Urinary System Flashcards
The functional unit of kidney. Note that Bowman’s capsule is not part of it.
Nephron
permeable to H2O but not sodium. Therefore H2Ois reabsorbed and the filtrate becomes more concentrated (hypertonic).
Descending Loop of Henle
permeable to sodium but not H2O. Therefore salt is reabsorbed and the filtrate becomes less concentrated (hypotonic).
Ascending Loop of Henle
The vasa recta of the nephron runs counter to the loop of Henle.
This acts to multiply the resorption of H2O.
Countercurrent multiplier system
The hormone aldosterone will act on the — to increase sodium reabsorption.
distal convoluted tubule
The hormone ADH will increase water permeability through aquaporin increase.
Also responsive to aldosterone similar to the distal convoluted tubule.
Collecting duct
Renal hormones
Released from juxtaglomerular cells in response to low blood pressure.
Responds to sensors from the macula densa of low sodium concentration or baroreceptor stretch reflex of low renal perfusion pressure.
Triggers angiotensinogen, a cleavage enzyme that result in production of angiotensin II.
Renin
Renal hormones
Triggered by renin and results in release of aldosterone.
Angiotensin II
Renal hormones
Synthesized in adrenal cortex.
Main function: regulates sodium and potassium ion balance by increasing Na+ re-absorption and K+ excretion in the distal convoluted tubule.
This will also lead to increase in blood pressure due to Na+ and water reabsorption.
Aldosterone
Renal hormones
Also called vasopressin.
Synthesized in hypothalamus and released by posterior pituitary.
Regulates blood osmolarity and blood pressure by acting on the collecting duct of the kidney to increase water reabsorption.
ADH
Function of renin-angiotensin-aldosterone system
Regulates blood pressure and fluid volume.
A hormone produced by kidneys that triggers production of RBCs in the bone marrow.
Erythropoietin
pH and electrolyte regulation of the kidneys
Through the nephron, the kidneys regulate the balance of reabsorption and excretion of water and electrolytes.
They also regulate blood pH through reabsorption of bicarbonate and H+ ions affecting the bicarbonate buffer system.
Kidney excretes nitrogenous wastes like
ammonia and urea.
Urine is produced by
the kidney, stored in the bladder, and exits through the urethra.
Made of smooth muscle, it contracts during urination.
Detrusor muscle
Made of smooth muscle and under involuntary (parasympathetic) control.
Internal urinary sphincter
Made of skeletal muscle and under voluntary control.
External urinary sphincter
Cortex vs medulla
Cortex contains Bowman’s capsule, proximal and distal convoluted tubules.
Medulla contains the Loop of Henle and collecting duct.
Responsible for moving solutes from blood to the filtrate fluid.
Movement is regulated by hydrostatic pressure.
Bowman’s capsule
Network of capillaries at the start of a kidney through which filtrate enters.
Helps filter out large molecules like proteins.
Glomerulus
Renal pathway
Glomerulus → Bowman’s capsule → proximal convoluted tubule → Loop of Henle → distal convoluted tubule → collecting duct
A measure of the volume of fluid being filtered through the kidney.
Glomerular filtration rate
The pressure in the blood vessels that “pushes” filtrate into the kidney through the glomerulus.
Higher hydrostatic pressure leads to increased GFR.
Hydrostatic pressure
Afferent and efferent arterioles in renal physiology
Blood flow goes into the kidney through the afferent arteriole and exits through the efferent arteriole.
Vasoconstriction of the afferent arteriole decreases GFR whereas vasoconstriction of the efferent arteriole increases GFR.
Osmotic pressure in renal physiology
The osmotic pressure in the tubule “sucks” filtrate into the kidney.
Higher solute concentration in the tubule increases osmotic pressure and increases GFR.
