MCQ 4 - Renal System Flashcards
Components of urinary system
2 Kidneys = produces urine
Ureter = transports urine to urinary bladder
Urinary bladder = stores urine prior elimination - process called urination
Urethra = conducts urine to exterior (semen too in males)
3 Major functions of urinary system
Excretion = removes organic waste from body fluids
Elimination = discharge of waste products to environment
Homeostatic regulation = of volume + solute concentration of blood
Location and position of the kidney
Either side of vertebral column (T12 + L3)
Against dorsal abdominal wall
Right kidney lower (left superior to right) (right inferior to left)
Adrenals on upper surface - on superior surface
Embedded in fat
5 main homeostatic functions in urinary system
Regulate blood volume + pressure = adjust water loss in urine, release erythropoietin + renin
Regulate plasma conc. (Na, K, Cl ions) = lost via urine, Ca ions controlled in kidneys via calcitriol synthesis
Stabilise blood pH = control loss of H + bicarbonate ions in urine
Conserve valuable nutrients
Assist liver = detoxifying poisons
2 functional layers of kidney
Cortex
Medulla
Name of lobed structures in kidney
Medullary pyramids
What is hilum
Central fissure where - renal artery/vein, lymphatics, nerves, ureter enter and leave
What is the renal calyces
Joining to form renal pelvis where urine empties
Waste excretion
3 main parts
Filtration = filters serum (including waste, toxins, nutrients, ions, water) Reabsorption = selectively absorbs needed substances Secretion = secretes unwanted substances
What is urine
Nitrogenous by-product from protein metabolism = urea, uric acid, creatine, broken down haemoglobin, urobilin gives colour, toxins, drugs, waste
What is the blood supply to the kidney?
How does it enter/leave?
25% of cardiac output through kidney
Blood is filtered approximately 60 times a day
Blood enters via renal artery
Clean blood leaves via renal vein (waste out via ureter)
Structure of renal artery
Segmented arteries then to…
Interlobar arteries between renal pyramids
Structure of nephron (in order)
Renal corpuscle (glomerulus + bowmans capsule) = FILTRATION Proximal convoluted tubule = REABSORPTION/SECRETION Loop of Henle = REABSORPTION Distal convoluted tubule = REABSORPTION/SECRETION Collecting duct = REABSORPTION
Divide nephron structure into 2 functional layers (cortex + medulla)
Cortex = glomerulus + convoluted tubule (distal + proximal)
Medulla = loop of Henle, collecting duct + tubular capillaries
How is the kidney kept into position
Fibrous capsule = layer of collagen fibres covering outer surface of entire organ
Perinephric fat = thick layer of adipose tissue, surrounding fibrous capsule
Renal fascia = dense, fibrous outer layer, anchors kidney to structures around it
Renal pyramids
In renal medulla 6-18 Distinct triangular structures Base of pyramid touches cortex Tip of pyramid (renal papilla) projects into renal sinus
Renal columns
Bands of cortical tissue
Separate renal pyramids
In medulla
Renal circulation order
Blood circulation
Renal artery ➡️ segmented arteries ➡️ interlobar arteries ➡️ arcuate arteries ➡️ cortical radiate arteries ➡️ afferent arterioles ➡️ glomerulus ➡️ efferent arteriole ➡️ peritubular capillaries ➡️ venules ➡️ cortical radiate veins ➡️ arcuate veins ➡️ interlobar veins ➡️ renal veins
Name of the kidneys functional unit
Nephron
Juxtamedullary nephrons (15%)
Adapted for water reabsorption
Long loop of Henle extends into medulla
No lymphatic drainage
Regulates volume of urine
Cortical nephron (85%)
Small loop of Henle
Adapted for regulation of urine composition, not volume
Good lymphatic supply
What’s the glomerulus (filtration)
Filter unit Input = afferent arteriole Output = efferent arteriole (smaller diameter) High pressure Ball of narrow capillaries Sits in Bowman’s capsule
Peri-tubular capillaries
Input = efferent arterioles
Output = renal venous system
Adapted for absorption - porous/low pressure
Divide nephron of kidney into capillary and tubular portions
Capillary = glomerulus + peri-tubular capillaries
Tubular = PCT, loop of Henle, DCT, collecting duct
Types of cell in tubular portion of the kidneys nephron
Modified epithelial cells: Squamous, cuboidal Microvilli Fenestrations Selectively permeable Transporter expression
Cellular structure of glomerulus
Fenestrated epithelium (holes) Podocytes = strength Mesangial cells - structural, contractile, phagocytic Negatively charged Collagen Extracellular matrix
Glomerular filtration rate (GFR)
KF (kidney permeability constant) x net filtration pressure
Kf = ml min-1 mmHg-1 = dependant on membrane permeability + filtration area
