1. Urinary System

2. Myth or Fact?
1.  Urinating on a jellyfish sting will help alleviate the pain.      FALSE
2.  It is safe to drink your own urine.
Short term – YES, Long term – NO 3.  If someone is sleeping and you put their hand in warm water, they will pee their pants.   FALSE
4.   Holding your urine can cause a bladder infection  There is a fish that will follow a urine stream and enter the urethra.      FALSE

3. Functions of the Urinary System
Cells produce waste that can become toxic if they accumulate
The urinary system functions to:
removes salts and nitrogenous wastes
maintains normal concentration of water and electrolytes
maintains pH, controls red blood cell production and blood pressure

4. Composition of the Urinary System
consists of a pair of KIDNEYS which remove substances from the blood
URETERS which transport urine from the kidneys to the bladder
urinary BLADDER stores urine
URETHRA conveys urine to the outside of the body

5. KIDNEYS
KIDNEYS
URETERS
BLADDER
SPHINCTER
URETHRA

6. Kidneys
Lie on either side of the vertebral column deep in the abdominal cavity
positioned behind the parietal peritoneum (retroperitoneally)
lateral side is convex, medial is concave, kidneys sit in a depression called the renal sinus
Entrance is called the HILUM

7. Kidneys
-Superior end of the kidney forms a funnel shaped sac - renal pelvis -renal medulla = center of the kidney -renal cortex = outer shell around the medulla; the cortex appears granulated due to the presence of nephrons -renal arteries and veins supply blood to  the kidneys
The nephron is the functional unit of the kidney

9. Renal Arteries and Veins
Arteries attach to the abdominal aorta
Veins attach to the inferior vena cava
Interlobar arteries pass between the renal pyramids
Afferent arterioles lead to the nephrons

10. NEPHRONS - functional unit of the urinary system
Quick Analogy:  A nephron is to the urinary system as the _________________ is to the nervous system
-each kidney contains about 1 million nephrons -renal corpuscle: composed of a tangled cluster called a glomerulus which filters fluid
Pathway = glomerulus -> proximal tubulue --> nephron loop (also called loop of henle) --> distal tubule --> collecting duct --> ureter --> bladder

14. What blood vessel enters the glomerulus?

15. Urine Formation
(1) Glomerular filtration - urine formation begins, plasma is filtered
(2) Tubular reabsorption - returns most of the fluid to the body
(3) Tubular secretion - removes what is not needed; produces urine

16. Glomerular Filtration
Involves the filtration of blood plasma in the glomerulus
Increased blood pressure in the glomerulus forces water and dissolved molecules to move from the lumen (walls) of capillaries, across the filtration membrane, and into Bowman’s capsule
Larger sized proteins DO NOT pass through the filtration system; they exit through the arterioles

17. Glomerular Filtration
The walls of the glomerulus contain pores
The size of the pores determines what size substances can pass through the glomerulus

18. Tubular Reabsorption
Glomerular filtration rate is so high, that the entire blood volume enters the tubules in less than 30 minutes
Reabsorption of almost all the filtrate must occur quickly before dehydration occurs
Tubular reabsorption is the process by which solutes and water are removed from the tubular fluid and transported into the blood. It is called reabsorption (and not absorption) because these substances have already been absorbed once (in the intestines).
Majority of reabsorption occurs in the proximal convoluted tubule!

19. Tubular Reabsorption Substances can be reabsorbed through two ways:
(1) Paracellular – substances diffuse between cells
(2) Transcellular – substances pass through the cell
Reabsorption can occur through passive transport (osmosis and diffusion) or active transport (Na+/K+ pump)

21. Aldosterone
Some hormones, like aldosterone, are responsible for controlling reabsorption rates
Aldosterone is a steroid secreted by the adrenal glands that is responsible for controlling the reabsorption of water and sodium
Aldosterone regulates blood pressure by controlling the rate at which water and ions are reabsorbed. If it increases the rate of water and sodium reabsorption, more water and salt is retained, therefore increasing blood pressure.
Diuretics act AGAINST aldosterone, decreasing reabsorption rates of water so more water is passed, lowering blood pressure

22. Tubular Secretion Tubular secretion has two main functions:
(1) regulate blood pH by secreting hydrogen ions
(2) Secreting other substances removes them from the body so that they will become urine
Secretion only occurs via ACTIVE TRANSPORT!

23. Tubular Secretion
When the filtrate has arrived at the distal convoluted tubule, 80% of filtered water and more solutes (mostly sodium and chlorine) have been reabsorbed
Tubular secretion occurs in the tubules, but mostly in the collecting duct

24. Urine Composition 95 % Water
Contains urea and uric acid (characteristic smell)
Can contain trace amino acids

25. Urine may also contain other chemicals that can be detected.
Hormones present in a pregnant woman are detectable in urine

26. Urine Elimination
After urine forms in the nephrons, the ureters (starting with the renal pelvis) carry the urine away to the bladder
Bladder is an expandable structure that stores urine before it is eliminated from the body.
Transitional epithelial cells change shape to allow for expansion and contraction.

27. Micturation = urination; as the bladder fills this reflex occurs though it is also under voluntary control
Urethra = tube carries urine to the outside of the body
Detrusor Muscle - attach to bladder and sphincter, control urination

29. Disorders of the Urinary System
Many urinary problems can be solved by drinking enough water.
 So how much fluid does the average, healthy adult living in a temperate climate need? The Institute of Medicine determined that an adequate intake (AI) for men is roughly 3 liters (about 13 cups) of total beverages a day. The AI for women is 2.2 liters (about 9 cups) of total beverages a day.

30. Kidney Stones
Extracorporeal shock wave lithotripsy (ESWL) is a procedure used to shatter simple stones in the kidney or upper urinary tract. Ultrasonic waves are passed through the body until they strike the dense stones, and make them smaller. Small pieces of the stone can then passed from the body.

32. Commonly known as a "bladder infection“
Cystitis = bacteria enters the bladder or kidneys (kidney infection); more common in women because the urethra is shorter
Commonly known as a "bladder infection“
UTI = urinary tract infection
Frequent  need to urinate Pain in the abdomen Burning sensation during urination Cloudy, bad-smelling urine Blood in the urine Leaking urine Low back pain Fever and chills Nausea and poor appetite

33. Catheters
 In medicine, a catheter is a tube that can be inserted into a body cavity, duct, or vessel. 
 The process of inserting a catheter is catheterization.
Catheterization of the bladder is a common medical procedure, often performed by nurses

35. Overactive Bladder = sudden contractions of the bladder produce sensation of urgency, also more common in women
Incontinence - inability to control urination (or defecation)

36. When Kidneys Fail.... Dialysis may be used to clean the blood
(hemodialysis)
4 hours, 3 times a week
Patients will eventually need a new kidney

37. Domino Kidney Transplants or Kidney Exchanges - when you aren't a match for a family member, you can participate in a kidney exchange.