What are the structural differences between juxtamedullary and cortical nephrons?

•JUX nephrons have LONG loops of henle (with thin segments) and renal corpuscles that are near the cortex-medulla junction. whereas, cortical nephrons have SHORT loops of Henle and renal corpuscles that lie more superficially in the cortex

•efferent arterioles of JUX nephrons supply vasa recta efferent arteriols of cortical supply peritubular capillaries

What type of capillaries are the glomerular capillaries? What is their function?

The glomerular capillaries are fenestrated capillaries. Their function is to filter large amounts of plasma into the glomerular capsule.

Extrinsic and intrinsic controls of GFR serve two different purposes. What are they?

•Intrinsic controls serve to maintain a nearly constant GFR in spite of changes in the systemic BP.
•Extrinsic controls serve to maintain systemic BP.

Calculate net filtration pressure given the following values: glomerular hydrostatic pressure = 50 mm Hg, blood colloid osmotic pressure = 25 mm Hg, capsular hydrostatic pressure = 20 Hg.

50 mm Hg – (25 mm Hg + 20) mm Hg = 5 mm Hg

Describe two main ways in which angiotensin II increases blood pressure and blood volume.

•Stimulate ADH secretion from the anterior pituitary which increases water retention by the kidneys and also increases blood pressure

•Stimulate aldosterone secretion from the adrenal cortex which increases sodium retention in the kidneys leading to more water retention by the kidneys and helping to increase blood pressure too.

In what part of the nephron does the majority of reabsorption occur?

The majority of reabsorption occurs in the proximal convoluted tube.

How are primary and secondary active transport processes (both shown in Figure 25.14) different?
In primary active transport process the energy for the process is provided directly by the cleavage of of ATP

In secondary active transport process the energy for the process is provided by Na+ concentration gradiaent. As Na+ moves down its concentration gradient it drives the movement of glucose against its concentration gradient.

How does the movement of Na+ drive the reabsorption of water and solutes?

The reabsorption of Na+ by primary active transport drives the reabsorption of amino acids and glucose by secondary active transport. It also drives passive reabsorbtion of water by osmosis. The reabsorbtion of water leaves behind other solutes, which become more concentrate and can therfore be reabsorbed by diffusion.

List several substances that are secreted into the kidney tubules.

H+, K+, NH+, creatinine, urea and uric acid are secreted into the kidney tubules.

Describe the special characteristics of the descending and ascending limbs of the loop of Henle that cause the formation of the medullary osmotic gradient.

•The descending limb is permeable to water and impermeable to NaCl

•The ascending limb is permeable to NaCl and impermeable to water

Under what conditions is ADH released from the posterior pituitary? What effect does ADH have on the collecting ducts?

ADH is released from the posterior pituitary in response to the hyperosmotic extracellular fluid. ADH causes insertion of aquaporins into the apical membrane of the principal cells of the collecting ducts

What would you expect the normal clearance value for amino acids to be? Explain.

Normal clearance value for amino acids is zero. You would expect this because amino acids arevaluable as nutrients and as the building blocks of proteins synthesis. You would nt want to lose these in urine.

What are the three major nitrogenous wastes excreted in the urine?

The three major nitrogenous wastes excreted in the urine are creatinine, urea and uric

A kidney stone blocking a ureter would interfere with urine flow to which organ? Why would the pain occur in waves?

A kidney stone blocking a ureter would interfere with urine flow to the bladder. The pain would occur in waves that coincide with peristaltic contractions of the smooth muscle of the ureter.

What is the trigone of the bladder, and which landmarks define its borders?

The trigone of the bladder is a smooth trangular region at the base of the bladder. Its borders are the openings of the two ureters and the urethra.

Name the three regions of the male urethra.

Prostatic Urethra – about 2.5 cm long, runs within the prostate

Intermediate part of the Urethra – runs through the urogenital diaphragm, extends 2cm from the prostate to the beginning of the penis

Spongy Urethra – about 15 long, through the penis and opens at the external urethral orifice

How does the detrusor muscle respond to increased firing of the parasympathetic fibers that innervate it? How does this affect the internal urethral sphincter?

The detrusor muscle contracts in response to increased firing of the parasympathetic nerves. The internal urethral sphincter opens

Name the three sets of embryonic kidneys in the order that they develop.

The embryonic kidneys in the order that they develop are the pronephros, mesonephrosand the metanephros.

List two factors that might contribute to urinary retention in elderly men.

The bladder shrinks and loses tone and an increase in the size of the prostate can lead to urinary retension in elderly men.