1. Urinary System

2. Urinary System Functions of Urinary System:
Excretion- removing nitrogenous wastes, certain salts and excess water from blood.
Maintain acid-base balance
Secrete waste products in the form of urine – remove waste from body
Eliminate urine from bladder

3. What if kidneys are not working properly?
Toxic wastes would accumulate in the cells, poisoning them

4. Reasons for elevated BUN

6. Kidneys Bean-shaped organs
                                                                                                                        
Bean-shaped organs
Located between peritoneum and the back muscles (RETROPERITONEAL)
Renal Pelvis- funnel shaped structure at the beginning of the ureter

8. Medulla Inner, striated layer
Striated cones (divisions) are renal pyramids
Base of each pyramid faces cortex, while apex empties into cuplike cavities called calyces

9. Cortex
Composed of millions of microscopic functional units called nephrons

10. Nephrons Functional unit of the kidney
Over 1 million in each kidney which comprise 140 miles of filters and tubes
Parts include:
Bowman’s capsule
Glomerulus
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting tubule

13. Nephron structure
Afferent arteriole – blood from renal artery enters through this…
Bowman’s capsule – double-walled hollow capsule – surrounds glomerulus
Glomerulus – knotty ball formed from afferent arterioles finely dividing – contains 50 separate capillaries
Proximal convoluted tubule – twisted tubular branch off Bowman’s capsule

14. Nephron structure cont’d
Loop of Henle – proximal convoluted tubule descends into the medulla forming large loop
Distal convoluted tubule – ascending limb of Henle’s loop
Collecting tubule – distal tubule opens into collecting tubule

15. Urine Formation in the Nephron
1- Filtration
2. Reabsorption
3- Secretion

16. Filtration First step in urine formation
Blood from renal artery enters glomerulus
High blood pressure in glomerulus forces fluid (Filtrate) to move into Bowman’s capsule (function of glomerulus is to filter substances from the blood)
Filtrate does not contain plasma proteins or RBCs- they are too big
Bowman’s capsule filters out 125cc of fluid/min. – 7500cc/hour
As filtrate continues through nephron, 90% of water is reabsorbed

17. Reabsorption
Water and useful substances are reabsorbed in proximal convoluted tubule
If blood levels of certain substances are high (glucose, amino acids, vitamins, sodium) then those substances will not be reabsorbed
Useful substances filter out of the renal tubules and back into the capillaries around the tubules = reabsorption

18. Filtration

19. Secretion Opposite of reabsorption
Secretion transports substances from blood into collecting tubules
Substances include creatinine, hydrogen ions, potassium ions, and some drugs
Electrolytes are selectively secreted to maintain body’s acid-base balance

20. Urinary Output Average= 1500 ml/day
Urinalysis- examination of urine to determine presence of blood cells, bacteria, acidity level, specific gravity and physical characteristics (color, clarity and odor)
Normal in urinalysis = Ammonia
not normal = glucose, blood, pus

21. Ureters One from each kidney Carry urine from kidney to bladder
Smooth muscle tube with mucous membrane lining
Peristalsis pushes urine down ureters
The tubes that connect the kidneys and bladder.

22. Path of urine formation
Afferent arteriole - Glomerulus – Bowman’s capsule – proximal convoluted tubule – loop of Henle – distal convoluted tubule – collecting tubule – renal pelvis - ureter

24. Urinary Bladder Hollow, muscular organ – in the pelvic cavity
Made of elastic fibers and involuntary muscle
Stores urine- usually about 500cc
Emptying urine (voiding) is involuntary but controlled through nervous system (voluntary)
Function = store and aid in elimination of urine
Urine leaves through urethra to outside opening = Urinary Meatus

25. Chemical Control
Reabsorption of H2O in distal convoluted tubule controlled by ADH (antidiuretic hormone)
Secretion and regulation of ADH controlled by hypothalamus
Diuretics inhibit reabsorption of H2O
Medications can replace chemicals created by body i.e. renin = diuretic
Production of urine is controlled by ADH and aldosterone

26. Chemical Control

27. Renin Urinary System
Whereas adrenaline and noradrenaline enhance vasoconstriction, aldosterone influences the filtration function of the kidneys. The kidneys retain more sodium and water in the body and excrete more potassium. The vasopressin from the pituitary gland prevents the excretion of water without affecting the electrolytes sodium and potassium.
In this way, the overall volume of blood in the body is increased: more blood is pumped through constricted arteries, which increases the pressure exerted on the artery walls – the blood pressure.

28. Chemical Control
Aldosterone: promtoes excretion of potassium and hydrogen ions and reabsorption of sodium ions; acting on the distal tubules and collecting ducts of the nephron, increasing reabsorption of ions and water in the kidney, to cause the conservation of sodium, secretion ofpotassium, increase in water retention, and increase in blood pressure and blood volume
If blood pressure drops too low, or blood volume gets too low, or too concentrated (not enough water in it), ADH released

29. ADH
When the blood becomes more concentrated, as happens when an animal is deprived of water, ADH is secreted and causes more water to be absorbed from the collecting ducts so that concentrated urine is produced. When plenty of water has been consumed, and the blood is dilute, no ADH is secreted and no or little water is absorbed from the collecting ducts, so dilute urine is produced.

30. Chemical Control
Diuretics increase urinary output by inhibiting reabsorption of water

31. Nervous Control
Direct control through nerve impulses on kidney blood vessels
Indirect control through stimulation of endocrine glands, whose hormonal secretions will control
urinary secretion

32. Disorders of the Urinary System
Renal Calculi (Kidney Stones)
Made of crystals of calcium phosphate and uric acid
Gradually they get larger until they block ureters…can causey hydronephrosis
First symptom- severe pain
Other symptoms- nausea and vomiting, frequency, chills, fever, hematuria
Diagnosis- by symptoms, ultrasound, or x-ray
Rx- increase fluids to flush out stone, medications, and if needed- lithotripsy

33. Lithotripsy Surgical procedure to remove kidney stones
                                       
Surgical procedure to remove kidney stones
Shock waves hit dense stones and break them up
Done on outpatient basis

34. Nephritis Inflammation of the kidney (kidney infection) Incontinence =
Involuntary urination

35. Updated July 29, 2005
    
Cystitis
Inflammation of the mucous membrane lining of the urinary bladder
Most common cause- E. Coli
Symptoms- Dysuria (painful urination), lower abd pain, and frequency
Usually in females (shorter urethra)
Rx- antibiotics

36. Dialysis (Hemodialysis)
Used for kidney failure
Involves the passage of blood through device with semipermeable membrane
Dialysis serves as substitute kidney… replaces filtration
Blood from patient flows through machine and is filtered
Can be done at home or in clinic
Takes 2-4 hours, 2-3 times a week

37. Kidney Transplant As a last resort
Involves donor organ from someone with a similar immune system
Main complication- rejection

38. Terminology Enuresis- bedwetting Incontinence – involuntary urination
Gylcosuria- sugar in urine
Nocturia- frequent urination at night
Polyuria- large amounts of urine
Anuria- no urine produced
Hematuria- blood in urine
Diuretic- drug or substance to increase urine production
Oliguria – decreased urine production (sign of kidney failure)