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Urinary System. Introduction. Consists of Two kidneys Two ureters One urinary bladder One urethra. Introduction. Urine is excreted from each kidney through its ureter and is stored in the urinary bladder. Introduction. Urine is expelled from the body through the urethra.

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Introduction
Introduction

  • Consists of

  • Two kidneys

  • Two ureters

  • One urinary bladder

  • One urethra


Introduction1
Introduction

  • Urine is excreted from each kidney through its ureter and is stored in the urinary bladder


Introduction2
Introduction

  • Urine is expelled from the body through the urethra


Anatomy of kidneys
Anatomy of Kidneys

  • Retroperitoneal organs


External anatomy of kidneys
External Anatomy of Kidneys

  • Hilus – A vertical fissure near the center of the concave medial border


External anatomy of kidneys1
External Anatomy of Kidneys

  • Ureters leave and blood vessels, lymphatic vessels, and nerves enter and exit at the hilus


Internal anatomy of kidneys
Internal Anatomy of Kidneys

  • Consists of

  • Cortex

  • Medulla

  • Pyramids

  • Papillae

  • Columns

  • Minor and Major calyces

  • Renal pelvis


Internal anatomy of kidneys1
Internal Anatomy of Kidneys

  • Nephron – functional unit of the kidney


Blood and nerve supply of the kidneys
Blood and Nerve Supply of the Kidneys

  • Blood enters the kidney through the renal artery


Blood and nerve supply of the kidneys1
Blood and Nerve Supply of the Kidneys

  • Blood exits via the renal vein


Nephrons
Nephrons

  • Consists of

  • Renal corpuscle

  • Renal tubule


Renal corpuscle
Renal Corpuscle

  • Where fluid is filtered


Renal corpuscle1
Renal Corpuscle

Consists of

  • Glomerulus

  • Glomerular Capsule


Renal corpuscle2
Renal Corpuscle

  • Glomerulus – capillary knot


Renal corpuscle3
Renal Corpuscle

  • The glomerular capsule consists of

  • Visceral layer

  • Parietal layer

  • Capsular Space


Renal corpuscle4
Renal Corpuscle

  • The visceral layer consists of modified simple squamous epithelial cells called podocytes


Renal corpuscle5
Renal Corpuscle

  • The parietal layer consists of simple squamous epithelium and forms the outer wall of the capsule


Renal corpuscle6
Renal Corpuscle

  • Fluid filtered from the glomerular capillaries enters the capsular space


Renal corpuscle7
Renal Corpuscle

  • Capsular space – the space between the two layers of the glomerular capsule


Renal tubule
Renal Tubule

  • Filtered fluid passes through here


Nephron
Nephron

  • Renal tubule

  • Proximal convoluted tubule

  • Loop of Henle

  • Distal convoluted tubule


Nephron1
Nephron

  • Distal convoluted tubules of several nephrons drain into to a single collecting duct


Nephron2
Nephron

  • Many collecting ducts drain into a small number of papillary ducts


Nephron3
Nephron

  • These empty urine into the minor calyces


Nephron4
Nephron

  • Loop of henle consists of

  • Descending limb

  • Thin ascending limb

  • Thick ascending limb


Nephron5
Nephron

  • Two types of nephrons

  • Cortical nephron

  • Juxtamedullary nephron


Cortical nephron
Cortical Nephron

  • Has its glomerulus in the outer portion of the cortex


Cortical nephron1
Cortical Nephron

  • And a short loop of Henle that penetrates only into the outer region of the medulla


Juxtamedullary nephron
Juxtamedullary Nephron

  • Has its glomerulus deep in the cortex close to the medulla


Juxtamedullary nephron1
Juxtamedullary Nephron

  • Its long loop of Henle stretches through the medulla and almost reaches the papilla


Renal tubule and collecting duct
Renal Tubule and Collecting Duct

  • Most of the cells of the distal convoluted tubule have receptors for ADH and aldosterone


Juxtaglomerular apparatus jga
Juxtaglomerular Apparatus (JGA)

  • Helps regulate blood pressure and the rate of blood filtration by the kidneys


Juxtaglomerular apparatus jga1
Juxtaglomerular Apparatus (JGA)

  • Consists of

  • Juxtaglomerular cells

  • Macula Densa


Juxtaglomerular cells
Juxtaglomerular Cells

  • Located on an afferent arteriole


Macula densa
Macula Densa

  • Located on the distal convoluted abutting the JG cells


Renal physiology
Renal Physiology

  • Nephrons and collecting ducts perform three basic processes while producing urine


Renal physiology1
Renal Physiology

  • Glomerular filtration

  • Tubular secretion

  • Tubular reabsorption


Glomerular filtration
Glomerular Filtration

  • Glomerular filtrate - the fluid that enters the capsular space


Glomerular filtration1
Glomerular Filtration

  • The principle of filtration – to force fluids and solutes through a membrane by pressure


Glomerular filtration2
Glomerular Filtration

  • Glomerular Filtration rate (GFR) – the amount of filtrate formed by both kidney per minute


Glomerular filtration3
Glomerular Filtration

  • GFR – 125ml/minute


Glomerular filtration4
Glomerular Filtration

  • This amounts of 180 liters of filtrate per day


Glomerular filtration5
Glomerular Filtration

  • Because of further processing we only excrete 1-2 liters of urine per day


Glomerular filtration6
Glomerular Filtration

  • Only call it urine after it drips out of the collecting ducts into the calyceal system


Neural autoregulation
Neural Autoregulation

  • Through the ANS


Neural autoregulation1
Neural Autoregulation

  • During extreme emergencies such as shock, sympathetics to afferent arterioles cause them to constrict


Neural regulation
Neural Regulation

  • Blood flow into glomerular capillaries is greatly decreased and GFR drops


Neural regulation1
Neural Regulation

  • Lowering of renal blood flow has two consequences


Neural regulation2
Neural Regulation

1. Reduces urine output, which conserves blood volume


Neural regulation3
Neural Regulation

2. It permits greater blood flow to other body tissues


Neural regulation4
Neural Regulation

  • Severe hypotension can cause death of part of the tubules, decreases urine output, and kidney failure


Hormonal regulation
Hormonal Regulation

  • With mild drops of BP sympathetics stimulate renin secretion on JG cell by targeting B1 receptors


Hormonal regulation1
Hormonal Regulation

  • Renin converts angiotensinogen to angiotensin I


Hormonal regulation2
Hormonal Regulation

  • Angiotensin I is converted by angiotensin converting enzyme to angiotensin II


Hormonal regulation3
Hormonal Regulation

  • Angiotensin II causes efferent arteriole to constrict more than afferent arterioles, maintaining filtration


Hormonal regulation4
Hormonal Regulation

  • Angiotensin II also leads to the formation of aldosterone


Hormonal regulation5
Hormonal Regulation

  • Aldosterone causes sodium and water retention and potassium excretion


Principles of renal transport
Principles of Renal Transport

  • Reabsorption – returns most of the filtered water and many of the filtered solutes (such as glucose, sodium, etc.) to the bloodstream


Principles of renal transport1
Principles of Renal Transport

  • Tubular secretion – the transfer of materials from the blood and tubule cells into tubular fluid


Principles of renal transport2
Principles of Renal Transport

  • Tubular secretion helps control blood pH and helps eliminate other substances from the body


Principles of renal transport3
Principles of Renal Transport

  • Solute reabsorption drives water reabsorption


Reabsorption in the proximal convoluted tubule
Reabsorption in the Proximal Convoluted Tubule

  • The majority of the solute and water reabsorption from filtered fluid occurs in the proximal convoluted tubules


Reabsorption in the proximal convoluted tubule1
Reabsorption in the Proximal Convoluted Tubule

  • Reabsorption of Na and other solutes creates an osmotic gradient that promotes reabsorption of water by osmosis


Reabsorption in the proximal convoluted tubule2
Reabsorption in the Proximal Convoluted Tubule

  • Proximal convoluted Na transporters promote reabsorption of organic solutes such as

  • Glucose

  • Amino acids

  • Bicarbonate ions

  • Water

  • Na

  • K

  • Cl

  • Other ions and vitamins


Secretion of nh3 and nh4 in the proximal convoluted tubule
Secretion of NH3 and NH4 in the Proximal Convoluted Tubule

  • The deamination of the amino acid glutamine by PCT cells generates NH3 and new HCO3-


Secretion of nh3 and nh4 in the proximal convoluted tubule1
Secretion of NH3 and NH4 in the Proximal Convoluted Tubule

  • Most NH3 quickly binds to H+ and becomes NH4+


Secretion of nh3 and nh4 in the proximal convoluted tubule2
Secretion of NH3 and NH4 in the Proximal Convoluted Tubule

  • NH4+ can substitute H+ aboard the Na+/H+ antiporters and be secreted into tubular fluid


Reabsorption in the loop of henle
Reabsorption in the Loop of Henle

  • Water reabsorption is not directly coupled with sodium reabsorption


Reabsorption in the loop of henle1
Reabsorption in the Loop of Henle

  • In the descending limb, water is reabsorbed via osmosis


Reabsorption in the loop of henle2
Reabsorption in the Loop of Henle

  • As water is reabsorbed from the descending limb, the osmolality of the filtrate increases


Reabsorption in the loop of henle3
Reabsorption in the Loop of Henle

  • In the ascending limb, Na+, K+, Cl- symporters reclaim Na+, Cl-, and K+ ions from the tubular lumen fluid.


Reabsorption in the loop of henle4
Reabsorption in the Loop of Henle

  • As sodium and chloride are reabsorbed from the ascending limb, the osmolality of the filtrate decreases


Reabsorption in the dct
Reabsorption in the DCT

  • As fluid flows along the DCT, reabsorption of Na+ and Cl- continues due to Na+ - Cl- symporters


Reabsorption in the dct1
Reabsorption in the DCT

  • The DCT serves as the major site where parathyroid hormone stimulates reabsorption of Ca2+ and excretion of phosphate


Reabsorption and secretion in the collecting duct
Reabsorption and Secretion in the Collecting Duct

  • Aldosterone increases Na+ and water reabsorption as well as K+ secretion by the collecting ducts and late distal convoluted tubules


Reabsorption and secretion in the collecting duct1
Reabsorption and Secretion in the Collecting Duct

  • Some cells secrete H+ into the filtrate and reabsorb HCO3- into the bloodstream


Reabsorption and secretion in the collecting duct2
Reabsorption and Secretion in the Collecting Duct

  • These cells help maintain body fluid pH by excreting excess H+ when the pH is too low or by reabsorbing less HCO3- when the pH is too high.


Reabsorption and secretion in the collecting duct3
Reabsorption and Secretion in the Collecting Duct

  • ADH regulates water reabsorption by increasing permeability in the Collecting Duct and DCT


Production of dilute and concentrated urine
Production of Dilute and Concentrated Urine

  • The rate at which water is lost from the body depends mainly on ADH


Production of dilute and concentrated urine1
Production of Dilute and Concentrated Urine

  • When ADH level is very low, the kidneys produce dilute urine and excrete excess water


Production of dilute and concentrated urine2
Production of Dilute and Concentrated Urine

  • When ADH level is high, the kidneys secrete concentrated urine and conserve water


Ureters
Ureters

  • Each of the two ureters connects the renal pelvis of one kidney to the urinary bladder


Urinary bladder
Urinary Bladder

  • Located in the pelvic cavity posterior to the pubic symphysis


Urinary bladder1
Urinary Bladder

  • In the floor of the urinary bladder is a small, smooth triangular area, the trigone.


Urinary bladder2
Urinary Bladder

  • The ureters enter the urinary bladder near two posterior points in the triangle


Urinary bladder3
Urinary Bladder

  • The urethra drains the urinary bladder from the anterior point of the triangle


Urinary bladder4
Urinary Bladder

  • In the area around the opening to the urethra, the circular fibers of the muscularis form the internal urethral sphincter


Urinary bladder5
Urinary Bladder

  • The internal urethral sphincter contracts in response to sympathetics, and relaxes in response to parasympathetic stimulation


Urinary bladder6
Urinary Bladder

  • Below the internal sphincter is the external urethral sphincter, which is composed of skeletal muscle


Urethra
Urethra

  • A tube leading from the floor of the urinary bladder to the exterior


Urethra1
Urethra

  • Functions to discharge urine from the body


Urethra2
Urethra

  • The male urethra also serves as the duct for ejaculation of semen


Incontinence
Incontinence

  • A lack of voluntary control over urination


Retention
Retention

  • Failure to void urine completely or normally


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