Physiology Of The Urinary Tract Flashcards
What is oliguria ?
A low urine output.
What are the functions of the kidney ?
To get rid of body waste (urea, creatinine, uric acid, bilirubin, metabolites of hormones) and foreign chemicals (toxins, drugs, pesticides, food additive).
To control volume and electrolytes composition of the body. Maintain homeostasis and a stable environment for the cell.
Regulate body fluid osmolality and electrolytes concentration.
Regulate arterial pressure, acid base balance, erythrocyte production.
Secretion, metabolism and excretion of hormones
Gluconeogenesis.
How does it regulate arterial pressure ?
Long term regulation : excreting variable amount of sodium and water.
Short term regulation : secreting renin ==> creation of vasoactive product : angiotensin 2.
Flow of blood through the kidney.
Renal artery => segmental arteries => interlobar arteries => arcuate arteries => interlobular arteries
=> afférent arterioles => glomerular capillaries => efferent arterioles
=> peritubular capillaries / vasa recta
=> interlobular veins => arcuate veins => interlobar veins => segmental veins => renal vein
How does the efferent arterioles regulate hydrostatic pressure ?
High hydrostatic pressure in glomerular capillaries ⇒ rapid filtration
Low hydrostatic pressure in peritubular capillaries ⇒ rapid fluid reabsorption
Who many nephrons do we have throughout our lives ?
Each kidney possess around 800 000 to 1 000 000 nephrons. They cannot be regenerated and the amount decrease of 10% after 40 years. But the remaining nephrons can adapt.
Flow of the ‘future urine’ through the kidney.
Absorption in the glomerulus from the glomerular capillaries.
=> bowman’s capsule => proximal tubule
=> loop of henle : descending limb => thin ascending limb => thick ascending limb
=> distal tubule => macula densa => distal tubule
=> connecting tubule => cortical collecting tubule => medullary collecting tubule => collecting duct
=> renal papillae => renal pelvis
What are the different type of nephron ?
Cortical nephron has a glomeruli in the outer cortex and a short loop of henle but an extensive network of peritubular capillaries.
Juxtamedullary nephron has a glomeruli deep in the renal cortex and a long loop of henle with long efferent arteriole that extend down the outer medulla where it divide into peritubular capillaries (vasa recta).
What is micturition ?
The process of empty the full bladder. When the tension rise above a threshold it elicit the micturition reflex.
What characterise the detrusor muscle ?
Its fibres extend in all direction and their cells are used with each other. It creates a low resistance electrical pathway thus the entire bladder can contract at once.
