Urinary/Renal System Flashcards
What organs does the renal system include? (4)
Kidneys, ureters, bladder, urethra
What is the purpose of the urinary system? (4)
- Eliminate waste from the body
- Regulate blood volume/pressure
- Control levels of electrolytes/metabolites
- Regulate blood pH
What are the kidneys?
Two bean-shaped retroperitoneal organs in the superior dorsal abdominal cavity (partly protected by lower ribs)
Filters blood and makes urine
What is the ureter?
Tube that carries urine from each kidney to urinary bladder
Located in the inferior ventral pelvic cavity
What is the urinary bladder?
An expandable sac holding urine
What is the urethra?
Tube that transports urine from bladder to outside of body
What is the renal hilum?
Indented area of the kidney
What is the renal hilum an entrance for? (5)
Renal artery and vein, ureter, nerves, lymphatics
What are the functions of the kidney? (7)
(A WET BED)
Control Acid-base balance
Control Water balance
Maintain Electrolyte balance
Remove Toxins and waste from body
Control Blood pressure
Produce Erythropoietin
Activate vitamin D
What is the purpose of erythropoietin (EPO)? (2)
A hormone that acts on RBCs to protect against destruction
Stimulates stem cells to increase RBC production
What produces EPO hormone?
Produced by specialized cells called interstitial cells in the kidney
What is the renal cortex?
Outer layer of kidney
What is the renal medulla?
Inner region of kidney
What are the renal pyramids?
Secreting apparatus and tubules
Where are the renal nephrons?
Mostly in the kidney cortex
Has short/thin segments in loop of Henle
What is the renal pelvis?
Receives urine from collecting tubes of nephrons
What are the layers of renal connective tissue? (3)
Renal fascia - anchors to other structures (most outer)
Adipose capsule - protects/anchors (middle)
Renal capsule - continuous with ureter (inner)
What are nephrons?
Minute/microscopic structural/functional unit of the kidney
About 1m of these filtering units per kidney
What are the two kinds of nephrons? - mostly based on location of glomerulus
- Cortical: about 85% of nephrons and loop of Henle is shorter in medulla
- Juxtamedullary: about 15% and loop of Henle is loner in the medulla
What is the glomerulus?
Mass of fenestrated capillaries fed by the afferent arteriole and drains into efferent arteriole
What do the glomerulus capillaries consist of? (3)
- Glomerular endothelial cells line it
- Basement membrane (barrier) lies below endothelium (external/internal lamina)
- Epithelium attaches to Podocytes of the visceral epithelium of Bowman capsule
What is the glomerular (Bowman’s) capsule?
Where filtrate is collected within its lumen
What are the layers of the Bowman’s capsule?
Parietal
Visceral (covered by Podocytes)
What are podocytes and nephrin of the Bowman’s capsule?
Podocytes: feet-like projections that increase surface area for filtration
Nephrin: proteins linking podocytes together and allows small molecules to pass
What is the movement of filtration of the glomerulus? (4)
Capillaries endothelial cells
Basement membrane
Podocytes
Lumen of Bowman capsule
What are the five basic elements of the juxtaglomerular apparatus?
Terminal portion of afferent arteriole
Juxtaglomerular JC cells within afferent arteriole
Macular densa
Mesangial cells
Efferent arteriole at glomerulus
What are the juxtaglomerular JC cells within the afferent arteriole? (2)
- Smooth muscle cells: arteriole constriction
- Granular cells: sense arteriole BP, synthesize/store/secrete enzyme renin
What is the macula densa?
Segment of corner of ascending loop of Henle and distal tubule
Detects Na/K concentration of fluid in tubule to activate renin release
What are the mesangial cells of the juxtaglomerular apparatus? (2)
- Intraglomerular cells: support cells to glomerulus, produces phagocytes to remove trapped residues/debris
- Extraglomerular cells: not well known
What are the functions of the nephron? (5)
- Regulates extracellular fluid/osmolarity, electrolyte concentration, acid-base balance
- Excretes waste
Secretes renin - Produces erythropoietin
- Converts vit. D to active form
Where does filtration of the nephron occur?
Glomerulus
Where does reabsorption of the nephron occur?
Tubules
Where does secretion of the nephron occur?
Tubules
Where does excretion of the nephron occur?
Collecting duct
What are the two major parts of a nephron?
- Glomerular (Bowman’s) capsule
- Long renal tubule (connects to common collecting duct)
What are the three steps of the formation of urine?
- Glomerular filtration
- Tubular reabsorption & secretion
- Water conservation
Which is larger: the afferent or efferent arteriole?
The afferent arteriole (large inlet, small outlet)
Blood hydrostatic pressure is high as a result
This pressure and osmotic pressure drive water and solutes from blood plasma through a filtration membrane (like a sieve) into nephron space
Where are the points of reabsorption in the nephron tubules?
- Proximal convoluted tubule
- Loop of Henle (little water reabsorption, Na/K/Cl symporters)
- Early distal convoluted tubules (Na/Cl absorbed, parathyroid hormone stimulates Ca reabsorption and inhibits phosphate reabsorption)
- Late distal convoluted tubule & collecting duct
