THE URINARY SYSTEM

1
THE URINARY SYSTEM

• Chapter 25

2
Introduction

• Urology is the branch of medicine that deals with
  the urinary system.
• There are three functions of the urinary system
• Regulates volume, composition, and pH of body
  fluids.
• Excretes metabolic wastes.
• Regulates blood pressure, RBC production,
  synthesizes calcitriol, and performs
  gluconeogenesis.

3
Basic Gross Anatomy

• Two kidneys
• Two ureters
• Urinary bladder
• Urethra

4
External Anatomy of the Kidneys

• Within the muscular wall of the back between
  T12-L3.
• Renal hilus
• Connective tissue layers
• Renal capsule
• Adipose capsule
• Renal fascia

5
Internal Anatomy of the Kidneys

• Renal Cortex
• Renal Medulla
• Renal pyramids
• Renal papillae
• Renal columns
• Renal Pelvis
• With major calyces and minor calyces

6
Blood Supply of the Kidney
7
Nephron Anatomy

• Renal Corpuscle
• Glomerulus
• Bowmans capsule
• Renal Tubules
• Proximal convoluted tubule (PCT)
• Loop of Henle
• Distal convoluted tubule (DCT)

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Renal Corpuscle
9
Filtration Membrane
10
Podocytes
11
Filtration Membrane
12
Renal Tubules
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Renal Tubules
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Types of Nephrons

• Cortical Nephrons
• Juxtamedullary nephrons

15
Renal Physiology

• Occurs in Three Steps
• Non-selective filtration
• Tubular reabsorption
• Tubular secretion

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NON-SELECTIVE FILTRATION

• Step 1

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Renal Physiology
18
Non-Selective Filtration
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Glomerular Filtration Rate
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REABSORPTION

• Step 2A

21
Tubular Reabsorption
22
Tubular Reabsorption
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Tubular Reabsorption
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Tubular Reabsorption at the PCT

• Glucose, lactate, amino acids and vitamins 100
• Bicarbonate ions 90
• Water and sodium ions 65
• Potassium ions 55
• Chloride ions 50
• Others are hormonally controlled

25
Tubular Reabsorption
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Tubular Reabsorption
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Countercurrent Mechanism
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Tubular Reabsorption
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Tubular Reabsorption at the Loop

• Chloride 35
• Potassium 30
• Sodium ions 25
• Water 10

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Tubular Reabsorption
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Tubular Reabsorption
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Tubular Reabsorption at the DCT

• Water 25
• Chloride 10
• Sodium ions 10

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Tubular Reabsorption
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Tubular Reabsorption
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SECRETION

• Step 2B

36
Tubular Secretion
37
Regulation by Hormones

• Antidiuretic hormone (ADH)
• Aldosterone
• Atrial natriuretic peptide (ANP)
• Renin and Angiotensin II

38
Urine Formation

• Urine composition
• 90-95 water
• Solutes constitute the other 5
• Metabolic wastes (urea, uric acid, and
  creatinine)
• Ions (Na, K, PO43-, SO42-, Ca2, Mg2)
• Toxins and pigments (urochrome)
• Hormones
• Urine characteristics
• Yellow in color
• Slightly aromatic or ammonia odor
• pH slightly acidic (can vary from 4.5 to 8.0)
• Specific gravity 1.001 to 1.035

39
Abnormal Urine Constituents
40
Ureters
41
Urinary Bladder and Urethra
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Micturition
43
Micturition
44
Homeostatic Imbalances

• Renal calculi
• Urethritis
• Cystitis
• Incontinence
• Urinary retention
• Horseshoe kidney
• Polycystic kidney
• Renal infarct

• Ptosis
• Hydronephrosis
• Pyelitis
• Pyelonephritis
• Anuria Hyperuria
• Hypospadias
• Diabetes insipidus
• Cystocele