Urinary System Flashcards
Functions of the Urinary System (8)
- Filters Wastes from Blood
- Regulates Ion Levels in Plasma
- Regulates Blood pH
- Conserves Valuable Nutrients
- Regulates Blood Volume
- Regulates RBC Production
- Stores Urine
- Excretes Urine
Organs of the Urinary System
- Kidneys
- Ureters
- Urinary Bladder
- Urethra
Kidney Location
At level of which vertebrae?
Which is higher?
- against dorsal body wall
- retroperitoneal
- at level of T12 to L3
- left kidney higher than right
Two Coverings of the Kidneys
Fibrous Capsule - tough dense CT, surrounds each kidney, giving it shape and a barrier
Adipose Capsule - external to fibrous capsule, surrounds and protects kidney, keeping it in correct location
What is this entire organ?
kidney
What are the three regions of the kidney?
Renal Cortex - outer region; granular appearance
Renal Medulla - inner to cortex; darker
Renal Sinus - large space medial to hilum containing calices, blood vessels, renal pelvis, nerves and fat
Renal Cortex
- outer layer of kidney containing renal corpuscles and parts of renal tubules
Renal Medulla
- inner layer of kidney containing renal pyramids with loops of Henle
What’s this outer layer?
Renal Capsule
- outer dense CT layer
- thin, transparent and lies directly on renal surface
What is this space or notch?
Renal Hilus
- notch in kidney where renal artery and nerve enter and renal vein and ureter exit
Renal Pyramids
- cone-shaped medullary structures containing loops of henle
- 6-18 per medulla
- wide, outer edge is base
- narrow, inner edge near papillae is apex
Renal Columns
- cortical tissue between pyramids
- path of interlobar arteries and veins
Renal Papilla
- pointed end of renal pyramid
- site of collecting duct drainage into calyx
Minor Calyx
- funnel-like structure which collects urine from collecting ducts at papillae
Major Calyx (pl. Calices)
- collects urine from minor calyx and drains it to renal pelvis
Renal Pelvis
- chamber formed by merging of the two major calyces
- connected to ureter
What is the entire structure highlighted by the green line?
What type is it? And what is the other type?
Nephron
- the functional unit of the kidney
- shown here is a Juxtamedullary Nephron, meaning its corpuscle is close to the medulla and its loop of Henle extends deep into the medulla to create an osmotic gradient for creating different concentrations of urine (15% of nephrons are JM)
- the other kind is a Cortical Nephron, its corpuscle is further into the cortex and its loop of Henle just barely dips into the medulla (85% of nephrons)
What are the two components of the nephron?
Renal Corpuscle - glomerulus and Bowman’s capsule
Renal Tubule - PCT, loop of Henle, DCT
What is the entire bracketed structure?
Renal Corpuscle
- site of filtration within nephron
- spherical structure located in cortex
- made up of outer Bowman’s capsule and inner glomerulus
What is it?
What are its layers and their cells?
Bowman’s (or Glomerular) Capsule
- double walled capsule around glomerulus
- receives filtrate and empties into PCT
Two Layers:
- Visceral Layer (inner) - branching podocytes interdigitate and cling to glomerulus
- Parietal Layer (outer) - simple squamous epithelium
What is this bundle of tubes?
Glomerulus
- a knot of specialized capillaries within a Bowman’s capsule
- capillaries are fenestrated and porous to allow filtration into capsular space
What is the lumen of the Bowman’s capsule called?
Capsular Space
What are the capillaries of the glomerulus called?
Glomerular capillaries
(duh)
What is this starred structure and how can you differentiate it from other similar structures?
Afferent arteriole
- it is larger than the efferent arteriole to maintain high pressure within the corpuscle for filtration
What is the starred structure and how can you differentiate it from other similar structures?
efferent arteriole
- it is narrower in diameter than the afferent arteriole, which helps maintain pressure within the glomerulus for filtration
What are the two poles of a renal corpuscle?
Vascular Pole - where arterioles enter and exit
Urinary Pole - where PCT exits
What are the blue highlighted cells?
Podocytes
- cells which sit on glomerular capillaries and make up the visceral layer of the Bowman’s capsule
- their pedicel processes interdigitate, creating slits through which blood filters
What are the blue highlighted structures?
Pedicels
- interdigitating podocyte processes which form slits through which blood filters
Name the collection of structures through which blood flows in the renal corpuscle.
What are its three main components?
Filtration Membrane
- Fenestrated Capillary Endothelium
- Basement Membrane
- Filtration Slits (between pedicels)
The entire structure running from corpuscle to collecting tubule here:
Renal Tubule
- series of tubules through which post-corpuscular filtrate passes and is processed into urine
3 parts:
- Proximal Convoluted Tubule
- Loop of Henle
- Distal Convoluted Tubule
what is it?
what is its function in filtrate processing?
proximal convoluted tubule
- portion of renal tubule between bowman’s capsule and loop of Henle
- reabsorbs nutrients, plasma proteins and electrolytes and releases them into surrounding interstitial fluid
What are these green highlighted structures?
What are its two parts?
Loop of Henle
- AKA nephron loop
- delivers fluid from PCT to DCT
Two limbs:
- descending limb - down into medulla from corpuscle
- ascending limb - up to DCT from medulla
What is the green highlighted structure here?
What is its function in filtrate processing?
Distal Convoluted Tubule
- twisted portion of renal tubule closest to collecting duct
- actively secretes ions, acids, drugs and toxins and reabsorbs sodium from urine
What is this highlighted tube?
collecting duct
- collects urine from DCTs of several nephrons
- runs through cortex into medulla
What is this green highlighted structure?
papillary duct
- adjacent collecting tubules join to form larger ducts at the papilla which drain into minor calices
renal artery
green vessels:
segmental artery
2
interlobar artery
arcuate artery
red #1
interlobular artery
AKA cortical radiate artery
- the smaller, purplish tube network
peritubular capillaries
- located around PCT and DCT
vasa recta
- thin-walled looping straight capillaries surrounding the loop of Henle in juxtamedullary nephrons
- maintains osmotic gradient in medulla for concentration of urine
15
interlobular vein
blue vessel:
arcuate vein
blue vessel:
interlobar vein
(no segmental vein, de-oxygenated blood goes straight from interlobar to renal vein)
renal vein
(no segmental vein, de-oxygenated blood goes straight from interlobar to renal vein)
What is the entire structure marked I :
- what is its function?
- what are its parts?
Juxtaglomerular Apparatus
- controls blood pressureby releasing renin which produces angiotensin and causes vasoconstriction
2 Main Parts:
- Afferent Arteriole - granular cells
- Distal Convoluted Tuble - macula densa cells
What is indicated by the large orange arrow?
Macula Densa Cells
- tall, modified columnar cells on DCT closest to glomerular arterioles
- sense osmolarity of tubular fluid
Granular Cells
- modified smooth muscle cells of afferent arteriole wall
- release renin when stimulated by macula densa cells, renin then activates angiotensin, causing vasoconstriction and a subsequent increase in blood pressure
indicated by arrows:
- what are they?
- what cells and layers are they lined with?
Ureters
- 25 cm x 1.7 cm, muscular tubes which peristalticly carry urine to the bladder from the kidneys
- retroperitoneal and enter bladder posteriorly via a valve
- line with transitional epithelium and two layers of smooth muscle (inner longitudinal, outer circular)
Part C
What is it? Where is it?
What are its cells and layers?
Urinary Bladder
- collapsible, muscular sac which stores urine
- located on pelvic floor, posterior to pubic symphysis
- anterior to rectum in males, vagina & uterus in females
- line with transitional epithelium
- 3 layers of smooth muscle (detrusor muscle is the spirally, longitudinally and circularly arranged bladder muscle)
What is this green highlighted structure?
What cells line it?
What are the gender differences in its structure?
urethra
- tube inferior to bladder which moves urine out of the body and carries semen during ejaculation
- lined by transitional epithelium (distal urethra has stratified columnar in men)
- males: 20 cm, three regions
- females: 3-4 cm
Internal Urethral Sphincter
- between bladder and urethra
external urethral sphincter
- within urogenital diaphragm
The three regions of the male urethra (1, 2 and 3, respectively):
- Prostatic Urethra - passes through prostate
- Membranous Urethra - through urogenital diaphragm
- Spongy (penile) Urethra - passes through the length of the penis
4
glomerulus
6
distal convoluted tubule
- lumen appears clear
- one near vascular pole of corpuscle has macula densa cells (larger, more columnar) on one side
7
proximal convoluted tubule
- lumens appear fuzzy due to epithelial microvilli
1
glomerular capsule
- bowman’s capsule surrounding glomerulus
What is this tissue?
renal medulla
- all tubules and collecting ducts, no glomeruli visible
what is this tissue?
renal cortex
- glomeruli visible (boxed at bottom)
What is the outer CT layer of kidney and what does it look like on a slide?
renal capsule
- thin outer CT layer
What is this structure? And what kind of cells line its lumen?
Urinary Bladder
- transitional epithelium
What are the layers of the bladder wall and how do they look on a slide?
- Mucosa (transitional epithelium and basement membrane)
- Submucosa
- Muscularis (detrusor muscle)
