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66 Cards in this Set
- Front
- Back
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The organs of the urinary system are:
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kidneys, ureters, bladder, and urethra
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What is the function of the kidney
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adjust solute and water concentration
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What is the function of the ureters
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a muscular tube that leads from the renal pelvis to the bladder, conduit for formed urine,
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What is the fx of the bladder?
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a muscular sac on the pelvic floor that distends and expands.
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What are the primary functions of the urinary system?
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they are to regulate blood pressure, and the chemical make up of blood
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What are the secondary functions of of the urinary system?
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metabolism of Vitamin D, production of renin and erythropoeitin, and gluconeogensis
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What is gluconeogenesis?
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glocuse production from non-carbohydrate precursurs (amino acids, fatty acids.)
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Where are the kidneys located?
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retroperitoneally in the superior lumbar region
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What is the size of a kidney?
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it resembles a large bar of soap
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Which kidney is higher? The right or the left?
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the right kidney lies lower than the left, because it is crowded by the liver.
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What is the space within the renal sinus filled with?
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the ureter, blood vessels, lyphatics and nerves
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What is sitting atop each kidney?
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the adrenal glands.
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name the three layers of the supportive tissue around each kidney
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renal capsule, adipose capsule, and renal fascia.
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Renal capsule:
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a fibrous transparent structure that sticks directly to the kidneys surface
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What is the adipose capsule?
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fatty mass that attaches the kidney to the posterior body wall and provides cushion.
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What is the renal fascia?
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the outer layer of dense fibrous CT that anchors the kidney and adrenal gland to surrounding structures.
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What are the 3 distinct layers of the kidney?
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the cortex, medulla and pelvis
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What is the most superficial region of the kidney? And what is its function?
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it is the renal cortex, and urine formation occurs here.
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What is the layer underneath the cortex? And what is it comprised of?
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the renal medulla, and it is comprised of renal pyramids.
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What constitutes a lobe of the kidney?
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one single renal pyramid, and its cortical tissue.
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Trace the flow of urine…
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Urine formed in the renal cortex --> then travels through collecting ducts of the renal medulla --> then drips out renal papillae ---> into minor calyces --> major calyces --> into the renal pelvis ---> ureters --> Urinary bladder ---> exits through the urethra.
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What kind if muscle allows the flow of urine?
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smooth muscle
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What is a nephron? What are its components and functions?
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a nephron is the most basic functional unit of the kidney. It is comprised of the glomerulus, bowmans capsule, and tubules. Its function is glomerular ultrafiltration, and tubular reabsorbtion and secretion.
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What is the Glomerulus?
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Also known as the renal corpuscle, it receives blood from afferent arterioles, and is drained by efferent afterioles. Its primary function is filtration. (delivers ultrafiltrate of plasma
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What are the components of the Glomerular filatration barrier?
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1.) the glomerular endothelial cell 2.) the glomerular basment membrane 3.) urinary epithelial cell
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What does the glomerular filtration barrier do?
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it allows the free entry of water, and small solutes into the glomerulus. It also stops entry of cells and proteins.
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What is are other names for the Proximal Tubule?
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renal tubule, and proximal convoluted tubule
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What fraction of ultrafiltrate is reabsorbed in the proximal tubule?
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2/3rds
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What type of epithelium is located in the proximal tubule?
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simple cuboidal
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What are the ions reabsorbed by the proximal convoluted tube?
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ions reabsorbed are sodium, clioride, bicarbonate, water, and calcium, amino acids, phosphate and glucose…
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What is the primary function of the proximal convulted tubule?
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reabsorbtion,… but it also secretes.
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What is secreted by the proximal distal tubule?
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Hydrogen ions are secreted inot the lumen along with organic acid and drugs
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What happens if there is a change in volume of ECF in the proximal tubule?
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Changes in extracellular fluid will result in a change in the rate of reabsorbtion. It ends up delivering more or less isotonic fluid to other parts of the nephron. For example: an alteration of salt and water reabsorbtion in the loop of Henle.
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Give another name for the Loops of Henle.
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Nephron Loop
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What is the thin decending loop permeable to?
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it is freely permeable to water only.
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What is the ascending loop permeable to?
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the ascending thick loops is inpermeable to H20
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What is the main function of the Loop of Henle?
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reabsorbtion of water and calcium and secretion.
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What is the main function of the Distal Convoluted Tubule?
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reabsorbtion, secretion and excretion. (20% of this is water and 10% is salts of filtrate)
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What kind of epithelium is found in the Distal Convoluted Tubule?
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simple cuboidal, but with no microvilli
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What hormones regulate the distal convoluted tubule?
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Aldosterone (increases sodium reabsorbtion) and ANF (atrial nuritic factor - which regulates sodium excretion.)
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What does parathyroid hormone stimulate?
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it increases Calcium reabsorbtion
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What is the function, location and cellular composition of JGA (juxtaglomerular apparatus)?
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it is located next to the afferent and efferent arterioles. It regulates the pressure and entrance of blood flow. And consists of 3 cells: macula densa and granula cells.
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What are the two intrinsic mechanisms of maintaining Glomerular filtration rate?
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myogenic regulation and tubuloglomerular feedback mechanism
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What happens in myogenic regulation?
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attempts to maintain a constant filtration pressure. Therefore if BP drops, the efferent constricts and BP is increases within the glomerulus. If BP increases, then the efferent arteriole dilates resulting in a decrease of glomerular BP.
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What do baroreceptors do?
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baroreceptor cells help sense changes in pressure and react accordingly.
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What happens in tubuglomerular feedback mechanism?
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High sodium concentraton in the Distal convoluted tubule indicates a high Glomerular filtration ---- thus, Low Na+ indicates Low GFR (slow)
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If GFR is high, what do the macula densa cells do?
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it increases the release of vasoconstrictor - which acts on the afferent afteriole. This reduces glomerular blood pressure and glomerular filtration rate.
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If GFR is low, what do the macula densa cells do?
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it releases less vasoconstrictor, which causes the afferent afteriole to dilate. This results in an increase of glomerular blood pressure and filtration rate
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What are the two extrinsic mechanisms that affect Glomerular filtration rate?
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the two mechanisms are sympathetic neural mechanism and the renin-angiotensin mechanism - both of these decrease glomerular filtration rate to help maintain sufficient systemic blood pressure.
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What happens in sympathetic neural mechanism?
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when sympathetic nervous system activity increases, norephinephrine and epinephrine both act to constrict the afferent arteriole.resulting in a lower blood pressure
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What happens in the renin-angiotensin mechanism?
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JGA releases renin when Blood pressure drops (measured by the stretch of the afferent arteriole.) When renin is released, it cleaves angiotensin I, and Angiotensin I is converted to Angiotensin II by the Angiotensin converting enzyme (ACE).
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What is Angiotensin II and what does it do?
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it is a vacoconstrictor that increases systemic blood volume and blood pressure. *stimulates thirst, and triggers the release of ADH
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What does ADH (antidiuretic Hormone do?
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it stimulates reabsorbtion of water in the distal convoluted tubule.
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What does aldosterone do?
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it reduces sodium ion loss in urine, therefore reducing water loss (Wherever sodium goes, water will follow)
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How many ml/min is the renal blood flow to the kidneys?
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1,200 (represents 20% of cardiac output)
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How many ml/min is the renal plasma to the kidneys?
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660 ml/min.
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Equation for Blood Volume?
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Blood volume = Plasma volume (55%) + Blood Cell Volume (45%) [hematocrit]
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What is the normal glomerular filtration rate?
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125 ml/min. - the rate at which blood filtrate is flowing from glomerular capillaries into Bowmans capsule.
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Filtration Fraction
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125 ml/min over 625 ml/min = 0.20
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Rememeber : There is an inverse relationship between renal plasma and plasma oncotic pressure. Therefore,
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an increase in renal plasma will cause a decrease in the plasma oncotic pressure
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What is glomerular hydrostatic pressure?
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it is the blood pressure in the glomerular capillaries.
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What is the driving force of water reabsorbtion?
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a high osmolarity (concentration) of extracellular fluid that is generated by NaCl and urea
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in the afferent arteriole, if Renal Blood Flow and GFR are increased, then Resistance is?
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Decreased
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In the afferent arteriole, if Renal Blood Flow and GFR are decreased then Resistance is?
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Increased
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In the efferent arteriole, if extracellular resistance is decreased, then
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Renal Blood Flow is increased, and glomerular filtration rate is decreased. Filtration Fraction is <20%
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In the efferent arteriole, if extracellular resistance is increased, then…
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Renal Blood Flow is decreased, and glomerular filtration rate is increased. Filtration fraction is >20%
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