Exam 3 Howard Urinary System Flashcards
What are the functions of the urinary system?
- Maintain homeostasis
- Remove toxic byproducts of metabolism from blood
- Remove urine from body
- Endocrine (produce hormones)
- Convert vitamin D precursor to active vitamin D
What are the parts of the urinary system?
- Kidneys
- Ureters
- Bladder
- Urethra
____ are conserved when maintaining homeostasis in the urinary system
Fluids and nutrients
What hormones are produced by the urinary system?
- Renin
- Erythropoietin
- Prostaglandins
What is regulated when maintaining homeostasis in the urinary system?
- Blood pressure
- Fluid volume
- Acid/base balance
What are some characteristics of the kidneys?
Large, red, bean-shaped
Where are the kidneys situated?
Retroperitoneal in the posterior abdominal wall
Why is the right kidney lower than the left kidney?
Due to the position of the liver superior to it
Which portion of the kidney faces medially?
Concave
Which portion of the kidney is situated laterally?
Convex
What is found on the concave portion of the kidney?
Recessed central fissure called hilum
The kidney is embedded in:
Perirenal fat
The ___ is a fat filled extension of the hilum
Renal sinus
____ connects to the ureters
Renal pelvis
What are the approximate measurements of the kidney?
11 cm x 4-5 cm x 2-3 cm
What region is the cortex of the kidney in?
Juxtamedullary region
What color is the outer cortex of the kidney?
Dark brown, granular
How many renal pyramids are located in the medulla?
6-12
What are the characteristics of the renal pyramids?
Striated
Base towards cortex
Apex towards hilum
The apex of the renal pyramid connects to:
Renal papilla
What side of the renal pyramid forms the corticomedullary border?
Base
What are the three parts of the kidney lobe?
Renal pyramid
Cortical arch
Cortical columns of Bertin
What are the cortical columns of Bertin also known as?
Renal columns
What do the renal columns resemble?
Cortex
What are the ducts of Bellini?
Tubes of each pyramid converge
What do the ducts of Bellini drain into?
Minor calyx
True or false: the human kidney is multilobular
True
___ minor calyces drain into major calyces
2-3
Where do major calyces drain into?
Renal pelvis
___ major calyces drain into renal pelvis
3-4
In what organisms are multilobular kidneys found?
Humans and swine
In what organisms are unilobular kidneys found?
Monkeys and carnivores
The convex surface of the fetal kidney is ____
Irregular due to development stage
The papilla of the fetal kidney projects into:
Pelvicalyceal space
What is the kidney capsule made up of?
- dense irregular collagenous CT
- occasional elastic fibers and smooth muscle cells
- occasional capsular vessels
What is the unit of structure and function in the kidney?
Uriniferous tubule
The uriniferous tubule is highly ____
Convoluted
What is the function of the uriniferous tubule?
Modifies fluid to make urine
The epithelia of the uriniferous tubule have ____
Basal lamina
What are the two components of the uriniferous tubule?
Nephron
Collecting tubule
There are ____ nephrons per kidney
1-3 million
What are the characteristics of the nephron?
Densely packed, scant CT stroma
How many nephrons does a single collecting duct drain?
Several
What do the collecting ducts converge to form?
Ducts of Bellini
What are the two types of nephrons?
- Cortical
- Juxtamedullary
What are the two components of the nephron?
- Renal corpuscle
- Complex tubular system
15% of nephrons are ____
Juxtamedullary
The juxtamedullary nephron is about ___ in length
40 mm
Which component of the nephron filters fluid expressed from the blood?
Renal corpuscle
What component of the nephron modifies filtrate to form urine?
Complex tubular system
What structures are included in the cortex of the nephron?
- Renal corpuscle
- Proximal and distal convoluted tubules
- Collecting tubules
What structures are included in the medulla?
Loops of Henle
Larger collecting tubules
The capillary bed of the renal corpuscle is:
Completely arterial
What are the two portions of the renal corpuscle?
- Glomerulus (capillary tuft)
- Bowman’s capsule
The vascular pole of the renal corpuscle contains:
Afferent and efferent arterioles
What does the urinary pole of the renal corpuscle form?
Connection with proximal tubule
What is the glomerulus?
Tufts of fenestrated anastomosing capillaries
What are the characteristics of the fenestrated anastomosing capillaries in the glomerulus?
- Large pores
- 70-90 nm
- Only exclude elements of blood and proteins larger than 69 kDa
What are the two layers of Bowman’s capsule?
- Parietal (simple squamous epithelium)
- Visceral (podocytes)
What are podocytes?
Highly modified epithelial cells with a filtering function
What are the two types of cytoplasmic extensions of the podocytes?
- Primary
- Secondary (pedicel) - create filtration slits
What are the two types of mesangial cells?
Extraglomerular and intraglomerular mesangial cells
What are the two functions of the intraglomerular mesangial cells?
- Phagocytic
- Contractile
What is the function of the phagocytic intraglomerular mesangial cells?
Clear basal lamina of proteins and other large molecules trapped by basal lamina
What is the function of contractile intraglomerular mesangial cells?
Have receptors for angiotensin II which causes vasoconstriction, thus reducing flow
How does fluid leave capillaries?
Fenestrae
What size particles are the limits for filtration?
Greater than 69 kDa
The basal lamina impedes:
Negatively charged molecules
What passes through the filtration slit diaphragm?
Uncharged and less than 4 nm
Glomerular ultrafiltrate is located in:
Bowman’s space
Where does glomerular ultrafiltrate flow into?
Proximal tubule
True or false: glomerular ultrafiltrate is not yet urine
True
What type of epithelium makes up Bowman’s capsule?
Simple squamous epithelium
What is Bowman’s capsule also known as?
Urinary space
What type of tissue makes up the glomerulus?
Capillary tuft (endothelium)
Can you distinguish podocytes from mesangial cells with H & E?
No
What are the two components of the proximal portion of the nephron?
- Convoluted tubule
- Descending thick limb of Henle (straight portion)
What makes up the limbs and loop of Henle in the nephron?
- This descending limb
- loop
- Ascending thin limb
What are the three components of the distal portion of the nephron?
- Ascending thick limb straight portion (Pars recta)
- Macula densa
- Convoluted tubule (Pars convoluta)
What are the histological characteristics of the proximal tubule?
- Simple cuboidal
- Eosinophilic granular cytoplasm
- Elaborate striated border
- Intricate lateral processes (lateral cell membranes not apparent)
What does the proximal tubule recover?
- 67-80% of Na+, Cl-, H2O
- All of glucose, amino acids, and proteins
The proximal tubule eliminates:
Organic solutes, drugs, toxins
What are the histological characteristics of the Henle complex?
- Squamous epithelium
- Bulging nuclei
- Descending limb
- Ascending limb
What is the descending limb of the Henle complex permeable to?
Water, urea, sodium, chloride, and other ions
The ____ is only moderately permeable to water
Ascending limb of Henle complex
What is the ascending thick limb of the distal tubule impermeable to?
Water or urea
What type of pump does the ascending thick limb of the distal tubule possess?
Chloride (and possibly sodium) pump that actively transports chloride/sodium from the lumen
____ is impermeable to water and urea
Convoluted part of the distal tubule
What type of pump does the convoluted portion of the distal tubule contain?
Basal Na+/K+ ATPase powered sodium-potassium exchange pump
What is the macula densa a junction between?
Recta and convoluta
What are the histological characteristics of the distal tubule?
Luminal space more apparent
More nuclei
Paler staining
More proximal convoluted tubules present in any one area because they are longer
____ is the modified portion of the distal tubule between ascending thick limb and distal convoluted tubule
Macula densa
What are the juxtaglomerular cells of afferent arteriole?
Modified smooth muscle cells of afferent arteriole
What do the granules of the juxtaglomerular cells contain?
- Renin
- Also contain angiotensin-converting enzyme (ACE), angiotensin I, angiotensin II
What type of mesangial cells does the juxtaglomerular apparatus contain?
Extraglomerular
____ is missing in the juxtaglomerular apparatus
Basal lamina (so cells are in direct contact)
The juxtaglomerular apparatus monitors:
Composition of filtrate
Collecting tubules are primarily:
Conduits
What type of epithelium do collecting tubules have?
Simple cuboidal
What are the 3 major divisions of the collecting tubules?
- Cortical
- Medullary
- Papillary
Cortical collecting ducts contain ___ epithelium located in ____
Cuboidal; medullary rays
What are the two major cell types of the cortical collecting ducts?
- Principal
- Intercalated
____ are evident in cortical collecting ducts
Lateral cell membranes
What do the intercalated cells of the cortical collecting ducts do?
Actively transport and secrete H+, thus modulating acid-base balance
Which collecting ducts have a larger caliber?
Medullary collecting tubules
____ is a union of several cortical collecting tubules
Medullary collecting tubules
The inner zone of the medulla contains ____ cells only
Principal cells
The outer zone of the medulla contains:
Both principal and intercalated cells
What are papillary collecting tubules also known as?
Ducts of bellini
What are papillary collecting tubules formed by?
Union of medullary collecting tubules
Papillary collecting tubules contain ____ epithelium
Large, tall simple columnar
Where are papillary collecting tubules located?
At apex of renal pyramid
What do the papillary collecting tubules empty into?
Minor calyx
The kidney medulla appears:
Striated
Many vascular elements are noted in the renal medulla, which are called:
Vasa recta spuria
What are the 5 components of the excretory passages?
- Minor and major calyces
- Renal pelvis of the kidney
- Ureter
- Single urinary bladder
- Single urethra
Where does the apex of the renal pyramid sit?
In minor calyx
What is the apex of the renal pyramid covered in?
Transitional epithelium
What is the coat of the minor calyces made of?
Thin muscular coat (smooth muscle) which propels urine
What happens to the walls as you move down the excretory passages?
Walls thicken
What does the ureter do?
Conveys urine from kidneys to bladder
What does the single urinary bladder do?
Stores urine
What does the single urethra do?
Conveys urine to outside of the body
The ureter delivers urine to:
Bladder
What type of tissues make up the ureter?
- Mucosa (epithelium + CT), convoluted
- Muscular coat
- Fibrous connective tissue covering
What are the three layers of the muscular coat of the ureter?
Inner longitudinal
Middle circular
Outer longitudinal
What type of epithelium does the ureter have?
Transitional
____ stores urine
Bladder
The mucosa of the urinary bladder has folds when:
Empty
The urinary bladder has what kind of epithelium?
Transitional
What are the layers of the muscularis of the urinary bladder?
Inner longitudinal
Middle circular
Outer longitudinal
What happens to the shape of the transitional epithelium cells when distended?
Dome shaped cells become flat
