body fluid_240529_073801.pdf

Body fluids Esmaeil musa  Body fluid ECF ICF Interstitial fluid: Transcellular fluid: Plasma Liquid found A body fluid that is not inside the cells between cells or bu...

Body fluids Esmaeil musa  Body fluid ECF ICF Interstitial fluid: Transcellular fluid: Plasma Liquid found A body fluid that is not inside the cells between cells or but is separated from the plasma and tissues e.g.: lymph interstitial fluid by cellular barriere.g.: CSF, pleural fluid, synovial fluid, and peritoneal fluid  CEREBROSPINAL FLUID (CSF) CHEMISTRY Both the central nervous system and spinal cord are covered by three protective membranes referred to as the meninges, they are: i. Piamater, is the innermost layer, located immediately adjacent to the nervous tissue, and highly vascular ii. Arachnoid mater, the middle layer, is the spider weblike structure iii. Duramater, is the outermost layer, close to the bone, very tough, fibrous tissue CSF filled the space between the pia and the arachnoid, called sunarachnoid space  CSF defined as a dynamic, metabolically active, clear, colorless fluids that surround the CNS and SC, and fills a number of cavities located within the brain The brain contains 4 cavities called ventricles, which are connected to each other Two C-shaped lateral ventricles are connected to the midline third ventricle by interventricular foramen The cerebral aqueduct connects the third ventricle to the fourth ventricle, which is continuous with the central canal, a long thin cylindrical cavity that runs the length of the spinal cord  The lining of the ventricles and central canal is composed of epithelial cells called ependymal cells The vascularized lining of the ventricles formed a tissue called the choroid plexus, which consist of the pia matter, capillaries, and ependymal cells, which their main function are synthesis of CSF The epithelial cells are connected by tight junctions making the epithelial layer relatively tight, whereas the underlying fenestrated capillaries are relatively leaky, this enables the passage of compounds from the blood to the epithelial cells  The production of CSF depends on the transcellular movement of Na+ primarily driven by the Na+/K+ ATPase expressed at the luminal membrane facing the CSF  The movement of Na+ is accompanied by Cl− and HCO3− as well as water that follows the solute gradient The water transport is distributed from the blood system to the ventricular system through aquaporin-1 (AQP1) water channels  Excessive amount is reabsorbed by arachnoid villi and retuned back into venous system thus maintaining a consistent amount of CSF fluid Factors that facilitate movement of CSF 1. Oncotic pressure: the oncotic pressure of plasma is higher than that of CSF 2. Hydrostatic pressure: the hydrostatic pressure of CSF is higher than that of subdural venous sinus  So,It resembles to (but not identical) in composition to the plasma It is a mixture of water, proteins at low concentrations, ions, neurotransmitters, and glucose that is renewed three to four times per day In normal healthy adults ✓the rate of formation of CSF is 100 to 250 ml per 24 hours ✓Total volume of CSF is approx. 100 to 200 ml ✓In neonate volume of CSF is approx. 10 to 60ml  Functions of Cerebrospinal Fluid (CSF) 1. CSF plays a crucial role in maintaining central nervous system (CNS) homeostasis by clearing waste products from the highly active metabolic regions of the CNS 2. It provides mechanical protection to the brain and spinal cord, acting as a cushion against physical trauma and sudden movements 3. CSF facilitates communication between the CNS and peripheral nervous system, lymphatic system, vascular system, and immune system, ensuring coordination and response to various stimuli 4. CSF aids in the delivery of essential nutrients to the CNS 5. The glymphatic system, a recently proposed mechanism, plays a role in waste removal from the brain parenchyma 6. Buoyancy  So, it is considered very valuable as a diagnostic aid in the evaluation of inflammatory conditions, infections involving the brain, spinal cord, and subarachnoid hemorrhage  CSF evaluation Normal CSF is clear and colorless and gives no coagulum or sediment on standing, if it is not contaminated (sterile) Abnormalities in appearance may arise in regard to: a) Color b) Turbidity c) Coagulum a) Color The presence of blood is the main cause of an abnormal color Normally no RB cells should be present 1. Trauma: Some blood may be introduced as a result of trauma, while doing the LP In such cases, the first few drops are most mixed up with blood, so that if the first one or two ml is collected separately, the subsequent fluid should be clear or nearly clear (use two to three consecutive bottles for collection) The supernatent fluid after centrifugation would also be clear 2. Pathological: Hemorrhagic fluid obtained in subarachnoid hemorrhage, hemorrhage into the ventricles, and following neurosurgical operations 3. Xanthochromia: This is the yellow coloration of CSF This can be due either to Hb or to other pigments, usually bilirubin/or carotenoids Bilirubin can be detected in CSF after 6 hours after the hemorrhage, reaches a maximum concentration in approx. 10 days time The supernatant fluid obtained after centrifugation shows yellow coloration 4. Froin’s syndrome: is a rare condition characterized by the coexistence of three specific features in the cerebrospinal fluid (CSF): i. Xanthochromia ii. High protein level iii. Marked coagulation Occurs because of obstruction of CSF flow within the subarachnoid space, during spinal meningitis and CSF flow blockage by tumor mass or abscess 5. Other Causes of Yellow Coloration of CSF The yellow coloration can be due to high CSF bilirubin(Both unconjugated bilirubin and conjugated bilirubin) in conditions like cholestatic jaundice and in icterus neonatorum b) Turbidity: Turbidity is seen when there is marked increase in the number of cells or when organisms are present and hence found in meningitis specially in coccal type The CSF obtained from viral meningitis or tubercular meningitis is usually not turbid as the cell response in these cases are lymphocytic c) Coagulum: Normal CSF does not form a fibrin clot on standing In pathological hemorrhagic CSF, fibrinogen present in the blood of CSF may be sufficient to form a clot  Estimation of CSF Proteins Determination of CSF proteins is usually done by turbidimetric methods but some of the colorimetric methods for estimation of proteins have also been used Methodology (Turbidimetric Method) Reagents Sulphosalicylic acid 3 % solution Proteinometer standards—one set Procedure One ml of CS fluid is mixed with 3 ml of Sulphosalicylic acid reagent in a small test tube Mix and allow to stand for 5 minutes The turbidity developed is compared against the tubes of proteinometer set CSF proteins and central nervous system Low CSF protein May be normally occur in young children between 6 months and 12 years Patient with increased CSF turnover Removal large amount of CSF ✓CSF leak induced by trauma or puncture ✓Increased intracranial pressure due to increased reabsorption of protein by arachnoid villi  Serum and CSF albumin Goal To assess the permeability of blood brain barrier 𝐶𝑆𝐹 𝑎𝑙𝑏𝑢𝑚𝑖𝑛 𝑚𝑔/𝑑𝑙 CSF/ serum albumin = 𝑠𝑒𝑟𝑢𝑚 𝑎𝑙𝑏𝑢𝑚𝑖𝑛 𝑔/𝑑𝑙 Normal ratio 1:230  CSF IGg  Pleural fluid Pleural fluid is the liquid that accumulates in the pleural space, which is the area between the lungs and the chest cavity. The pleura is a thin, double-layered membrane that lines the surface of the lungs (visceral pleura) and the inside of the chest wall (parietal pleura) being a useful measure to diagnose and assess disease, trauma, and other abnormalities  Composition: Pleural fluid is primarily composed of water, but it also contains other components: ✓Electrolytes: Such as sodium, potassium, and chloride ions ✓Proteins: Including albumin and globulins ✓Cells: These can be white blood cells (from immune responses) or mesothelial cells (lining the pleura) pH: 7.6 – 7.64  Pleural fluid formation It is believed that the fluid enters the pleural space originates in the capillaries in the parietal pleural Pleural fluid absorbed by lymphatic vessels in the parietal pleural by means of stoma in the parietal pleural Rate of formation equals the rate of absorption which is about 0.01 – 0.02 ml/kg per hr  Pleural fluid production (approximately 15-20 mL/day) is dependent on the same Starling forces that govern the movement of fluid between vascular and interstitial spaces throughout the body The hydrostatic pressure that tends to force fluid out of capillaries is higher in the capillaries of the parietal pleura than in both the pleural space and the capillaries of the visceral pleura The opposing colloid osmotic (oncotic) pressure, due to protein concentration, is the same in both parietal and visceral pleura capillaries, and much lower in the pleural space The net effect of these pressure gradients is continuous movement of an ultrafiltrate of plasma from the capillaries of the parietal pleura to the pleural space Excess fluid is drained to lymphatics via holes (stomata) in the parietal pleura  Function: ✓Lubrication: Pleural fluid acts as a lubricant, allowing the lungs to move smoothly within the chest cavity during breathing ✓Surface Tension Regulation: It helps maintain the surface tension between the pleural layers, preventing lung collapse ✓Immune Defense: Pleural fluid contains immune cells that help protect against infections ✓Transfer media: transfer of substance between lung tissue to systemic circulation ✓Waste Removal: It assists in removing waste products from the pleural space  CAUSES OF PLEURAL EFFUSION Pleural effusions occur when more fluid enters the pleural space than is removed ; mechanisms of influx and/or efflux may be disturbed Effusions are classified as either transudates or exudates Transudative effusions are the result of a disturbance of the Starling forces (hydrostatic and oncotic pressures) involved in normal pleural fluid production Increased hydrostatic pressure is the cause of the transudative pleural effusion that occurs in patients with heart failure Reduced plasma albumin concentration and consequent reduced plasma oncotic pressure is the cause of the transudative effusion associated with nephrotic syndrome and cirrhosis In the case of transudative effusions, the pleura is not the source of the problem and remains intact Typically due to systemic factors  Exudative effusions are usually the result of change (e.g. increased capillary permeability, lymphatic blockage) within the pleura This loss of pleural integrity and associated exudative effusion can be the result of an infectious, inflammatory or neoplastic disease process, not necessarily (indeed not usually) originating in the pleura There are many conditions that may be complicated by pleural effusion e.g, pneumonia, malignant disease and pulmonary embolism, TB, or drug induced are the four most common causes Typically due to local factors