Urinary System

• Components of Urinary System

  • 2 kidneys
  • 2 ureters
  • 1 urinary bladder
  • 1 urethra
• Functions of Urinary System

  • excretion
  • blood volume and blood pressure control
  • pH regulation
  • concentration of solutes
  • vitamin D production
  • RBC concentration
• Renal function

  .1. Regulatory function

  • fluid balance: osmotic pressure
  • acid base balance: electrolyte regulation

  2. Secretory function

  • renin production
  • erythropoietin production

  3. Excretory function
• Renal capsule

  • connective tissue around each kidney
  • protects and acts as barrier
• Hilum

  • indentation
  • contains renal artery, veins, nerves, ureter
• Renal Sinus

  • contains renal pelvis, blood vessels, fat
• Renal cortex

  • outer portion of kidney
• Renal medulla

  • inner portion of kidney
• Renal pelvis

  • funnel shape
  • where calyces join
  • narrows to form ureter
• Calyx

  • tip of pyramid
• Renal pyramid

  • junction between cortex and medulla
• Kidney

  • covered by a thin connective tissue capsule
  • consists of outer cortex and medullary pyramid
• Nephron

  • found within outer cortex and medullary pyramid
  • structural and functional unit of kidney
  • produces urine
  • about 1000000 nephrons in each human kidney
• Renal corpuscle

  • aka Malpighian corpuscle
  • blood filtering component of the nephron of kidney
  • consists of: glomerulus, glomerular capsule (Bowman's capsule)
• Glomerulus

  • tuft of capillaries composed of endothelial cells
• Bowman's capsule

  • part of renal corpuscle
  • initial part of nephron
  • double walled cup that encloses glomerulus
• Mesangial cells

  • specialized cells in the glomerulus attached to the capillaries
  • synthesize the ECM
  • provide structural support for glomerular capillaries
  • function as macrophages
  • contractile and regulate glomerular blood flow and pressure changes
  • produces interleukins in response to injury or damage
• 2 types of Nephrons

  • cortical nephrons
  • juxtamedullary nephrons
• Cortical nephrons

  • 85%
  • shorter, mostly in cortex of kidney
  • produce standard urine
• Juxtamedullary nephron

  • 15%
  • juxta = next to
  • next to the medulla
  • responsive to ADH
  • can concentrate urine
• Juxtaglomerular apparatus

  • special structure formed by the distal convoluted tubule and glomerular afferent arteriole
  • regulate blood pressure and filtration rate of the glomerulus
• Juxtaglomerular cells

  • derived from smooth muscle cells
  • juxtaglomerular cells of afferent arteriole secrete renin when blood pressure in arteriole falls
• Renin

  • increases blood pressure via the renin angiotensin aldosterone system
• Ureter

  • star shaped lumen due to convoluted mucosa
  • mucosa: lined by transitional epithelium
  • muscularis: inner longitudinal layer of smooth muscle, outer circular layer of smooth muscle
• Urinary bladder

  • lined with transitional epithelium underlined by a collagenous lamina propria
  • submucosa: elastic fibers
  • muscularis: muscular layer of three coats of smooth muscle
• Antidiuretic Hormone

  • increases absorption of water from the filtrate to the blood
• Parathyroid Hormone (PTH)

  • increases reabsorption of calcium
• Aldosterone

  • increases reabsorption of sodium and excretion of potassium
• Atrial natriuretic peptide (ANP)

  • decreases reabsorption of sodium
  • increase GFR
• Angiotensin II

  • reduces water loss
  • stimulate thirst and encourages water intake
  • reduces GFR
  • stimulate PCT to reabsorb NaCl and H2O
  • stimulate aldosterone and ADH secretion
• Calcitonin

  • weak effects similar to parathyroid hormone
• Calcitriol

  • weak effects similar to parathyroid hormone
• Epinephrine and Norepinephrine

  • induce renin secretion
  • constrict afferent arteriole
  • reduce GFR and urine volume
• Renin angiotensin system

  • regulated blood pressure and fluid balance in body
• Steps of renin production of kidney

  1. renin released by kidney because low blood volume/blood sodium OR high blood potassium
  2. renin converts angiotensinogen to angiotensin I
  3. Angiotensin I is metabolized into angiotensin II by ACE
  4. Angiotensin II stimulate release of aldosterone
  5. angiotensin II and aldosterone work together to restore balance
• Respiratory acidosis

  • occurs when the lungs can’t remove enough of the carbon dioxide produced by the body
• Respiratory alkalosis

  • occurs when one breathe too fast or too deep and carbon dioxide levels drop too low
  • causes pH of blood to rise and become too alkaline
• Metabolic acidosis

  • condition in which there is too much acid in the body fluids
• Diabetic acidosis

  • develops when substances called ketone bodies (which are acidic) build up during uncontrolled diabetes
• Hyperchloremic acidosis

  • caused by the loss of too much sodium bicarbonate from the body, which can happen with severe diarrhea