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Chapter 20
Where are your kidneys? In relation to the peritoneum? They are in the posterior abdominal cavity, near the twelfth rib, liver and spleen, and are located behind the parietal peritoneum (retroperitoneal).
What is the functional unit of  the kidney? The nephron
What are the parts of a nephron? The renal corpuscle which is made up of the glomerulus (capillaries) and Bowman's capsule (this is where filtration takes place), the proximal convoluted tubule, the loop of Henle (nephron loop) (this part concentrates urine), the distal convoluted tubule and collecting duct.
Why is the structure of the efferent and afferent arterioles so critical to the functioning of the kidney?
The afferent or incoming arteriole is larger than the efferent or outgoing arteriole. This helps maintain the high blood pressure needed by the kidney if it is to filter blood.
How much kidney do you need to survive? Two-thirds of one kidney
What are the functions of the kidneys besides waste management? The kidneys regulate blood volume and composition, blood pressure, and pH balance.
What three processes are used to make urine ? Filtration (in the renal corpuscle), tubular absorption and tubular secretion.
What three structures make up the filtration membrane? What does each layer filter?
The fenestrated epithelium of the capillary holds back cells; everything else goes through. The basement membrane stops large proteins from going through into the filtrate or forming urine, and the slit membrane between the pedicels of the podicytes stops medium sized proteins from passing into the urine.
What type of epithelium is found in the proximal convoluted tubules? What functions occur here?
Simple cuboidal cells with microvilli to increase the surface area for tubular reabsorption. Tubular secretion also occurs here.
What is the juxtaglomerular apparatus?  It is made up of the macula densa in the ascending limb of the loop of Henle and the juxtaglomerular cells in the afferent arteriole. These monitor the composition of the fluid in the tubules and can adjust local blood pressure in the kidneys or can secrete renin to maintain enough systemic blood pressure to keep the kidneys functioning properly.
What two types of cells make up the distal convoluted tubules and collecting ducts, and what are the functions of these cells? They are  the principle cells, which respond to ADH and aldosterone, and the intercalated cells which secrete H+ to maintain pH balance in the body.
What force drives fluid out of the glomerular capillaries? The only force that pushes fluid out of the blood and into the capillaries is blood hydrostatic pressure.
What two forces oppose glomerular filtration? These are the osmotic pressure of the blood and the hydrostatic pressure of the fluid in Bowman's capsule.
What is tubular reabsorption? What is reabsorbed in the PCT? This is where substances that we want to keep are taken out of the filtrate and back into the blood in the peritubular capillaries. Substances reabsorbed in the proximal convoluted tubule include sodium, water, and almost all of the glucose and amino acids.
What do we mean by "where sodium goes, water follows"? The osmotic pressure created when sodium passes through a membrane into another compartment draws water after the sodium.
What do we mean by a tranport maximum, and what happens when it is exceeded? This is the fastest rate at which the tubules can absorb a particular substance. When this rate is exceeded, not all of that substance is reabsorbed, and some spills out in the urine. This is what happens in diabetes mellitus, and why the urine contains glucose.
How does ADH affect the DCT and collecting ducts? What does aldosterone do here?
ADH or antidiuretic hormone, causes the DCT and collecting ducts to put water channels into their membranes. Without these channels, water cannot be reabsorbed into the body in these places and it remains in the urine, making large volumes of urine.
What is tubular secretion, and what are the two main functions of tubular secretion? This is a second chance to get rid of substances we don't want in the body. These substances are transported out of the blood in the peritubular capillaries and into the tubules of the kidney, so they can be passed with the urine. Tubular secretion rids our bodies of drugs and waste products, and also of H+ which maintains pH.
How is a dilute urine produced? Easy, just shut off the production of ADH. A concentrated urine?
This is harder, we need to use the loop of Henle to produce a concentration gradient of sodium in the medulla of the kidney by the counter-current mechanism. When ADH is present and the urine passes through the collecting ducts, the high concentrations of sodium in the medulla draw water out of the urine and concentrate it.
What factors would increase the specific gravity of urine? Anything that would cause water to be lost from the body - sweating, fever, dehydration, vomitting, diarrhea, etc.
Decrease it ? A decrease in ADH or a large intake of water.
What is diabetes insipidus? A lack of ADH. We see signs similar to sugar diabetes - taking in and putting out large volumes of water. (polydipsia and polyuria).
How does the urethra differ in the male and the female? How are they the same? The male's urethra is much longer, and passes not only urine, but also semen. In both sexes the urethra carries urine from the bladder to the outside of the body.