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The Urinary System.

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Presentation on theme: "The Urinary System."— Presentation transcript:

1 The Urinary System

2 Overview The urinary system balances the water content in the blood as well as ions of Na and K and pH. It Regulates the volume and composition of the fluids and excrete unwanted materials.

3 Anatomy of the Urinary System

4 Internal Kidney Structure

5 Urinary Bladder Anatomy
Rugae- Flods of the bladder Detrusor Muscle – smooth muscle Trigone Urethral Sphincter -Involuntary Urethra

6 Physiology 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 micturition Inability 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

7 Urethra Small 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.

8 Microscopic Structure of the functional unit of a kidney is the Nephron.
Components of the Nephron Bowman’s Capsule Proximal convoluted tubule Loop of Henle Distal convoluted tubule Collecting duct There are approximately 1.25 million nephrons Per Kidney.

9 Glomeruli – Many glomerulus
Glomerular capillaries

10 Bowman’s Capsule + Glomerulus = Renal corpuscle

11 The loop of Henle dips into the medulla into a renal pyramid.

12 The collecting ducts empty into the calyces which empty into the renal pelvis.

13 Blood vessels of the Kidneys
About 1200 ml of blood flows through the kidneys every minute Which means approximately 1/5 of all the blood pumped by the heart per minute goes to the kidneys. Usual direction of blood flow is Arteries-Arterioles-Capillaries-venules-veins

14 Blood flow through Kidney tissue follows this path…
Renal Artery Interlobular artery-penetrate the cortex Afferent arteriole Glomerulus Efferent arteriole Peritubular capillaries(vasa recta) Venules Interlobular vein Renal Vein

15 Function 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)

16 Kidney Failure means homeostatic failure and
If not relieved, inevitable DEATH.

17 Kidneys also… Influence the rate of secretion of the hormones
ADH – Antidiuretic hormone Aldosterone and synthesize erythropoietin –active form of vitamin D and prostaglandins.

18 Urine is formed by 3 means
Formation of urine Urine is formed by 3 means 1. 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

19 2. Reabsorption- movement of molecules out of the tubule and into the peritubular blood.

20 3. Secretion – movement of the molecules out of the peritubular blood into the tubule for excretion.

21 Filtration Occurs through the glomerular capiliaries to the Bowman’s Capsule Large 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.

22 Blood cells are too large to filter out. So what does filter out?
Water Salts Bicarbonate H+ Urea Glucose Amino acids Some drugs

23 Returned to the blood immediately: Reabsorption occurs mostly in the PCT.
Water and ions Glucose and amino acids Passive 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.

24 Reabsorption 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.

25 Urine vs. Filtrate Filtrate 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.

26 In 24 hours 150 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 –dilute Final Filtrate - concentrated

27 Excretion Urea - protein breakdown
Uric acid – nucleic acids are metabolized. Creatinine – Actively secreted into filtrate associated with metabolism in muscle tissue.

28 Balance of Water and electrolytes
We cannot lose more water than we take in. Water is lost by…. Respiration, Perspiration, Solid waste, & Urine Water is taken in in Foods, beverages and metabolism.

29 Electrolyte balance ADH – 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.

30 Aldosterone – Regulates Sodium content
Renin-angiotensin mechanism – When blood pressure is low the enzyme renin catalyzed reactions that produce angiotensin II which causes vasoconstriction of blood vessels causing an increase in blood pressure which helps filtration.

31 Buffers 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 NH3 HCl

32 Renal 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.

33 Renal Calculi AKA Kidney stones

34 Renal 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.

35 Urinary tract infections UTIs
Urethritis -Bacterial infections – inflammation of the urethra- STDs often cause urethritis – more common in males Cystitis – inflammation of the bladder- can also accompany kidney stones and tumors Nephritis – Kidney disease – bacterial or viral infections

36 Kidney Failure AKA Renal Failure
Acute Renal Failure – Sudden BUN Blood Urea Nitrogen High 1st stage Loss of nephrons 2nd stage Kidney can no longer adapt to the loss of nephrons. Remaining nephrons cannot handle the load 3rd stage Complete shutdown- Edema and hypertension occurs

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