Urinary Anatomy Study Guide Flashcards
What are the major organs of the urinary system
kidneys, ureters, urinary bladder, urethra
kidneys
major excretory organs, create urine
Ureters
transport urine from kidneys to bladder
Urinary bladder
temporarily stores urine
Urethra
transports urine out of the body
How do the kidneys maintain homeostasis
Regulate total water volume 1and solute concentration
Regulating ion concentrations in extracellular fluid
Ensuring long term acid base balance
Excreting metabolic wastes, toxins, drugs
Producing erythropoietin
Producing renin
Activating vitamin d
Carrying out gluconeogenesis (production of glucose)
Renin
regulate blood pressure
erythropoietin
regulate rbc function
What structures enter/exit the renal hilum?
Ureters, blood vessels, lymphatics, nerves
3 layers surrounding the kidney
renal fascia (superficial), perirenal fat capsule (middle), fibrous/renal capsule (deep)
Renal ptosis
1 or both kidneys drop to a lower position
- Caused by loss of surrounding fatty tissue (emaciation/rapid weight loss)
- Can lead to kink in ureter and back up of urine into kidney
Hydronephrosis
backup of urine into the kidney because of ureteral obstruction or infection (like UTI) – can cause kidney damage, tissue death, renal failure
Pyelonephritis
inflammation or infection of the kidney, usually extensions of UTIs (can cause kidney to swell, abscesses form, and pelvis fills with pus)
dialysis
Process of removing waste and extra fluid from the body when the kidneys are unable to
order of urine flow from origination in the nephrons to exiting the body through the external urethral orifice.
Urine is created in the nephron and drains continuously through the renal papillae
Renal pyramid
Minor calyx
Major calyx
Renal pelvis
Ureter
bladder
urethra
order of arterial blood flow into the kidney starting with the aorta.
Aorta → renal artery → segmental artery → interlobar artery → arcuate artery → cortical radiate (interlobular) artery
Memorize the order to venous blood flow out of the kidney starting with the cortical radiate veins.
Cortical radiate (interlobular) veins → arcuate veins → interlobar veins → renal vein → IVC *no segmental veins
function of a nephron
Structural and functional unit of the kidney, it forms urine
- Makes cell-free and protein-free filtrate from blood
- Chemicals are either added/subtracted from filtrate
- Filtrate is emptied into collecting ducts where it becomes urine
What are the 2 parts of a renal corpuscle?
- Glomerulus: tuft of capillaries
- glomerular/bowman’s capsule: hollow structure that surrounds glomerulus and is continuous with renal tubule, has parietal and visceral layer, and filtrations slits (filtration slits: clefts/openings between foot processes. Filtrate passes through these slits and into the capsular space)
type of endothelium that makes up the glomerulus
Fenestrated endothelium - highly porous, allowing efficient formation of filtrate
podocytes
Branching epithelial cells in the visceral layer of the glomerular capsule. They terminate in foot processes. they function in protection of filtrate
3 parts of the renal tubule
Proximal convoluted tube: closest to the renal corpuscle
Nephron loop: u-shaped, hairpin turn, has ascending and descending limbs Distal convoluted tube: furthest from the renal corpuscle, drains into collecting duct
PCT structure
cuboidal cells with dense microvilli that form a brush border
- Increased surface area
- Large mitochondria
Nephron loop structure
u shaped structure with two limbs
DCT structure
cuboidal cells with very few microvilli
PCT function
reabsorption of water + solutes and secretion of substances, confined to renal cortex
DCT function
secretion, less absorption, confined to renal cortex
Nephron loop function
- Descending limb: proximal part is continuous with PCT; distal part (descending thin limb) is simple squamous epithelium
- Ascending limb: typically thicker, cuboidal and columnar cells, right side
Collecting ducts
run side by side through medullary pyramids and receive filtrate from many different nephrons
Fused collecting ducts
deliver urine through the renal papillae to the minor calyces
two major types of cells within collecting ducts
Principal cells
Intercalated cells
Principal cells
more plentiful, sparse, short microvilli, maintain the body’s water/Na+ balance
Intercalated cells
cuboidal cells with abundant microvilli, exist in types A and B – both help maintain the acid base balance of blood
two classes of nephrons
cortical (85%) and juxtamedullary (15%)
cortical nephrons
Almost entirely in the cortex
Peritubular capillaries
Juxtamedullary nephrons
Originate near the cortex - medulla junction
Have long nephron loops that deeply invade the renal medulla
Important for the production of concentrated urine
Vasa recta
Glomerulus
- Its capillaries are specialized for filtration
- 99% of filtration will be absorbed
- Glomerular Capillaries are fed and drained by arterioles - O2 is not dropped off
afferent arterioles
enter the glomerulus
Arises from the cortical radiate arteries
Efferent arterioles
leave the glomerulus
Feeds into the peritubular capillaries/vasa recta
Peritubular capillaries
- Lower pressure, porous capillaries adapted for reabsorption of water solutes from the filtrate within the renal tubule
- arise from efferent arterioles and cling to any adjacent renal tubules in the cortex
- Empty into into venules → cortical radiate veins
What keeps the pressure high within a glomerulus?
The afferent arteriole is larger than the efferent arteriole, so blood pressure in the glomerulus is high – increased filtration
Memorize the order to venous blood flow out of the kidney starting with the cortical radiate veins.
Cortical radiate (interlobular) veins → arcuate veins → interlobar veins → renal vein → IVC *no segmental veins
Where do the nephron’s glomerulus, peritubular capillary, and afferent + efferent arterioles fit into the pathway of blood flow that you memorized above?
(first five steps) → Cortical radiate arteries → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries → venules → cortical radiate veins → (next 4 steps)
JGC
Juxtaglomerular complex, Found in each nephron, region where the most distal portion of the ascending limb of the nephron loop lies against the afferent arteriole feeding the glomerulus
- Both structures are modified at the point of contact
- Plays important role in regulating the rate of filtrate formation and systemic blood pressure
3 cell populations of the JGC
macula densa, granular cells (juxtaglomerular cells), extraglomerular mesangial cells
Macula densa
- Tall, closely packed cells in the ascending limb of the nephron loop
- Chemoreceptors that sense the NaCl content of filtrate entering the DCT
Granular cells (juxtaglomerular cells)
- enlarged smooth muscle cells in the afferent arteriole wall
- Act as mechanoreceptors to sense blood pressure in the afferent arteriole
- Contain secretory granules for the enzyme renin
Extraglomerular mesangial cells
- Located between the arteriole and tubule cells
- Interconnected by gap junctions
- May pass regulatory signals between macula densa and granular cells
