University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2024
Views:

199

Pages:

39
Author:

ohhbabymylovek21

Physiology Lecture title : Body water regulation Date: 8/ Nov /2021 Main Topics • • • • Intracellular fluids and Extracellular fluids Ionic composition of body fluid compartments Measuring the volumes of the fluid compartments Fluid movements between body compartments (Infusion of isotonic NaCl. Diarrhea loss of isotonic fluids. Excessive NaCl intake. Sweating in desert) • Abnormalities of body fluid volume regulation (Hypoosmotic dehydration and Overhydration. Hyperosmotic dehydration and Overhydration. • Edema (definition, types, difference between IC & EC edema) Movement of fluids between compartments Major forces that regulate water movement between compartments: 1. Colloid osmotic pressure (oncotic): pressure induced by proteins (albumin) inside the blood → promotes absorption 2. Hydrostatic pressure: the pressure of the blood against the wall, due to the force of gravity → promotes filtration Sheet Note 1 • The arteriole end of the capillary has a dominant hydrostatic pressure . While , the venule end has a dominant colloid pressure. • The hydrostatic pressure at the arteriole end is larger than the collid pressure, so the fluid will go out(filtrate), however, the colloid pressure at the venous end of capillary is larger than the hydrostatic pressure, that means the tissue fluid will be absorbed. Shifts of water between compartments • At steady state, ECF osmolarity and ICF osmolarity are equal → water shifts between the ECF and ICF compartments. • Solutes such as NaCl and Mannitol do not cross cell membranes and are confined to ECF. • Fluids move unassisted across cell membranes only because of osmolarity differences. Sheet Note 2 • According to the diagram here , the total body water for a normal adult is 45L . • Also , the osmolarity of the body compartment normally is 300 mOsm/L • The x axis shows the volume of the ICF and the ECF. • While , the y axis shows the osmolarity of these body compartments. Sheet Note 3 • If the solute concentration of any compartment changes , the osmolarity of that particular compartment will change. ( shift in the y axis , either up or down ) • If the volume of any compartment changes , the shift in the diagram will be either to the right or to the left. Fluid movement between body compartments 1. Infusion of isotonic NaCl (addition of isotonic fluid): a. ECF volume increases b. no change occurs in the osmolarity of ECF or ICF: because osmolarity is unchanged, water does not shift between the ECF and ICF compartments c. Plasma protein concentration and hematocrit decrease because the addition of fluid to the ECF dilutes the protein and red blood cells. d. Arterial blood pressure increases because ECF volume increases. Hematocrit is the percentage by volume of red cells in your blood. ICF ECF Sheet Note 4 • The infusion of the solution will be to the ECF. • Hematocrit is important to be determined in order to study the size and the number of RBCs . Also , studying the amount of the hemoglobin in the blood. • plasma % 45 RBCs : • The volume of the blood is directly proportional to the arterial blood pressure. Fluid movement between body compartments 2. Diarrhea-loss of isotonic fluid (isosmotic volume contraction) a. b. c. d. e. ECF volume decreases, but no change occurs in the osmolarity of ECF or ICF. The osmolarity is unchanged, water does not shift between the ECF and ICF compartments. Plasma protein concentration and hematocrit increase because the loss of ECF concentrates the protein in RBCs. The ECF osmolarity is unchanged, the RBCs will not shrink or swell. Arterial blood pressure decreases because ECF volume decreases. ICF ECF Fluid movement between body compartments 3. Excessive NaCI intake-addition of NaCl (hyperosmotic volume expansion) a. b. c. d. The osmolarity of ECF increases because osmoles (NaCl) have been added to the ECF. Water shifts from ICF to ECF. As a result of this shift, ICF osmolarity increases until it equals that of ECF. As result of the shift of water out of the cells, ECF volume increases (volume expansion) and ICF volume decreases. Plasma protein concentration and hematocrit decrease due to the increase in ECF volume. ICF ECF Sheet Note 5 • According to the third scenario , arterial blood pressure increases due to the increase in the ECF volume. • Note about the second scenario(Diarrhea-loss of isotonic fluid ): Isosmotic volume contraction Occurs when isosmotic fluid is lost from diarrhea. -Because the fluid lost in diarrhea has roughly the same osmolarity as that of the ECF, the volume, but not the osmolarity, of extracellular fluid decreases. -And, because osmolarity remained stable, there is no water shift from the intracellular compartment, which remains unchanged. Fluid movement between body compartments 4. Sweating in a desert-loss of water (hyperosmotic volume contraction) a. The osmolarity of ECF increases because sweat is hyposmotic b. ECF volume decreases due of the loss of volume in the sweat. Water shifts out of ICF →osmolarity increases until it is equal to ECF osmolarity → ICF volume decreases. c. Plasma protein concentration increases because of the decrease in ECF volume. d. Hematocrit unchanged: water shifts out of the RBCs, decreasing their volume and offsetting the concentrating effect of the decreased ECF volume ICF ECF Sheet Note 6 • The main loosed component in sweating is water . Also , there is a loss of salts in a small amounts. • Hyposmotic= decrease in extracellular fluid osmolarity • Be aware that sweat is hyposmotic, that is, its water:solute ratio is higher than that of the blood. • Loss of water in ECF leads to volume decrease . As a result of that , osmolarity of the ECF increases . Sheet Note 7 The whole volume of the blood is 5L . It divided into : 1. 2. 3L in the blood plasma 2L in the RBCs as a water Fluid movement between body compartments ……. Summary The effect of various conditions on TBW, ECF, ICF, ECF osmolarity, and serum Na+ levels. Sheet Note 8 • NC means no change. • Note about next slide: -Extra-cellular fluid contains large quantities of Na and Cl ions but only small amount of K, Mg and phosphate ions. In contrast, intracellular fluid contains large amount of K and phosphate ions, moderate amount of Mg ions and exceedingly few Ca ions. The ionic composition of body fluid • The plasma and interstitial fluid are separated by highly permeable capillary membrane, their ionic compositions are similar and they are considered as one large compartment of homogeneous fluid. • The most important difference between plasma and interstitial fluid is the higher concentration of protein in the plasma, which was due to the low permeability of capillary membrane to the plasma proteins. Na(meq K(meq/L) Ca(meq/L) Cl(meq/L) Glucose /L) (mgm/dL) pH P CO2 P O2 Extra-cellular 142 4 5 103 90 7.4 35 46 Intra-cellular 14 140 <1 4 10 7.0 20 50 Main Topics • • • • Intracellular fluids and Extracellular fluids Ionic composition of body fluid compartments Measuring the volumes of the fluid compartments Fluid movements between body compartments (Infusion of isotonic NaCl. Diarrhea loss of isotonic fluids. Excessive NaCl intake. Sweating in desert) • Abnormalities of body fluid volume regulation (Hypoosmotic dehydration and Overhydration. Hyperosmotic dehydration and Overhydration. • Edema (definition, types, difference between IC & EC edema) Abnormalities of body fluid volume regulation 1. Change in osmolality: a. Hyponatremia: Excessive loss of Na+ or administration of hypotonic fluids b. Hypernatremia: Results by excessive intake of Na+ or administration of hypertonic fluids Hypernatremia : Na+ conc. • Water loss • Na+ excess Hyponatremia : Na+ conc. • Water excess • Na+ loss Normal plasma [Na+] = 140−145 mmol/L Abnormalities of body fluid volume regulation 2. Change in volume: a. b. Hypovolemia: Results from excessive loss of fluids Hypervolemia: Results from excessive intake or administration of fluids • • • • Dehydration: loss of H2O only Overhydration: gain of H2O only Hypovolemia: loss of H2O and solutes Hypervolemia: gain of H2O and solutes. Copyright © 2021 Sheet Note 9 • Diarrhea is considered as hypovolemia. • While , heavy sweating is considered as dehydration. Consequences of Hyponatremia and Hypernatremia • Water moves in and out of cells. → Cells swell (hyponatremia) or shrink (hypernatremia). • Neurologic function is altered (confusion, seizures). • Rapid shrinking can tear vessels and cause hemorrhage • Rapid swelling can cause herniation (Because the skull is rigid, the brain cannot increase its volume by more than 10% without being forced down the neck (herniation). Sheet Note 10 • brain herniation, or cerebral herniation, occurs when brain tissue, blood, and cerebrospinal fluid (CSF) shifts from their normal position inside the skull. The condition is usually caused by swelling from a head injury, stroke, bleeding, or brain tumor. • For knowledge ( from google ) Main Topics • • • • Intracellular fluids and Extracellular fluids Ionic composition of body fluid compartments Measuring the volumes of the fluid compartments Fluid movements between body compartments (Infusion of isotonic NaCl. Diarrhea loss of isotonic fluids. Excessive NaCl intake. Sweating in desert) • Abnormalities of body fluid volume regulation (Hypoosmotic dehydration and Overhydration. Hyperosmotic dehydration and Overhydration. • Edema (definition, types, difference between IC & EC edema) Edema Edema: accumulation of fluids in the interstitial compartment due to sodium and water retention , which result in swelling • Happened most often in feet, ankles, and legs, and less often in face, hands and abdomen Edema .. Types 1. Intracellular: Swelling inside the cell, caused by: a. Hyponatremia b. Depressed metabolism c. Lack of the nutrition to the cells d. Inflammation 2. Extracellular: Accumulation of fluids in the interstitial space - most common - caused by many conditions Sheet Note 11 • The most common edema type is the extracellular one . • being depressed can drain your energy and motivation. This makes it harder for you to take good care of yourself. In turn, this may cause your physical condition to get worse. • As a consequence , Depressed metabolism could lead to several disorders such as obesity and Diabetes mellitus • For knowledge ( from google ) Sheet Note 12 How lack of nutrition leads to edema ? • Low protein levels in the blood caused by malnutrition can cause edema. proteins help to hold salt and water inside the blood vessels so fluid does not leak out into the tissues. • For knowledge ( from google ) Fluid exchange between blood and the interstitial fluid • Fluid exchange between blood and the interstitial fluid occurs at the level of the capillaries • Capillaries are the smallest blood vessels, they have thin walls to allow an easy exchange of fluids across their walls Sheet Note 13 • After blood leaves the capillaries to the interstitial space , it returns to the capillaries after passing through the lymphatic system. • Causes of edema according to doctor: - Problems in hydrostatic pressure - Problems in oncotic pressure - Problems in reabsorption in lymphatic system - Problems in the permeability of the cells and blood vessels Control of Body Fluid Distribution 1. Distribution across cell membranes : determined by osmotic forces (mainly from electrolytes) 2. Distribution across capillaries : determined by hydrostatic and colloid osmotic forces Edema … Causes A. Abnormal leakage of fluid from plasma to the interstitial space 1. High capillary hydrostatic pressure • Excess fluid retention by kidneys - Acute or chronic kidney failure - Glomerulonephritis - Mineralocorticoid excess •Decreased arteriolar resistance - Vasodilator drugs - Autonomic insufficiency • Increased venous pressure - Congestive heart failure - High output heart failure (e.g., anemia) - Venous obstruction - Venous valve failure - Cirrhosis Sheet Note 14 • High capillary hydrostatic pressure leads to excess filtration , so the fluids will accumulate in the interstitial spaces casing edema. • Glomerulonephritis is a group of diseases that injure the part of the kidney that filters blood (called glomeruli). As a consequence of that injury , proteins can pass to the urine . Cause of Edema 2. Decreased plasma proteins (low oncotic pressure) • Loss of proteins - Burns, wounds - Nephrosis - Gastroenteropathy • Failure to produce proteins - Malnutrition - Cirrhosis - Analbuminemia Sheet Note 15 • Blood proteins are mainly synthesized in the liver . • Analbuminemia: is a rare congenital anomaly of albumin characterised by very low levels of this protein. Cause of Edema 3. Increased capillary permeability • Immune reactions (histamine) • Toxins • Burns • Prolonged ischemia • Vitamin deficiency (e.g., vitamin C) • Pre-eclampsia and eclampsia in pregnancy B. Failure of lymphatic uptake Blockage of lymphatics (lymphatic obstruction) • Cancer • Surgery • Infections (e.g., filaria nematodes) Sheet Note 16 • filaria nematodes are thread-like parasitic nematodes (roundworms) that cause lymph nodes infection. Edema -Summary

Body Water Regulation

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