ADVANCED RENAL ANATOMY AND PHYSIOLOGY Body Fluids and Gross External Anatomy Internal Gross Anatomy of Kidney

BODY FLUIDS Water is the major component of the body Makes up 45-80% of the body weight

DISTRIBUTION OF BODY WATER Two major compartments Intracellular ( Inside cells) 2/3 of total body water Extracellular ( Outside cells) 1/3 of total body water Intravascular (within a blood vessel) 5% of body weight Interstitial (water between cells, organs, tissues) 15% of body weight

DISTRIBUTION OF BODY WATER Solvent Any liquid in which a substance can be dissolved Solute Substance being dissolved Solution Stable mixture of two or more substances in a single phase

DISTRIBUTION OF BODY WATER Colloid State of matter where large molecules are suspended in a liquid Colloid dispersion Substance with components of one or two phases

DISTRIBUTION OF BODY WATER Movement of water Water diffuses freely Osmotic pressure Force produced by solvent particles of a solution as they move through a semi-permeable membrane Depends on the number of particles in a solution Inversely proportional to the volume of a solvent Varies directly with temperature

DISTRIBUTION OF BODY WATER Osmosis The movement from high concentration to low concentration across a membrane Equalize concentration on either side Isotonic 0.9% Hypertonic > 0.9% Will draw water out of cells or tissues anley/outlines/Diffosm osAP/image196.gif

WHAT IS THIS GARBAGE?!!!

OSMOTIC PRESSURE Typical membranes restrict passage of colloidal particles Proteins account for plasma’s high colloid osmotic pressure Albumins 60% of plasma proteins Most abundant protein for transporting

CONTROL OF WATER MOVEMENT Regulated by Thirst Low water intake-levels of sodium increase Kidneys decrease urine volume High sodium-body increases amount of retained water Kidneys secrete ADH Water excretion by the Kidneys

Water Loss Sensible water loss Urine and GI tract Vomiting, diarrhea, suctioning from stomach Insensible water loss Skin (Fever) Lungs (Inadequate humidity) Artificial airways Increased ventilation Tracheostomy patient may lose an additional 700ml/day of water if humidification is inadequate

KIDNEYS Kidneys are Retroperitoneal Lie behind (outside) the lining of the abdominal cavity

KIDNEYS Maintain the volume and concentration of body fluids by Filtration and re-absorption of sodium Water secretion regulated by anti- diuretic hormone (ADH) Any material that is filtered and not reabsorbed will be lost in urine

FUNCTION OF THE URINARY SYSTEM Homeostasis of the body Controlling volume and concentration of blood Removing and restoring select amounts of water and solutes Excreting select amounts of wastes

FUNCTION OF THE KIDNEYS Excrete end products of metabolism Control concentration of body fluids

FUNCTION OF THE KIDNEYS Erythropoiesis Mechanism to speed up production of RBC’s Stimulated by oxygen deficiency in the kidney cells

EXTERNAL ANATOMY Renal Cortex Outer region of kidney Three layers of tissue around kidney Renal capsule Adipose capsule Renal fascia

INTERNAL ANATOMY

INTERNAL ANATOMY Parenchyma Area of cortex that includes pyramids Nephron Functional unit

RENAL BLOODFLOW 20% of blood pumped by the heart each minute enters the kidneys through the renal artery

SUBSTANCES CLEARED FROM THE BLOOD Excess ions Sodium is 90% of the positive ions in extracellular fluid Increased sodium=increase extracellular osmotic pressure Decreased sodium-decreased extracellular osmotic pressure Kidney controls concentration of sodium by regulating amount of water in the body Secretion of ADH and thirst

Anti Diuretic Hormone (ADH) ADH affects the Reabsorption of water in the distal convoluted tubule and collecting duct Increased ADH = increased Reabsorption of water Released by posterior pituitary gland via stimulation from the hypothalamus

SODIUM Primary positive ion in extracellular fluid Fluids (blood plasma, i.e. intravascular) Osmoreceptors in hypothalamus Responsible for maintaining optimal salt and water balance in the body Sense balance of sodium and water concentration in extracellular fluid

SODIUM Osmoreceptors in hypothalamus (cont) Loss of body water Hypernatremia Excess body water Hyponatremia

SODIUM Same system can be used in medical treatment to regulate body fluids Diuretic drug given Kidneys excrete sodium Osmoreceptors in blood Additionally sense lower sodium concentration in the blood Hypertension is an early sign of renal failure

POTASSIUM Normal mEq/L Primary intracellular cation Important in maintaining fluid and electrolyte balance in body Muscle contraction and sending nerve impulses Action potential

POTASSIUM Hypokalemia Potentially fatal Accompanies diarrhea/vomiting/increased diuresis Symptoms include Muscle weakness Paralytic ileus ECG abnormalities (Arrhythmia, Cardiac arrest) Decreases reflexes Respiratory paralysis Alkalosis May need to replace K whenever diuretics are given

POTASSIUM Increased potassium Metabolic acidosis Direct stimulation of kidney to transport potassium into urine Indirect stimulation of adrenal cortex to produce aldosterone Kidney cells transport potassium into urine

CALCIUM Deficit Affect bone and tooth formation Too much Kidney stones Long term defect Osteoporosis Adults need mg calcium daily

RENAL FAILURE Decrease in glomerular filtration rate Increased serum creatinine Chronic renal failure Develops slowly w/ few symptoms Kidney diseases Acute renal failure Rapidly progresses Characterized by oliguria

NEPHRON Functional unit of the kidney Regulates water and soluable substances Filtering blood Reabsorbing what is needed Excreting the rest as urine

NEPHRON Eliminate waste Regulate blood volume and pressure Control levels of electrolytes and metabolites Regulate blood Ph Function regulated by endocrine system ADH Aldosterone Hormone that governs Na+ Reabsorption in the kidneys Parathyroid hormone

NEPHRON Nephron composed of 2 sections Renal corpuscle Initial filtering component Filters out large solutes Delivers water and small solutes to renal tubules Renal tubule Specializes in reabsorption and secretion

NEPHRON Controls blood concentration and volume Removing selected amounts of water and electrolytes Regulate blood pH Regulates secretion of H + and reabsorption of HCO 3 - Remove toxic wastes from blood Remove materials from the blood Return materials the body requires Eliminate anything left over

NEPHRON FUNCTION Filtration Filters a large portion of plasma through glomerular membrane to nephron tubules Reabsorption Movement of substances out of the renal tubules into the blood capillaries Fluid flows into tubules Unwanted substances pass to urine Substances needed by body reabsorbed back into plasma (capillaries) Secretion Substances in plasma directly secreted into epithelial cells lining tubules Into tubular fluid ***Urine formed by three processes: Filtration,Reabsorption, secretion

NEPHRON ANATOMY Kidney composed of approximately 1,000,000 nephrons Nephron composed of renal tubule and vascular supply Renal corpuscle Cortex of kidney Renal tubule Dips into medulla

RENAL CORPUSCLE Renal corpuscle contains Bowman’s capsule Glomerulus inside Bowman's capsule Site of initial urine formation Glomerular filtrate Fluid from the glomerulus to Bowman’s capsule Composition of fluid almost same as plasma No significant amount of protein Fluids further processed along the nephron to form urine In the average adult, approximately 125 mL/min (180 L/day) of fluid is filtered across the glomerulus

PROXIMAL CONVOLUTED TUBULE Fluid leaves the Bowman’s capsule and flows into the proximal convoluted tubule.

LOOP OF HENLE Leaves the proximal convoluted tubule and flows into the loop of Henle. Loop of Henle is part of the nephron and is found in the medulla of the kidney

DISTAL CONVOLUTED TUBULE Cells lining the tubule have numerous mitochondria Allows active transport to take place Ion transport regulated by the endocrine system Parathyroid hormone Reabsorbs more calcium Excretes more phosphate Aldosterone Reabsorbs sodium Excretes more potassium

COLLECTING DUCTS Begins in the renal cortex Extends deep into medulla Urine passes by medullary interstitium hypertonic Collecting duct will become permeable to water in presence of ADH Can reabsorb as much as ¾ water by osmosis *** Collecting duct not considered part of the full nephron

THE JOURNEY CONTINUES Lower portions of collecting duct permeable to urea Urine leaves through the renal papilla Into the renal calyces Renal pelvis Ureter Bladder Urethra

Start to Finish Glomerulus Proximal convoluted tubule Loop of Henle Distal convoluted tubule Collecting tubule Ureter Urinary bladder Urethra

FORCES CONTROLLING FLUID EXCHANGE Glomerular filtration rate (GFR) Quantity of glomerular filtrate formed each minute in all nephrons of both kidneys Normal is 125 mL/min (180 liters/day)

FORCES CONTROLLING FLUID EXCHANGE