1. The Urinary System

2. Principle Organs
Kidneys
Ureters
Urinary bladder
Urethra

3. Overall Function Maintain homeostasis Adjust water content
Regulate ion levels
Ex: Na & K
Control pH of blood

4. Anatomy of the Kidney Outer region is the renal cortex
Inner region is the renal medulla
Medullary tissue forms renal pyramids
Calyces are cup-like structures that touch the base of the pyramids
Calyces empty into renal pelvis which then empties in the ureter

5. Blood Vessels of the Kidney
The renal artery, which brings blood to kidney, branches off the abdominal aorta.
The renal artery branches into arterioles and then flows into capillaries of the glomerulus.
It then flows back into an arteriole before branching into more capillaries in the renal cortex.
It finally leaves the kidney through the renal vein.

6. The Nephron
The kidney is mainly made up of small filtering units called nephrons
Structures of the nephron in order that fluids flow:
Renal corpuscle (includes glomerulus and Bowman’s capsule)
Bowman’s capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting duct

7. The Nephron
Blood enters the renal corpuscle through the afferent arteriole
It flows through the capillaries of the glomerulus inside Bowman’s capsule
The glomerulus has many large pores called fenestrations
Fluids then exit through the proximal (closest to Bowman’s capsule) convoluted tubule

8. The Nephron
Fluid then flows into the Loop of Henle (descending then ascending loop) that dips down into the medulla
Next the distal convoluted tubule runs by the efferent arteriole and touches the juxtaglomerular apparatus
Mechano and chemo receptors located in the juxtaglomerular apparatus aid in control of blood pressure and concentration of solute in the urine
Finally fluid exits through collecting ducts

9. Peritubular Capillaries
Blood flow in the Kidney
Renal artery  interlobular arteries  afferent arteriole glomerulus capillaries  efferent arteriole  peritubular capillaries (vasa recta)  renal venules  renal vein

11. Other Excretory System Organs
Urinary bladder – collapsible bag for storing urine,
micturition(urination)-voiding urine from bladder
Ureter – tube running from each kidney to the urinary bladder
Urethra – tube running from the bladder to outside the body

12. Urinary Bladder
Wall of the bladder is made of smooth muscle called the detruser muscle
An empty bladder has folds called rugae

13. Ureters and Urethra Female urethra is ~ 3 cm long
Male urethra passes through the prostate gland

14. Kidney Physiology - Urine Formation
Filtration - In the glomerulus small filtrates and water move into Bowman’s capsule
Tubular Reabsorption occurs as molecules move out of the tubules and into the blood
Tubular Secretion occurs as molecules move out of the peritubular blood back into the tubules

15. Filtration
Filtration into the glomerulus occurs because of hydrostatic pressure
The body would not survive if all substances that were filtered out of plasma were excreted in urine.

16. Filtration in Glomerulus
In the renal corpuscle water and smaller solutes, ions and glucose move through fenestrations into Bowman’s capsule.

17. Reabsorption in Proximal Tubule
Na+ is actively pumped out of tubule filtrate and water follows. Glucose is actively reabsorbed.
Cl-, PO42-, urea and other solutes passively diffuse out then water follows through osmosis

18. Loop of Henle Descending loop Water is reabsorbed into the blood
Urea is passively secreted into the tubule
Ascending Loop
Na+ is actively reabsorbed and Cl- follow

19. Secretion in Distal Tubule
Reabsorption of Na+ (active) and Cl-
Water will be reabsorbed only in the presence of ADH.
Secretion of K+, H+ and some drugs occur
Collecting tubule has the same function except urea is reabsorbed.

21. Urine Volume
Cells in the juxtaglomerular apparatus are sensors for urine concentration and water volume
ADH and aldosterone cause the reabsorption of water in the distal convoluted tubule
The heart can secrete atrial natriuretic hormone (ANH) which causes the secretion of Na+ into urine and then water follows

22. Urine Composition Nitrogenous wastes, from protein metabolism, urea
Electrolytes
Toxins
Pigments, yellow results from breakdown of old blood cells
Hormones
Abnormal constituents
Blood
Glucose
Albumin
Casts (hardened mucus)
calculi

23. Urine pH Normal pH of urine 4.6-8 A highly acidic urine pH occurs in:
Acidosis
Uncontrolled diabetes
Diarrhea
Starvation and dehydration
Respiratory diseases in which carbon dioxide retention occurs and acidosis develops
A highly alkaline urine occurs in:
Urinary tract infection
Chronic renal failure
Respiratory diseases that involve hyperventilation (blowing off carbon dioxide and the development of alkalosis)
An accurate measurement of urinary pH can be done only on a freshly voided specimen. If urine must be kept for any length of time before analysis, it should be refrigerated.
During sleep, decreased pulmonary ventilation causes respiratory acidosis. As a result, a first waking urine specimen is usually highly acidic.
Bacteria causing a urinary tract infection or bacterial contamination will produce alkaline urine.
A diet rich in citrus fruits, most vegetables, and legumes will keep the urine alkaline.
A diet high in meat and cranberry juice will keep the urine acidic.
Urine pH is an important screening test for the diagnosis of renal disease, respiratory disease, and certain metabolic disorders.
If urine pH is to be useful, it is necessary to use pH information in comparison with other diagnostic information.
An accurate measurement of urinary pH can be done only on a freshly voided specimen.
During sleep, decreased pulmonary ventilation causes respiratory acidosis. As a result, a first waking urine specimen is usually highly acidic.
Bacteria causing a urinary tract infection or bacterial contamination will produce alkaline urine.
A diet rich in citrus fruits, most vegetables, and legumes will keep the urine alkaline.
A diet high in meat and cranberry juice will keep the urine acidic.

24. Disorders of the Urinary System
Hydronephrosis- a blockage of urine flow
Renal Calculi
kidney stones are crystallized mineral chunks that build up in the renal pelvis or calyces.
Renal Carcinomas
Tumors that usually develop in one kidney
Renal ptosis
Persons with really low body fat may lack fat around kidney and it may drop causing kinks in ureters.

25. Disorders of the Urinary System
Glycosuria- glucose in urine
Hematuria- Blood in urine
Pyuria- pus in urine
Dysuria- painful urination
Polyuria- large amounts of urine
Oliguria- scant urine
Anuria- absence of urine
Incontinence- uncontrolled urination

26. Disorders of the Urinary System
Urinary tract infections
Usually caused by bacteria
Can be an inflammation of urethra, bladder or kidney

27. Disorders of the Urinary System
Kidney Function is normally measured with a blood urea nitrogen test(BUN)
Normal ranges BUN 5 to 26 mg/dL
Kidney Failure
Acute failure caused by trauma or disease
Chronic kidney failure must be treated with dialysis and eventually transplant

28. Disorders of the Urinary System
Dialysis- the process of artificially filtering the blood of urea
Blood is moved through dialysis tubing which is permeably to small solutes.
The tubing is continually being bathed in hypotonic solution