Urology & Renal Flashcards
What is the urinary system composed of?
Kidneys, ureters, bladder, and the urethra
What are the main functions of the kidney?
Excretion of metabolic products such as urea, uric acid, creatinine
Excretion of foreign substances
Homeostasis of bodily fluids, electrolytes, and acid-base balance
Regulates blood pressure
Secretes hormones such as erythropoietin and renin
What are the anatomical structures of the kidney?
Cortex, medulla, minor calyx, major calyx, ureter, renal artery, and renal vein
Where does the urine once formed, travel through in the kidney?
Minor calyx to the Major calyx and then through the ureter
What are the functions of the peritubular capillaries?
Provide oxygen and nutrients to the nephron to allow them to perform their functions
Help in reabsorption of different substances along the nephron and then take it away to the circulatory system
Help in secretion of different substances into the tubular fluid
What is the function of the detrusor muscle?
Contracts to build pressure in the urinary bladder to support urination
What does stretching of the trigone to its limit lead to?
Signals sent to the brain about the need for urination
Is it the internal or external sphincter that gives involuntary control to prevent urination?
Internal sphincter - must be relaxed for urination to proceed
External sphincter gives voluntary control to prevent urination
What is the function of the bulbourethral gland?
Produces thick lubricant which is added to watery semen to promote sperm survival
What are the 2 different cell type classes in the collecting duct and describe their mitochondria density?
Principal cells - Low density of mitochondria
Intercalated cells - High density of mitochondria
What are the anatomical differences between the juxtamedullary and superficial nephrons?
The glomerulus of the superficial nephron is in the upper cortex of the kidney, whereas the juxtamedullary nephron has its glomerulus closer to the medullary border
The Loop of Henle in the superficial nephron only extends to the outer medulla, whereas the one in the juxtamedullary nephron extends into the inner medulla
Why does the cortex have a granular appearance, whereas the medulla has a striated appearance?
The loop of Henle extending through the medulla gives it its striated appearance
What are the 3 cell types making up the juxtamedullary apparatus?
Extraglomerular mesangial cells, macula densa (distal convoluted tubule), and juxtaglomerular cells (afferent arteriole).
What are the main functions of the juxtaglomerular apparatus?
GFR regulation through tubular-glomerular feedback mechanism
Renin secretion for regulating blood pressure
What are the 4 main renal processes?
Glomerular filtration
Reabsorption
Secretion
Excretion
Is glomerular filtration a passive or active process?
Passive
Describe the permeability of the filtration barrier
Highly permeable to fluids and small solutes
Impermeable to cells and proteins
What is the name of the spaces between capillary endothelium and how big are they?
Fenestrae
70nm in diameter
What substances can pass through fenestrae?
Water, ions, and small proteins
What substances can pass through the slit diaphragm of the glomerular basement membrane?
Water and small solutes only
What are podocytes?
Highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule
What is the name of the ‘pulling’ pressure exerted by the solutes?
Oncotic pressure - fluid molecules are drawn in across a semipermeable membrane
What is the name of the force that causes the glomerular filtration from the glomerulus into the Bowman’s capsule?
Hydrostatic pressure from glomerular capillaries
How do you calculate the net ultrafiltration pressure?
Puf = HPgc - HPbw - πgc
Puf - Net ultrafiltration pressure
HPgc - hydrostatic pressure in glomerular capillaries
HPbw - hydrostatic pressure in bowman’s capsule
πgc - Oncotic pressure of plasma proteins in glomerular capillaries
What is meant by the glomerular filtration rate and how do you calculate it?
Amount of fluid filtered from the glomeruli into the Bowman’s capsule per unit time (ml/min)
GFR = Puf x Kf
Kf - ultrafiltration coefficient (membrane and surface area available for filtration)
What is the GFR for a healthy male and female respectively?
Male -> 90-140ml/min
Female -> 80-125ml/min
What does a fall in GFR show about the excretory products in the plasma?
That there is an increase in the excretory products in the plasma
Describe the myogenic mechanism used to regulate the GFR when arterial pressure is high
Arterial pressure increases Afferent arteriole stretches Arteriole contracts Vessel resistance rises Blood flow reduces GFR stays the same
Describe the tubuloglomerular feedback mechanism used to regulate the GFR
Increase/Decrease in GFR
Increased/Decreased NaCl in Loop of Henle
Change is detected by macula densa
Increased/Decreased ATP and adenosine discharged
Afferent arteriole constricts/dilates
Blood flow decreases/increases
GFR stabilizes
What is meant by renal clearance?
Number of liters of plasma that are completely cleared of the substance per unit time
Therefore it is only concerned with the excretory role of the kidneys