5Urinary Bladder Anatomy Rugae- Flods of the bladderDetrusor Muscle – smooth muscleTrigoneUrethral Sphincter -InvoluntaryUrethra
6Physiology of the bladder function The bladder stretches as it fills with urine and when there is 250mL you feel the need to void.Voiding begins with voluntary relaxation of the external urethral sphincter muscle.Once you relax the urethral sphincter the involuntary response of contraction takes over. AKA micturitionInability to void because kidneys are not excreting urine is known as suppression.Inability to void even though urine is present in the bladder is known as retention.Involuntary micturition = Incontinance
7UrethraSmall tube lined with mucous membrane leading from the floor of the bladder to the exterior of the body.In females this distance is about 3cm.In males this distance extends along a winding path for about 20 cm and passes through the middle of the prostate gland just after leaving the bladder. & is shared as part of the reproductive system.
8Microscopic Structure of the functional unit of a kidney is the Nephron. Components of the NephronBowman’s CapsuleProximal convoluted tubuleLoop of HenleDistal convoluted tubuleCollecting ductThere are approximately1.25 million nephronsPer Kidney.
9Glomeruli – Many glomerulus Glomerularcapillaries
11The loop of Henle dips into the medulla into a renal pyramid.
12The collecting ducts empty into the calyces which empty into the renal pelvis.
13Blood vessels of the Kidneys About 1200 ml of blood flows through the kidneys every minuteWhich means approximately 1/5 of all the blood pumped by the heart per minute goes to the kidneys.Usual direction of blood flow isArteries-Arterioles-Capillaries-venules-veins
14Blood flow through Kidney tissue follows this path… Renal ArteryInterlobular artery-penetrate the cortexAfferent arterioleGlomerulusEfferent arteriolePeritubular capillaries(vasa recta)VenulesInterlobular vein Renal Vein
15Function of the kidney KIDNEYS… Process blood plasma and excrete urine.Most important organs in the body for maintaining fluid-electrolyte and acid-base balances.Excrete Nitrogenous wastes from protein metabolism. (urea)
16Kidney Failure means homeostatic failure and If not relieved,inevitable DEATH.
17Kidneys also… Influence the rate of secretion of the hormones ADH – Antidiuretic hormoneAldosteroneand synthesize erythropoietin –active form of vitamin D and prostaglandins.
18Urine is formed by 3 means Formation of urineUrine is formed by 3 means1. Filtration – the movement of water and solutes from the plasma in the glomerulus, across the glomerular-capsular membrane, and into the capsular space of the Bowman’s capsule
192. Reabsorption- movement of molecules out of the tubule and into the peritubular blood.
203. Secretion – movement of the molecules out of the peritubular blood into the tubule for excretion.
21FiltrationOccurs through the glomerular capiliaries to the Bowman’s CapsuleLarge substances are separated from small substances.Blood cells and blood proteins are typically TOO large to filter through the glomerulus so as the blood leaves the glomerulus in the efferent arteriole it is relatively clean and has lost most of its fluid.
22Blood cells are too large to filter out. So what does filter out? WaterSaltsBicarbonateH+UreaGlucoseAmino acidsSome drugs
23Returned to the blood immediately: Reabsorption occurs mostly in the PCT. Water and ionsGlucose and amino acidsPassive and Active transport mechanisms are at work in the tubules.MANY Carriers are available for materials that need to be reclaimed.Very few carriers for things that are of little or no use to the body.
24Reabsorption in Reverse: Secretion And it gets rid of substances not already in the filtrate such as drugs.H+ and K+ and creatinine move from the peritubular blood to the tubule.
25Urine vs. FiltrateFiltrate contains everything that blood plasma does (except proteins)Most of the Water, nutrients and necessary ions are reabsorbed by the time it reaches the collecting ducts.Urine contains most of the waste and unneeded substances.
26In 24 hours150 to 180 liters of blood plasma filter through the kidneys (nephrons)Only 1 to 1.8 liters of urine are produced.WHAT HAPPENS TO MOST OF THE FILTRATE?Initial Filtrate –diluteFinal Filtrate - concentrated
27Excretion Urea - protein breakdown Uric acid – nucleic acids are metabolized.Creatinine – Actively secreted into filtrateassociated with metabolism inmuscle tissue.
28Balance of Water and electrolytes We cannot lose more water than we take in.Water is lost by….Respiration, Perspiration, Solid waste, & UrineWater is taken inin Foods, beverages and metabolism.
29Electrolyte balanceADH – prevents excess water loss by causing the collecting duct cells to reabsorb more water which increases blood volume and blood pressure.Alcohol disrupts ADH and less water is reabsorbed creating more dilute urine.If ADH is not present up to 25 liters /day could by flushed from the body.= severe dehydration.
30Aldosterone – Regulates Sodium content Renin-angiotensin mechanism –When blood pressure is low the enzyme renin catalyzed reactions that produceangiotensin II which causes vasoconstriction of blood vessels causing an increase in blood pressure which helps filtration.
31Buffers Keep the balance Acidosis- When blood pH drops below 7.35.Alkalosis – When blood pH rises above 7.45.Sodium Bicarbonate ions NaHCO3-Bicarbonate ion HCO3-Ammonia NH3HCl
32Renal threshold The limit for certain substances in the blood. Substances over the limit are forced out into the filtrate.Glucose and not reabsorbed over the threshold limit.
34Renal and Urinary disorders Hydronephrosis – Urine backs up into the kidney, causing swelling.Renal calculi – crystallized mineral chunks that develop in the calyces or renal pelvis(staghorn calculi) = renal colic(PAIN)Renal ptosis – Kidneys may drop, Ureters may kink and obstruct urine flow.
35Urinary tract infections UTIs Urethritis -Bacterial infections – inflammation of the urethra- STDs often cause urethritis – more common in malesCystitis – inflammation of the bladder- can also accompany kidney stones and tumorsNephritis – Kidney disease – bacterial or viral infections
36Kidney Failure AKA Renal Failure Acute Renal Failure – SuddenBUN Blood Urea Nitrogen High1st stage Loss of nephrons2nd stage Kidney can no longer adapt to the loss of nephrons. Remaining nephrons cannot handle the load3rd stage Complete shutdown- Edema and hypertension occurs