Chapter 26 - Urinary System Flashcards
2 Main Functions of the Urinary System
- Osmotic Regulation = Regulating osmotic pressure of H20 & other body fluids
- Elimination of nitrogenous & other wastes
4 Different Types of Nitrogenous Wastes
- Amino Acids
- Ammonia
- Urea
- Uric Acid
Amino Acids
- 4 Uses:
1. Protein synthesis
2. ATP synthesis
3. Gluconeogenesis
4. Fat synthesis - Amine (NH2) groups must be removed before 2, 3, or 4
Ammonia
- NH2 groups + hydrogen = Ammonia (NH3)
- Very toxic
- Excreted by fish & amphibians
- NH3 + H20 -> NH4+ + OH- = ammonium hydroxide
Urea
-Main nitrogenous waste excreted by mammals
-Less toxic than ammonia
-Synthesis requires significant amounts of energy
-Is an amino acid
*Liver urea cycle:
CO2 + 2NH3 + ATP -> Urea + H2O
Uric Acid
- Excreted by birds, reptiles & insects
- Relatively non-toxic
- Low water-solubility
- Synthesis is energy-demanding
- Nucleic acid metabolism: purines (G & A) -> xanthine hypoxanthine -> uric acid
4 Components of the Human Urinary System
- Kidneys (pair)
- Ureters (pair)
- Urinary Bladder
- Urethra
Kidneys
- Shaped like kidney-beans
- Location: paravertebral & retroperitoneal; below diaphragm
3 Layers Surrounding Kidneys
- Renal Capsule: Around outside of kidney
- Adipose Capsule: Surrounds renal capsule
- Renal Fascia: CT outside of adipose capsule
Hilum
Concave depression at center of kidney
Nephroptosis
- AKA “Floating Kidney”
- Occurs due to weakening of renal fascia & adipose tissue
- Can lead to hydronephrosis
Hydronephrosis
Atrophy of the kidneys, leading to renal failure
3 Areas of the Kidney
- Cortex
- Medulla
- Pelvis
* All 3 are composed of parenchyma & supporting stroma
Renal Cortex
- Granular outer & juxtamedullary areas
- Composed of renal columns
Renal Medulla
- Striated, located in the middle area
- Composed of renal pyramids
Renal Pelvis
- Hollow, inner area for urine collection (via minor calyces)
- Renal sinus = fat-filled cavity
8 Functions of the Kidneys
- Regulates blood & ECF electrolytes
- Regulates blood volume
- Regulates blood pH
- Removes toxic wastes & foreign substances from blood
- Regulates blood pressure
- Maintains blood osmolarity
- Produce hormones (calcitriol, EPO)
- Helps regulate blood glucose via glycogenolysis, glycogenesis & gluconeogenesis
Nephrons
- Functional units of the kidneys
- 2 main components
2 Main Components of the Nephrons
- Renal Corpuscle
2. Renal Tubule
Renal Corpuscle (2 Parts)
- Bowman’s Capsule
2. Glomerulus
Bowman’s Capsule
- AKA “Glomerular Capsule”
- Cuplike structure, which receives glomerular filtrate
- 2 Layers: visceral layer & parietal layer
- Capsular Space/ “Bowman’s Space” = Space between visceral & parietal layers; receives glomerular filtrate
Glomerulus
Capillary tuft surrounded by visceral layer of Bowman’s capsule
Filtration Membrane of the Glomerulus (3 Parts)
- Fenestrated Glomerular Endothelium
- Glomerular Basement Membrane
- Slit Membrane
Fenestrated Glomerular Endothelium
- Permeable to plasma components
- Contains mesangial cells; regulate the surface area available for filtration