Chapter 23
The Urinary System
I. Introduction
A. Functions of kidneys
1. Filter plasma โ Filter plasma by eliminating wastes and returning useful
chemical
2. Regulate blood volume and pressure โ by eliminating or conserving water
3. Regulate osmolarity โ control water and solutes eliminated
4. Control blood pressure and electrolyte balance โ secrete renin
5. Control RBC count โ secrete erythropoietin
6. Regulate acid-base balance โ secrete hydrogen
B. Nitrogenous waste โ substance that is useless to the body (Fig. 23.2, pg. 907)
1. Urea โ by-product of protein catabolism
2. Uric acid โ by-product of nucleic acid catabolism
3. Creatinine โ by-product of creatine phosphate catabolism
II. Anatomy of the kidney
A. Location (Fig. 23.3, pg. 909)
1. Against posterior abdominal wall at the level of T12-L3
2. Retroperitoneal
B. Layers (Fig. 23.3, pg. 909)
1. Renal fascia โ Fibrous Connective tissue that binds the kidney to the
abdominal wall.
2. Perirenal fat capsule โ cushions the kidney and holds it in place
3. Fibrous capsule โ encloses the kidney and protects it
C. Renal parenchyma (Fig. 23.4, pg. 909)
1. Tissue that forms urine
2. Renal sinus โ medial cavity occupied by blood vessels, lymph vessels,
nerves, and urine-collecting structures
3. Renal cortex โ outer zone
4. Renal medulla โ inner zone
a. Renal columns โ extensions of the renal cortex that divide the
renal medulla
b. Renal pyramids โ tissues that contains urine producing structures
c. Renal papilla โ blunt point of the renal pyramid
5. Minor calyx โ cusped
6. Major calyx โ convergence of minor calyces forming a urine passageway
7. Renal pelvis โ convergence of major calyces forming funnel-like drain for
urine
D. Renal circulation (Fig. 23.5, pg. 910)
1. Arteries โ renal artery ๏ segmental artery ๏ interlobar artery ๏
arcuate artery ๏ interlobular artery
2. Finer branches (Fig. 23.6, pg. 911)
