Exam 4 pt. 1 Flashcards
What are the major organs of the urinary system? What are each of their functions?
o Kidneys: major excretory organs, create urine
o Ureters: transport urine from kidneys to bladder
o Urinary Bladder: temporarily stores urine
o Urethra: transports urine out of the body
How to the kidneys maintain homeostasis?
o Kidneys: the body’s major excretory organs
o Kidneys maintain the body’s internal environment by:
o Regulating total water volume and total solute concentration
o Regulating ion concentrations in extracellular fluid (ECF)
o Ensuring long-term acid-base balance
o Excreting metabolic wastes, toxins, drugs
o Producing erythropoietin to regulate RBC function
o Producing renin to regulate blood pressure
o Activating vitamin D
o Carrying out gluconeogenesis (production of glucose)
What is Renin? Erythropoietin?
Producing erythropoietin to regulate RBC function
Producing renin to regulate blood pressure
What structures enter/exit the renal hilum?
Renal Hilum: point of entrance/exit for ureters, blood vessels, lymphatics, nerves
List the 3 layers surrounding the kidney. Know which layer is the most superficial. Which layer is the deepest?
o Renal Fascia: anchoring outer layer of dense fibrous connective tissue
o Perirenal Fat Capsule: fatty cushion
o Fibrous/Renal Capsule: transparent capsule – prevents spread of infection to the kidneys
(superficial to deepest)
Define renal ptosis
o Renal Ptosis: condition in which 1 or both kidneys drop to a lower position
Caused by loss of surrounding fatty tissue – likely with emaciation or rapid weight loss
Can lead to a kink in the ureter and the back up of urine into the kidney
Define hydronephrosis
o Hydronephrosis: backup of urine into the kidney because of ureteral obstruction or infection
Can cause kidney damage, tissue death, renal failure
Define pyelonephritis
o Pyelonephritis: inflammation or infection of the kidney
Often extensions of urinary tract infections (UTIs)
In females, UTIs are generally caused by the spread of fecal bacteria, less often by blood-borne bacteria
In severe pyelonephritis, the kidney swells, abscesses form, and the pelvis fills with pus
How do hydronephrosis and pyelonephritis relate to urinary tract infections and renal calculi?
What is dialysis?
Dialysis: process of removing waste and extra fluid from the body when the kidneys are unable to
Review gross kidney anatomy – cortex, medulla, major and minor calyces, papillae, pyramids, and pelvis.
Renal Cortex: lighter color, granular appearance
Renal Medulla: darker color, contains cone-shaped masses called renal pyramids
* Papilla: the apex of each pyramid
* Renal Columns: projections from the renal cortex that divide the renal pyramids
Renal Pelvis: funnel-shaped tube, continuous with the ureter
* Major Calyces: branching extensions of the pelvis
* Minor Calyces: subdivisions of the major calyces, enclose the papillae
Review gross kidney anatomy – cortex, medulla, major and minor calyces, papillae, pyramids, and pelvis.
Know the order of urine flow from origination in the nephrons to exiting the body through the external urethral orifice.
o Urine is created in the nephrons and drains continuously through the renal papillae.
Renal Pyramid
Minor Calyx
Major Calyx
Renal Pelvis
Ureter
Memorize the order of arterial blood flow into the kidney starting with the aorta.
o Because the kidneys are responsible for cleaning and adjusting the composition of blood, they have a rich blood supply
o The renal arteries deliver 1/4th of cardiac output to the kidneys each minute!
o Arterial Flow
aorta -> renal artery -> segmental -> interlobar -> arcuate -> cortical radiate (interlobular)
Memorize the order to venous blood flow out of the kidney starting with the cortical radiate veins.
Venous Flow
cortical radiate (interlobular) -> arcuate -> interlobar -> renal vein -> IVC
There are no segmental veins!
Generally, what is the function of a nephron?
o Nephron: the structural + functional unit of the kidney, forms urine
o > 1 million nephrons per kidney
o Each nephron makes cell-free and protein-free filtrate from blood
o Chemicals are either added and/or subtracted from filtrate
o Filtrate is emptied into collecting ducts where it becomes urine
What are the 2 parts of a renal corpuscle?
o Glomerulus: tuft of capillaries composed of fenestrated endothelium - highly porous, allows for efficient formation of filtrate
o Glomerular/Bowman’s Capsule: cup-shaped, hollow structure that surrounds the glomerulus, continuous with the renal tubule
Parietal Layer: simple squamous epithelium
Visceral Layer: clings to the glomerular capillaries, contains branching epithelial cells called podocytes
Podocytes terminate in foot processes
Filtration Slits: clefts/openings between foot processes. Filtrate passes through these slits and into the capsular space.
What type of endothelium makes up the glomerulus? Why is this structure important?
o Glomerulus: tuft of capillaries composed of fenestrated endothelium - highly porous, allows for efficient formation of filtrate
What are podocytes? Where are they found? What function do they participate in?
What are the 3 parts of the renal tubule? Differentiate between the 2 limbs of the nephron loop.
o Renal Tubule: about 3cm long, consists of a single layer of epithelial cells + basement membrane, each region has a unique histology and function
o Three Major Parts
Proximal Convoluted Tubule (PCT): closest to the renal corpuscle
Nephron Loop (Loop of Henle): u-shaped, a hairpin turn; has ascending and descending limbs
Distal Convoluted Tubule (DCT): furthest from the renal corpuscle; drains into the collecting duct
Histologically, what is different or unique about the structure of the different sections of the tubule?
What functions are best performed by the different sections of the tubule?
o PCT
Cuboidal cells with dense microvilli that form a brush border
Increased surface area
Large mitochondria
Functions in reabsorption of water + solutes and secretion of substances
Confined to renal cortex
o Nephron Loop
Formerly called the Loop of Henle
U-shaped structure with two limbs
* Descending Limb: proximal part is continuous with PCT; distal part is the descending thin limb (simple squamous epithelium)
* Ascending Limb: typically thicker, cuboidal + columnar cells
o DCT
Cuboidal cells with very few microvilli
Functions more in secretion, less reabsorption
Confined to renal cortex
Be prepared to label the portions of a renal tubule using anatomical landmarks.
What is a collecting duct? Fused collecting ducts become….? What are the two major types of cells within it?
o Two Cell Types
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
o Collecting Ducts run side-by-side through the medullary pyramids and receive filtrate from many different nephrons
o Collecting ducts fuse together to deliver urine through the renal papillae to the minor calyces
What are the two classes of nephrons? Be prepared to differentiate between them in a picture.
o Two major categories of nephrons
o Cortical Nephrons (85%)
entirely in the cortex
o Juxtamedullary Nephrons (15%)
Originate near the cortex-medulla junction
Have long nephron loops that deeply invade the renal medulla
