Urinary System Flashcards
What is the general overview + pathway of the urinary system?
What is the function of the urinary system?
- water and electrolyte homeostasis
- filtration of cellular wastes from blood
- selective reabsorption of water/solutes
- regulation of fluid balance
- maintain electrolyte homeostasis/acid-base balance
- excretion of metabolic waste products, bioactive substances (including drugs), and excess water
- production of hormones: renin + erythropoietin
- regulation of blood pressure
- juxtaglomerular apparatus
- activation of vitamin D
What are some clinical signs of renal and non-renal diseases related to the kidneys?
What is the basic structure of the kidney?
- capsule
- renal lobe/pyramid
- outer cortex
- inner medulla
- papillae/crest
- calices (dilations of renal pelvis)
- pelvis (dilation of proximal ureter)
Kidneys are composed of lobes that may be?
- single, multiple, or fused
What kinds of lobes are shown?
- unilobular: typical of carnivores
- multilobular: typical of large ruminants (each lobe is distinctly outlined by deep grooves, lacks a renal pelvis)
- multilobular: kidney of pig
What are the important tissues of the kidney?
What are features of the nephron?
- the functional unit of the kidney
- site of osmoregulation via:
- filtration of water and small molecules from blood plasma to form a filtrate
- selective reabsorption of most of the water and other molecules from the filtrate
What are important structures in the regions of the kidney?
- cortex
- renal corpuscles
- proximal tubules
- distal convoluted tubules
- collecting tubules
- peritubular capillary plexuses
- medulla
- loops of Henle
- collecting ducts
- vasa recta
What is this structure? What are some visible features?
- renal cortex
- renal corpuscles
What structure is shown? What are features indicated?
- renal cortex
- renal corpuscle
- proximal tubules
- distal convoluted tubules
What is the renal corpuscle composed of?
What is this? What are some features? What is its main function?
- glomerulus of a renal corpuscle
Describe filtration at the glomerulus
What is indicated in this image? What is its function?
- podocytes
- filtration
What are the 3 components of the filtration barrier? What is the outcome?
- ENDOTHELIUM of glomerular capillary loops (CL) w/ fenestrations
- glomerular BASEMENT MEMBRANE (GBM) =fused basal laminae of capillaries and podocytes
- PODOCYTES with pedicels (foot processes)
- outcome: albumin and larger molecules are retained, all smaller molecules cross freely with ultrafiltrate
What kind of endothelium is in kidneys?
- fenestrated
What feature is shown in the image?
- glomerulus of kidney
What are the steps of urine formation?
- primary/glomerular filtrate is produced by ultrafiltration of blood in renal corpuscle
- composition of ultrafiltration is similar to blood plasma, it does NOT contain most proteins
- Reabsorption of most substances: 98% of filtrate reabsorbed (most of water and NA+, all glucose and amino acids)
- tubular secretion: K+, H+, NH4+, bile salts, drug metabolites
- waste molecules + some water remain in tubular system and eventually empty into ureter, urine stored in bladder pending voiding/micturition
What are features of mesangial cells?
- phagocytic
- contractile
- support
- mesangial cells+ matrix = mesangium
What animals do not have glomerulus?
- teleostei fish
- renal tubule instead
What are the types renal tubules?
- proximal tubule
- Henle’s loop: thin descending and thick ascending limb of nephron
- distal convoluted tubule
What structure is shown? What are some features?
- proximal convolute tubule
- begin at urinary pole of renal corpuscles
- only in cortex
- single layer of cuboidal epithelial cells with microvilli (brush border)
- highly metabolically active cells w/ many mitochondria
- Na+/K+ pumps, aquaporins, peroxisomes, endosomes, lysosomes
- resorb glucose, Na+/H2O, amino acids, peptides and low molecular weight proteins
What is the structure shown? Some features?
- proximal convoluted tubules
- microvilli (brush border)
- basal laminae
- lateral borders have inter-digitations of lateral cell processes, making cell limits indistinct
- basal surface has a folded membrane: basal striations
What is the structure shown and what are the arrows indicating? What does this structure absorb? Activate?
- proximal convoluted tubules
- brush border
- absorb:
- 85% of Na+ and H2O, 100% of glucose and amino acids
- selectively: anions, cations, urea
- activate: vitamin D
What is this structure shown and some features present?
- convoluted tubule
- microvilli: PCT only
- basal striations: both PCT/DCT. Folds of plasma membrane w/ ATP driven Na+ pump
- mitochondria: provide ATP for pump
What is the structure shown? Some features?
- loop of Henle (nephron loop)
- continues from proximal convoluted tubule
- U-shaped with segments
- thick descending: cuboidal epithelium
- thin segment: squamous epithelium
- thick ascending: cuboidal epithelium
- in medulla only
What is this structure? What are the labeled features?
- loop of henle
- CT: collecting tubules
- CD: collecting ducts
- T: thin segment
- A: ascending thick segment
- V: vasa recta: capillary loop that parallels the course of nephron loops,facilitating ion and water exchange
What are the labeled structures? What are features of structure A?
- A: distal convoluted tubule
- B: proximal convoluted tubule
- continues from thick ascending segment of loop of henle
- single layer of cuboidal epithelial cells
- no microvilli
- only in cortex
- site of action of ALDOSTERONE
- contain specialized chemoreceptor cells of MACULA DENSA
What is this structure?
- distal convoluted tubule
What is this structure? Some features?
- collecting duct
- connect distal convoluted tubule to renal papillae/crest
- lumen contains primitive urine
- cuboidal to low columnar epithelium
- site of ANTIDIURETIC HORMONE (ADH) via aquaporin receptors
- *not part of nephron
What is the structure? What are the functions of its cells?
- collecting ductule
- lined by simple low columnar to cuboidal epithelium composed of principal and intercalated cells
- principal cells: reabsorb Na+ and H2O
- intercalated cells: participate in acid-base balance
What structure is shown? What are the arrows indicating?
- renal papilla: papillary ducts
- terminal portion of collecting ducts are papillary ducts (thick arrow)
- which empty at the area cribrosa (AC) of the renal crest of renal papilla (dashed lines)
- vasa recta (thin arrow) take away water passing through collecting and papillary ducts
What is the papilla or renal crest?
- the terminal portion of the inner medulla, which extends into the renal pelvis or calices
What are features of vasculature in the urinary system?
- high blood supply (25% of cardiac output)
- terminal (end) or artery system
- renal artery > interlobar artery > arcuate artery > interlobular artery > intralobular artery > afferent arterioles > efferent arteriole > intralobular vein > interlobular vein > arcuate vein
- afferent arterioles: glomerulus (capillaries)
- efferent arteriole: peritubular capillaries (surround tubules) and vasa recta (surrounds loops of henle)
What are features of interstitium in the urinary system?
- sparse, especially in cortex, more present in the medulla
- between basement membrane and tubules
- interstitial cells: fibroblasts, bone marrow derived cells, unique lipid-laden interstitial cell (stellate shaped) that is especially prominent in the inner medulla (produces prostaglandin E2)
What are features of lymphatics in the urinary system?
- found in the interstitium surrounding intrarenal arteries
T/F: the kidney has afferent innervation to the smooth muscle of arteries, afferent and efferent arterioles, and descending vasa recta
- false; efferent innervation
What is this structure?
- glomerulus
What are the two parts of the juxtaglomerular apparatus?
- macula densa cells: chemoreceptors that sense Na+ concentrations in filtrate
- juxtaglomerular cells: modified smooth muscle cells of mainly afferent and some efferent arterioles. Detect variations in blood pressure (baroreceptors) and secrete renin into vessel lumen
What are the kinds of receptors in the juxtaglomerular apparatus, and what part are they associated with?
- macula densa of DCT: Na+ Chemoreceptor
- J.G. Cells of afferent/efferent arteriole: baroreceptor
- secrete hormone renin in response to low Na+ in filtrate and low blood pressure
How does the juxtaglomerular apparatus increase blood pressure?
Label the features of this structure
Name the labeled features
What is the tubular organ of the urinary system? What are the 4 layers/tunics?
- ureter
- tunica mucosa (lamina mucosa, lamina propria, lamina muscularis)
- tunica submucosa
- true submucosa because lamina muscularis (muscularis mucosae) separates submucosa from mucosae
- submucosa: lamina propria because no lamina muscularis
- tunica muscularis
- tunica serosa/adventitia
What is this structure? What are some features?
- ureter
- tube that conveys urine from renal pelvis to bladder
- tunica mucosa: urothelium/transitional epithelium (U)
- tunica submucosa:lamina propria (LP); no lamina muscularis
- tunica muscularis (M): 3 layers of smooth muscle, outer and inner longitudinal, middle circular, autonomic innervation (peristalsis)
- tunica adventitia
What is this structure? What are the arrows indicating?
- urinary bladder: stores urine
- tunica mucosa: urothelium
- lamina propria present, lamina muscularis (thin incomplete bands of smooth muscle except in cats)
- tunica submucosa
- tunica muscularis:
- 3 layers (outer/inner longitudinal, middle circular)
- smooth muscle (detrusor muscle)
- skeletal muscle sphincter near urethra
- tunica serosa/adventitia
What is this structure? Label A + B
- bladder
- A: lamina propria mucosae
- B: epithelium mucosae
What is this feature? What species? Why?
- urinary bladder
- horse
- presence of glands (g)
What is this structure? Some features? What are the arrows indicating?
- urethra
- lined initially w/ transitional epithelium, then stratified squamous (near external urethral orifice)
- accessory sex glands
- mucous glands (diffuse prostate in ruminants/boars/cats)
- male:
- vascular stratum (corpus spongiosum)
- tunica muscularis/urethral sphincter
- smooth muscle proximally, skeletal muscle display
- female:
- shorter, infection more likely
- dog: urethra, prostate
T/F: the kidney develops from the lateral mesoderm
- false: intermediate mesoderm
Describe renal development
- pronephros: regresses in mammals
- mesonephros: genital tract
- forms nephrons that secrete fluid into amnion early in development, regresses later
- mesonephric duct (wolffian duct): retained in males forming epididymus, vas deferens, seminal vesicles
- metanephros: kidney
T/F: the mesonephros becomes the adult kidney
- false; metanephros
- metanephros
- ureteric bud: outgrowth of mesonephric duct
- collecting bugles form, bifurcate, and nephros begin to develop
- metanephros duct becomes ureter
- urinary bladder and urethra are derived from endoderm
