Urinary System Flashcards
What are the components of the urinary system?
Kidneys
Ureters-conduct urine from kidneys to bladder
Urinary bladder-distensible reservoir for urine
Urethra-fibromuscular tube conveys urine from bladder to exterior
What are the functions of the kidneys?
Remove metabolic waste
Conserve body fluid, produce urine
Regulate pH and blood pressure
Endocrine organ that produce erythropoietin and renin
What are the parts of the kidney macrostructure?
Capsule formed by DICT made by collagen fibers, fibroblasts and myofibroblasts
Renal calyces consisting of minor and major calyces lined with transitional epithelium,no more change in urine
Renal pelvis larfer reservoir open into ureter
Hilum
What are the 2 parts of the kidney substance?
Cortex-external part- in fresh specimen more red than medulla
Medulla- Internal part
What are the parts of the kidney cortex?
Renal corpuscles only found in cortex
Renal tubules
Renal columns found between pyramids of medulla
What are the components of the renal tubules?
Cortical labyrinth made of convoluted tubules
Medullary rays formed by straight tubules and collecting dusts
What are the components of the medulla?
Pyramids (8-12) formed by the renal tubules
Papilla-tip of the pyramid formed by the perforated plate called the area cribosa where collecting ducts empty into minor calyces
What are the divisions of the medulla?
Outer medulla made of thick and thin tubules. Consists of 2 parts:
The outer stripe -only thick tubules present
The inner stripe- both thick and thin tubules present
Inner medulla made of only thin tubules
What is the nephron?
Functional unit of kidney.Consists of:
renal corpuscles
renal tubules with unclear lateral sides
Each nephron is unbranched
Several nephrons empty into a collecting tubule via connecting tubule
What are the characteristics of the renal corpuscle?
Spherical structure whose major function is filtration of blood
Consists of glomerulus surrounded by Bowman’s capsule
What are the characteristics of the Bowman’s capsule?
2 layers providing entry and exit for blood vessels and renal tubules
Parietal layer is a simple squamous epithelium
Visceral layer is formed by modified epithelial cells with processes called podocytes
Between the 2 layers is the urinary space
What are the processes of the podocytes?
Primary processes-larger
Secondary processes or pedicels envelop glomerular capillaries by interdigitating and leaving small gaps called filtration slits
Slit diaphragm is a negatively charged barrier located at the base of the filtration slits and formed by component of glycocalyx of adjacent cells
What is the vascular pole?
Area of Bowman’s capsule where blood vessels enter and exit corpuscle
What is the urinary pole?
Area of Bowman’s capsule where proximal convolute tubule draining urinary space originates
What are the characteristics of the glomerulus?
Cluster of fenestrated capillaries without diaphragm and a single basal lamina
Mesangial cells located at the end of capillaries
What are the functions of the mesangial cells?
Control glomerular flow
Possess angiotensin 2 receptors causing a reduction in blood flow
Structural support for glomerulus
Phagocytose of residue and protein trapped on basal lamina
What are the different kidney tubules?
Proximal convoluted tubule (PCT) Loop of Henle subdivided into 4 parts: thick and thin descending limbs and thin and thick ascending limbs Distal convoluted tubule (DCT) Connecting tubules Collecting tubules
What are the characteristics of the PCT?
Formed by large cuboidal cells with well developed microvilli forming a brush border
Tight and adherens junctions seal the apical border
Basal striations are formed by mitochondria
Function in reabsorption of AA, proteins and ions
Ultrafiltrate is isotonic to plasma
What are the characteristics of the thick descending limb of the loop of Henle?
Also called proximal straight tubule is shorter and lined with simple cuboidal epithelium
It is similar to PCT
Present only in the outer stripe of the outer medulla
What are the characteristics of the thin descending limb of the loop of Henle?
Lined with simple squamous epithelium
Highly permeable to water
Sodium chloride and urea enter filtrate leading to hyperosmotic fluid
Found in inner stripe of outer medulla and inner medulla
What are the characteristics of the thin ascending limb of the loop of Henle?
Lined with simple squamous epithelium
Impermeable for water
Highly permeable to sodium chloride leading to hypotonic filtrate
Only present in the inner medulla
What are the characteristics of the thick ascending limb of the loop of Henle?
Also called distal straight tubule
Lined with simple cuboidal epithelium
Similar to DCT
Impermeable to water and urea
Transport sodium and chloride ions from lumen to interstitium leading to more hypotonic filtrate compare to thin ascending limb
Forms macula densa
Long runs from inner stripe of the outer medulla through the outer stripe into cortex
What are the characteristics of the DCT?
Formed by cuboidal cells
No brush border present
Has a prominent basal striations formed by mitochondria
Function in reabsorption of sodium, chloride and bicarbonate ions
What are the characteristics of the connecting tubule?
Connects DCT to the collecting duct
Lined with simple cuboidal epithelium
What are the characteristics of the collecting duct?
Lined with simple cuboidal epithelium
made of 2 types of cells:
Principal cells-main type with no interdigitating lateral membranes
Intercalated cells-regulate pH by transporting hydrogen and bicarbonate ions in and out of cells
What are the functions of the principal cells?
Respond to vasopressin (ADH)
Open water channels decreasing urine volume and increasing urine concentration and blood pressure
What are the different types of collecting ducts?
Cortical collecting ducts in medullary rays of cortex
Medullary collecting ducts in medulla
Papillary collecting ducts emptying into minor calyces
What is the osmolarity of the ultrafiltrate through the nephron?
Isotonic- Thick descending limb Hyperosmotic- Thin descending limb Hypo osmotic- thin and thick ascending limbs and collecting duct Hyperosmotic- Medullary interstitium Isotonic- Cortical interstitium
What are the types of nephrons?
Juxtamedullary nephrons
Cortical nephrons
What are the characteristics of the juxtamedullary nephrons?
Renal corpuscles closer to medulla
Long loops of Henle with both descending and ascending thin limbs
What are the characteristics of the cortical nephrons?
Renal corpuscles closer to the capsule
Short loops of Henle with only thin descending limb
No thin ascending limb
What are the components of the juxtaglomerular apparatus?
Macula densa
Juxtaglomerular cells
Extraglomerular mesangial cells
What are the characteristics of the macula densa?
Formed by modified epithelium of the thick ascending limb of the loop of Henle
major function is to sense the chloride concentration in the tubule
What are the characteristics of the juxtaglomerular cells?
Modified smooth muscle cells
Release renin through its secretory granules
What are the characteristics of the extraglomerular mesangial cells?
Located in the cleft between macula densa and the afferent and efferent arterioles
Provide structural support and transmit signals from macula densa to juxtaglomerular cells
What are the characteristics of the arterial supply of the kidneys?
Kidneys receive blood supply via renal arteries which break into smaller arteries: segmental and lobar arteries
Interlobar arteries are branches of the lobar arteries and travel between the pyramids give off arcuate arteries
Arcuate arteries mark the boundary between the cortex and medulla
Interlobular arteries run perpendicular to arcuate and give off afferent arteriole which supplies glomerulus
Efferent arterioles drain capillaries of glomerulus and give rise to second capillary bed
Peritubular capillaries for cortical nephrons
Vasa recta for juxtamedullary nephrons
What are the characteristics of the venous drainage of the kidney?
Peritubular capillaries drain into interlobular or stellate veins
Stellate veins drain into interlobular veins
Ascending vasa recta drain into arcuate veins tributaries of interlobar veins and accompany the arcuate arteries
Interlobar veins unite to form renal vein
What are the characteristics of the ureter?
Lining is formed by transitional epithelium
Muscularis is fromed by 3 layers of smooth muscle (inner and outer longitudinal and middle circular)
Adventitia is made of adipose tissue, CT and nerves
What are the characteristics of urinary bladder?
Lining is transitional epithelium
Has a thick muscularis and forms detrusor muscle
Has serosa(upper part) and adventitia
What are the characteristics of transitional cell carcinoma?
Common epithelial malignant tumor and agressive
Occurring in kidney pelvis, ureter and bladder
What are the parts of the male urethra?
Prostatic-transitional epithelium, ejaculatory ducts open @ the beginning
Membranous-columnar epithelium, pseudostratified/stratified- external urethral sphincter made of skeletal muscle
Penile-pseudostratified columnar, stratified squamous, (glands of Littre)
What are the characteristics of the female urethra?
Short
Lined with transitional, pseudo columnar and stratified columnar
External sphincter is made of striated voluntary muscles
