Exam 4 Review:  Chapter 25:  The Nephron III - Blood Supply &JuxtaGlomerular Apparatus

afferent arteriole - A terminal branch of the intralobar artery which supplies blood, under high pressure, to the glomerulus in the renal corpuscle; its vasomotor tone is under complex control by the ANS and epinephrine, the renin - angiotensin system, the antagonistic effects of aldosterone and atrial natriuretic peptide, and local controls in order to maintain the appropriate blood pressure and flow in the glomerulus to achieve an effective glomerular filtration rate (GFR); to maintain high blood pressure in the glomerulus, the diameter of the afferent arteriole is adjusted to be larger than that of the corresponding efferent arteriole.

glomerulus - The network or tuft of fenestrated capillary endothelial cells covered by a layer of specialized epithelial cells (the visceral layer of the renal corpuscle), the podocytes, through which water and small dissolved solutes pass to enter the capsular space of the renal corpuscle of the nephron of the kidney; these capillaries are unusual in having a high blood pressure which is necessary for maintaining an effective glomerular filtration rate (GFR) to produce the plasma filtrate from which urine will be made.

efferent arteriole - A distal branch of the intralobar artery which receives blood, under high pressure, from the glomerulus in the renal corpuscle and supplies blood to the peritubular capillaries and the vasa recta; its vasomotor tone is under complex control by the ANS and epinephrine, the renin - angiotensin system, the antagonistic effects of aldosterone and atrial natriuretic peptide, and local controls in order to maintain the appropriate blood pressure and flow in the glomerulus to achieve an effective glomerular filtration rate (GFR); to maintain high blood pressure in the glomerulus, the diameter of the efferent arteriole is adjusted to be smaller than that of the corresponding afferent arteriole.

peritubular capillaries - The main capillaries of the renal cortex which arise from the efferent arteriole after it leaves the renal corpuscle and wrap around the renal tubules, especially the proximal and distal tubules, to supply nutrients and oxygen to the tubules, to carry away wastes from the tubular cells, and to be the circulation available for exchange of materials between the blood and the plasma filtrate by the processes of tubular reabsorption and tubular secretion; these are low blood pressure vessels.

vasa recta - The main capillaries of the renal medulla which arise from the efferent arteriole after it leaves the renal corpuscle and wrap around the loops of the nephrons, especially the long loops of the juxtaglomerular nephrons, to supply nutrients and oxygen to the medullary tissues, to carry away wastes from the medullary tissues, and to be the circulation available for exchange of materials between the blood and the plasma filtrate in the loops (water, urea, sodium chloride) involved in water conservation regulated by ADH; these are low blood pressure vessels.

vasoconstriction - Any decrease in the diameter of blood vessels due to the contraction of the smooth muscle in the vessel's walls; usually regulated by the autonomic NS and certain hormones.

juxtaglomerular apparatus (JGA) - A specialized collection of two cell types, macula densa cells and juxtaglomerular cells, located at the juncture of the afferent and efferent arterioles with a portion of the distal convoluted tubule of the nephron of the kidney; the two cell types participate in the negative feedback regulation of (1) systemic blood pressure and blood volume via the renin-angiotensin system, (2) local control of glomerular filtration rate (GFR), i.e., "tubuloglomerular feedback," by nitric oxide (NO) production, and (3) hematopoiesis via the production of erythropoietin by cells of the peritubular capillary endothelium of the kidney.

macula densa cells - Specialized chemoreceptor cells in the wall of the distal convoluted tubule at the JGA of the nephron of the kidney which respond to changes in solute concentration (especially sodium levels) in the urine in the distal convoluted tubule and to oxygen levels in the blood passing to the glomerulus; this sensory information is conveyed to the juxtaglomerular cells which will adjust their output of renin accordingly.

juxtaglomerular cells - Specialized smooth muscle cells which act as mechanoreceptors which stretch in response to increases in the blood pressure of the afferent arteriole; they also synthesize and secrete the enzyme renin which serves to activate the inactive precursor, angiotensinogen (made by the liver), into angiotensin I; renin secretion is increased by a fall in plasma Na+ concentration, and by prostaglandins, sympathetic ANS activity, circulating epinephrine and a decrease in afferent arteriolar blood pressure; renin secretion is decreased by a rise in plasma Cl- concentration, angiotensin II, ADH (antidiurectic hormone) and increased blood pressure. aka - granular cells of the JGA

List:

3. the sequence of blood vessels from the arcuate arteries to arcuate veins of the kidney in the sequence in which they are encountered by a circulating RBC.

          arcuate artery → interlobular artery → afferent arteriole → glomerular capillaries → efferent arteriole → peritubular capillaries → vasa recta (perhaps) → interlobular vein → arcuate vein

Sketch and label:

6.  a simple sketch of the juxtaglomerular apparatus and list the functional roles of each component part.

juxtaglomerular apparatus (JGA) - A specialized collection of two cell types, macula densa cells and juxtaglomerular cells, located at the juncture of the afferent and efferent arterioles with a portion of the distal convoluted tubule of the nephron of the kidney; the two cell types participate in the negative feedback regulation of (1) systemic blood pressure and blood volume via the renin-angiotensin system, (2) local control of glomerular filtration rate (GFR), i.e., "tubuloglomerular feedback," by nitric oxide (NO) production, and (3) hematopoiesis via the production of erythropoietin by cells of the peritubular capillary endothelium of the kidney.

macula densa cells - Specialized chemoreceptor cells in the wall of the distal convoluted tubule at the JGA of the nephron of the kidney which respond to changes in solute concentration (especially sodium levels) in the urine in the distal convoluted tubule and to oxygen levels in the blood passing to the glomerulus; this sensory information is conveyed to the juxtaglomerular cells which will adjust their output of renin accordingly.

juxtaglomerular cells - Specialized smooth muscle cells which act as mechanoreceptors which stretch in response to increases in the blood pressure of the afferent arteriole; they also synthesize and secrete the enzyme renin which serves to activate the inactive precursor, angiotensinogen (made by the liver), into angiotensin I; renin secretion is increased by a fall in plasma Na+ concentration, and by prostaglandins, sympathetic ANS activity, circulating epinephrine and a decrease in afferent arteriolar blood pressure; renin secretion is decreased by a rise in plasma Cl- concentration, angiotensin II, ADH (antidiurectic hormone) and increased blood pressure. aka - granular cells of the JGA