Urinary System (Herron) Flashcards
What structure conducts urine from nephron tubules to renal papillae?
collecting ducts
Collecting ducts span what two portions of the kidney?
cortex and medulla
Why do proximal convoluted tubules appear to have a more blurred/fuzzy border than distal?
they have a (microvilli) brush border, which increases its surface area
What type of cell lines the thin segment?
What type of cell lines the collecting duct?
squamous
cuboidal
How can you differentiate between collecting ducts and distal conv tubules?
the cuboidal cells of the collecting duct are sharply/clearly differentiated
What does the cortical labyrinth consist of?
renal corpuscles, proximal convoluted tubules, distal convoluted tubules
What does the medullary ray consist of?
aggregation of straight tubules and collecting ducts (between cortical labyrinth)
What is notable about the relationaship between the efferent arterioles and the tubules?
the arteriole continues into the peritubular capillaries; these capillaries and the tubule are constantly exchanging materials via the interstitium
The kidney is covered by:
a capsule, composed of connective tissue
The hilum contains:
renal vessels
renal nerves
renal pelvis
Pyramids are located in the (medulla/cortex), and the apex of a pyramid is called the:
medulla
renal papilla
The tissue between adjacent pyramids is called the:
What is its function?
renal column
medullary extension of the renal cortex which allows the cortex to be better anchored
(note: they are regarded as part of the medulla, but they contain cortical tissue)
What are the components of a renal lobe?
medullary pyramid and the overlying cortex
1/2 of the renal columns on each side of pyramid
(also notes that it is the nephrons grouped around a single medullary ray which drain into a single collecting duct)
What are calyces, and what is the difference between a major and minor calyx?
- extensions of the renal pelvis
- minor calyx surrounds one renal papilla
- major calyx is the combination of two or more minor calyces
What 3 hormones do the kidneys produce?
Erythropoietin
Renin
Converts vitamin D precursor to active form of vitamin D
This structure is the beginning of a nephron and the site where blood is filtered:
renal corpuscle
T/F: Collecting ducts are part of nephrons.
F
What structures originate from renal corpuscles and ends at collecting ducts?
tubules
In humans, a normal kidney contains ____ to _____ nephrons
800,000 to 1,000,000
Proximal thick segment is comprised of:
Prox. convoluted tubule (PCT)
Prox. straight tubule (PST)
Distal thick segment is comprised of:
Medullary thick ascending limb (MTAL)
Cortical thick ascending limb (CTAL)
Distal convoluted tubule (DCT)
Connecting segment
Masca densa is a specialized portion of the:
distal straight tubule
The Loop of Henle is comprised of:
Medullary thick ascending limb
Prox. straight tubule
Thin limb
What types of tubules penetrate the medulla?
Straight tubules
Collecting ducts conducts urine from _____ to ____
nephron tubules to renal papillae
Collecting ducts consist of:
Cortical collecting duct (CCD)
Medullary collecting duct (MCD)
Where are the ducts if Bellini located?
renal papilla
What is often visible in proximal tubule cells under light microscopy? What surface are these on?
Brush border (apical microvilli) luminal surface
Proximal tubules are (half/twice) as long as distal tubules, and display (more/less) nuclei in cross section.
twice
less
What are the two layers of the Bowman’s capsule? How do these relate to the structural organization of the renal corpuscle?
Parietal (simple squamous cells) forms the outer wall of Bowman’s capsule
The visceral layer adheres to the capillary tuft
Between the two layers is the urinary space
Where are mesangial cells located, and what is their function in the renal corpuscle?
distributed amongst the capillaries
- phagocytose debris
- provide structural support
- secrete substances for repair of glomerulus, such as IL1 and platelet-derived growth factor
(note: their primary purpose may be to clear up the basement membrane)
What are the 3 types of nephrons?
- cortical nephrons, which have short loop of Henle (dip into outer medulla)
- Juxtamedullary nephrons, which are close to the medullary boundary and have long loop of Henle (that extends deep into inner medulla)
- Intermediate,which have an intermediate-length loop of Henle
The arcuate artery divides:
cortex and outer medulla
What are the two subdivisions of the cortex, and what do the consist of?
Cortical labyrinths
- renal corpuscles
- proximal convoluted tubules
- distal convoluted tubules
Medullary rays
aggregation of straight tubules and collecting ducts
(lies between cortical labyrinth)
A lobule consists of: (3)
medullary ray
the 2 adjacent 1/2 labyrinths
The medulla does NOT have: It DOES (only) have:
no labyrinths or medullary rays!
only tubules and collecting ducts
What nephron structures will you find in the medulla?
proximal straight tubule
thin limb
distal straight tubule
The kidney receives __% of cardiac output; 90% of this goes to the:
25
cortex
What are the progressive branches of the renal artery? 1. renal artery 2. 3. 4. 5. 6. afferent arterioles
- renal
- lobar arteries
- interlobar arteries
- arcuate
- interlobular
- afferent
What type of artery are located around the boundaries of the papillae?
arcuate
What arteries ar located midway between medullary rays?
interlobular
What arteries give rise to the tuft of capillaries that forms the glomerulus?
afferent arterioles
Capillaries in the glomerulus reunite to form:
efferent arteriole
What does the efferent arteriole give rise to, and where are these located?
peritubular capillaries
surround the nearby tubules
What are arteriole rectae?
Efferent arterioles from the juxtamedullary glomeruli that descend into the medulla
The three principal activities of nephrons in producing urine are (and where do they occur?):
1. Filtration of blood -- renal corpuscle creates ultrafiltrate (aka provisional urine)
- Reabsorption – PCT (mostly)
Reabsorbs filtered products back into the blood
(water, electrolytes, and glucose) - Secretion
Substances from blood into tubules (where urine exists)
(H+, K+, NH3 and certain drugs)
What is in the ultrafiltrate?
H2O
Na+ (and other ions)
glucose
waste products (urea, uric acid, creatinine)
What component of the endothelium allows fast movement of water?
aquaporin-1 water channels
Filtration apparatus consists of what three components?
- Fenestrated endothelium of glomerulus (i.e., capillary)
- Basement membrane of the glomerulus (the loops of capillaries)
- Basement membrane of podocytes
What is the principal component of the filtration?
Glomerular basement membrane
What are filtration slits?
elongated spaces between pedicels which change in size/patency (actin in pedicels)
What layers comprise the glomerular basal lamina? What are their locations and functions?
- Lamina rara externa
- -adjacent to the podocyte processes
- -impede passage of negatively charged molecules - Lamina rara interna
- -adjacent to the capillary endothelium
- -impede passage of negatively charged molecules - Lamina densa
overlapping portion of the two basal laminae
How does the endothelium of the filtration apparatus differ from the endothelium of other capillaries?
larger
more numerous fenestrations
What molecules are allowed to pass through the glomerular basement membrane?
neutrally charged and less than 70,000 Daltons
What prevents the passage of negative molecules across the GBM (regardless of size)?
heparan sulfate and sialic acid
Why does the presence of albumin in the urine = kidney damage?
albumin generally excluded, but is so close to the minimal passage size that if the filter is damaged, albumin will appear in the urine
What causes proteinuria in diabetes mellitus?
(even though physically thicker than normal) the basal lamina is functionally leaky so an excessive amount of protein is lost in the urine
What are the three conditions that may present together in diabetes mellitus, and what are they called (when all 3 present)?
- proteinurea (due to leaky basement lamina)
- hypoalbuminemia (due to loss of albumin through the basement lamina)
- edema (due to low colloid pressure)
*Nephrotic syndrome
Reabsorption occurs when filtered products in the renal tubules are reabsorbed back into:
peritubular capillaries
Secretion occurs when products from peritubular capillaries are secreted into: (where, for the most part?)
(provisional) urine in thin limb, distal tubules and collecting ducts.
products = H+, K+, NH3 and certain drugs
What is the major site of reabsorption, where ___% of glucose is reabsorbed from ultrafiltrate?
proximal convoluted tubule
100 (theoretically)
A person typically excretes ___ to ___ liters of urine daily
1.5 to 3
The juxtaglomerular apparatus consists of:
and functions in:
macula densa, the juxtaglomerular cells (on afferent and efferent arterioles) and extraglomerular mesangial cells
regulation of blood pressure
How do macula densa cells compare to adjacent tubule cells?
narrower; usually taller; more crowded
Juxtaglomerular cells of the afferent and efferent arterioles are what type of specialized cell?
What is the function of JG cells?
smooth muscle
When low Na+ intake or decreased volume of circulating blood, secrete renin to activate renin-angiotensin-aldosterone to restore homeostasis (note: MD signals the secretion of renin)
Mesangial cells secrete:
What does this do?
platelet derived growth factor (PDGF)
responds to glomerular injury
*The primary purpose may be to clean glomerulus basement membrane.
What pathways does urine take to reach the bladder?
- kidneys
- minor calyces
- major calyces
- renal pelvis
- ureters
- bladder
All excretory passages except ______ are lined by transitional epithelium, which is:
the lower part of the urethra
stratified or pseudostratified columnar epithelium
What are the layers of the muscularis of the ureter? How do these contribute to urine flow?
- inner longitudinal layer
- middle circular layer
- outer longitudinal layer (only at lower end of ureter)
Regular peristaltic contractions of the muscularis muscles
The lumen of the bladder is lined with _____ (cell type). The wall of the bladder is comprised of 3 layers:
transitional epithelium
inner longitudinal layer, middle circle, and outer longitudinal layer (smooth muscle) **note: the muscularis in the bladder is thicker than in the ureter
