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Cairan tubuh farmasi

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  • 1. Keseimbangan Cairan Tubuh & Elektrolit Departemen Fisiologi Fak. Kedokteran USU
  • 2. Total Cairan Tubuh  Infant mempunyai kandungan lemak, tulang lebih rendah & sedangkan kandungan air sebesar 73% atau lebih  Total cairan tubuh berkurang seiring pertambahan usia  Pria sekitar 60% berat badan; Wanita sekitar 50% berat badan  Hal ini disebabkan karena pada wanita:  Kandungan lemak lebih tinggi  Otot rangka lebih sedikit  Pada usia tua, kandungan air sekitar 45%
  • 3. Fluid Compartments  Water occupies two main fluid compartments  Intracellular fluid (ICF) – about two thirds by volume, contained in cells  Extracellular fluid (ECF) – consists of two major subdivisions  Plasma – the fluid portion of the blood  Interstitial fluid (IF) – fluid in spaces between cells  Other ECF – lymph, cerebrospinal fluid, eye humors, synovial fluid, serous fluid, and gastrointestinal secretions
  • 4. Electrolyte Composition of Body FluidsCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 26.2
  • 5. Beberapa mekanismesehingga suatu zat dapatmelewati membran1. Difusi2. Difusi yang dipermudah3. Osmosis4. Endositosis dan eksositosis, dan5. Epithelial transport
  • 6. Difusi Yang Dipermudah Transport Aktif Transport Aktif Primer Pompa Natrium-Kalium Transport Aktif Primer Pompa Kalsium Transport Aktif Sekunder: Kotransport Natrium pada Glukosa dan Asam Amino
  • 7. Transport Aktif Saat membran sel menggerakkan molekul zat untuk mendaki melawan gradien konsentrasi (atau mendaki melawan arus listrik atau melawan gradien tekanan,) maka proses ini disebut transport aktif. Memerlukan energi  Transport aktif primer: dalam bentuk ATP  Transport aktif sekunder: gradien konsentrasi ion natrium
  • 8. Osmosis Keadaan pergerakan netto air yang disebabkan karena adanya pebedaan konsentrasi disebut osmosis
  • 9. Endositosis dan Eksositosis Endositosis merupakan suatu mekanisme dimana membran meliputi (membungkus) bahan – bahan yang penting atau cairan ekstraseluler dan isinya. Dua bentuk dasar dari endositosis adalah pinositosis dan fagositosis.
  • 10. Cerebrospinal Fluid Kapasitas Cerebral cavitiy sekitar 1600-1700 mililiter  150 ml merupakan cerebrospinal fluid, sisanya otak dan medulla spinalis Cerebrospinal fluid tersebut terdapat pada ventricle otak, cisterna dan subarachnoid space antara otak & medulla spinalis
  • 11.  Fungsi utama CSF sebagai bantalan otak, keduanya memiliki gravitasi yg hampir sama
  • 12. Blood–Cerebrospinal FluidandBlood-Brain Barriers Terdapat antara darah & CSF & cairan otak Barriers antara choroid plexus dan membran kapiler jaringan semua area parenkhim otak kecuali sebagian hipothalamus, kelenjar pineal, area postrema yang mana pada daerah ini bahan-bahan (substans) jaringan lebih mudah berdifusi ke jaringan
  • 13. Pembentukan CSF dibentuk dengan kecepatan 500ml per hari. 2/3 dari CSF berasal dari plexus choroideus pada ventrikel 4, terutama pada 2 ventrikel bagian lateral Sebagian CSF merupakan hasil sekresi ependymal seluruh permukaan ventrikel dan membran arachnoid, dan sebagian berasal dari otak sendiri melalui bagian perivascular sekeliling pembuluh darah yang melewati otak
  • 14. Aliran CSF  Melalui choroid plexuses dan kemudian melalui sistem cerebrospinal. Cairan yang disekresikan di lateral ventricles mula-mula menuju third ventricle; kemudian setelah bertambah mengalir kebawah menuju aqueduct of Sylvi sampai fourth ventricle, tempat cairan bertambah.  Akhirnya cairan keluar melalui 3 lubang kecil ; 2 foramen Luschka sebelah lateral dan sebuah midline foramen Magendie, memasuki cisterna magna, (ruangan cairan yang berada di belakang medulla dan antar acerebellum). Cisterna magna merupakan lanjutan ruangan subarachnoid yang berada di sekeliling otak dan medulla spinalis
  • 15.  Hampir seluruh CSF kemudian mengalir dari cisterna magna melalui ruang subarachnoid sekeliling cerebrum. CSF mengalir melalui arachnoidal villi menuju sinus venous sagittal dan sinuses venous yang lain. Dan CSF dikosongkan menuju aliran vena melalui pori- pori vili ini
  • 16. Teori Pembentukan CSF Sekresi CSF oleh plexus choroideus merupakan active transport sodium ions melalui epithelial cells yang berada di bagian luar plexus. Ion sodium menarik ion chlorida. Kedua ion in meningkatkan konsentrasi sodium chloride di CSF yang mana kemudian segera menyebabkan osmosis air
  • 17.  Glukosamemasuki CSF dan ion potassium dan bicarbonate keluar CSF menuju kapiler
  • 18. Susunan CSF Karakteristik CSF sebagai berikut: Tekanan osmotik, kira-kira sama dengan plasma, konsentrasi ion , juga kira-kira sama dengan plasma; ion chlorida sekitar 15 per cent Lebih besar dari plasma; ion potassium, kira-kira 40 per cent lebih sedikit; dan glucosa, sekitar 30 per cent lebih sedikit
  • 19. Water Intake and Output Figure 26.4Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 20. Acid-Base Balance  Normal pH of body fluids  Arterial blood is 7.4  Venous blood and interstitial fluid is 7.35  Intracellular fluid is 7.0  Alkalosis or alkalemia – arterial blood pH rises above 7.45  Acidosis or acidemia – arterial pH drops below 7.35 (physiological acidosis)Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 21. Regulation of Water Intake: Thirst Mechanism Figure 26.5Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 22. Mechanisms and Consequences of ADH Release Figure 26.6Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 23. Regulation of Sodium Balance: AldosteroneCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 26.8
  • 24. Mechanisms and Consequences of ANP Release Figure 26.10Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 25. Disorders of Water Balance: Dehydration  Water loss exceeds water intake and the body is in negative fluid balance  Causes include: hemorrhage, severe burns, prolonged vomiting or diarrhea, profuse sweating, water deprivation, and diuretic abuse  Signs and symptoms: cottonmouth, thirst, dry flushed skin, and oliguria  Prolonged dehydration may lead to weight loss, fever, and mental confusion  Other consequences include hypovolemic shock and loss of electrolytesCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 26. Disorders of Water Balance: Dehydration 1 Excessive loss of H2O from 2 ECF osmotic 3 Cells lose H2O ECF pressure rises to ECF by osmosis; cells shrink (a) Mechanism of dehydration Figure 26.7aCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 27. Disorders of Water Balance: Hypotonic Hydration  Renal insufficiency or an extraordinary amount of water ingested quickly can lead to cellular overhydration, or water intoxication  ECF is diluted – sodium content is normal but excess water is present  The resulting hyponatremia promotes net osmosis into tissue cells, causing swelling  These events must be quickly reversed to prevent severe metabolic disturbances, particularly in neuronsCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 28. Disorders of Water Balance: Hypotonic Hydration 1 2 ECF osmotic 3 H2O moves into Excessive H2O enters the ECF pressure falls cells by osmosis; cells swell(b) Mechanism of hypotonic hydration Figure 26.7bCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 29. Disorders of Water Balance: Edema  Atypical accumulation of fluid in the interstitial space, leading to tissue swelling  Caused by anything that increases flow of fluids out of the bloodstream or hinders their return  Factors that accelerate fluid loss include:  Increased blood pressure, capillary permeability  Incompetent venous valves, localized blood vessel blockage  Congestive heart failure, hypertension, high blood volumeCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 30. Edema  Hindered fluid return usually reflects an imbalance in colloid osmotic pressures  Hypoproteinemia – low levels of plasma proteins  Forces fluids out of capillary beds at the arterial ends  Fluids fail to return at the venous ends  Results from protein malnutrition, liver disease, or glomerulonephritis, sindroma nefrotikCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 31. Edema  Blocked (or surgically removed) lymph vessels:  Cause leaked proteins to accumulate in interstitial fluid  Exert increasing colloid osmotic pressure, which draws fluid from the blood  Interstitial fluid accumulation results in low blood pressure and severely impaired circulationCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 32. Caused by excess water lossHypernatremia or overall sodium excess Excess salt intake, hypertonic solutions, excess(Na > 145, aldosterone,diabetes insipidus,sp gravity < increased water loss, water deprivation1.010) S&S: thirst, dry, flushed skin, dry, stick tongue and mucous membranes Occur s with net loss of sodium or net water excessHyponatremia Kidney disease with salt wasting, adrenal insufficiency, GI losses,(Na < 135, increased sweating, diuretics, SIADH S&S: personality change, postural hypotension, postural dizziness, abdsp gravity > cramping, diarrhea, tachycardia,1.030 convulsions and coma
  • 33. Regulation of Potassium Balance  Hyperkalemia and hypokalemia can:  Disrupt electrical conduction in the heart  Lead to sudden death  Hydrogen ions shift in and out of cells  Leads to corresponding shifts in potassium in the opposite direction  Interferes with activity of excitable cellsCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 34. Regulation of Calcium  Ionic calcium in ECF is important for:  Blood clotting  Cell membrane permeability  Secretory behavior  Hypocalcemia:  Increases excitability  Causes muscle tetanyCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 35. Regulation of Calcium  Hypercalcemia:  Inhibits neurons and muscle cells  May cause heart arrhythmias  Calcium balance is controlled by parathyroid hormone (PTH) and calcitoninCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 36. Regulation of Calcium and Phosphate  PTH promotes increase in calcium levels by targeting:  Bones – PTH activates osteoclasts to break down bone matrix  Small intestine – PTH enhances intestinal absorption of calcium  Kidneys – PTH enhances calcium reabsorption and decreases phosphate reabsorption  Calcium reabsorption and phosphate excretion go hand in handCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 37. Influence of Calcitonin  Released in response to rising blood calcium levels  Calcitonin is a PTH antagonist, but its contribution to calcium and phosphate homeostasis is minor to negligible InterActive Physiology®: PLAY Fluid, Electrolyte, and Acid/Base Balance: Electrolyte HomeostasisCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 38. Acid-Base Balance  Normal pH of body fluids  Arterial blood is 7.4  Venous blood and interstitial fluid is 7.35  Intracellular fluid is 7.0  Alkalosis or alkalemia – arterial blood pH rises above 7.45  Acidosis or acidemia – arterial pH drops below 7.35 (physiological acidosis)Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 39. Hydrogen Ion Regulation  Concentration of hydrogen ions is regulated sequentially by:  Chemical buffer systems – act within seconds  The respiratory center in the brain stem – acts within 1-3 minutes  Renal mechanisms – require hours to days to effect pH changesCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 40. Respiratory Acidosis and Alkalosis  Result from failure of the respiratory system to balance pH  PCO2 is the single most important indicator of respiratory inadequacy  PCO2 levels  Normal PCO2 fluctuates between 35 and 45 mm Hg  Values above 45 mm Hg signal respiratory acidosis  Values below 35 mm Hg indicate respiratory alkalosisCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 41. Respiratory Acidosis and Alkalosis  Respiratory acidosis is the most common cause of acid-base imbalance  Occurs when a person breathes shallowly, or gas exchange is hampered by diseases such as pneumonia, cystic fibrosis, or emphysema, impaired activity of diaphragm muscle and impaired respiratory control in the brain stem  Respiratory alkalosis is a common result of hyperventilation and is caused by low level of oxygen in the plasma, meningitis, head injury and anxietyCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 42. Metabolic Acidosis  All pH imbalances except those caused by abnormal blood carbon dioxide levels  Metabolic acid-base imbalance – bicarbonate ion levels above or below normal (22-26 mEq/L)  Metabolic acidosis is the second most common cause of acid-base imbalance  Typical causes are ingestion of too much alcohol and excessive loss of bicarbonate ions,such as diarrhea, and excessive vomitting  Other causes include accumulation of lactic acid, shock, ketosis in diabetic crisis, starvation, and kidney failure,high extracellular K+Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 43. Metabolic Alkalosis  Rising blood pH and bicarbonate levels indicate metabolic alkalosis  Typical causes are:  Vomiting of the acid contents of the stomach  Hypokalemia  Intake of excess base (e.g., from antacids)  Constipation, in which excessive bicarbonate is reabsorbedCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 44. Respiratory and Renal Compensations  Acid-base imbalance due to inadequacy of a physiological buffer system is compensated for by the other system  The respiratory system will attempt to correct metabolic acid-base imbalances  The kidneys will work to correct imbalances caused by respiratory diseaseCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 45. Respiratory Compensation  In metabolic acidosis:  The rate and depth of breathing are elevated  Blood pH is below 7.35 and bicarbonate level is low  As carbon dioxide is eliminated by the respiratory system, PCO2 falls below normal  In respiratory acidosis, the respiratory rate is often depressed and is the immediate cause of the acidosisCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 46. Respiratory Compensation  In metabolic alkalosis:  Compensation exhibits slow, shallow breathing, allowing carbon dioxide to accumulate in the blood  Correction is revealed by:  High pH (over 7.45) and elevated bicarbonate ion levels  Rising PCO2Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 47. Renal Compensation  To correct respiratory acid-base imbalance, renal mechanisms are stepped up  Acidosis has high PCO2 and high bicarbonate levels  The high PCO2 is the cause of acidosis  The high bicarbonate levels indicate the kidneys are retaining bicarbonate to offset the acidosisCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
  • 48. Renal Compensation  Alkalosis has Low PCO2 and high pH  The kidneys eliminate bicarbonate from the body by failing to reclaim it or by actively secreting it InterActive Physiology®: PLAY Fluid, Electrolyte, and Acid/Base Balance: Acid/Base HomeostasisCopyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings