Urinary System Flashcards
What is the difference between excretion and elimination?
-Excretion removes metabolic waste while elimination removes indigestible material (dietary fiber)
What are the principle organs involved in excretion?
-Lungs, liver, skin, kidneys
What are the units comprising the kidney called?
-Nephrons
What are the three regions of the kidney?
-Outer cortex, inner medulla, renal pelvis
What structures are in the outer cortex regions?
-Bowman’s capsule/glomerulus and convoluted tubules
What structures are in the medulla?
-Loop of Henle and collecting duct
What structures are in the pelvis?
-Collecting tubules
Trace the flow of the kidney.
-Capsule –> Proximal Convoluted Tubule –> Loop of Henle –> Distal Convoluted Tubule –> Collecting Duct –> Ureter –> Urinary Bladder –> Urethra
What surrounds most of the nephron?
Peritubular capillary - aids in reabsorption of aa, glucose, salts, water
What are the three steps of urine formation?
-Filtration, Secretion, Reabsoption
What drives filtration?
-Passive, driven by hydrostatic pressure of blood
What is relation of filtrate and blood plasma?
-Isotonic
What is secreted into filtrate in secretion step?
-Waste substance (acids, ions, metabolites) from interstitial fluid by passive/active transport
What is reabsorbed and returned to blood?
- Glucose, salts, amino acids (active)
- Water (passive)
Where does reabsorption occur mainly?
-Proximal convoluted tubule (active)
After reabsorption, what is formed?
-Concentrated urine hypertonic to blood
What is the primary function of the nephron?
-Clean blood plasma of unwanted substances through selective permeability and osmolarity gradient of nephron
Where is the primary site of nutrient reabsorption?
-Proximal convoluted tubule
Where is the major site of secretion of substances into the filtrate?
-Distal convoluted tubule
What is the descending loop of Henle permeable to?
-Permeable to water but not to ions or urea
What is the thin ascending limb of the loop of Henle permeable to?
-Permeable to ions (passive), impermeable to water
What is the thick ascending limb of the loop of Henle’s function?
-Active reabsorption of sodium, potassium, and chloride
What creates the osmolarity gradient between the tubules and interstitial fluid?
-Na+ and Cl-
Which direction does tissue osmolarity increase from?
-Cortex to inner medulla
