolytes, and dissolved substances. It transports red and white blood cells, platelets, nutrients, hormones, and waste products throughout the circulatory system. • Contains albumin and globulins • Maintains blood pressure and volume • Distributes heat throughout body
- 6. Factors Influencing WaterDistribution Osmotic Forces Driven by electrolyte concentrations—sodium in ECF and potassium in ICF— osmosis pulls water toward areas of higher solute concentration to maintain balance. Oncotic Pressure Large plasma proteins, especially albumin, cannot easily cross capillary walls. They create oncotic pressure that retains water in blood vessels, preventing excessive fluid loss to tissues. Membrane Regulation Cell membranes and capillary walls act as selective barriers, containing specialized channels and pumps that control water movement and maintain compartment- specific compositions.
- 7. Water in Motion Everyminute, approximately 20 liters of fluid filters through capillary walls, with 99% being reabsorbed. This continuous exchange ensures rapid nutrient delivery and waste removal while maintaining precise fluid balance across all compartments.
- 8. Water Intake andLoss: A Delicate Balance The body maintains water homeostasis through careful regulation of intake and output. Even small imbalances can significantly impact physiological function. 2.5L Total Daily Intake From beverages, food, and metabolism 2.5L Total Daily Loss Through kidneys, skin, lungs, and GI tract 1.5L Kidney Regulation Primary adjustment mechanism
- 9. Hormonal Regulation ofWater Balance Three key hormonal systems work in coordination to maintain optimal fluid volume and composition. Produced by: Posterior pituitary gland Trigger: Increased blood osmolarity or decreased blood volume Action: Promotes water reabsorption in kidney collecting ducts, concentrating urine and conserving water during dehydration 1 Antidiuretic Hormone (ADH) 2 Renin-Angiotensin-Aldosterone System (RAAS) Produced by: Kidneys, adrenal glands Trigger: Low blood pressure or low sodium levels Action: Increases sodium and water retention, raises blood volume and pressure through aldosterone secretion and vasoconstriction 3 Atrial Natriuretic Peptide (ANP) Produced by: Heart atria Trigger: Increased blood volume stretching atrial walls Action: Promotes sodium and water excretion by kidneys, reduces blood volume and pressure, opposes RAAS effects
- 10. Acid-Base Balance: Water'sRole in pH Regulation Maintaining blood pH within the narrow range of 7.35-7.45 is critical for survival. Water participates directly in the chemical reactions that stabilize pH and prevent dangerous fluctuations. The bicarbonate buffer system represents the body’s primary defense against pH changes: 01 Bicarbonate Buffering HCO₃⁻ in extracellular fluid neutralizes excess acids, maintaining stable pH in blood and tissues 02 Water as Reactant Water participates in hydration of CO₂ and dissociation reactions, enabling rapid pH adjustments 03 Renal Regulation Kidneys control bicarbonate reabsorption and hydrogen ion secretion, providing long-term pH stability 04 Respiratory Compensation Lungs adjust CO₂ elimination rate, providing minute-to-minute pH control through ventilation changes
- 11. Kidney Nephron: TheMaster Regulator Each kidney contains approximately 1 million nephrons, microscopic filtration units that process 180 liters of filtrate daily while reabsorbing 99% of filtered water. 1 Glomerular Filtration Blood pressure drives water and small molecules through capillary walls into Bowman's capsule 2 Proximal Tubule Reabsorption 65% of filtered water returns to blood along with glucose, amino acids, and sodium 3 Loop of Henle Concentration Creates osmotic gradient enabling production of concentrated urine when needed 4 Collecting Duct Fine-Tuning ADH regulates final water reabsorption, determining urine concentration and volume 5 Acid-Base Adjustments Secretes H⁺ ions and reabsorbs HCO₃⁻ to maintain blood pH within normal range