Renal Physiology (I) - Kidney Function & Physiological Anatomy
1RENAL PHYSIOLOGY (I) m KIDNEY FUNCTION &PYSIOLOGICAL ANATOMY Mohammed Abdel Gawad
OBJECTIVES2 Introduction Functions of the kidney Physiological anatomy of the kidney Nephron & its types Renal circulation & renal blood flow Nervous supply of the kidney
INTRODUCTION – THE KIDNEY3 A retroperitoneal organ T11-L3 Normal size: 11-15cm in adults. Right kidney usually shorter than the left (upper limit of variation in length between right & left 1.5 cm)
FUNCTIONS OF THE KIDNEY4 1- Execratory function: a. metabolites b. drugs c. toxins 2- Homeostatic function: a. Maintenance of water balance. b. Maintenance of electrolyte balance. c. Maintenance of acid-base balance. 3- Endocrine (hormonal) secretory function: a) Renin by the juxtaglomerular cells (JG) b) Erythropoietin hormone by endothelial cells of peritubular capillaries of renal cortex c) Prostaglandins. 4- Endocrine (hormonal) metabolic function: The kidney converts vitamin D3 → active 1,25dihydroxycholecalciferol by alpha one hydroxylase enzyme in cells of PCT under effect of PTH.
KIDNEYS BLOOD FLOW RATE14 - One fourth (25%) of the cardiac output passes into the kidney/minute (1300 ml blood/minute). - The high renal blood flow does not reflect a high O2 consumption (kidneys utilize 8% of the total O2 consumption of the body). - This high blood flow is related to the homeostatic function of the kidney → allows a high rate of glomerular filtration
NERVE SUPPLY15 The renal blood vessels are supplied by splanchnic nerves, vasoconstrictors → renal blood is reduced in stress condition due to sympathetic stimulation → blood is shifted to vital organs The kidney also receives input from the parasympathetic nervous system, by way of the renal branches of Vagus nerve (Cranial nerve X), the function of this is yet unclear. Sensory input from the kidney travels to the T10-11 levels of the spinal cord and is sensed in the corresponding dermatome. Thus, pain in the flank region may be referred from corresponding kidney
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