Urinary System Flashcards
Function of kidneys (6)
- Excretion of wastes
- Regulation of water
- Regulation of Acid base
- Regulation of electrolytes
- Endocrine function
- Urine production
Formation of the kidney
- in the nephrotomes of Mesoderm
- three phases
1. Pronephros
2. Mesonephros
3. Metanephros
Pronephros
- 3rd week
- pronephric tubules form in nephrotomes of neck
- Openings to celom and pronephric duct
- do not function –> no Connection with circulation
Mesonephros
- 4th week
- Mesonephric tubules in nephrotomes of Thorax and upper lumbal
- two Ends:
blind end –> mesonephric corpuscle with blood vessels for Filtration
other end links to mesonephric (wolfman) duct - FUNCTION until 8-9th week
- in males: develops into genital ducts
Metanephros
- 5th week
- metanephrogenic tissue in lower lumbar nephrotomes –> tubules are formed
- Metanephric bud grows into tissue – > Ureter, pelvis…
- FUNCTION in weeks 9-10
Fetal kidneys
- Nephrons are formed until birth
- Urine into amniotic cavity
- Urine has low concentration
- kidneys are not repsonsible for excretion of waste!! –> placenta does this instead
Newborn and child kidneys
- birth: kidneys have lobulated appearance
- disappears during childhood because more Nephrons grow
Adult kidneys
- amount of CT increases
- abilities of Filtration decrease
Capsules of the kidney
- Adipose capsule: White adipose tissue (außen)
- Fibrous capsule: dense irregular CT and few smooth muscle fibers (innen)
Stroma and parenchyma of kidney
- Stroma: loose CT rich in reticular fibers
- Parenchyma: corpuscular and tubular epithelium
Anatomical parts of kidney
RENAL CORTEX:
- corpuscles and convoluted tubules
- extends between pyramids as columns
RENAL MEDULLA
- loops of Henle and collecting tubules –> pyramids
- extend into Cortex as medullary rays
LOBE
medullary pyramid and associated cortical tissue
LOBULE
medullary ray and surrounding cortical material
Nephron
Renal corpuscle
- Bowman’s capsule
- Glomerulus with afferent and efferent arterioles and capillaries
Renal tubules
- proximal convoluted tubule
- loop of Henle
- distal convoluted tubule
Function of a nephron
- Filtration
- Reabsorption
- Secretion
Types of nephrons
SHORT
- corpuscles are in outer part of Cortex
- short loops of Henle
- all parts of Nephron are in Cortex
- afferent art. is wider than efferent art.
INTERMEDIATE
- corpuscles in midregion of Cortex
- loops of Henle of intermediate length –> extend into Medulla
- afferent art. is wider than efferent art.
LONG
- corpuscles in proximity to the base of a pyramid
- Long loop descending Deep into Medulla
- afferent art. is equal to efferent art.
Glomerulus
- 20 capillary loops
- afferent arteriole, capillaries, efferent arteriole
- vascular pole: area where arterioles enter and leave
Glomerular capillaries are…
…fenestrated
Bowman’s capsule layers
- Parietal layer
- Capsular space
- Visceral layer
Parietal layer of Bowman’s capsule
- simple squamous
- passes into cuboidal epith. in proximal tubule –> URINARY / TUBULAR POLE
Visceral layer of Bowman’s capsule
- simple squamous –> composed of podocytes
- bodies of podocytes face capsular space
- trabeculae (Primary processes) embrace capillaries
- pedicles (secondary processes) apply to b.m.
- Filtration slits between secondary processes
- slit diaphragms Bridge over Filtration slits (NEPHRIN)
Glomerular Filtration barrier
- Endothelium of capillary
- Glomerular b.m. with three layers
>Lamina rara interna
>Lamina densa
>lamina rara externa - Podocytes
–> passage of water, electrolytes, Glucose, low weight proteins
Inner (intraglomerular) mesangium
- where capillaries are not covered by podocytes
- composed of mesangial cells –> resemble pericytes
Functions of inner mesangium (5)
- contracts
- assists in Filtration
- phagocytosis
- support of capillaries
- secretes vasoactive factors
Proximal tubule and functions
- convoluted part and straight part
- simple cuboidal Epithelium
- apical microvilli –> brush border
- basal striations and mitochondria between them
FUNCTIONS OF CONVOLUTED TUBULE
- reabsoption of water, Na, Cl, Glucose, aa from Primary Urine to blood
- Secretion of cretinine, dyes, drugs, Vitamins to Urine
FUNCTIONS OF STRAIGHT TUBULE
- same functions, but not as specialized for reabsorption
Loop of Henle
DESCENDING LIMB
- thick Segment = straight part of proximal tubule
- thin Segment –> water Reabsorption
ASCENDING LIMB
- thin Segment –> Na and Cl Reabsorption
- thick Segment = straight part of distal tubule
Thin Segment of loop of henle
- simple squamous
- microvilli on apical surface
Distal tubule and functions
Parts:
- straight tubule
- macula densa
- convoluted tubule
- simple cuboidal Epithelium
- basal striations, few microvilli
FUNCTIONS OF STRAIGHT TUBULE
- Reabsorption of Na, Cl
FUNCTIONS OF CONVOLUTED TUBULE
- Reabsorption of Na, water
- Secretion of Ammonium, drugs
Renal collecting tubule
- not part of Nephron
- simple cuboidal –> simple columnar towards ducts of Bellini (tip of pyramid)
Types of epithelial cells in renal collecting tubule
- principal: pale, few organelles, gew Shirt microvilli, songle non-motile cilium for chemical Signals
- -> REABSORPTION OF WATER
- dark/ intercalated cells: dark, mutliple organelles
- -> SECRETION OF H OR HCO3
Juxtaglomerular apparatus
- Juxtaglomerular cells
- Macula densa
- Extraglomerular mesangium
–> controls glomerular blood flow and systemic blood pressure
Juxtaglomerular cells
- modified smooth muscle cells in afferent arteriole
- secrete renin –> for Regulation of blood pressure and renin-angiotensin-aldosterone mechanism
Macula densa
- in wall of distal tubule
- b.m. is very thin or does not exist
- cells are sensitive to concentration of Na in Urine
- act as chemoreceptors –> promote renin secretion and contraction of mesangial cells
Extraglomerular mesanglium
- between afferent and efferent arteriole and macula densa
- continuous with intraglomerular mesangium
- irregulary shaped cells with processes
- Signal to intraglomerular mesangium which make capillaries wider or narrower
Interstitial cells in renal connective tissue
- resemble fibroblasts
- produce prostaglandins (for contraction of smooth muscle cells and mesangial cells)
- produe Erythropoietin (promotes erythropoiesis in bone marrow)
Developmental Sources of the urinary tract
Ureter –> from metanephric bud
Bladder and upper part of urethra –> from urogenital sinus
Wall of cayxes and renal pelvis
Mucosa:
- transitional Epithelium
- lamina propria
Muscular layers:
- inner longitudinal
- outer circular
Adventitia
Wall of ureter
Mucosa:
- transitional Epithelium
- lamina propria
Muscular layers
- inner longitudinal
- middle circular
- outer longitudinal (in lower part)
Adventitia
Wall of urinary bladder
Mucosa
- transitional epith.
- lamina propria
Muscular layer:
- inner longitudinal
- middle circular
- outer longitudinal
Serosa or adventitia
Wall of urethra
Mucosa:
- Males: transitional (prostatic part), pseudostratified (membranous and spongy part), stratifies squamous (terminal part)
- Females: transitional (initial part), stratified squamous (terminal part)
- lamina propria
Muscular layers
- inner longitudinal
- circular
- outer longitudinal (in lower part)
Adventitia
