1. Chapter 15 The Urinary System

2. Functions of the Urinary System
1. Elimination of waste
Nitrogenous wastes
Toxins
Drugs
2. Regulates homeostasis
(kidney function)
Water balance
Electrolytes
Acid-base balance in the blood
Blood pressure
RBC blood cell production
Activation of vit. D

3. Organs of the Urinary system
Kidneys
Ureters
Urinary bladder
Urethra

4. Location of the Kidneys
Against dorsal wall
T12 to L3
Right lower than left
Attached to ureters, renal blood vessels, & nerves at renal hilus
Atop kidney is adrenal gland

5. Coverings of the Kidneys
1. Renal capsule
Surrounds kidney
2. Adipose capsule
protection
keeps kidney in location

6. Regions of the Kidney Renal cortex – outer region
Renal medulla – inside the cortex
Renal pelvis – inner collecting tube

7. Kidney Structures
Medullary pyramids – triangular regions of tissue in medulla
Renal columns – extensions of cortex-like material inward
Calyces – cup-shaped structures that funnel urine towards renal pelvis

8. Blood Flow in the Kidneys

9. Nephrons Structural and functional units of the kidneys Forms urine
Main structures
a. Glomerulus
b. Renal tubule

10. Glomerulus Specialized capillary bed
Arterioles on both sides (maintains high pressure)
Large afferent arteriole
Narrow efferent arteriole
Capillaries covered with podocytes from the renal tubule
Glomerulus sits within a glomerular capsule (1st part of the renal tubule)

11. Renal Tubule Glomerular (Bowman’s) capsule Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule

12. Types of Nephrons 1. Cortical 2. Juxtamedullary entirely in cortex
most nephrons
2. Juxtamedullary
at boundary of cortex & medulla

13. Peritubular Capillaries
Arise from efferent arteriole
Normal, low pressure capillaries
Attached to venule
Cling to renal tubule
Reabsorb substances from collecting tubes
Urine Formation
Filtration
Reabsorption
Secretion

14. Filtration Nonselective passive process
Water and solutes smaller than proteins are forced through capillary walls (Filtrate same as blood plasma)
Blood cells cannot pass out to the capillaries
Filtrate - collected in glomerular capsule and leaves via the renal tubule

15. Reabsorption Peritubular capillaries reabsorb
- Some water, Glucose, Amino acids, Ions
Some passive, most active
Most reabsorption occurs in proximal tubule
Not Reabsorbed
Nitrogenous waste products
- Urea
- Uric acid
- Creatinine
Excess water

16. Secretion – Reabsorption in Reverse
Materials move from peritubular capillaries into renal tubules
H+ & K+
Creatinine
Materials left in renal tubule move to ureter