Disturbances of water and electrolyte balance Disturbances of
第十六章 水和电解质代谢紊乱 (Disturbances of water and electrolyte balance)
第二节 水、钠代谢紊乱 (Disturbances of water and sodium balance)
类型(Classification) v脱水(dehydration) ◆高渗性 ◆低渗性 ◆等渗性 v水过多(water excess)
v低钠血症(hyponatremia) 血钠<130 mmol/L v高钠血症(hypernatremia) 血钠>150 mmol/L
一、脱水(Dehydration) 体液容量减少(>2%)。 body water deficit
(一) 高渗性脱水 (hypertonic dehydration) 1. 概念(concept) v water loss>sodium loss v [Na+] >150 mmol/L v plasma osmotic pressure > 310 mmol/L 低容量性高钠血症 (hypovolemic hypernatremia)
4.防治的病理生理基础 (pathophysiological basis of prevention and treatment) v 及时补水 v 适当补钠
(二) 低渗性脱水 (Hypotonic dehydration) 1. 概念(concept) v sodium loss > water loss v [Na+] <130 mmol/L v plasma osmotic pressure < 280 mmol/L 低容量性低钠血症 (hypovolemic hyponatremia)
二、水过多 (Water excess) 体液容量增多。 Excess of body water.
(一)水中毒 (water intoxication) 1. 概念(concept) v 低渗性液体在体内潴留的病理过程 v serum[Na+] < 130 mmol/L v plasma osmotic pressure < 280 mmol/L 高容量性低钠血症 (hypervolemic hyponatremia)
(1)血管内外液体交换异常 (imbalance of exchange between intra- and extra-vascular fluid) 组织液生成>回流 Alteration in capillary hemodynamics that favors the movement of fluid from the vascular space into interstitium.
v毛细血管流体静压增高 (increased capillary hydrostatic pressure) v血浆胶体渗透压降低 (decreased plasma colloid osmotic pressure) ★摄入↓; ★合成↓; ★丢失↑
v 微血管壁通透性↑ (increased capillary permeability) v 淋巴回流障碍 (lymphatic obstruction)
(2) 体内外液体交换平衡失调 (imbalance of exchange between intra- and extra-body fluid)
v肝性水肿(hepatic edema) 特点: 腹水为主 What is the mechanism of hepatic edema?
第三节 钾代谢及钾代谢障碍 (Potassium homeostasis and its disorders)
一、正常钾代谢(Normal metabolism of potassium) 1. 摄入(intake): 食物 2. 吸收(absorption): 肠道
3. 分布(distribution): 98% 细胞内(ICF) 2% 细胞外(ECF) serum [K+] 3. 5~5. 5 mmol/L 4. 排泄(excretion) : 肾(urine 80%~ 90%)
5. 功能(function) v参与细胞代谢(Promoting the cell metabolism) v维持细胞膜静息电位 (Maintenance of the resting membrane potential) v调节渗透压和酸碱平衡 (Regulating the osmotic pressure and acid-base balance)
6. 钾平衡的调节 (Regulation of potassium balance) 跨细胞转移 肾调节
二、低钾血症 (Hypokalemia) 概念 (concept) Serum [K+] < 3. 5 mmol/L 缺钾(potassium deficit) 体内钾缺失
(一)原因和机制 (Causes and mechanisms) 1. 摄入不足 (decreased K+ intake) 钾来源减少 不吃也排 Hypokalemia
3. 钾向细胞内转移 v胰岛素治疗(insulin therapy) v碱中毒(alkalosis) v 低钾性家族性周期性麻痹 (hypokalemic familial periodic paralysis)
3. 对肾功能的影响 (effect on renal function) 集合管对ADH反应性降低 多尿(polyuria) 4. 对酸碱平衡的影响 (effect on acid-base balance) 低血钾 碱中毒
三、高钾血症 (Hyperkalemia) 概念(Concept) 血 [K+] > 5. 5 mmol/L
(一)原因和机制 (Causes and mechanisms) 1. 排钾减少 (decreased K+ excretion) 少尿(oliguria)
2. K+从细胞内逸出 (K+ shifts out of cells) v 细胞损伤(cell injury) v 酸中毒(acidosis) 3. 入钾过多 (increased K+ intake)
3. 对酸碱平衡的影响 (effects on acid-base balance) 高血钾 酸中毒
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