Body Fluid Physiology Lecture 2 PDF

BODY FLUID PHYSIOLOGY LECTURE 2...

BODY FLUID PHYSIOLOGY LECTURE 2 DR. ALI KAMAL AL-DULAIMI CONSULTANT GENERAL SURGEON COLLEGE OF MEDICENE alkafeel.edu.iq [email protected] 1 alkafeel.edu.iq [email protected] 23 September 2024  Learning Objectives…….. 1. REVIEW OF BODY FLUID COMPARTMENTS. 2. MOVEMENT OF BODY FLUID. 3. REGULATIONS OF BODY FLUID AND ELECTROLYTE. 4. DISORDER OF WATER BALANCE. alkafeel.edu.iq [email protected] 2 alkafeel.edu.iq [email protected] 23 September 2024 alkafeel.edu.iq [email protected] 3 alkafeel.edu.iq [email protected] 23 September 2024 alkafeel.edu.iq [email protected] 4 alkafeel.edu.iq [email protected] 23 September 2024  "How does water move between the body compartments?" alkafeel.edu.iq [email protected] 5 alkafeel.edu.iq [email protected] 23 September 2024  Movement of body fluids: Membrane transport processes: 1) passive transport it is the movement of substances across a membrane  from higher lower concentration (down a concentration gradient)  it does not require metabolic energy. Passive transport : simple diffusion facilitated diffusion alkafeel.edu.iq [email protected] 6 alkafeel.edu.iq [email protected] 23 September 2024  Simple Diffusion is the movement of substances like ions, atoms, and molecules from an area of their higher concentrate to lower concentration with out the involvement of any other molecules like a carrier protein. alkafeel.edu.iq [email protected] 7 alkafeel.edu.iq [email protected] 23 September 2024  Facilitated diffusion: It is a transport of substances across a biological membrane from an area of higher concentration to lower concentration by a carrier proteins alkafeel.edu.iq [email protected] 8 alkafeel.edu.iq [email protected] 23 September 2024  2) Active transport It is the movement of a substance across a membrane against gradient From low concentration to high concentration Active transport requires Energy and involves specific carrier proteins. 9 alkafeel.edu.iq [email protected] 23 September 2024 alkafeel.edu.iq [email protected] alkafeel.edu.iq [email protected] 10 alkafeel.edu.iq [email protected] 23 September 2024  Movement of fluids due to: 1) Hydrostatic pressure 2) osmotic pressure: 1) Hydrostatic pressure: It is physiological processes that regulate fluids intake & output as well as movement of water& substances dissolved in it between the body compartments. Hydrostatic pressure is the pressure exerted by a fluid at equilibrium due to the force of gravity. It is defined as the weight of the fluid above a specific point in the fluid column. 2) osmotic pressure: The pressure exerted by the flow of water through a semi-permeable membrane separating two solutions with different conc. alkafeel.edu.iq [email protected] 11 alkafeel.edu.iq [email protected] 23 September 2024  Osmosis: It is diffusion of a solvent (water molecules) through a : semi-permeable membrane from low solute concentration to high solute concentration Osmotic pressure: It is the pressure which forces the water to move from where there is little dissolved solute to alkafeel.edu.iq lots dissolved solutes. [email protected] 12 alkafeel.edu.iq [email protected] 23 September 2024 Osmotic pressure: It is determined by :  the number of particles per unit volume of fluids  The amount of osmotic pressure exerted by a solute is proportional to the number of molecules or ions. Osmoles : is the unit used to express the concentration in term of numbers of particles. alkafeel.edu.iq [email protected] 13 alkafeel.edu.iq [email protected] 23 September 2024  Illu capillary microcirculation.jpg  Osmotic pressure Or (Oncotic pressure) The net pressure that drives reabsorption (the movement of fluid from the interstitial fluid back into the capillaries) Where as  Hydrostatic pressure forces fluid out of the capillary, osmotic pressure draws fluid back in. alkafeel.edu.iq [email protected] 14 alkafeel.edu.iq [email protected] 23 September 2024  What Diffusion is movement of molecules from an area of are their higher concentration to area of their lower the differences concentration. and similarities between Facilitated diffusion is movement of molecules from an area of their higher concentration to area of their Diffusion, lower concentration through a cell membrane with help of membrane bound protein channels or carrier proteins Facilitated Osmosis is movement of water molecules from an area diffusion, of their higher concentration to area of their lower concentration through a semipermeable membrane. Osmosis and Active transport is movement of molecules from an Active area of their lower concentration to area of their higher concentration using energy in form of ATP by pump alkafeel.edu.iq transport ? [email protected] proteins. 15 alkafeel.edu.iq [email protected] 23 September 2024  Regulation of body fluids (water) Daily intake = output of water alkafeel.edu.iq [email protected] 16 alkafeel.edu.iq [email protected] 23 September 2024 Regulation of body fluids : The core principle of fluid balance is that the amount of water lost from the body must equal the amount of water taken in ; the: Output = Input (respiration, perspiration, (eating and drinking, urination, defecation ) parenteral intake ) Water Balance: exists when water intake equals water output. alkafeel.edu.iq [email protected] 17 alkafeel.edu.iq [email protected] 23 September 2024 alkafeel.edu.iq [email protected] 18 alkafeel.edu.iq [email protected] 23 September 2024  Water Balance In a person whose health is normal, the quantity of water gained in a day is approximately equal to the quantity lost (output). The quantity of water consumed in a day (intake) varies considerably. The average adult in a comfortable environment takes in about 2300 mL of water daily. alkafeel.edu.iq [email protected] 19 alkafeel.edu.iq [email protected] 23 September 2024   About two-thirds of this quantity comes from drinking water and other beverages;  about one-third comes from foods-fruits, vegetables, and soups.  About 200 mL of water is produced each day as a byproduct of cellular respiration. This water, described as metabolic water, alkafeel.edu.iq [email protected] 20 alkafeel.edu.iq [email protected] 23 September 2024  Water Intake  The volume of water gained each day varies from one individual to the next.  daily water is gained from:  60% of drinking.  30% comes from moist foods.  10% from the water of metabolism. alkafeel.edu.iq [email protected] 21 alkafeel.edu.iq [email protected] 23 September 2024  the total average gain to 2500 mL each day. The same volume of water is constantly being lost from the body by the following routes: alkafeel.edu.iq [email protected] 22 alkafeel.edu.iq [email protected] 23 September 2024   The kidneys excrete the largest quantity of water lost each day. About 1 to 1.5 liters of water are eliminated daily in the urine. The normal urine output (0.5 –1 ml/ k.g /hr.).  Oliguria, decreased urine output< 300 ml/ 24 hours.  The skin Although sebum and keratin help prevent dehydration, water is constantly evaporating from the skin’s surface. Larger amounts of water are lost from the skin as sweat when it is necessary to cool the body.  The lungs expel water along with carbon dioxide.  The intestinal tract eliminates water along with the feces. alkafeel.edu.iq [email protected] 23 alkafeel.edu.iq [email protected] 23 September 2024 alkafeel.edu.iq [email protected] 24 alkafeel.edu.iq [email protected] 23 September 2024  Sense of Thirst  The control center for the sense of thirst is located in the brain’s hypothalamus. This center plays a major role in the regulation of total fluid volume.  A decrease in fluid volume or  an increase in the concentration of body fluids stimulates the thirst center, causing a person to drink water.  Dryness of the mouth also causes a sensation of thirst. alkafeel.edu.iq [email protected] 25 alkafeel.edu.iq [email protected] 23 September 2024   Excessive thirst, such as that caused by excessive urine loss in cases of diabetes, is called polydipsia. The thirst center should stimulate enough drinking to balance fluids, but this is not always the case.  During vigorous exercise, especially in hot weather, the body can dehydrate rapidly. People may not drink enough to replace needed fluids.  In addition, if plain water is consumed, the dilution of body fluids may depress the thirst center. alkafeel.edu.iq [email protected] 26 alkafeel.edu.iq [email protected] 23 September 2024  Regulation of Water Output:  The distal convoluted tubules and collecting ducts of the nephrons regulate water output.  Antidiuretic hormone from the posterior pituitary causes a reduction in the amount of water lost in the urine.  When drinking adequate water, the ADH mechanism is inhibited, and more water is expelled in urine. alkafeel.edu.iq [email protected] 27 alkafeel.edu.iq [email protected] 23 September 2024  Water balance regulation the physiological mechanisms involved in water balance regulation: 1. Kidneys and Nephrons Filtration: Blood is filtered in the glomerulus of the nephron, where water, electrolytes, and waste products are separated. Reabsorption: In the renal tubules, water is reabsorbed back into the bloodstream, primarily in the proximal convoluted tubule and loop of Henle. Concentration: The collecting ducts adjust water reabsorption based on the body’s needs, influenced by hormones like antidiuretic hormone (ADH). alkafeel.edu.iq [email protected] 28 alkafeel.edu.iq [email protected] 23 September 2024  2. Hormonal Regulation:  Antidiuretic Hormone (ADH): Produced by the hypothalamus and released from the posterior pituitary, ADH increases water reabsorption in the kidneys, reducing urine output when the body is dehydrated.  Aldosterone: Secreted by the adrenal glands, it promotes sodium reabsorption and water retention in the kidneys. alkafeel.edu.iq [email protected] 29 alkafeel.edu.iq [email protected] 23 September 2024  3. Thirst Mechanism - When the body senses dehydration or increased plasma osmolality, osmoreceptors in the hypothalamus trigger the sensation of thirst, prompting fluid intake. 4. Fluid Intake and Output - Water is obtained from drinking fluids and consuming food. - Metabolic water (produced during cellular respiration). - Water is lost through urine, sweat, respiration, and feces. - The kidneys play a pivotal role in regulating the volume and concentration of urine based on the body's hydration status. 5. Osmoregulation: The balance of electrolytes, particularly sodium and potassium, is essential for water balance. Changes in osmolarity stimulate hormonal responses to maintain equilibrium. alkafeel.edu.iq [email protected] 30 alkafeel.edu.iq [email protected] 23 September 2024  6. Physiological Responses to Dehydration:  Increased ADH secretion: Enhances water reabsorption.  Increased thirst: Encourages fluid intake.  Reduced urine output: Concentrates urine to conserve water. 7. Physiological Responses to Overhydration:  Decreased ADH secretion: Reduces water reabsorption.  Increased urine output: Dilutes urine to eliminate excess water. alkafeel.edu.iq [email protected] 31 alkafeel.edu.iq [email protected] 23 September 2024  Disorders of water balance: Dehydration water loss exceeds water intake alkafeel.edu.iq [email protected] 32 alkafeel.edu.iq [email protected] 23 September 2024  Symptoms of dehydration 1. Thirst: The earliest sign of dehydration is thirst 2. Dry mouth and sticky saliva: These are caused due to reduced saliva production. 3. Concentrated urine: Dark yellow and infrequent urine. The kidneys try to conserve water by reducing urine production, thereby making it more concentrated. 4. Irritability and headache: Neurological effects of dehydration 5. Fatigue: decreased blood volume, leading to low blood pressure, leading to lightheadedness and dizziness. 6. Muscle cramps: Fluid loss results in electrolyte imbalance. 7. Rapid heart rate: due to reduced blood volume. 8. Dry skin and sunken eyes: 9. Heat stroke: Severe dehydration, especially during hot weather, can cause heat stroke, characterised by confusion, alkafeel.edu.iq disorientation and affected speech. [email protected] 33 alkafeel.edu.iq [email protected] 23 September 2024  Disorders of water balance: Dehydration: water loss exceeds water intake Physiological Responses to Dehydration:  Increased ADH secretion: Enhances water reabsorption.  Increased thirst: Encourages fluid intake.  Reduced urine output: Concentrates urine to conserve water. alkafeel.edu.iq [email protected] 34 alkafeel.edu.iq [email protected] 23 September 2024  Hypotonic hydration: ECF is diluted (there is increase in water, causing ECF sodium levels to be lower (hyponatremia), increase in osmosis occurs and tissue cells swell (oedema). alkafeel.edu.iq [email protected] 35 alkafeel.edu.iq [email protected] 23 September 2024  Overhydration (Water Intoxication): occurs when the body takes in more water than it can excrete. Mechanism 1.Hyponatremia: excess water dilutes sodium levels, results in hyponatremia (low sodium concentration). Normal sodium levels (135 to 145) mEq/L. Levels below 135 mEq/L can lead to symptoms and complications. 2. Cellular Swelling: As sodium levels decrease, water moves into cells to balance the osmotic pressure. This leads to cellular swelling, particularly in neurons, which can cause neurological symptoms. 3. Increased Intracranial Pressure: Swelling of brain cells can increase intracranial pressure, leading to symptoms such as headaches, confusion, seizures, and in severe cases, coma or death. 4. Hormonal Regulation: In overhydration, ADH secretion inhibited, but if water intake exceeds the kidneys' ability to excrete, hyponatremia can still occur. alkafeel.edu.iq [email protected] 36 alkafeel.edu.iq [email protected] 23 September 2024  Symptoms of (Water Intoxication): Mild Symptoms: Nausea, Headache, Fatigue. Severe Symptoms: Confusion or disorientation, Muscle weakness or cramps, Seizures, Coma. alkafeel.edu.iq [email protected] 37 alkafeel.edu.iq [email protected] 23 September 2024  Edema The excess of both solutes and water, which is also termed (isotonic) volume excess. The additional fluid is retained in the Extracellular Compartment resulting in fluid accumulation In the interstitial spaces. alkafeel.edu.iq [email protected] 38 alkafeel.edu.iq [email protected] 23 September 2024  Electrolytes The chief extracellular cation is Na+ The chief intracellular cations are k+ Cations Positively charged Sodium Na+ Potassium K+ Calcium Ca++ Magnesium Mg++ -Cl- is the predominant anion outside cells whereas -phosphates constitute the bulk of intracellular anions. Anions Negatively charged Chloride Cl- Phosphate PO4- Bicarbonate HCO3- alkafeel.edu.iq [email protected] 39 alkafeel.edu.iq [email protected] 23 September 2024  Electrolytes important in  Control the fluid balance of the body.  Muscle contraction.  Energy generation  almost every major biochemical reaction in the body  Contributing to acid–base regulation.  Facilitating enzyme reactions.  Transmitting neuromuscular reactions. Electrolyte Balance: exists when the quantities of electrolytes gained equals the amount lost. alkafeel.edu.iq [email protected] 40 alkafeel.edu.iq [email protected] 23 September 2024  Regulation of Electrolyte Intake: A person ordinarily obtains sufficient electrolytes from food eaten. Electrolyte Output: Losses of electrolytes occur through  sweating,  in the feces,  in urine. alkafeel.edu.iq [email protected] 41 alkafeel.edu.iq [email protected] 23 September 2024  Electrolyte Normal Values:  Na : 135-145 meq / L  K: 3.5-5 meq / L  Ca : 4.5-5.5 mEq /L  Mg : 1.5-2.5 mEq /L  Cl : 98-107 meq / L  P : 2.5-4.5 mg/ dL alkafeel.edu.iq [email protected] 42 alkafeel.edu.iq [email protected] 23 September 2024  Hyponatremia (Low Sodium) 1. Causes:  Excessive water intake  SIADH (Syndrome of Inappropriate ADH secretion)  Heart failure  Liver cirrhosis  Kidney disease  Certain medications (e.g., diuretics, antidepressants) 2. Clinical Features:  Nausea and vomiting  Headache  Confusion  Seizures  Coma (in severe cases) 3. Treatment:  Fluid restriction (for mild cases)  Slow sodium correction with hypertonic saline  Treat underlying cause  Medications (e.g., vasopressin receptor antagonists, diuretics) alkafeel.edu.iq [email protected] 43 alkafeel.edu.iq [email protected] 23 September 2024  Hypernatremia: 1. Causes:  Inadequate water intake  Excessive water loss (e.g., severe diarrhea, burns)  Diabetes insipidus  Excessive sodium intake  Cushing's syndrome 2. Clinical Features:  Thirst  Dry mucous membranes  Altered mental status  Muscle twitching  Seizures  Coma (in severe cases) 3. TREATMENT  Gradual rehydration with hypotonic fluids  Treat underlying cause  Monitor electrolytes closely during correction alkafeel.edu.iq [email protected] 44 alkafeel.edu.iq [email protected] 23 September 2024  Hypokalemia (Low Potassium): 1. causes  Excessive potassium loss (e.g., diuretics, vomiting, diarrhea)  Inadequate potassium intake  Shift of potassium into cells (e.g., insulin administration) 2. Clinical Features:  Muscle weakness  Cardiac arrhythmias  Constipation  Fatigue 3. Treatment: a) Oral supplementation (for mild cases):  Potassium chloride: 40-100 mEq/day in divided doses  Potassium citrate: 30-90 mEq/day in divided doses b) IV supplementation (for severe cases or if oral route not possible):  Potassium chloride: 10-20 mEq/hour, max 40 mEq/hour c) Treat underlying cause d) Magnesium supplementation if needed alkafeel.edu.iq [email protected] 45 alkafeel.edu.iq [email protected] 23 September 2024  Hyperkalemia (High Potassium): 1. causes:  Kidney dysfunction  Excessive potassium intake  Cellular shift of potassium (e.g., acidosis, tissue damage)  Medications (e.g., ACE inhibitors, potassium-sparing diuretics) 2. Clinical Features:  Muscle weakness  Cardiac arrhythmias (potentially life-threatening)  Paresthesias  Nausea 3. Treatment: a) Calcium gluconate (for cardiac membrane stabilization):  10 mL of 10% solution IV over 10 minutes b) Insulin with glucose:  Regular insulin: 10 units IV  Dextrose: 25-50 g (50-100 mL of 50% dextrose) IV c) Beta-agonists:  Albuterol: 10-20 mg nebulized over 10 minutes d) Sodium bicarbonate (if metabolic acidosis present):  50 mEq IV over 5 minutes e) Dialysis in severe cases alkafeel.edu.iq [email protected] 46 alkafeel.edu.iq [email protected] 23 September 2024 Hypocalcemia (Low Calcium): 1.Causes:  Vitamin D deficiency  Hypoparathyroidism  Chronic kidney disease  Magnesium deficiency 2. Clinical Features:  Tetany  Muscle cramps  Seizures  QT prolongation on ECG (Trousseau sign) carpal spasm after BP cuff 3. Hypocalcemia Treatment: inflated due to increased neuromuscular excitability. a) Acute treatment (symptomatic or severe):  Calcium gluconate: 1-2 g IV over 10-20 minutes b) Oral supplementation (for chronic management):  Calcium carbonate: 1000-2000 mg daily in divided doses  Calcium citrate: 1000-2000 mg daily in divided doses c) Vitamin D supplementation:  Cholecalciferol (Vitamin D3): 1000-2000 IU daily  Calcitriol: 0.25-1 mcg daily d) Magnesium correction (if needed):  Oral: 250-400 mg elemental magnesium daily  IV: 1-2 g of magnesium sulfate over 5-60 minutes Facial Twitching(Chvostek Sign). e) Treat underlying cause Tap facial nerve in front of ear → facial spasm alkafeel.edu.iq [email protected] 47 alkafeel.edu.iq [email protected] 23 September 2024  Hypercalcemia (High Calcium): 1. Causes:  Hyperparathyroidism  Malignancy  Vitamin D toxicity  Certain medications (e.g., thiazide diuretics) 2. Clinical Features:  Fatigue  Confusion  Constipation  Kidney stones  Shortened QT interval on ECG 3. Treatment: a) IV fluids:  Normal saline: 200-300 mL/hour, adjusted based on patient's fluid status b) Bisphosphonates: c) Calcitonin:  4 IU/kg subcutaneously or IM every 12 hours d) Loop diuretics (after adequate hydration):  Furosemide: 20-40 mg IV every 1-4 hours e) Glucocorticoids (for vitamin D-mediated hypercalcemia):  Prednisone: 20-40 mg orally daily f) Treat underlying cause alkafeel.edu.iq [email protected] 48 alkafeel.edu.iq [email protected] 23 September 2024   it is important for the healthcare team to know whether a patient’s intake and output are equal;  a 24-hour intake & output record is kept.  The intake record includes all the liquid the patient has taken in. fluids administered intravenously as well as those consumed by mouth ( water, other beverages, and liquid foods, such as soup etc.).  The output record includes  the quantity of urine excreted in the same 24-hour  estimation of fluid losses due to ( fever, vomiting, diarrhea, bleeding, wound discharge, or other causes). alkafeel.edu.iq [email protected] 49 alkafeel.edu.iq [email protected] 23 September 2024  Home work What are the types of fluids used in replacement therapy? alkafeel.edu.iq [email protected] 50 alkafeel.edu.iq [email protected] 23 September 2024  ANY QUESTIONS? alkafeel.edu.iq [email protected] 51 alkafeel.edu.iq [email protected] 23 September 2024  Thank you for Listing alkafeel.edu.iq [email protected] 52 alkafeel.edu.iq [email protected] 23 September 2024