9. Urinary System Flashcards
Purpose of the urinary system
- Removal of waste products
- Assist liver to detoxify poisons
- Regulating blood volume and pressure
- Regulating plasma concentration of Na+, K+ & Cl-
- Helping to stabilize blood pH
- Conservation of valuable nutrients
Osmolarity
Number of particles in specific volume of solution
Gravity
Plasma and bodily fluids in urine. Normal: 290-300 mOsm/L
Where are kidneys located?
Either side of the vertebral column, located in the abdominal cavity (retroperitoneal space).
Left kidney is superior to the right because of the liver.
The Ureters
- Approx 30 cm long
- Has smooth muscles for peristalsis
- Liner with transitional epithelium
The Urinary Bladder
Has folds for expansion: rugae
Has stretch receptors for micturition
Is muscular: smooth muscle = dertruser muscle
Layers of the Urinary Bladder
Transitional epithelium
Laminate propria
Submucosa
Transitional epithelium of the urethra
Non-keratinised stratified squamous cells
The Nephron
Structural and functional units that form urine— Approximately 1 million per kidney
Functions of the nephron
- Filtering the blood
- Reabsorbing useful materials from blood filtration
- Secretion of waste into urine
Two main parts of the nephron
- Renal Corpuscle
- Renal Tubule
Blood vessels of the nephron do what?
- Deliver blood to nephron so I can be filtered
- Facilitate exchange of substances
Components of Renal Corpuscle
- Glomerules (a tuft of capillaries) which form a high-pressure capillary bed
- The double layered glomerular (Bowman’s) capsule which wraps around the capillaries;  Visceral layer composed of podocytes
Rebuke Tubule
The structure where filtrate is processed and modified into urine
Components of the renal tubule
- Proximal convoluted tubal (PCT)
- Loop of Henle (ascending and descending limb)
- Distal Convoluted Tubule (DCT)
- Collecting Duct
Proximal Convoluted Tube
- Directly attaches to corpuscle
- lined with simple cuboidal epithelium
- MICROVILLI on a local surface for greater surface area
Much of PCT filtrate is reabsorbed
- Especially water, glucose, amino acids and ions.
- Secretion helps to manage pH and rid the body of toxic foreign substances
Purpose of Loop of Henle
Works to establish salt concentration gradient in the medulla to promote recovery of water from filtrate
Loop of Henle (descending limb)
Freely permeable to water, but not salt
Loop of Henle (ascending limb)
Impermeable to water, but permeable to salt
Function of Distal Convoluted Tubule
- Functions more in secretion than reabsorption.
- Recovery of water and sodium is influenced by hormones: aldosterone and antidiuretic hormone (ADH)
Glomerular Filtration Rate
Amount of filtrate formed by both kidneys each minute.
Homeostasis requires kidneys to maintain a relatively constant GFR.
Juxtaglomerular Apparatus (JGA)
- Important in regulation of filtration formation and blood pressure.
- Regulates blood pressure in the kidney in conjunction with the ANS
JGA in DCT: Macula Densa
- Cuboidal cells which monitor fluid compensation (Na+)
- Single non-motile cilium monitors flow rate
